comment.php

<?php
/**
 * Core Comment API
 *
 * @package WordPress
 * @subpackage Comment
 */

/**
 * Check whether a comment passes internal checks to be allowed to add.
 *
 * If manual comment moderation is set in the administration, then all checks,
 * regardless of their type and whitelist, will fail and the function will
 * return false.
 *
 * If the number of links exceeds the amount in the administration, then the
 * check fails. If any of the parameter contents match the blacklist of words,
 * then the check fails.
 *
 * If the comment author was approved before, then the comment is automatically
 * whitelisted.
 *
 * If all checks pass, the function will return true.
 *
 * @since 1.2.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $author       Comment author name.
 * @param string $email        Comment author email.
 * @param string $url          Comment author URL.
 * @param string $comment      Content of the comment.
 * @param string $user_ip      Comment author IP address.
 * @param string $user_agent   Comment author User-Agent.
 * @param string $comment_type Comment type.
 * @return bool If all checks pass, true, otherwise false.
 */
function check_comment($author, $email, $url, $comment, $user_ip, $user_agent, $comment_type) {
	global $wpdb;

	// If manual moderation is enabled, skip all checks and return false.
	if ( 1 == get_option('comment_moderation') )
		return false;

	/** This filter is documented in wp-includes/comment-template.php */
	$comment = apply_filters( 'comment_text', $comment, null, array() );

	// Check for the number of external links if a max allowed number is set.
	if ( $max_links = get_option( 'comment_max_links' ) ) {
		$num_links = preg_match_all( '/<a [^>]*href/i', $comment, $out );

		/**
		 * Filters the number of links found in a comment.
		 *
		 * @since 3.0.0
		 * @since 4.7.0 Added the `$comment` parameter.
		 *
		 * @param int    $num_links The number of links found.
		 * @param string $url       Comment author's URL. Included in allowed links total.
		 * @param string $comment   Content of the comment.
		 */
		$num_links = apply_filters( 'comment_max_links_url', $num_links, $url, $comment );

		/*
		 * If the number of links in the comment exceeds the allowed amount,
		 * fail the check by returning false.
		 */
		if ( $num_links >= $max_links )
			return false;
	}

	$mod_keys = trim(get_option('moderation_keys'));

	// If moderation 'keys' (keywords) are set, process them.
	if ( !empty($mod_keys) ) {
		$words = explode("\n", $mod_keys );

		foreach ( (array) $words as $word) {
			$word = trim($word);

			// Skip empty lines.
			if ( empty($word) )
				continue;

			/*
			 * Do some escaping magic so that '#' (number of) characters in the spam
			 * words don't break things:
			 */
			$word = preg_quote($word, '#');

			/*
			 * Check the comment fields for moderation keywords. If any are found,
			 * fail the check for the given field by returning false.
			 */
			$pattern = "#$word#i";
			if ( preg_match($pattern, $author) ) return false;
			if ( preg_match($pattern, $email) ) return false;
			if ( preg_match($pattern, $url) ) return false;
			if ( preg_match($pattern, $comment) ) return false;
			if ( preg_match($pattern, $user_ip) ) return false;
			if ( preg_match($pattern, $user_agent) ) return false;
		}
	}

	/*
	 * Check if the option to approve comments by previously-approved authors is enabled.
	 *
	 * If it is enabled, check whether the comment author has a previously-approved comment,
	 * as well as whether there are any moderation keywords (if set) present in the author
	 * email address. If both checks pass, return true. Otherwise, return false.
	 */
	if ( 1 == get_option('comment_whitelist')) {
		if ( $author != '' && $email != '' ) {
			$comment_user = get_user_by( 'email', wp_unslash( $email ) );
			if ( ! empty( $comment_user->ID ) ) {
				$ok_to_comment = $wpdb->get_var( $wpdb->prepare( "SELECT comment_approved FROM $wpdb->comments WHERE user_id = %d AND comment_approved = '1' LIMIT 1", $comment_user->ID ) );
			} else {
				// expected_slashed ($author, $email)
				$ok_to_comment = $wpdb->get_var( $wpdb->prepare( "SELECT comment_approved FROM $wpdb->comments WHERE comment_author = %s AND comment_author_email = %s and comment_approved = '1' LIMIT 1", $author, $email ) );
			}
			if ( ( 1 == $ok_to_comment ) &&
				( empty($mod_keys) || false === strpos( $email, $mod_keys) ) )
					return true;
			else
				return false;
		} else {
			return false;
		}
	}
	return true;
}

/**
 * Retrieve the approved comments for post $post_id.
 *
 * @since 2.0.0
 * @since 4.1.0 Refactored to leverage WP_Comment_Query over a direct query.
 *
 * @param  int   $post_id The ID of the post.
 * @param  array $args    Optional. See WP_Comment_Query::__construct() for information on accepted arguments.
 * @return int|array $comments The approved comments, or number of comments if `$count`
 *                             argument is true.
 */
function get_approved_comments( $post_id, $args = array() ) {
	if ( ! $post_id ) {
		return array();
	}

	$defaults = array(
		'status'  => 1,
		'post_id' => $post_id,
		'order'   => 'ASC',
	);
	$r = wp_parse_args( $args, $defaults );

	$query = new WP_Comment_Query;
	return $query->query( $r );
}

/**
 * Retrieves comment data given a comment ID or comment object.
 *
 * If an object is passed then the comment data will be cached and then returned
 * after being passed through a filter. If the comment is empty, then the global
 * comment variable will be used, if it is set.
 *
 * @since 2.0.0
 *
 * @global WP_Comment $comment
 *
 * @param WP_Comment|string|int $comment Comment to retrieve.
 * @param string                $output  Optional. The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which correspond to
 *                                       a WP_Comment object, an associative array, or a numeric array, respectively. Default OBJECT.
 * @return WP_Comment|array|null Depends on $output value.
 */
function get_comment( &$comment = null, $output = OBJECT ) {
	if ( empty( $comment ) && isset( $GLOBALS['comment'] ) ) {
		$comment = $GLOBALS['comment'];
	}

	if ( $comment instanceof WP_Comment ) {
		$_comment = $comment;
	} elseif ( is_object( $comment ) ) {
		$_comment = new WP_Comment( $comment );
	} else {
		$_comment = WP_Comment::get_instance( $comment );
	}

	if ( ! $_comment ) {
		return null;
	}

	/**
	 * Fires after a comment is retrieved.
	 *
	 * @since 2.3.0
	 *
	 * @param mixed $_comment Comment data.
	 */
	$_comment = apply_filters( 'get_comment', $_comment );

	if ( $output == OBJECT ) {
		return $_comment;
	} elseif ( $output == ARRAY_A ) {
		return $_comment->to_array();
	} elseif ( $output == ARRAY_N ) {
		return array_values( $_comment->to_array() );
	}
	return $_comment;
}

/**
 * Retrieve a list of comments.
 *
 * The comment list can be for the blog as a whole or for an individual post.
 *
 * @since 2.7.0
 *
 * @param string|array $args Optional. Array or string of arguments. See WP_Comment_Query::__construct()
 *                           for information on accepted arguments. Default empty.
 * @return int|array List of comments or number of found comments if `$count` argument is true.
 */
function get_comments( $args = '' ) {
	$query = new WP_Comment_Query;
	return $query->query( $args );
}

/**
 * Retrieve all of the WordPress supported comment statuses.
 *
 * Comments have a limited set of valid status values, this provides the comment
 * status values and descriptions.
 *
 * @since 2.7.0
 *
 * @return array List of comment statuses.
 */
function get_comment_statuses() {
	$status = array(
		'hold'		=> __( 'Unapproved' ),
		'approve'	=> _x( 'Approved', 'comment status' ),
		'spam'		=> _x( 'Spam', 'comment status' ),
		'trash'		=> _x( 'Trash', 'comment status' ),
	);

	return $status;
}

/**
 * Gets the default comment status for a post type.
 *
 * @since 4.3.0
 *
 * @param string $post_type    Optional. Post type. Default 'post'.
 * @param string $comment_type Optional. Comment type. Default 'comment'.
 * @return string Expected return value is 'open' or 'closed'.
 */
function get_default_comment_status( $post_type = 'post', $comment_type = 'comment' ) {
	switch ( $comment_type ) {
		case 'pingback' :
		case 'trackback' :
			return 'closed';
			break;
		default :
			$supports = 'comments';
			$option = 'comment';
	}

	// Set the status.
	if ( 'page' === $post_type ) {
		$status = 'closed';
	} elseif ( post_type_supports( $post_type, $supports ) ) {
		$status = get_option( "default_{$option}_status" );
	} else {
		$status = 'closed';
	}

	/**
	 * Filters the default comment status for the given post type.
	 *
	 * @since 4.3.0
	 *
	 * @param string $status       Default status for the given post type,
	 *                             either 'open' or 'closed'.
	 * @param string $post_type    Post type. Default is `post`.
	 * @param string $comment_type Type of comment. Default is `comment`.
	 */
	return apply_filters( 'get_default_comment_status' , $status, $post_type, $comment_type );
}

/**
 * The date the last comment was modified.
 *
 * @since 1.5.0
 * @since 4.7.0 Replaced caching the modified date in a local static variable
 *              with the Object Cache API.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $timezone Which timezone to use in reference to 'gmt', 'blog', or 'server' locations.
 * @return string|false Last comment modified date on success, false on failure.
 */
function get_lastcommentmodified( $timezone = 'server' ) {
	global $wpdb;

	$timezone = strtolower( $timezone );
	$key = "lastcommentmodified:$timezone";

	$comment_modified_date = wp_cache_get( $key, 'timeinfo' );
	if ( false !== $comment_modified_date ) {
		return $comment_modified_date;
	}

	switch ( $timezone ) {
		case 'gmt':
			$comment_modified_date = $wpdb->get_var( "SELECT comment_date_gmt FROM $wpdb->comments WHERE comment_approved = '1' ORDER BY comment_date_gmt DESC LIMIT 1" );
			break;
		case 'blog':
			$comment_modified_date = $wpdb->get_var( "SELECT comment_date FROM $wpdb->comments WHERE comment_approved = '1' ORDER BY comment_date_gmt DESC LIMIT 1" );
			break;
		case 'server':
			$add_seconds_server = date( 'Z' );

			$comment_modified_date = $wpdb->get_var( $wpdb->prepare( "SELECT DATE_ADD(comment_date_gmt, INTERVAL %s SECOND) FROM $wpdb->comments WHERE comment_approved = '1' ORDER BY comment_date_gmt DESC LIMIT 1", $add_seconds_server ) );
			break;
	}

	if ( $comment_modified_date ) {
		wp_cache_set( $key, $comment_modified_date, 'timeinfo' );

		return $comment_modified_date;
	}

	return false;
}

/**
 * The amount of comments in a post or total comments.
 *
 * A lot like wp_count_comments(), in that they both return comment stats (albeit with different types).
 * The wp_count_comments() actually caches, but this function does not.
 *
 * @since 2.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $post_id Optional. Comment amount in post if > 0, else total comments blog wide.
 * @return array The amount of spam, approved, awaiting moderation, and total comments.
 */
function get_comment_count( $post_id = 0 ) {
	global $wpdb;

	$post_id = (int) $post_id;

	$where = '';
	if ( $post_id > 0 ) {
		$where = $wpdb->prepare("WHERE comment_post_ID = %d", $post_id);
	}

	$totals = (array) $wpdb->get_results("
		SELECT comment_approved, COUNT( * ) AS total
		FROM {$wpdb->comments}
		{$where}
		GROUP BY comment_approved
	", ARRAY_A);

