Move version parameters to an API endpoint

lib/admin-page.php

@@ -325,6 +325,20 @@ function classicpress_check_can_migrate() {
 		return false;
 	}
 
+	// Get migration plugin parameters.
+	$parameters = classicpress_migration_parameters();
+	if ( is_wp_error( $parameters ) ) {
+?>
+		<div class="notice notice-error">
+			<p>
+				<?php echo $parameters->get_error_message(); ?>
+				<?php echo json_encode( $parameters->get_error_data() ); ?>
+			</p>
+		</div>
+<?php
+		return false;
+	}
+
 	// The first round of checks has passed.  Now, run a second round related
 	// to conditions that the user (or at least the hosting provider) has
 	// control over, and display the results in a table.
@@ -350,24 +364,26 @@ function classicpress_check_can_migrate() {
 	// Check: Supported WP version
 	// More versions can be added after they are confirmed to work.
 	global $wp_version;
-	$wp_version_min = '4.9.0';
-	$wp_version_max = '5.1.0';
+	$wp_version_min = $parameters['wordpress']['min'];
+	$wp_version_max = $parameters['wordpress']['max'];
 	$wp_version_check_intro_message = sprintf( __(
 		/* translators: 1: minimum supported WordPress version, 2: maximum supported WordPress version */
 		'This plugin supports WordPress versions <strong>%1$s</strong> to <strong>%2$s</strong> (and some newer development versions).',
 		'switch-to-classicpress'
 	), $wp_version_min, $wp_version_max );
 	$wp_version_check_intro_message .= "<br>\n";
+
 	if (
-		// Version is outside of our "stable release" range...
+		// Version is outside of our target range of WP stable releases...
 		(
 			version_compare( $wp_version, $wp_version_min, 'lt' ) ||
 			version_compare( $wp_version, $wp_version_max, 'gt' )
 		) &&
-		$wp_version !== '4.9' &&
-		// ... and it's not a known development release.
-		! preg_match( '#^5\.1\.1-(alpha|beta|rc)#i', $wp_version ) &&
-		! preg_match( '#^5\.2-(alpha|beta|rc)#i', $wp_version )
+		// ... and it doesn't match any other acceptable version patterns
+		empty( array_filter( $parameters['wordpress']['other'], function( $pattern ) {
+			global $wp_version;
+			return preg_match( $pattern, $wp_version );
+		} ) )
 	) {
 		/**
 		 * Filters whether to ignore the result of the WP version check.
@@ -387,7 +403,7 @@ function classicpress_check_can_migrate() {
 			);
 			echo "<br>\n";
 			_e(
-				'We cannot guarantee that the migration process is going to work, and may even leave your current installation partially broken.',
+				'We cannot guarantee that the migration process is going to work, and it may even leave your current installation partially broken.',
 				'switch-to-classicpress'
 			);
 			echo "<br>\n";

lib/update.php

@@ -83,31 +83,55 @@ function classicpress_override_wp_update_api( $preempt, $r, $url ) {
 		return $preempt;
 	}
 
-	if ( empty( $_POST['_build_url'] ) || empty( $_POST['version'] ) ) {
-		// Not sure what happened, but it's not good.
+	if (
+		! isset( $_GET['_migrate'] ) ||
+		! in_array( $_GET['_migrate'], array( 'classicpress', '_custom' ), true )
+	) {
+		// Not a request we're interested in; do not override.
 		return $preempt;
 	}
 
-	// TODO:
-	// - pull locale out of $url
-	// - forward to real ClassicPress API
-	// - POST variables are not the best place to store version & URL
+	switch ( $_GET['_migrate'] ) {
+		case 'classicpress':
+			$parameters = classicpress_migration_parameters();
+			if ( ! is_array( $parameters ) ) {
+				// Not sure what happened, but it's not good.
+				return $preempt;
+			}
+			$build_url = $parameters['classicpress']['build'];
+			$version   = $parameters['classicpress']['version'];
+			break;
+
+		case '_custom':
+			if (
+				! isset( $_POST['_build_url'] ) ||
+				! isset( $_POST['version'] )
+			) {
+				// Not sure what happened, but it's not good.
+				return $preempt;
+			}
+			$build_url = $_POST['_build_url'];
+			$version   = $_POST['version'];
+			break;
+	}
+
+	// TODO: do locales other than en_US need different handling?
 