	$comment_count = array(
		'approved'            => 0,
		'awaiting_moderation' => 0,
		'spam'                => 0,
		'trash'               => 0,
		'post-trashed'        => 0,
		'total_comments'      => 0,
		'all'                 => 0,
	);

	foreach ( $totals as $row ) {
		switch ( $row['comment_approved'] ) {
			case 'trash':
				$comment_count['trash'] = $row['total'];
				break;
			case 'post-trashed':
				$comment_count['post-trashed'] = $row['total'];
				break;
			case 'spam':
				$comment_count['spam'] = $row['total'];
				$comment_count['total_comments'] += $row['total'];
				break;
			case '1':
				$comment_count['approved'] = $row['total'];
				$comment_count['total_comments'] += $row['total'];
				$comment_count['all'] += $row['total'];
				break;
			case '0':
				$comment_count['awaiting_moderation'] = $row['total'];
				$comment_count['total_comments'] += $row['total'];
				$comment_count['all'] += $row['total'];
				break;
			default:
				break;
		}
	}

	return $comment_count;
}

//
// Comment meta functions
//

/**
 * Add meta data field to a comment.
 *
 * @since 2.9.0
 * @link https://codex.wordpress.org/Function_Reference/add_comment_meta
 *
 * @param int $comment_id Comment ID.
 * @param string $meta_key Metadata name.
 * @param mixed $meta_value Metadata value.
 * @param bool $unique Optional, default is false. Whether the same key should not be added.
 * @return int|bool Meta ID on success, false on failure.
 */
function add_comment_meta($comment_id, $meta_key, $meta_value, $unique = false) {
	$added = add_metadata( 'comment', $comment_id, $meta_key, $meta_value, $unique );
	if ( $added ) {
		wp_cache_set( 'last_changed', microtime(), 'comment' );
	}
	return $added;
}

/**
 * Remove metadata matching criteria from a comment.
 *
 * You can match based on the key, or key and value. Removing based on key and
 * value, will keep from removing duplicate metadata with the same key. It also
 * allows removing all metadata matching key, if needed.
 *
 * @since 2.9.0
 * @link https://codex.wordpress.org/Function_Reference/delete_comment_meta
 *
 * @param int $comment_id comment ID
 * @param string $meta_key Metadata name.
 * @param mixed $meta_value Optional. Metadata value.
 * @return bool True on success, false on failure.
 */
function delete_comment_meta($comment_id, $meta_key, $meta_value = '') {
	$deleted = delete_metadata( 'comment', $comment_id, $meta_key, $meta_value );
	if ( $deleted ) {
		wp_cache_set( 'last_changed', microtime(), 'comment' );
	}
	return $deleted;
}

/**
 * Retrieve comment meta field for a comment.
 *
 * @since 2.9.0
 * @link https://codex.wordpress.org/Function_Reference/get_comment_meta
 *
 * @param int $comment_id Comment ID.
 * @param string $key Optional. The meta key to retrieve. By default, returns data for all keys.
 * @param bool $single Whether to return a single value.
 * @return mixed Will be an array if $single is false. Will be value of meta data field if $single
 *  is true.
 */
function get_comment_meta($comment_id, $key = '', $single = false) {
	return get_metadata('comment', $comment_id, $key, $single);
}

/**
 * Update comment meta field based on comment ID.
 *
 * Use the $prev_value parameter to differentiate between meta fields with the
 * same key and comment ID.
 *
 * If the meta field for the comment does not exist, it will be added.
 *
 * @since 2.9.0
 * @link https://codex.wordpress.org/Function_Reference/update_comment_meta
 *
 * @param int $comment_id Comment ID.
 * @param string $meta_key Metadata key.
 * @param mixed $meta_value Metadata value.
 * @param mixed $prev_value Optional. Previous value to check before removing.
 * @return int|bool Meta ID if the key didn't exist, true on successful update, false on failure.
 */
function update_comment_meta($comment_id, $meta_key, $meta_value, $prev_value = '') {
	$updated = update_metadata( 'comment', $comment_id, $meta_key, $meta_value, $prev_value );
	if ( $updated ) {
		wp_cache_set( 'last_changed', microtime(), 'comment' );
	}
	return $updated;
}

/**
 * Queues comments for metadata lazy-loading.
 *
 * @since 4.5.0
 *
 * @param array $comments Array of comment objects.
 */
function wp_queue_comments_for_comment_meta_lazyload( $comments ) {
	// Don't use `wp_list_pluck()` to avoid by-reference manipulation.
	$comment_ids = array();
	if ( is_array( $comments ) ) {
		foreach ( $comments as $comment ) {
			if ( $comment instanceof WP_Comment ) {
				$comment_ids[] = $comment->comment_ID;
			}
		}
	}

	if ( $comment_ids ) {
		$lazyloader = wp_metadata_lazyloader();
		$lazyloader->queue_objects( 'comment', $comment_ids );
	}
}

/**
 * Sets the cookies used to store an unauthenticated commentator's identity. Typically used
 * to recall previous comments by this commentator that are still held in moderation.
 *
 * @since 3.4.0
 * @since 4.9.6 The `$cookies_consent` parameter was added.
 *
 * @param WP_Comment $comment         Comment object.
 * @param WP_User    $user            Comment author's user object. The user may not exist.
 * @param boolean    $cookies_consent Optional. Comment author's consent to store cookies. Default true.
 */
function wp_set_comment_cookies( $comment, $user, $cookies_consent = true ) {
	// If the user already exists, or the user opted out of cookies, don't set cookies.
	if ( $user->exists() ) {
		return;
	}

	if ( false === $cookies_consent ) {
		// Remove any existing cookies.
		$past = time() - YEAR_IN_SECONDS;
		setcookie( 'comment_author_' . COOKIEHASH, ' ', $past, COOKIEPATH, COOKIE_DOMAIN );
		setcookie( 'comment_author_email_' . COOKIEHASH, ' ', $past, COOKIEPATH, COOKIE_DOMAIN );
		setcookie( 'comment_author_url_' . COOKIEHASH, ' ', $past, COOKIEPATH, COOKIE_DOMAIN );

		return;
	}

	/**
	 * Filters the lifetime of the comment cookie in seconds.
	 *
	 * @since 2.8.0
	 *
	 * @param int $seconds Comment cookie lifetime. Default 30000000.
	 */
	$comment_cookie_lifetime = time() + apply_filters( 'comment_cookie_lifetime', 30000000 );
	$secure = ( 'https' === parse_url( home_url(), PHP_URL_SCHEME ) );
	setcookie( 'comment_author_' . COOKIEHASH, $comment->comment_author, $comment_cookie_lifetime, COOKIEPATH, COOKIE_DOMAIN, $secure );
	setcookie( 'comment_author_email_' . COOKIEHASH, $comment->comment_author_email, $comment_cookie_lifetime, COOKIEPATH, COOKIE_DOMAIN, $secure );
	setcookie( 'comment_author_url_' . COOKIEHASH, esc_url( $comment->comment_author_url ), $comment_cookie_lifetime, COOKIEPATH, COOKIE_DOMAIN, $secure );
}

/**
 * Sanitizes the cookies sent to the user already.
 *
 * Will only do anything if the cookies have already been created for the user.
 * Mostly used after cookies had been sent to use elsewhere.
 *
 * @since 2.0.4
 */
function sanitize_comment_cookies() {
	if ( isset( $_COOKIE['comment_author_' . COOKIEHASH] ) ) {
		/**
		 * Filters the comment author's name cookie before it is set.
		 *
		 * When this filter hook is evaluated in wp_filter_comment(),
		 * the comment author's name string is passed.
		 *
		 * @since 1.5.0
		 *
		 * @param string $author_cookie The comment author name cookie.
		 */
		$comment_author = apply_filters( 'pre_comment_author_name', $_COOKIE['comment_author_' . COOKIEHASH] );
		$comment_author = wp_unslash($comment_author);
		$comment_author = esc_attr($comment_author);
		$_COOKIE['comment_author_' . COOKIEHASH] = $comment_author;
	}

	if ( isset( $_COOKIE['comment_author_email_' . COOKIEHASH] ) ) {
		/**
		 * Filters the comment author's email cookie before it is set.
		 *
		 * When this filter hook is evaluated in wp_filter_comment(),
		 * the comment author's email string is passed.
		 *
		 * @since 1.5.0
		 *
		 * @param string $author_email_cookie The comment author email cookie.
		 */
		$comment_author_email = apply_filters( 'pre_comment_author_email', $_COOKIE['comment_author_email_' . COOKIEHASH] );
		$comment_author_email = wp_unslash($comment_author_email);
		$comment_author_email = esc_attr($comment_author_email);
		$_COOKIE['comment_author_email_'.COOKIEHASH] = $comment_author_email;
	}

	if ( isset( $_COOKIE['comment_author_url_' . COOKIEHASH] ) ) {
		/**
		 * Filters the comment author's URL cookie before it is set.
		 *
		 * When this filter hook is evaluated in wp_filter_comment(),
		 * the comment author's URL string is passed.
		 *
		 * @since 1.5.0
		 *
		 * @param string $author_url_cookie The comment author URL cookie.
		 */
		$comment_author_url = apply_filters( 'pre_comment_author_url', $_COOKIE['comment_author_url_' . COOKIEHASH] );
		$comment_author_url = wp_unslash($comment_author_url);
		$_COOKIE['comment_author_url_'.COOKIEHASH] = $comment_author_url;
	}
}

/**
 * Validates whether this comment is allowed to be made.
 *
 * @since 2.0.0
 * @since 4.7.0 The `$avoid_die` parameter was added, allowing the function to
 *              return a WP_Error object instead of dying.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $commentdata Contains information on the comment.
 * @param bool  $avoid_die   When true, a disallowed comment will result in the function
 *                           returning a WP_Error object, rather than executing wp_die().
 *                           Default false.
 * @return int|string|WP_Error Allowed comments return the approval status (0|1|'spam').
 *                             If `$avoid_die` is true, disallowed comments return a WP_Error.
 */
function wp_allow_comment( $commentdata, $avoid_die = false ) {
	global $wpdb;

	// Simple duplicate check
	// expected_slashed ($comment_post_ID, $comment_author, $comment_author_email, $comment_content)
	$dupe = $wpdb->prepare(
		"SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_parent = %s AND comment_approved != 'trash' AND ( comment_author = %s ",
		wp_unslash( $commentdata['comment_post_ID'] ),
		wp_unslash( $commentdata['comment_parent'] ),
		wp_unslash( $commentdata['comment_author'] )
	);
	if ( $commentdata['comment_author_email'] ) {
		$dupe .= $wpdb->prepare(
			"AND comment_author_email = %s ",
			wp_unslash( $commentdata['comment_author_email'] )
		);
	}
	$dupe .= $wpdb->prepare(
		") AND comment_content = %s LIMIT 1",
		wp_unslash( $commentdata['comment_content'] )
	);

	$dupe_id = $wpdb->get_var( $dupe );

	/**
	 * Filters the ID, if any, of the duplicate comment found when creating a new comment.
	 *
	 * Return an empty value from this filter to allow what WP considers a duplicate comment.
	 *
	 * @since 4.4.0
	 *
	 * @param int   $dupe_id     ID of the comment identified as a duplicate.
	 * @param array $commentdata Data for the comment being created.
	 */
	$dupe_id = apply_filters( 'duplicate_comment_id', $dupe_id, $commentdata );

	if ( $dupe_id ) {
		/**
		 * Fires immediately after a duplicate comment is detected.
		 *
		 * @since 3.0.0
		 *
		 * @param array $commentdata Comment data.
		 */
		do_action( 'comment_duplicate_trigger', $commentdata );
		if ( true === $avoid_die ) {
			return new WP_Error( 'comment_duplicate', __( 'Duplicate comment detected; it looks as though you&#8217;ve already said that!' ), 409 );
		} else {
			if ( wp_doing_ajax() ) {
				die( __('Duplicate comment detected; it looks as though you&#8217;ve already said that!') );
			}

			wp_die( __( 'Duplicate comment detected; it looks as though you&#8217;ve already said that!' ), 409 );
		}
	}

	/**
	 * Fires immediately before a comment is marked approved.
	 *
	 * Allows checking for comment flooding.
	 *
	 * @since 2.3.0
	 * @since 4.7.0 The `$avoid_die` parameter was added.
	 *
	 * @param string $comment_author_IP    Comment author's IP address.
	 * @param string $comment_author_email Comment author's email.
	 * @param string $comment_date_gmt     GMT date the comment was posted.
	 * @param bool   $avoid_die            Whether to prevent executing wp_die()
	 *                                     or die() if a comment flood is occurring.
	 */
	do_action(
		'check_comment_flood',
		$commentdata['comment_author_IP'],
		$commentdata['comment_author_email'],
		$commentdata['comment_date_gmt'],
		$avoid_die
	);

	/**
	 * Filters whether a comment is part of a comment flood.
	 *
	 * The default check is wp_check_comment_flood(). See check_comment_flood_db().
	 *
	 * @since 4.7.0
	 *
	 * @param bool   $is_flood             Is a comment flooding occurring? Default false.
	 * @param string $comment_author_IP    Comment author's IP address.
	 * @param string $comment_author_email Comment author's email.
	 * @param string $comment_date_gmt     GMT date the comment was posted.
	 * @param bool   $avoid_die            Whether to prevent executing wp_die()
	 *                                     or die() if a comment flood is occurring.
	 */
	$is_flood = apply_filters(
		'wp_is_comment_flood',
		false,
		$commentdata['comment_author_IP'],
		$commentdata['comment_author_email'],
		$commentdata['comment_date_gmt'],
		$avoid_die
	);

	if ( $is_flood ) {
		return new WP_Error( 'comment_flood', __( 'You are posting comments too quickly. Slow down.' ), 429 );
	}

	if ( ! empty( $commentdata['user_id'] ) ) {
		$user = get_userdata( $commentdata['user_id'] );
		$post_author = $wpdb->get_var( $wpdb->prepare(
			"SELECT post_author FROM $wpdb->posts WHERE ID = %d LIMIT 1",
			$commentdata['comment_post_ID']
		) );
	}

	if ( isset( $user ) && ( $commentdata['user_id'] == $post_author || $user->has_cap( 'moderate_comments' ) ) ) {
		// The author and the admins get respect.
		$approved = 1;
	} else {
		// Everyone else's comments will be checked.
		if ( check_comment(
			$commentdata['comment_author'],
			$commentdata['comment_author_email'],
			$commentdata['comment_author_url'],
			$commentdata['comment_content'],
			$commentdata['comment_author_IP'],
			$commentdata['comment_agent'],
			$commentdata['comment_type']
		) ) {
			$approved = 1;
		} else {
			$approved = 0;
		}

		if ( wp_blacklist_check(
			$commentdata['comment_author'],
			$commentdata['comment_author_email'],
			$commentdata['comment_author_url'],
			$commentdata['comment_content'],
			$commentdata['comment_author_IP'],
			$commentdata['comment_agent']
		) ) {
			$approved = EMPTY_TRASH_DAYS ? 'trash' : 'spam';
		}
	}

	/**
	 * Filters a comment's approval status before it is set.
	 *
	 * @since 2.1.0
	 * @since 4.9.0 Returning a WP_Error value from the filter will shortcircuit comment insertion and
	 *              allow skipping further processing.
	 *
	 * @param bool|string|WP_Error $approved    The approval status. Accepts 1, 0, 'spam' or WP_Error.
	 * @param array                $commentdata Comment data.
	 */
	$approved = apply_filters( 'pre_comment_approved', $approved, $commentdata );
	return $approved;
}

/**
 * Hooks WP's native database-based comment-flood check.
 *
 * This wrapper maintains backward compatibility with plugins that expect to
 * be able to unhook the legacy check_comment_flood_db() function from
 * 'check_comment_flood' using remove_action().
 *
 * @since 2.3.0
 * @since 4.7.0 Converted to be an add_filter() wrapper.
 */
function check_comment_flood_db() {
	add_filter( 'wp_is_comment_flood', 'wp_check_comment_flood', 10, 5 );
}

/**
 * Checks whether comment flooding is occurring.
 *
 * Won't run, if current user can manage options, so to not block
 * administrators.
 *
 * @since 4.7.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param bool   $is_flood  Is a comment flooding occurring?
 * @param string $ip        Comment author's IP address.
 * @param string $email     Comment author's email address.
 * @param string $date      MySQL time string.
 * @param bool   $avoid_die When true, a disallowed comment will result in the function
 *                          returning a WP_Error object, rather than executing wp_die().
 *                          Default false.
 * @return bool Whether comment flooding is occurring.
 */
function wp_check_comment_flood( $is_flood, $ip, $email, $date, $avoid_die = false ) {

	global $wpdb;

	// Another callback has declared a flood. Trust it.
	if ( true === $is_flood ) {
		return $is_flood;
	}

	// don't throttle admins or moderators
	if ( current_user_can( 'manage_options' ) || current_user_can( 'moderate_comments' ) ) {
		return false;
	}
	$hour_ago = gmdate( 'Y-m-d H:i:s', time() - HOUR_IN_SECONDS );

	if ( is_user_logged_in() ) {
		$user = get_current_user_id();
		$check_column = '`user_id`';
	} else {
		$user = $ip;
		$check_column = '`comment_author_IP`';
	}

	$sql = $wpdb->prepare(
		"SELECT `comment_date_gmt` FROM `$wpdb->comments` WHERE `comment_date_gmt` >= %s AND ( $check_column = %s OR `comment_author_email` = %s ) ORDER BY `comment_date_gmt` DESC LIMIT 1",
		$hour_ago,
		$user,
		$email
	);
	$lasttime = $wpdb->get_var( $sql );
	if ( $lasttime ) {
		$time_lastcomment = mysql2date('U', $lasttime, false);
		$time_newcomment  = mysql2date('U', $date, false);
		/**
		 * Filters the comment flood status.
		 *
		 * @since 2.1.0
		 *
		 * @param bool $bool             Whether a comment flood is occurring. Default false.
		 * @param int  $time_lastcomment Timestamp of when the last comment was posted.
		 * @param int  $time_newcomment  Timestamp of when the new comment was posted.
		 */
		$flood_die = apply_filters( 'comment_flood_filter', false, $time_lastcomment, $time_newcomment );
		if ( $flood_die ) {
			/**
			 * Fires before the comment flood message is triggered.
			 *
			 * @since 1.5.0
			 *
			 * @param int $time_lastcomment Timestamp of when the last comment was posted.
			 * @param int $time_newcomment  Timestamp of when the new comment was posted.
			 */
			do_action( 'comment_flood_trigger', $time_lastcomment, $time_newcomment );
			if ( true === $avoid_die ) {
				return true;
			} else {
				if ( wp_doing_ajax() ) {
					die( __('You are posting comments too quickly. Slow down.') );
				}

				wp_die( __( 'You are posting comments too quickly. Slow down.' ), 429 );
			}
		}
	}

	return false;
}

/**
 * Separates an array of comments into an array keyed by comment_type.
 *
 * @since 2.7.0
 *
 * @param array $comments Array of comments
 * @return array Array of comments keyed by comment_type.
 */
function separate_comments(&$comments) {
	$comments_by_type = array('comment' => array(), 'trackback' => array(), 'pingback' => array(), 'pings' => array());

	/*
	 * Short circuit as in calmPress there are no pings or trackbacks, but we
	 * want to maintain some backward compatibility.
	 */
	$comments_by_type['comment'] = $comments;

	return $comments_by_type;
}

/**
 * Calculate the total number of comment pages.
 *
 * @since 2.7.0
 *
 * @uses Walker_Comment
 *
 * @global WP_Query $wp_query
 *
 * @param array $comments Optional array of WP_Comment objects. Defaults to $wp_query->comments
 * @param int   $per_page Optional comments per page.
 * @param bool  $threaded Optional control over flat or threaded comments.
 * @return int Number of comment pages.
 */
function get_comment_pages_count( $comments = null, $per_page = null, $threaded = null ) {
	global $wp_query;

	if ( null === $comments && null === $per_page && null === $threaded && !empty($wp_query->max_num_comment_pages) )
		return $wp_query->max_num_comment_pages;

	if ( ( ! $comments || ! is_array( $comments ) ) && ! empty( $wp_query->comments )  )
		$comments = $wp_query->comments;

	if ( empty($comments) )
		return 0;

	if ( ! get_option( 'page_comments' ) ) {
		return 1;
	}

	if ( !isset($per_page) )
		$per_page = (int) get_query_var('comments_per_page');
	if ( 0 === $per_page )
		$per_page = (int) get_option('comments_per_page');
	if ( 0 === $per_page )
		return 1;

	if ( !isset($threaded) )
		$threaded = get_option('thread_comments');

	if ( $threaded ) {
		$walker = new Walker_Comment;
		$count = ceil( $walker->get_number_of_root_elements( $comments ) / $per_page );
	} else {
		$count = ceil( count( $comments ) / $per_page );
	}

	return $count;
}

/**
 * Calculate what page number a comment will appear on for comment paging.
 *
 * @since 2.7.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int   $comment_ID Comment ID.
 * @param array $args {
 *      Array of optional arguments.
 *      @type string     $type      Limit paginated comments to those matching a given type. Accepts 'comment',
 *                                  or 'all'.
 *                                  Default is 'all'.
 *      @type int        $per_page  Per-page count to use when calculating pagination. Defaults to the value of the
 *                                  'comments_per_page' option.
 *      @type int|string $max_depth If greater than 1, comment page will be determined for the top-level parent of
 *                                  `$comment_ID`. Defaults to the value of the 'thread_comments_depth' option.
 * } *
 * @return int|null Comment page number or null on error.
 */
function get_page_of_comment( $comment_ID, $args = array() ) {
	global $wpdb;

	$page = null;

	if ( !$comment = get_comment( $comment_ID ) )
		return;

	$defaults = array( 'type' => 'all', 'page' => '', 'per_page' => '', 'max_depth' => '' );
	$args = wp_parse_args( $args, $defaults );
	$original_args = $args;

	// Order of precedence: 1. `$args['per_page']`, 2. 'comments_per_page' query_var, 3. 'comments_per_page' option.
	if ( get_option( 'page_comments' ) ) {
		if ( '' === $args['per_page'] ) {
			$args['per_page'] = get_query_var( 'comments_per_page' );
		}

		if ( '' === $args['per_page'] ) {
			$args['per_page'] = get_option( 'comments_per_page' );
		}
	}

	if ( empty($args['per_page']) ) {
		$args['per_page'] = 0;
		$args['page'] = 0;
	}

	if ( $args['per_page'] < 1 ) {
		$page = 1;
	}

	if ( null === $page ) {
		if ( '' === $args['max_depth'] ) {
			if ( get_option('thread_comments') )
				$args['max_depth'] = get_option('thread_comments_depth');
			else
				$args['max_depth'] = -1;
		}

		// Find this comment's top level parent if threading is enabled
		if ( $args['max_depth'] > 1 && 0 != $comment->comment_parent )
			return get_page_of_comment( $comment->comment_parent, $args );

		$comment_args = array(
			'type'       => $args['type'],
			'post_id'    => $comment->comment_post_ID,
			'fields'     => 'ids',
			'count'      => true,
			'status'     => 'approve',
			'parent'     => 0,
			'date_query' => array(
				array(
					'column' => "$wpdb->comments.comment_date_gmt",
					'before' => $comment->comment_date_gmt,
				)
			),
		);

		$comment_query = new WP_Comment_Query();
		$older_comment_count = $comment_query->query( $comment_args );

		// No older comments? Then it's page #1.
		if ( 0 == $older_comment_count ) {
			$page = 1;

		// Divide comments older than this one by comments per page to get this comment's page number
		} else {
			$page = ceil( ( $older_comment_count + 1 ) / $args['per_page'] );
		}
	}

	/**
	 * Filters the calculated page on which a comment appears.
	 *
	 * @since 4.4.0
	 * @since 4.7.0 Introduced the `$comment_ID` parameter.
	 *
	 * @param int   $page          Comment page.
	 * @param array $args {
	 *     Arguments used to calculate pagination. These include arguments auto-detected by the function,
	 *     based on query vars, system settings, etc. For pristine arguments passed to the function,
	 *     see `$original_args`.
	 *
	 *     @type string $type      Type of comments to count.
	 *     @type int    $page      Calculated current page.
	 *     @type int    $per_page  Calculated number of comments per page.
	 *     @type int    $max_depth Maximum comment threading depth allowed.
	 * }
	 * @param array $original_args {
	 *     Array of arguments passed to the function. Some or all of these may not be set.
	 *
	 *     @type string $type      Type of comments to count.
	 *     @type int    $page      Current comment page.
	 *     @type int    $per_page  Number of comments per page.
	 *     @type int    $max_depth Maximum comment threading depth allowed.
	 * }
	 * @param int $comment_ID ID of the comment.
	 */
	return apply_filters( 'get_page_of_comment', (int) $page, $args, $original_args, $comment_ID );
}

/**
 * Retrieves the maximum character lengths for the comment form fields.
 *
 * @since 4.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return array Maximum character length for the comment form fields.
 */
function wp_get_comment_fields_max_lengths() {
	global $wpdb;

	$lengths = array(
		'comment_author'       => 245,
		'comment_author_email' => 100,
		'comment_author_url'   => 200,
		'comment_content'      => 65525,
	);

	if ( $wpdb->is_mysql ) {
		foreach ( $lengths as $column => $length ) {
			$col_length = $wpdb->get_col_length( $wpdb->comments, $column );
			$max_length = 0;