 	$data = array(
 		'offers' => array(
 			array(
 				'response' => 'upgrade',
-				'download' => $_POST['_build_url'],
+				'download' => $build_url,
 				'locale'   => 'en_US',
 				'packages' => array(
-					'full'        => $_POST['_build_url'],
+					'full'        => $build_url,
 					'no_content'  => false,
 					'new_bundled' => false,
 					'partial'     => false,
 					'rollback'    => false,
 				),
-				'current'         => $_POST['version'],
-				'version'         => $_POST['version'],
+				'current'         => $version,
+				'version'         => $version,
 				'php_version'     => '5.6.0',
 				'mysql_version'   => '5.0',
 				'new_bundled'     => '4.7',
@@ -223,6 +247,12 @@ function classicpress_override_upgrade_page() {
 		return;
 	}
 
+	$parameters = classicpress_migration_parameters();
+	if ( ! is_array( $parameters ) ) {
+		// Not sure what happened, but it's not good.
+		return;
+	}
+
 	// Save the WP version for possible later restoration by a future version
 	// of this plugin.
 	global $wp_version;
@@ -238,19 +268,15 @@ function classicpress_override_upgrade_page() {
 	$build_date = '20190305';
 
 	// Set `$_POST['version']` and `$_POST['locale']` with the same results
-	// from our update data, so that `find_core_update` will return a result.
-	$_POST['version'] = "$build_version+migration.$build_date";
-	$_POST['locale'] = 'en_US';
-	// Set `$_POST['_build_url']` for `classicpress_override_wp_update_api`.
-	$_POST['_build_url'] = 'https://github.com/ClassyBot/ClassicPress-nightly'
-		. "/releases/download/$build_version%2Bmigration.$build_date"
-		. "/ClassicPress-nightly-$build_version-migration.$build_date.zip";
+	// from our update data, so that `find_core_update()` will return a result.
+	$_POST['version'] = $parameters['classicpress']['version'];
+	$_POST['locale']  = 'en_US';
 
 	// Force loading a fresh response from the update API, which we will
 	// override with our own data.
 	wp_version_check( array(), true );
 
 	// Finished overriding the upgrade, now let it proceed in
-	// wp-admin/update-core.php (see `do_core_upgrade`).
+	// wp-admin/update-core.php (see `do_core_upgrade()`).
 }
 add_action( 'admin_head-update-core.php', 'classicpress_override_upgrade_page' );

switch-to-classicpress.php

@@ -152,3 +152,67 @@ function classicpress_plugin_action_links( $links ) {
 	'network_admin_plugin_action_links_' . plugin_basename( __FILE__ ),
 	'classicpress_plugin_action_links'
 );
+
+/**
+ * Call the ClassicPress API to determine which versions of WordPress and
+ * ClassicPress are supported by the migration plugin.
+ *
+ * This is handled on the ClassicPress servers, because most of the time a new
+ * version of WordPress or ClassicPress does not require a new version of the
+ * migration plugin.
+ *
+ * @since 1.0.1
+ *
+ * @return array {
+ *     "wordpress": {
+ *         "min": "4.9.0",
+ *         "max": "5.x.x",
+ *         "other": [
+ *             "^4\\.9$",
+ *             // patterns for development versions ...
+ *          ]
+ *      },
+ *      "classicpress": {
+ *          "build": "https://github.com/[...].zip",
+ *          "version": "1.x.x"
+ *      }
+ * }
+ */
+function classicpress_migration_parameters() {
+	$parameters = get_transient( 'classicpress_migration_parameters' );
+
+	if ( ! $parameters ) {
+		$response   = wp_remote_get( 'https://api-v1.classicpress.net/migration/' );
+		$parameters = null;
+
+		if ( is_wp_error( $response ) ) {
+			$status = $response->get_error_message();
+		} else {
+			$status = wp_remote_retrieve_response_code( $response );
+		}
+
+		if ( $status === 200 ) {
+			$parameters = json_decode( wp_remote_retrieve_body( $response ), true );
+			if ( is_array( $parameters ) ) {
+				set_transient(
+					'classicpress_migration_parameters',
+					$parameters,
+					1 * HOUR_IN_SECONDS
+				);
+			}
+		}
+
+		if ( ! is_array( $parameters ) ) {
+			return new WP_Error(
+				'classicpress_server_error',
+				__(
+					'Could not communicate with the ClassicPress API server',
+					'switch-to-classicpress'
+				),
+				array( 'status' => $status )
+			);
+		}
+	}
+
+	return $parameters;
+}