			// No point if we can't get the DB column lengths
			if ( is_wp_error( $col_length ) ) {
				break;
			}

			if ( ! is_array( $col_length ) && (int) $col_length > 0 ) {
				$max_length = (int) $col_length;
			} elseif ( is_array( $col_length ) && isset( $col_length['length'] ) && intval( $col_length['length'] ) > 0 ) {
				$max_length = (int) $col_length['length'];

				if ( ! empty( $col_length['type'] ) && 'byte' === $col_length['type'] ) {
					$max_length = $max_length - 10;
				}
			}

			if ( $max_length > 0 ) {
				$lengths[ $column ] = $max_length;
			}
		}
	}

	/**
	 * Filters the lengths for the comment form fields.
	 *
	 * @since 4.5.0
	 *
	 * @param array $lengths Associative array `'field_name' => 'maximum length'`.
	 */
	return apply_filters( 'wp_get_comment_fields_max_lengths', $lengths );
}

/**
 * Compares the lengths of comment data against the maximum character limits.
 *
 * @since 4.7.0
 *
 * @param array $comment_data Array of arguments for inserting a comment.
 * @return WP_Error|true WP_Error when a comment field exceeds the limit,
 *                       otherwise true.
 */
function wp_check_comment_data_max_lengths( $comment_data ) {
	$max_lengths = wp_get_comment_fields_max_lengths();

	if ( isset( $comment_data['comment_author'] ) && mb_strlen( $comment_data['comment_author'], '8bit' ) > $max_lengths['comment_author'] ) {
		return new WP_Error( 'comment_author_column_length', __( '<strong>ERROR</strong>: your name is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_author_email'] ) && strlen( $comment_data['comment_author_email'] ) > $max_lengths['comment_author_email'] ) {
		return new WP_Error( 'comment_author_email_column_length', __( '<strong>ERROR</strong>: your email address is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_author_url'] ) && strlen( $comment_data['comment_author_url'] ) > $max_lengths['comment_author_url'] ) {
		return new WP_Error( 'comment_author_url_column_length', __( '<strong>ERROR</strong>: your url is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_content'] ) && mb_strlen( $comment_data['comment_content'], '8bit' ) > $max_lengths['comment_content'] ) {
		return new WP_Error( 'comment_content_column_length', __( '<strong>ERROR</strong>: your comment is too long.' ), 200 );
	}

	return true;
}

/**
 * Does comment contain blacklisted characters or words.
 *
 * @since 1.5.0
 *
 * @param string $author The author of the comment
 * @param string $email The email of the comment
 * @param string $url The url used in the comment
 * @param string $comment The comment content
 * @param string $user_ip The comment author's IP address
 * @param string $user_agent The author's browser user agent
 * @return bool True if comment contains blacklisted content, false if comment does not
 */
function wp_blacklist_check($author, $email, $url, $comment, $user_ip, $user_agent) {
	/**
	 * Fires before the comment is tested for blacklisted characters or words.
	 *
	 * @since 1.5.0
	 *
	 * @param string $author     Comment author.
	 * @param string $email      Comment author's email.
	 * @param string $url        Comment author's URL.
	 * @param string $comment    Comment content.
	 * @param string $user_ip    Comment author's IP address.
	 * @param string $user_agent Comment author's browser user agent.
	 */
	do_action( 'wp_blacklist_check', $author, $email, $url, $comment, $user_ip, $user_agent );

	$mod_keys = trim( get_option('blacklist_keys') );
	if ( '' == $mod_keys )
		return false; // If moderation keys are empty

	// Ensure HTML tags are not being used to bypass the blacklist.
	$comment_without_html = wp_strip_all_tags( $comment );

	$words = explode("\n", $mod_keys );

	foreach ( (array) $words as $word ) {
		$word = trim($word);

		// Skip empty lines
		if ( empty($word) ) { continue; }

		// Do some escaping magic so that '#' chars in the
		// spam words don't break things:
		$word = preg_quote($word, '#');

		$pattern = "#$word#i";
		if (
			   preg_match($pattern, $author)
			|| preg_match($pattern, $email)
			|| preg_match($pattern, $url)
			|| preg_match($pattern, $comment)
			|| preg_match($pattern, $comment_without_html)
			|| preg_match($pattern, $user_ip)
			|| preg_match($pattern, $user_agent)
		 )
			return true;
	}
	return false;
}

/**
 * Retrieve total comments for blog or single post.
 *
 * The properties of the returned object contain the 'moderated', 'approved',
 * and spam comments for either the entire blog or single post. Those properties
 * contain the amount of comments that match the status. The 'total_comments'
 * property contains the integer of total comments.
 *
 * The comment stats are cached and then retrieved, if they already exist in the
 * cache.
 *
 * @since 2.5.0
 *
 * @param int $post_id Optional. Post ID.
 * @return object|array Comment stats.
 */
function wp_count_comments( $post_id = 0 ) {
	$post_id = (int) $post_id;

	/**
	 * Filters the comments count for a given post.
	 *
	 * @since 2.7.0
	 *
	 * @param array $count   An empty array.
	 * @param int   $post_id The post ID.
	 */
	$filtered = apply_filters( 'wp_count_comments', array(), $post_id );
	if ( ! empty( $filtered ) ) {
		return $filtered;
	}

	$count = wp_cache_get( "comments-{$post_id}", 'counts' );
	if ( false !== $count ) {
		return $count;
	}

	$stats = get_comment_count( $post_id );
	$stats['moderated'] = $stats['awaiting_moderation'];
	unset( $stats['awaiting_moderation'] );

	$stats_object = (object) $stats;
	wp_cache_set( "comments-{$post_id}", $stats_object, 'counts' );

	return $stats_object;
}

/**
 * Trashes or deletes a comment.
 *
 * The comment is moved to trash instead of permanently deleted unless trash is
 * disabled, item is already in the trash, or $force_delete is true.
 *
 * The post comment count will be updated if the comment was approved and has a
 * post ID available.
 *
 * @since 2.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|WP_Comment $comment_id   Comment ID or WP_Comment object.
 * @param bool           $force_delete Whether to bypass trash and force deletion. Default is false.
 * @return bool True on success, false on failure.
 */
function wp_delete_comment($comment_id, $force_delete = false) {
	global $wpdb;
	if (!$comment = get_comment($comment_id))
		return false;

	if ( !$force_delete && EMPTY_TRASH_DAYS && !in_array( wp_get_comment_status( $comment ), array( 'trash', 'spam' ) ) )
		return wp_trash_comment($comment_id);

	/**
	 * Fires immediately before a comment is deleted from the database.
	 *
	 * @since 1.2.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be deleted.
	 */
	do_action( 'delete_comment', $comment->comment_ID, $comment );

	// Move children up a level.
	$children = $wpdb->get_col( $wpdb->prepare("SELECT comment_ID FROM $wpdb->comments WHERE comment_parent = %d", $comment->comment_ID) );
	if ( !empty($children) ) {
		$wpdb->update($wpdb->comments, array('comment_parent' => $comment->comment_parent), array('comment_parent' => $comment->comment_ID));
		clean_comment_cache($children);
	}

	// Delete metadata
	$meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->commentmeta WHERE comment_id = %d", $comment->comment_ID ) );
	foreach ( $meta_ids as $mid )
		delete_metadata_by_mid( 'comment', $mid );

	if ( ! $wpdb->delete( $wpdb->comments, array( 'comment_ID' => $comment->comment_ID ) ) )
		return false;

	/**
	 * Fires immediately after a comment is deleted from the database.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The deleted comment.
	 */
	do_action( 'deleted_comment', $comment->comment_ID, $comment );

	$post_id = $comment->comment_post_ID;
	if ( $post_id && $comment->comment_approved == 1 )
		wp_update_comment_count($post_id);

	clean_comment_cache( $comment->comment_ID );

	/** This action is documented in wp-includes/comment.php */
	do_action( 'wp_set_comment_status', $comment->comment_ID, 'delete' );

	wp_transition_comment_status('delete', $comment->comment_approved, $comment);
	return true;
}

/**
 * Moves a comment to the Trash
 *
 * If trash is disabled, comment is permanently deleted.
 *
 * @since 2.9.0
 *
 * @param int|WP_Comment $comment_id Comment ID or WP_Comment object.
 * @return bool True on success, false on failure.
 */
function wp_trash_comment($comment_id) {
	if ( !EMPTY_TRASH_DAYS )
		return wp_delete_comment($comment_id, true);

	if ( !$comment = get_comment($comment_id) )
		return false;

	/**
	 * Fires immediately before a comment is sent to the Trash.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be trashed.
	 */
	do_action( 'trash_comment', $comment->comment_ID, $comment );

	if ( wp_set_comment_status( $comment, 'trash' ) ) {
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_status' );
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_time' );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_status', $comment->comment_approved );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_time', time() );

		/**
		 * Fires immediately after a comment is sent to Trash.
		 *
		 * @since 2.9.0
		 * @since 4.9.0 Added the `$comment` parameter.
		 *
		 * @param int        $comment_id The comment ID.
		 * @param WP_Comment $comment    The trashed comment.
		 */
		do_action( 'trashed_comment', $comment->comment_ID, $comment );
		return true;
	}

	return false;
}

/**
 * Removes a comment from the Trash
 *
 * @since 2.9.0
 *
 * @param int|WP_Comment $comment_id Comment ID or WP_Comment object.
 * @return bool True on success, false on failure.
 */
function wp_untrash_comment($comment_id) {
	$comment = get_comment( $comment_id );
	if ( ! $comment ) {
		return false;
	}

	/**
	 * Fires immediately before a comment is restored from the Trash.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be untrashed.
	 */
	do_action( 'untrash_comment', $comment->comment_ID, $comment );

	$status = (string) get_comment_meta( $comment->comment_ID, '_wp_trash_meta_status', true );
	if ( empty($status) )
		$status = '0';

	if ( wp_set_comment_status( $comment, $status ) ) {
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_time' );
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_status' );
		/**
		 * Fires immediately after a comment is restored from the Trash.
		 *
		 * @since 2.9.0
		 * @since 4.9.0 Added the `$comment` parameter.
		 *
		 * @param int        $comment_id The comment ID.
		 * @param WP_Comment $comment    The untrashed comment.
		 */
		do_action( 'untrashed_comment', $comment->comment_ID, $comment );
		return true;
	}

	return false;
}

/**
 * Marks a comment as Spam
 *
 * @since 2.9.0
 *
 * @param int|WP_Comment $comment_id Comment ID or WP_Comment object.
 * @return bool True on success, false on failure.
 */
function wp_spam_comment( $comment_id ) {
	$comment = get_comment( $comment_id );
	if ( ! $comment ) {
		return false;
	}

	/**
	 * Fires immediately before a comment is marked as Spam.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be marked as spam.
	 */
	do_action( 'spam_comment', $comment->comment_ID, $comment );

	if ( wp_set_comment_status( $comment, 'spam' ) ) {
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_status' );
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_time' );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_status', $comment->comment_approved );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_time', time() );
		/**
		 * Fires immediately after a comment is marked as Spam.
		 *
		 * @since 2.9.0
		 * @since 4.9.0 Added the `$comment` parameter.
		 *
		 * @param int        $comment_id The comment ID.
		 * @param WP_Comment $comment    The comment marked as spam.
		 */
		do_action( 'spammed_comment', $comment->comment_ID, $comment );
		return true;
	}

	return false;
}

/**
 * Removes a comment from the Spam
 *
 * @since 2.9.0
 *
 * @param int|WP_Comment $comment_id Comment ID or WP_Comment object.
 * @return bool True on success, false on failure.
 */
function wp_unspam_comment( $comment_id ) {
	$comment = get_comment( $comment_id );
	if ( ! $comment ) {
		return false;
	}

	/**
	 * Fires immediately before a comment is unmarked as Spam.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be unmarked as spam.
	 */
	do_action( 'unspam_comment', $comment->comment_ID, $comment );

	$status = (string) get_comment_meta( $comment->comment_ID, '_wp_trash_meta_status', true );
	if ( empty($status) )
		$status = '0';

	if ( wp_set_comment_status( $comment, $status ) ) {
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_status' );
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_time' );
		/**
		 * Fires immediately after a comment is unmarked as Spam.
		 *
		 * @since 2.9.0
		 * @since 4.9.0 Added the `$comment` parameter.
		 *
		 * @param int        $comment_id The comment ID.
		 * @param WP_Comment $comment    The comment unmarked as spam.
		 */
		do_action( 'unspammed_comment', $comment->comment_ID, $comment );
		return true;
	}

	return false;
}

/**
 * The status of a comment by ID.
 *
 * @since 1.0.0
 *
 * @param int|WP_Comment $comment_id Comment ID or WP_Comment object
 * @return false|string Status might be 'trash', 'approved', 'unapproved', 'spam'. False on failure.
 */
function wp_get_comment_status($comment_id) {
	$comment = get_comment($comment_id);
	if ( !$comment )
		return false;

	$approved = $comment->comment_approved;

	if ( $approved == null )
		return false;
	elseif ( $approved == '1' )
		return 'approved';
	elseif ( $approved == '0' )
		return 'unapproved';
	elseif ( $approved == 'spam' )
		return 'spam';
	elseif ( $approved == 'trash' )
		return 'trash';
	else
		return false;
}

/**
 * Call hooks for when a comment status transition occurs.
 *
 * Calls hooks for comment status transitions. If the new comment status is not the same
 * as the previous comment status, then two hooks will be ran, the first is
 * {@see 'transition_comment_status'} with new status, old status, and comment data. The
 * next action called is {@see comment_$old_status_to_$new_status'}. It has the
 * comment data.
 *
 * The final action will run whether or not the comment statuses are the same. The
 * action is named {@see 'comment_$new_status_$comment->comment_type'}.
 *
 * @since 2.7.0
 *
 * @param string $new_status New comment status.
 * @param string $old_status Previous comment status.
 * @param object $comment Comment data.
 */
function wp_transition_comment_status($new_status, $old_status, $comment) {
	/*
	 * Translate raw statuses to human readable formats for the hooks.
	 * This is not a complete list of comment status, it's only the ones
	 * that need to be renamed
	 */
	$comment_statuses = array(
		0         => 'unapproved',
		'hold'    => 'unapproved', // wp_set_comment_status() uses "hold"
		1         => 'approved',
		'approve' => 'approved', // wp_set_comment_status() uses "approve"
	);
	if ( isset($comment_statuses[$new_status]) ) $new_status = $comment_statuses[$new_status];
	if ( isset($comment_statuses[$old_status]) ) $old_status = $comment_statuses[$old_status];

	// Call the hooks
	if ( $new_status != $old_status ) {
		/**
		 * Fires when the comment status is in transition.
		 *
		 * @since 2.7.0
		 *
		 * @param int|string $new_status The new comment status.
		 * @param int|string $old_status The old comment status.
		 * @param object     $comment    The comment data.
		 */
		do_action( 'transition_comment_status', $new_status, $old_status, $comment );
		/**
		 * Fires when the comment status is in transition from one specific status to another.
		 *
		 * The dynamic portions of the hook name, `$old_status`, and `$new_status`,
		 * refer to the old and new comment statuses, respectively.
		 *
		 * @since 2.7.0
		 *
		 * @param WP_Comment $comment Comment object.
		 */
		do_action( "comment_{$old_status}_to_{$new_status}", $comment );
	}
	/**
	 * Fires when the status of a specific comment type is in transition.
	 *
	 * The dynamic portions of the hook name, `$new_status`, and `$comment->comment_type`,
	 * refer to the new comment status, and the type of comment, respectively.
	 *
	 * Typical comment types include an empty string (standard comment).
	 *
	 * @since 2.7.0
	 *
	 * @param int        $comment_ID The comment ID.
	 * @param WP_Comment $comment    Comment object.
	 */
	do_action( "comment_{$new_status}_{$comment->comment_type}", $comment->comment_ID, $comment );
}

/**
 * Clear the lastcommentmodified cached value when a comment status is changed.
 *
 * Deletes the lastcommentmodified cache key when a comment enters or leaves
 * 'approved' status.
 *
 * @since 4.7.0
 * @access private
 *
 * @param string $new_status The new comment status.
 * @param string $old_status The old comment status.
 */
function _clear_modified_cache_on_transition_comment_status( $new_status, $old_status ) {
	if ( 'approved' === $new_status || 'approved' === $old_status ) {
		foreach ( array( 'server', 'gmt', 'blog' ) as $timezone ) {
			wp_cache_delete( "lastcommentmodified:$timezone", 'timeinfo' );
		}
	}
}

/**
 * Get current commenter's name, email, and URL.
 *
 * Expects cookies content to already be sanitized. User of this function might
 * wish to recheck the returned array for validity.
 *
 * @see sanitize_comment_cookies() Use to sanitize cookies
 *
 * @since 2.0.4
 *
 * @return array Comment author, email, url respectively.
 */
function wp_get_current_commenter() {
	// Cookies should already be sanitized.

	$comment_author = '';
	if ( isset($_COOKIE['comment_author_'.COOKIEHASH]) )
		$comment_author = $_COOKIE['comment_author_'.COOKIEHASH];

	$comment_author_email = '';
	if ( isset($_COOKIE['comment_author_email_'.COOKIEHASH]) )
		$comment_author_email = $_COOKIE['comment_author_email_'.COOKIEHASH];

	$comment_author_url = '';
	if ( isset($_COOKIE['comment_author_url_'.COOKIEHASH]) )
		$comment_author_url = $_COOKIE['comment_author_url_'.COOKIEHASH];

	/**
	 * Filters the current commenter's name, email, and URL.
	 *
	 * @since 3.1.0
	 *
	 * @param array $comment_author_data {
	 *     An array of current commenter variables.
	 *
	 *     @type string $comment_author       The name of the author of the comment. Default empty.
	 *     @type string $comment_author_email The email address of the `$comment_author`. Default empty.
	 *     @type string $comment_author_url   The URL address of the `$comment_author`. Default empty.
	 * }
	 */
	return apply_filters( 'wp_get_current_commenter', compact('comment_author', 'comment_author_email', 'comment_author_url') );
}

/**
 * Inserts a comment into the database.
 *
 * @since 2.0.0
 * @since 4.4.0 Introduced `$comment_meta` argument.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $commentdata {
 *     Array of arguments for inserting a new comment.
 *
 *     @type string     $comment_agent        The HTTP user agent of the `$comment_author` when
 *                                            the comment was submitted. Default empty.
 *     @type int|string $comment_approved     Whether the comment has been approved. Default 1.
 *     @type string     $comment_author       The name of the author of the comment. Default empty.
 *     @type string     $comment_author_email The email address of the `$comment_author`. Default empty.
 *     @type string     $comment_author_IP    The IP address of the `$comment_author`. Default empty.
 *     @type string     $comment_author_url   The URL address of the `$comment_author`. Default empty.
 *     @type string     $comment_content      The content of the comment. Default empty.
 *     @type string     $comment_date         The date the comment was submitted. To set the date
 *                                            manually, `$comment_date_gmt` must also be specified.
 *                                            Default is the current time.
 *     @type string     $comment_date_gmt     The date the comment was submitted in the GMT timezone.
 *                                            Default is `$comment_date` in the site's GMT timezone.
 *     @type int        $comment_karma        The karma of the comment. Default 0.
 *     @type int        $comment_parent       ID of this comment's parent, if any. Default 0.
 *     @type int        $comment_post_ID      ID of the post that relates to the comment, if any.
 *                                            Default 0.
 *     @type string     $comment_type         Comment type. Default empty.
 *     @type array      $comment_meta         Optional. Array of key/value pairs to be stored in commentmeta for the
 *                                            new comment.
 *     @type int        $user_id              ID of the user who submitted the comment. Default 0.
 * }
 * @return int|false The new comment's ID on success, false on failure.
 */
function wp_insert_comment( $commentdata ) {
	global $wpdb;
	$data = wp_unslash( $commentdata );

	$comment_author       = ! isset( $data['comment_author'] )       ? '' : $data['comment_author'];
	$comment_author_email = ! isset( $data['comment_author_email'] ) ? '' : $data['comment_author_email'];
	$comment_author_url   = ! isset( $data['comment_author_url'] )   ? '' : $data['comment_author_url'];
	$comment_author_IP    = ! isset( $data['comment_author_IP'] )    ? '' : $data['comment_author_IP'];

	$comment_date     = ! isset( $data['comment_date'] )     ? current_time( 'mysql' )            : $data['comment_date'];
	$comment_date_gmt = ! isset( $data['comment_date_gmt'] ) ? get_gmt_from_date( $comment_date ) : $data['comment_date_gmt'];

	$comment_post_ID  = ! isset( $data['comment_post_ID'] )  ? 0  : $data['comment_post_ID'];
	$comment_content  = ! isset( $data['comment_content'] )  ? '' : $data['comment_content'];
	$comment_karma    = ! isset( $data['comment_karma'] )    ? 0  : $data['comment_karma'];
	$comment_approved = ! isset( $data['comment_approved'] ) ? 1  : $data['comment_approved'];
	$comment_agent    = ! isset( $data['comment_agent'] )    ? '' : $data['comment_agent'];
	$comment_type     = ! isset( $data['comment_type'] )     ? '' : $data['comment_type'];
	$comment_parent   = ! isset( $data['comment_parent'] )   ? 0  : $data['comment_parent'];

	$user_id  = ! isset( $data['user_id'] ) ? 0 : $data['user_id'];

	$compacted = compact( 'comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_author_IP', 'comment_date', 'comment_date_gmt', 'comment_content', 'comment_karma', 'comment_approved', 'comment_agent', 'comment_type', 'comment_parent', 'user_id' );
	if ( ! $wpdb->insert( $wpdb->comments, $compacted ) ) {
		return false;
	}

	$id = (int) $wpdb->insert_id;

	if ( $comment_approved == 1 ) {
		wp_update_comment_count( $comment_post_ID );

		foreach ( array( 'server', 'gmt', 'blog' ) as $timezone ) {
			wp_cache_delete( "lastcommentmodified:$timezone", 'timeinfo' );
		}
	}

	clean_comment_cache( $id );

	$comment = get_comment( $id );

	// If metadata is provided, store it.
	if ( isset( $commentdata['comment_meta'] ) && is_array( $commentdata['comment_meta'] ) ) {
		foreach ( $commentdata['comment_meta'] as $meta_key => $meta_value ) {
			add_comment_meta( $comment->comment_ID, $meta_key, $meta_value, true );
		}
	}

	/**
	 * Fires immediately after a comment is inserted into the database.
	 *
	 * @since 2.8.0
	 *
	 * @param int        $id      The comment ID.
	 * @param WP_Comment $comment Comment object.
	 */
	do_action( 'wp_insert_comment', $id, $comment );

	return $id;
}

/**
 * Filters and sanitizes comment data.
 *
 * Sets the comment data 'filtered' field to true when finished. This can be
 * checked as to whether the comment should be filtered and to keep from
 * filtering the same comment more than once.
 *
 * @since 2.0.0
 *
 * @param array $commentdata Contains information on the comment.
 * @return array Parsed comment information.
 */
function wp_filter_comment($commentdata) {
	if ( isset( $commentdata['user_ID'] ) ) {
		/**
		 * Filters the comment author's user id before it is set.
		 *
		 * The first time this filter is evaluated, 'user_ID' is checked
		 * (for back-compat), followed by the standard 'user_id' value.
		 *
		 * @since 1.5.0
		 *
		 * @param int $user_ID The comment author's user ID.
		 */
		$commentdata['user_id'] = apply_filters( 'pre_user_id', $commentdata['user_ID'] );
	} elseif ( isset( $commentdata['user_id'] ) ) {
		/** This filter is documented in wp-includes/comment.php */
		$commentdata['user_id'] = apply_filters( 'pre_user_id', $commentdata['user_id'] );
	}

	/**
	 * Filters the comment author's browser user agent before it is set.
	 *
	 * @since 1.5.0
	 *
	 * @param string $comment_agent The comment author's browser user agent.
	 */
	$commentdata['comment_agent'] = apply_filters( 'pre_comment_user_agent', ( isset( $commentdata['comment_agent'] ) ? $commentdata['comment_agent'] : '' ) );
	/** This filter is documented in wp-includes/comment.php */
	$commentdata['comment_author'] = apply_filters( 'pre_comment_author_name', $commentdata['comment_author'] );
	/**
	 * Filters the comment content before it is set.
	 *
	 * @since 1.5.0
	 *
	 * @param string $comment_content The comment content.
	 */
	$commentdata['comment_content'] = apply_filters( 'pre_comment_content', $commentdata['comment_content'] );
	/**
	 * Filters the comment author's IP address before it is set.
	 *
	 * @since 1.5.0
	 *
	 * @param string $comment_author_ip The comment author's IP address.
	 */
	$commentdata['comment_author_IP'] = apply_filters( 'pre_comment_user_ip', $commentdata['comment_author_IP'] );
	/** This filter is documented in wp-includes/comment.php */
	$commentdata['comment_author_url'] = apply_filters( 'pre_comment_author_url', $commentdata['comment_author_url'] );
	/** This filter is documented in wp-includes/comment.php */
	$commentdata['comment_author_email'] = apply_filters( 'pre_comment_author_email', $commentdata['comment_author_email'] );
	$commentdata['filtered'] = true;
	return $commentdata;
}

/**
 * Whether a comment should be blocked because of comment flood.
 *
 * @since 2.1.0
 *
 * @param bool $block Whether plugin has already blocked comment.
 * @param int $time_lastcomment Timestamp for last comment.
 * @param int $time_newcomment Timestamp for new comment.
 * @return bool Whether comment should be blocked.
 */
function wp_throttle_comment_flood($block, $time_lastcomment, $time_newcomment) {
	if ( $block ) // a plugin has already blocked... we'll let that decision stand
		return $block;
	if ( ($time_newcomment - $time_lastcomment) < 15 )
		return true;
	return false;
}

/**
 * Adds a new comment to the database.
 *
 * Filters new comment to ensure that the fields are sanitized and valid before
 * inserting comment into database. Calls {@see 'comment_post'} action with comment ID
 * and whether comment is approved by WordPress. Also has {@see 'preprocess_comment'}
 * filter for processing the comment data before the function handles it.
 *
 * We use `REMOTE_ADDR` here directly. If you are behind a proxy, you should ensure
 * that it is properly set, such as in wp-config.php, for your environment.
 *
 * See {@link https://core.trac.wordpress.org/ticket/9235}
 *
 * @since 1.5.0
 * @since 4.3.0 'comment_agent' and 'comment_author_IP' can be set via `$commentdata`.
 * @since 4.7.0 The `$avoid_die` parameter was added, allowing the function to
 *              return a WP_Error object instead of dying.
 *
 * @see wp_insert_comment()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $commentdata {
 *     Comment data.
 *
 *     @type string $comment_author       The name of the comment author.
 *     @type string $comment_author_email The comment author email address.
 *     @type string $comment_author_url   The comment author URL.
 *     @type string $comment_content      The content of the comment.
 *     @type string $comment_date         The date the comment was submitted. Default is the current time.
 *     @type string $comment_date_gmt     The date the comment was submitted in the GMT timezone.
 *                                        Default is `$comment_date` in the GMT timezone.
 *     @type int    $comment_parent       The ID of this comment's parent, if any. Default 0.
 *     @type int    $comment_post_ID      The ID of the post that relates to the comment.
 *     @type int    $user_id              The ID of the user who submitted the comment. Default 0.
 *     @type int    $user_ID              Kept for backward-compatibility. Use `$user_id` instead.
 *     @type string $comment_agent        Comment author user agent. Default is the value of 'HTTP_USER_AGENT'
 *                                        in the `$_SERVER` superglobal sent in the original request.
 *     @type string $comment_author_IP    Comment author IP address in IPv4 format. Default is the value of
 *                                        'REMOTE_ADDR' in the `$_SERVER` superglobal sent in the original request.
 * }
 * @param bool $avoid_die Should errors be returned as WP_Error objects instead of
 *                        executing wp_die()? Default false.
 * @return int|false|WP_Error The ID of the comment on success, false or WP_Error on failure.
 */
function wp_new_comment( $commentdata, $avoid_die = false ) {
	global $wpdb;

	if ( isset( $commentdata['user_ID'] ) ) {
		$commentdata['user_id'] = $commentdata['user_ID'] = (int) $commentdata['user_ID'];
	}

	$prefiltered_user_id = ( isset( $commentdata['user_id'] ) ) ? (int) $commentdata['user_id'] : 0;

	/**
	 * Filters a comment's data before it is sanitized and inserted into the database.
	 *
	 * @since 1.5.0
	 *
	 * @param array $commentdata Comment data.
	 */
	$commentdata = apply_filters( 'preprocess_comment', $commentdata );

	$commentdata['comment_post_ID'] = (int) $commentdata['comment_post_ID'];
	if ( isset( $commentdata['user_ID'] ) && $prefiltered_user_id !== (int) $commentdata['user_ID'] ) {
		$commentdata['user_id'] = $commentdata['user_ID'] = (int) $commentdata['user_ID'];
	} elseif ( isset( $commentdata['user_id'] ) ) {
		$commentdata['user_id'] = (int) $commentdata['user_id'];
	}

	$commentdata['comment_parent'] = isset($commentdata['comment_parent']) ? absint($commentdata['comment_parent']) : 0;
	$parent_status = ( 0 < $commentdata['comment_parent'] ) ? wp_get_comment_status($commentdata['comment_parent']) : '';
	$commentdata['comment_parent'] = ( 'approved' == $parent_status || 'unapproved' == $parent_status ) ? $commentdata['comment_parent'] : 0;

	if ( ! isset( $commentdata['comment_author_IP'] ) ) {
		$commentdata['comment_author_IP'] = $_SERVER['REMOTE_ADDR'];
	}
	$commentdata['comment_author_IP'] = preg_replace( '/[^0-9a-fA-F:., ]/', '', $commentdata['comment_author_IP'] );

	if ( ! isset( $commentdata['comment_agent'] ) ) {
		$commentdata['comment_agent'] = isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT']: '';
	}
	$commentdata['comment_agent'] = substr( $commentdata['comment_agent'], 0, 254 );

	if ( empty( $commentdata['comment_date'] ) ) {
		$commentdata['comment_date'] = current_time('mysql');
	}

	if ( empty( $commentdata['comment_date_gmt'] ) ) {
		$commentdata['comment_date_gmt'] = current_time( 'mysql', 1 );
	}

	$commentdata = wp_filter_comment($commentdata);

	$commentdata['comment_approved'] = wp_allow_comment( $commentdata, $avoid_die );
	if ( is_wp_error( $commentdata['comment_approved'] ) ) {
		return $commentdata['comment_approved'];
	}

	$comment_ID = wp_insert_comment($commentdata);
	if ( ! $comment_ID ) {
		$fields = array( 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content' );

		foreach ( $fields as $field ) {
			if ( isset( $commentdata[ $field ] ) ) {
				$commentdata[ $field ] = $wpdb->strip_invalid_text_for_column( $wpdb->comments, $field, $commentdata[ $field ] );
			}
		}

		$commentdata = wp_filter_comment( $commentdata );

		$commentdata['comment_approved'] = wp_allow_comment( $commentdata, $avoid_die );
		if ( is_wp_error( $commentdata['comment_approved'] ) ) {
			return $commentdata['comment_approved'];
		}

		$comment_ID = wp_insert_comment( $commentdata );
		if ( ! $comment_ID ) {
			return false;
		}
	}

	/**
	 * Fires immediately after a comment is inserted into the database.
	 *
	 * @since 1.2.0
	 * @since 4.5.0 The `$commentdata` parameter was added.
	 *
	 * @param int        $comment_ID       The comment ID.
	 * @param int|string $comment_approved 1 if the comment is approved, 0 if not, 'spam' if spam.
	 * @param array      $commentdata      Comment data.
	 */
	do_action( 'comment_post', $comment_ID, $commentdata['comment_approved'], $commentdata );

	return $comment_ID;
}

/**
 * Send a comment moderation notification to the comment moderator.
 *
 * @since 4.4.0
 *
 * @param int $comment_ID ID of the comment.
 * @return bool True on success, false on failure.
 */
function wp_new_comment_notify_moderator( $comment_ID ) {
	$comment = get_comment( $comment_ID );

	// Only send notifications for pending comments.
	$maybe_notify = ( '0' == $comment->comment_approved );

	/** This filter is documented in wp-includes/comment.php */
	$maybe_notify = apply_filters( 'notify_moderator', $maybe_notify, $comment_ID );

	if ( ! $maybe_notify ) {
		return false;
	}

	return wp_notify_moderator( $comment_ID );
}

/**
 * Send a notification of a new comment to the post author.
 *
 * @since 4.4.0
 *
 * Uses the {@see 'notify_post_author'} filter to determine whether the post author
 * should be notified when a new comment is added, overriding site setting.
 *
 * @param int $comment_ID Comment ID.
 * @return bool True on success, false on failure.
 */
function wp_new_comment_notify_postauthor( $comment_ID ) {
	$comment = get_comment( $comment_ID );

	$maybe_notify = get_option( 'comments_notify' );

	/**
	 * Filters whether to send the post author new comment notification emails,
	 * overriding the site setting.
	 *
	 * @since 4.4.0
	 *
	 * @param bool $maybe_notify Whether to notify the post author about the new comment.
	 * @param int  $comment_ID   The ID of the comment for the notification.
	 */
	$maybe_notify = apply_filters( 'notify_post_author', $maybe_notify, $comment_ID );

	/*
	 * wp_notify_postauthor() checks if notifying the author of their own comment.
	 * By default, it won't, but filters can override this.
	 */
	if ( ! $maybe_notify ) {
		return false;
	}

	// Only send notifications for approved comments.
	if ( ! isset( $comment->comment_approved ) || '1' != $comment->comment_approved ) {
		return false;
	}

	return wp_notify_postauthor( $comment_ID );
}

/**
 * Sets the status of a comment.
 *
 * The {@see 'wp_set_comment_status'} action is called after the comment is handled.
 * If the comment status is not in the list, then false is returned.
 *
 * @since 1.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int|WP_Comment $comment_id     Comment ID or WP_Comment object.
 * @param string         $comment_status New comment status, either 'hold', 'approve', 'spam', or 'trash'.
 * @param bool           $wp_error       Whether to return a WP_Error object if there is a failure. Default is false.
 * @return bool|WP_Error True on success, false or WP_Error on failure.
 */
function wp_set_comment_status($comment_id, $comment_status, $wp_error = false) {
	global $wpdb;

	switch ( $comment_status ) {
		case 'hold':
		case '0':
			$status = '0';
			break;
		case 'approve':
		case '1':
			$status = '1';
			add_action( 'wp_set_comment_status', 'wp_new_comment_notify_postauthor' );
			break;
		case 'spam':
			$status = 'spam';
			break;
		case 'trash':
			$status = 'trash';
			break;
		default:
			return false;
	}

	$comment_old = clone get_comment($comment_id);

	if ( !$wpdb->update( $wpdb->comments, array('comment_approved' => $status), array( 'comment_ID' => $comment_old->comment_ID ) ) ) {
		if ( $wp_error )
			return new WP_Error('db_update_error', __('Could not update comment status'), $wpdb->last_error);
		else
			return false;
	}

	clean_comment_cache( $comment_old->comment_ID );

	$comment = get_comment( $comment_old->comment_ID );

	/**
	 * Fires immediately before transitioning a comment's status from one to another
	 * in the database.
	 *
	 * @since 1.5.0
	 *
	 * @param int         $comment_id     Comment ID.
	 * @param string|bool $comment_status Current comment status. Possible values include
	 *                                    'hold', 'approve', 'spam', 'trash', or false.
	 */
	do_action( 'wp_set_comment_status', $comment->comment_ID, $comment_status );

	wp_transition_comment_status($comment_status, $comment_old->comment_approved, $comment);

	wp_update_comment_count($comment->comment_post_ID);

	return true;
}

/**
 * Updates an existing comment in the database.
 *
 * Filters the comment and makes sure certain fields are valid before updating.
 *
 * @since 2.0.0
 * @since 4.9.0 Add updating comment meta during comment update.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $commentarr Contains information on the comment.
 * @return int Comment was updated if value is 1, or was not updated if value is 0.
 */
function wp_update_comment($commentarr) {
	global $wpdb;

	// First, get all of the original fields
	$comment = get_comment($commentarr['comment_ID'], ARRAY_A);
	if ( empty( $comment ) ) {
		return 0;
	}

	// Make sure that the comment post ID is valid (if specified).
	if ( ! empty( $commentarr['comment_post_ID'] ) && ! get_post( $commentarr['comment_post_ID'] ) ) {
		return 0;
	}

	// Escape data pulled from DB.
	$comment = wp_slash($comment);

	$old_status = $comment['comment_approved'];

	// Merge old and new fields with new fields overwriting old ones.
	$commentarr = array_merge($comment, $commentarr);

	$commentarr = wp_filter_comment( $commentarr );

	// Now extract the merged array.
	$data = wp_unslash( $commentarr );

	/**
	 * Filters the comment content before it is updated in the database.
	 *
	 * @since 1.5.0
	 *
	 * @param string $comment_content The comment data.
	 */
	$data['comment_content'] = apply_filters( 'comment_save_pre', $data['comment_content'] );

	$data['comment_date_gmt'] = get_gmt_from_date( $data['comment_date'] );

	if ( ! isset( $data['comment_approved'] ) ) {
		$data['comment_approved'] = 1;
	} elseif ( 'hold' == $data['comment_approved'] ) {
		$data['comment_approved'] = 0;
	} elseif ( 'approve' == $data['comment_approved'] ) {
		$data['comment_approved'] = 1;
	}

	$comment_ID = $data['comment_ID'];
	$comment_post_ID = $data['comment_post_ID'];

	/**
	 * Filters the comment data immediately before it is updated in the database.
	 *
	 * Note: data being passed to the filter is already unslashed.
	 *
	 * @since 4.7.0
	 *
	 * @param array $data       The new, processed comment data.
	 * @param array $comment    The old, unslashed comment data.
	 * @param array $commentarr The new, raw comment data.
	 */
	$data = apply_filters( 'wp_update_comment_data', $data, $comment, $commentarr );

	$keys = array( 'comment_post_ID', 'comment_content', 'comment_author', 'comment_author_email', 'comment_approved', 'comment_karma', 'comment_author_url', 'comment_date', 'comment_date_gmt', 'comment_type', 'comment_parent', 'user_id', 'comment_agent', 'comment_author_IP' );
	$data = wp_array_slice_assoc( $data, $keys );

	$rval = $wpdb->update( $wpdb->comments, $data, compact( 'comment_ID' ) );

	// If metadata is provided, store it.
	if ( isset( $commentarr['comment_meta'] ) && is_array( $commentarr['comment_meta'] ) ) {
		foreach ( $commentarr['comment_meta'] as $meta_key => $meta_value ) {
			update_comment_meta( $comment_ID, $meta_key, $meta_value );
		}
	}

	clean_comment_cache( $comment_ID );
	wp_update_comment_count( $comment_post_ID );
	/**
	 * Fires immediately after a comment is updated in the database.
	 *
	 * The hook also fires immediately before comment status transition hooks are fired.
	 *
	 * @since 1.2.0
	 * @since 4.6.0 Added the `$data` parameter.
	 *
	 * @param int   $comment_ID The comment ID.
	 * @param array $data       Comment data.
	 */
	do_action( 'edit_comment', $comment_ID, $data );
	$comment = get_comment($comment_ID);
	wp_transition_comment_status($comment->comment_approved, $old_status, $comment);
	return $rval;
}

/**
 * Whether to defer comment counting.
 *
 * When setting $defer to true, all post comment counts will not be updated
 * until $defer is set to false. When $defer is set to false, then all
 * previously deferred updated post comment counts will then be automatically
 * updated without having to call wp_update_comment_count() after.
 *
 * @since 2.5.0
 * @staticvar bool $_defer
 *
 * @param bool $defer
 * @return bool
 */
function wp_defer_comment_counting($defer=null) {
	static $_defer = false;

	if ( is_bool($defer) ) {
		$_defer = $defer;
		// flush any deferred counts
		if ( !$defer )
			wp_update_comment_count( null, true );
	}

	return $_defer;
}

/**
 * Updates the comment count for post(s).
 *
 * When $do_deferred is false (is by default) and the comments have been set to
 * be deferred, the post_id will be added to a queue, which will be updated at a
 * later date and only updated once per post ID.
 *
 * If the comments have not be set up to be deferred, then the post will be
 * updated. When $do_deferred is set to true, then all previous deferred post
 * IDs will be updated along with the current $post_id.
 *
 * @since 2.1.0
 * @see wp_update_comment_count_now() For what could cause a false return value
 *
 * @staticvar array $_deferred
 *
 * @param int|null $post_id     Post ID.
 * @param bool     $do_deferred Optional. Whether to process previously deferred
 *                              post comment counts. Default false.
 * @return bool|void True on success, false on failure or if post with ID does
 *                   not exist.
 */
function wp_update_comment_count($post_id, $do_deferred=false) {
	static $_deferred = array();

	if ( empty( $post_id ) && ! $do_deferred ) {
		return false;
	}

	if ( $do_deferred ) {
		$_deferred = array_unique($_deferred);
		foreach ( $_deferred as $i => $_post_id ) {
			wp_update_comment_count_now($_post_id);
			unset( $_deferred[$i] ); /** @todo Move this outside of the foreach and reset $_deferred to an array instead */
		}
	}

	if ( wp_defer_comment_counting() ) {
		$_deferred[] = $post_id;
		return true;
	}
	elseif ( $post_id ) {
		return wp_update_comment_count_now($post_id);
	}

}

/**
 * Updates the comment count for the post.
 *
 * @since 2.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $post_id Post ID
 * @return bool True on success, false on '0' $post_id or if post with ID does not exist.
 */
function wp_update_comment_count_now($post_id) {
	global $wpdb;
	$post_id = (int) $post_id;
	if ( !$post_id )
		return false;

	wp_cache_delete( 'comments-0', 'counts' );
	wp_cache_delete( "comments-{$post_id}", 'counts' );

	if ( !$post = get_post($post_id) )
		return false;

	$old = (int) $post->comment_count;

	/**
	 * Filters a post's comment count before it is updated in the database.
	 *
	 * @since 4.5.0
	 *
	 * @param int $new     The new comment count. Default null.
	 * @param int $old     The old comment count.
	 * @param int $post_id Post ID.
	 */
	$new = apply_filters( 'pre_wp_update_comment_count_now', null, $old, $post_id );

	if ( is_null( $new ) ) {
		$new = (int) $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_approved = '1'", $post_id ) );
	} else {
		$new = (int) $new;
	}

	$wpdb->update( $wpdb->posts, array('comment_count' => $new), array('ID' => $post_id) );

	clean_post_cache( $post );

	/**
	 * Fires immediately after a post's comment count is updated in the database.
	 *
	 * @since 2.3.0
	 *
	 * @param int $post_id Post ID.
	 * @param int $new     The new comment count.
	 * @param int $old     The old comment count.
	 */
	do_action( 'wp_update_comment_count', $post_id, $new, $old );

	/** This action is documented in wp-includes/post.php */
	do_action( "edit_post_{$post->post_type}", $post_id, $post );

	/** This action is documented in wp-includes/post.php */
	do_action( 'edit_post', $post_id, $post );

	return true;
}

/**
 * Perform all enclosures.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 */
function do_all_pings() {
	global $wpdb;

	// Do Enclosures
	while ($enclosure = $wpdb->get_row("SELECT ID, post_content, meta_id FROM {$wpdb->posts}, {$wpdb->postmeta} WHERE {$wpdb->posts}.ID = {$wpdb->postmeta}.post_id AND {$wpdb->postmeta}.meta_key = '_encloseme' LIMIT 1")) {
		delete_metadata_by_mid( 'post', $enclosure->meta_id );
		do_enclose( $enclosure->post_content, $enclosure->ID );
	}
}

//
// Cache
//

/**
 * Removes a comment from the object cache.
 *
 * @since 2.3.0
 *
 * @param int|array $ids Comment ID or an array of comment IDs to remove from cache.
 */
function clean_comment_cache($ids) {
	foreach ( (array) $ids as $id ) {
		wp_cache_delete( $id, 'comment' );

		/**
		 * Fires immediately after a comment has been removed from the object cache.
		 *
		 * @since 4.5.0
		 *
		 * @param int $id Comment ID.
		 */
		do_action( 'clean_comment_cache', $id );
	}

	wp_cache_set( 'last_changed', microtime(), 'comment' );
}

/**
 * Updates the comment cache of given comments.
 *
 * Will add the comments in $comments to the cache. If comment ID already exists
 * in the comment cache then it will not be updated. The comment is added to the
 * cache using the comment group with the key using the ID of the comments.
 *
 * @since 2.3.0
 * @since 4.4.0 Introduced the `$update_meta_cache` parameter.
 *
 * @param array $comments          Array of comment row objects
 * @param bool  $update_meta_cache Whether to update commentmeta cache. Default true.
 */
function update_comment_cache( $comments, $update_meta_cache = true ) {
	foreach ( (array) $comments as $comment )
		wp_cache_add($comment->comment_ID, $comment, 'comment');

	if ( $update_meta_cache ) {
		// Avoid `wp_list_pluck()` in case `$comments` is passed by reference.
		$comment_ids = array();
		foreach ( $comments as $comment ) {
			$comment_ids[] = $comment->comment_ID;
		}
		update_meta_cache( 'comment', $comment_ids );
	}
}

/**
 * Adds any comments from the given IDs to the cache that do not already exist in cache.
 *
 * @since 4.4.0
 * @access private
 *
 * @see update_comment_cache()
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array $comment_ids       Array of comment IDs.
 * @param bool  $update_meta_cache Optional. Whether to update the meta cache. Default true.
 */
function _prime_comment_caches( $comment_ids, $update_meta_cache = true ) {
	global $wpdb;

	$non_cached_ids = _get_non_cached_ids( $comment_ids, 'comment' );
	if ( !empty( $non_cached_ids ) ) {
		$fresh_comments = $wpdb->get_results( sprintf( "SELECT $wpdb->comments.* FROM $wpdb->comments WHERE comment_ID IN (%s)", join( ",", array_map( 'intval', $non_cached_ids ) ) ) );

		update_comment_cache( $fresh_comments, $update_meta_cache );
	}
}

//
// Internal
//

/**
 * Close comments on old posts on the fly, without any extra DB queries. Hooked to the_posts.
 *
 * @access private
 * @since 2.7.0
 *
 * @param WP_Post  $posts Post data object.
 * @param WP_Query $query Query object.
 * @return array
 */
function _close_comments_for_old_posts( $posts, $query ) {
	if ( empty( $posts ) || ! $query->is_singular() || ! get_option( 'close_comments_for_old_posts' ) )
		return $posts;

	/**
	 * Filters the list of post types to automatically close comments for.
	 *
	 * @since 3.2.0
	 *
	 * @param array $post_types An array of registered post types. Default array with 'post'.
	 */
	$post_types = apply_filters( 'close_comments_for_post_types', array( 'post' ) );
	if ( ! in_array( $posts[0]->post_type, $post_types ) )
		return $posts;

	$days_old = (int) get_option( 'close_comments_days_old' );
	if ( ! $days_old )
		return $posts;

	if ( time() - strtotime( $posts[0]->post_date_gmt ) > ( $days_old * DAY_IN_SECONDS ) ) {
		$posts[0]->comment_status = 'closed';
		$posts[0]->ping_status = 'closed';
	}

	return $posts;
}

/**
 * Close comments on an old post. Hooked to comments_open.
 *
 * @access private
 * @since 2.7.0
 *
 * @param bool $open Comments open or closed
 * @param int $post_id Post ID
 * @return bool $open
 */
function _close_comments_for_old_post( $open, $post_id ) {
	if ( ! $open )
		return $open;

	if ( !get_option('close_comments_for_old_posts') )
		return $open;

	$days_old = (int) get_option('close_comments_days_old');
	if ( !$days_old )
		return $open;

	$post = get_post($post_id);

	/** This filter is documented in wp-includes/comment.php */
	$post_types = apply_filters( 'close_comments_for_post_types', array( 'post' ) );
	if ( ! in_array( $post->post_type, $post_types ) )
		return $open;

	// Undated drafts should not show up as comments closed.
	if ( '0000-00-00 00:00:00' === $post->post_date_gmt ) {
		return $open;
	}

	if ( time() - strtotime( $post->post_date_gmt ) > ( $days_old * DAY_IN_SECONDS ) )
		return false;

	return $open;
}

/**
 * Handles the submission of a comment, usually posted to wp-comments-post.php via a comment form.
 *
 * This function expects unslashed data, as opposed to functions such as `wp_new_comment()` which
 * expect slashed data.
 *
 * @since 4.4.0
 *
 * @param array $comment_data {
 *     Comment data.
 *
 *     @type string|int $comment_post_ID             The ID of the post that relates to the comment.
 *     @type string     $author                      The name of the comment author.
 *     @type string     $email                       The comment author email address.
 *     @type string     $url                         The comment author URL.
 *     @type string     $comment                     The content of the comment.
 *     @type string|int $comment_parent              The ID of this comment's parent, if any. Default 0.
 *     @type string     $_wp_unfiltered_html_comment The nonce value for allowing unfiltered HTML.
 * }
 * @return WP_Comment|WP_Error A WP_Comment object on success, a WP_Error object on failure.
 */
function wp_handle_comment_submission( $comment_data ) {

	$comment_post_ID = $comment_parent = 0;
	$comment_author = $comment_author_email = $comment_author_url = $comment_content = null;

	if ( isset( $comment_data['comment_post_ID'] ) ) {
		$comment_post_ID = (int) $comment_data['comment_post_ID'];
	}
	if ( isset( $comment_data['author'] ) && is_string( $comment_data['author'] ) ) {
		$comment_author = trim( strip_tags( $comment_data['author'] ) );
	}
	if ( isset( $comment_data['email'] ) && is_string( $comment_data['email'] ) ) {
		$comment_author_email = trim( $comment_data['email'] );
	}
	if ( isset( $comment_data['url'] ) && is_string( $comment_data['url'] ) ) {
		$comment_author_url = trim( $comment_data['url'] );
	}
	if ( isset( $comment_data['comment'] ) && is_string( $comment_data['comment'] ) ) {
		$comment_content = trim( $comment_data['comment'] );
	}
	if ( isset( $comment_data['comment_parent'] ) ) {
		$comment_parent = absint( $comment_data['comment_parent'] );
	}

	$post = get_post( $comment_post_ID );

	if ( empty( $post->comment_status ) ) {

		/**
		 * Fires when a comment is attempted on a post that does not exist.
		 *
		 * @since 1.5.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_id_not_found', $comment_post_ID );

		return new WP_Error( 'comment_id_not_found' );

	}

	// get_post_status() will get the parent status for attachments.
	$status = get_post_status( $post );

	if ( ( 'private' == $status ) && ! current_user_can( 'read_post', $comment_post_ID ) ) {
		return new WP_Error( 'comment_id_not_found' );
	}

	$status_obj = get_post_status_object( $status );

	if ( ! comments_open( $comment_post_ID ) ) {

		/**
		 * Fires when a comment is attempted on a post that has comments closed.
		 *
		 * @since 1.5.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_closed', $comment_post_ID );

		return new WP_Error( 'comment_closed', __( 'Sorry, comments are closed for this item.' ), 403 );

	} elseif ( 'trash' == $status ) {

		/**
		 * Fires when a comment is attempted on a trashed post.
		 *
		 * @since 2.9.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_trash', $comment_post_ID );

		return new WP_Error( 'comment_on_trash' );

	} elseif ( ! $status_obj->public && ! $status_obj->private ) {

		/**
		 * Fires when a comment is attempted on a post in draft mode.
		 *
		 * @since 1.5.1
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_draft', $comment_post_ID );

		if ( current_user_can( 'read_post', $comment_post_ID ) ) {
			return new WP_Error( 'comment_on_draft', __( 'Sorry, comments are not allowed for this item.' ), 403 );
		} else {
			return new WP_Error( 'comment_on_draft' );
		}

	} elseif ( post_password_required( $comment_post_ID ) ) {

		/**
		 * Fires when a comment is attempted on a password-protected post.
		 *
		 * @since 2.9.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'comment_on_password_protected', $comment_post_ID );

		return new WP_Error( 'comment_on_password_protected' );

	} else {

		/**
		 * Fires before a comment is posted.
		 *
		 * @since 2.8.0
		 *
		 * @param int $comment_post_ID Post ID.
		 */
		do_action( 'pre_comment_on_post', $comment_post_ID );

	}

	// If the user is logged in
	$user = wp_get_current_user();
	if ( $user->exists() ) {
		if ( empty( $user->display_name ) ) {
			$user->display_name=$user->user_login;
		}
		$comment_author       = $user->display_name;
		$comment_author_email = $user->user_email;
		$comment_author_url   = $user->user_url;
		$user_ID              = $user->ID;
		if ( current_user_can( 'unfiltered_html' ) ) {
			if ( ! isset( $comment_data['_wp_unfiltered_html_comment'] )
				|| ! wp_verify_nonce( $comment_data['_wp_unfiltered_html_comment'], 'unfiltered-html-comment_' . $comment_post_ID )
			) {
				kses_remove_filters(); // start with a clean slate
				kses_init_filters(); // set up the filters
			}
		}
	} else {
		if ( get_option( 'comment_registration' ) ) {
			return new WP_Error( 'not_logged_in', __( 'Sorry, you must be logged in to comment.' ), 403 );
		}
	}

	$comment_type = '';

	if ( get_option( 'require_name_email' ) && ! $user->exists() ) {
		if ( '' == $comment_author_email || '' == $comment_author ) {
			return new WP_Error( 'require_name_email', __( '<strong>ERROR</strong>: please fill the required fields (name, email).' ), 200 );
		} elseif ( ! is_email( $comment_author_email ) ) {
			return new WP_Error( 'require_valid_email', __( '<strong>ERROR</strong>: please enter a valid email address.' ), 200 );
		}
	}

	if ( '' == $comment_content ) {
		return new WP_Error( 'require_valid_comment', __( '<strong>ERROR</strong>: please type a comment.' ), 200 );
	}

	$commentdata = compact(
		'comment_post_ID',
		'comment_author',
		'comment_author_email',
		'comment_author_url',
		'comment_content',
		'comment_type',
		'comment_parent',
		'user_ID'
	);

	$check_max_lengths = wp_check_comment_data_max_lengths( $commentdata );
	if ( is_wp_error( $check_max_lengths ) ) {
		return $check_max_lengths;
	}

	$comment_id = wp_new_comment( wp_slash( $commentdata ), true );
	if ( is_wp_error( $comment_id ) ) {
		return $comment_id;
	}

	if ( ! $comment_id ) {
		return new WP_Error( 'comment_save_error', __( '<strong>ERROR</strong>: The comment could not be saved. Please try again later.' ), 500 );
	}

	return get_comment( $comment_id );
}

/**
 * Registers the personal data exporter for comments.
 *
 * @since 4.9.6
 *
 * @param array $exporters An array of personal data exporters.
 * @return array $exporters An array of personal data exporters.
 */
function wp_register_comment_personal_data_exporter( $exporters ) {
	$exporters['wordpress-comments'] = array(
		'exporter_friendly_name' => __( 'WordPress Comments' ),
		'callback'               => 'wp_comments_personal_data_exporter',
	);

	return $exporters;
}

/**
 * Finds and exports personal data associated with an email address from the comments table.
 *
 * @since 4.9.6
 *
 * @param string $email_address The comment author email address.
 * @param int    $page          Comment page.
 * @return array $return An array of personal data.
 */
function wp_comments_personal_data_exporter( $email_address, $page = 1 ) {
	// Limit us to 500 comments at a time to avoid timing out.
	$number = 500;
	$page   = (int) $page;

	$data_to_export = array();

	$comments = get_comments(
		array(
			'author_email'              => $email_address,
			'number'                    => $number,
			'paged'                     => $page,
			'order_by'                  => 'comment_ID',
			'order'                     => 'ASC',
			'update_comment_meta_cache' => false,
		)
	);

	$comment_prop_to_export = array(
		'comment_author'       => __( 'Comment Author' ),
		'comment_author_email' => __( 'Comment Author Email' ),
		'comment_author_url'   => __( 'Comment Author URL' ),
		'comment_author_IP'    => __( 'Comment Author IP' ),
		'comment_agent'        => __( 'Comment Author User Agent' ),
		'comment_date'         => __( 'Comment Date' ),
		'comment_content'      => __( 'Comment Content' ),
		'comment_link'         => __( 'Comment URL' ),
	);

	foreach ( (array) $comments as $comment ) {
		$comment_data_to_export = array();

		foreach ( $comment_prop_to_export as $key => $name ) {
			$value = '';

			switch ( $key ) {
				case 'comment_author':
				case 'comment_author_email':
				case 'comment_author_url':
				case 'comment_author_IP':
				case 'comment_agent':
				case 'comment_date':
					$value = $comment->{$key};
					break;

				case 'comment_content':
					$value = get_comment_text( $comment->comment_ID );
					break;

				case 'comment_link':
					$value = get_comment_link( $comment->comment_ID );
					$value = sprintf(
						'<a href="%s" target="_blank" rel="noreferrer noopener">%s</a>',
						esc_url( $value ),
						esc_html( $value )
					);
					break;
			}

			if ( ! empty( $value ) ) {
				$comment_data_to_export[] = array(
					'name'  => $name,
					'value' => $value,
				);
			}
		}

		$data_to_export[] = array(
			'group_id'    => 'comments',
			'group_label' => __( 'Comments' ),
			'item_id'     => "comment-{$comment->comment_ID}",
			'data'        => $comment_data_to_export,
		);
	}

	$done = count( $comments ) < $number;

	return array(
		'data' => $data_to_export,
		'done' => $done,
	);
}

/**
 * Registers the personal data eraser for comments.
 *
 * @since 4.9.6
 *
 * @param  array $erasers An array of personal data erasers.
 * @return array $erasers An array of personal data erasers.
 */
function wp_register_comment_personal_data_eraser( $erasers ) {
	$erasers['wordpress-comments'] = array(
		'eraser_friendly_name' => __( 'WordPress Comments' ),
		'callback'             => 'wp_comments_personal_data_eraser',
	);

	return $erasers;
}

/**
 * Erases personal data associated with an email address from the comments table.
 *
 * @since 4.9.6
 *
 * @param  string $email_address The comment author email address.
 * @param  int    $page          Comment page.
 * @return array
 */
function wp_comments_personal_data_eraser( $email_address, $page = 1 ) {
	global $wpdb;

	if ( empty( $email_address ) ) {
		return array(
			'items_removed'  => false,
			'items_retained' => false,
			'messages'       => array(),
			'done'           => true,
		);
	}

	// Limit us to 500 comments at a time to avoid timing out.
	$number         = 500;
	$page           = (int) $page;
	$items_removed  = false;
	$items_retained = false;

	$comments = get_comments(
		array(
			'author_email'       => $email_address,
			'number'             => $number,
			'paged'              => $page,
			'order_by'           => 'comment_ID',
			'order'              => 'ASC',
			'include_unapproved' => true,
		)
	);

	/* translators: Name of a comment's author after being anonymized. */
	$anon_author = __( 'Anonymous' );
	$messages    = array();

	foreach ( (array) $comments as $comment ) {
		$anonymized_comment                         = array();
		$anonymized_comment['comment_agent']        = '';
		$anonymized_comment['comment_author']       = $anon_author;
		$anonymized_comment['comment_author_email'] = '';
		$anonymized_comment['comment_author_IP']    = wp_privacy_anonymize_data( 'ip', $comment->comment_author_IP );
		$anonymized_comment['comment_author_url']   = '';
		$anonymized_comment['user_id']              = 0;

		$comment_id = (int) $comment->comment_ID;

		/**
		 * Filters whether to anonymize the comment.
		 *
		 * @since 4.9.6
		 *
		 * @param bool|string                    Whether to apply the comment anonymization (bool).
		 *                                       Custom prevention message (string). Default true.
		 * @param WP_Comment $comment            WP_Comment object.
		 * @param array      $anonymized_comment Anonymized comment data.
		 */
		$anon_message = apply_filters( 'wp_anonymize_comment', true, $comment, $anonymized_comment );

		if ( true !== $anon_message ) {
			if ( $anon_message && is_string( $anon_message ) ) {
				$messages[] = esc_html( $anon_message );
			} else {
				/* translators: %d: Comment ID */
				$messages[] = sprintf( __( 'Comment %d contains personal data but could not be anonymized.' ), $comment_id );
			}

			$items_retained = true;

			continue;
		}

		$args = array(
			'comment_ID' => $comment_id,
		);

		$updated = $wpdb->update( $wpdb->comments, $anonymized_comment, $args );

		if ( $updated ) {
			$items_removed = true;
			clean_comment_cache( $comment_id );
		} else {
			$items_retained = true;
		}
	}

	$done = count( $comments ) < $number;

	return array(
		'items_removed'  => $items_removed,
		'items_retained' => $items_retained,
		'messages'       => $messages,
		'done'           => $done,
	);
}