Print email link as button with envelope icon

In the View Issue Details section of view.php page, user names were
displayed with a mailto: link. This is not consistent with the way these
links are printed in other locations, where it goes to the User
Information page (view_user_page.php).

With this commit:
- username now links to view_user_page.php
- the mailto: link is available as a button next to the username

Fixes #25686

core/print_api.php

@@ -220,17 +220,13 @@ function print_user_with_subject( $p_user_id, $p_bug_id ) {
 		return;
 	}
 
-	$t_username = user_get_username( $p_user_id );
-	$t_name = user_get_name( $p_user_id );
+	print_user( $p_user_id );
 
-	if( user_exists( $p_user_id ) && user_get_field( $p_user_id, 'enabled' ) ) {
+	if( user_exists( $p_user_id ) && user_is_enabled( $p_user_id ) ) {
 		$t_email = user_get_email( $p_user_id );
-		print_email_link_with_subject( $t_email, $t_name, $t_username, $p_bug_id );
-	} else {
-		$t_name = string_attribute( $t_name );
-		echo '<span style="text-decoration: line-through">';
-		echo '<a title="' . $t_name . '">' . $t_username . '</a>';
-		echo '</span>';
+
+		echo '&nbsp;';
+		print_email_link_with_subject( $t_email, '', '', $p_bug_id );
 	}
 }
 
@@ -1662,37 +1658,52 @@ function get_email_link( $p_email, $p_text ) {
 /**
  * print a mailto: href link with subject
  *
- * @param string $p_email  Email Address.
- * @param string $p_text   Link text to display to user.
- * @param string $p_tooltip The tooltip to show.
- * @param string $p_bug_id The bug identifier.
+ * @param string  $p_email  Email Address.
+ * @param string  $p_text   Link text to display to user.
+ * @param string  $p_tooltip The tooltip to show.
+ * @param string  $p_bug_id The bug identifier.
+ * @param boolean $p_show_as_text By default, show link as button with envelope icon.
  * @return void
  */
-function print_email_link_with_subject( $p_email, $p_text, $p_tooltip, $p_bug_id ) {
+function print_email_link_with_subject( $p_email, $p_text, $p_tooltip, $p_bug_id, $p_show_as_text = false )
+{
 	if( !is_blank( $p_tooltip ) && $p_tooltip != $p_text ) {
 		$t_tooltip = ' title="' . $p_tooltip . '"';
 	} else {
 		$t_tooltip = '';
 	}
 
 	$t_bug = bug_get( $p_bug_id, true );
-	if( !access_has_project_level( config_get( 'show_user_email_threshold', null, null, $t_bug->project_id ), $t_bug->project_id ) ) {
-		echo $t_tooltip != '' ? '<a' . $t_tooltip . '>' . $p_text . '</a>' : $p_text;
+	$t_show_user_email_threshold = config_get( 'show_user_email_threshold', null, null, $t_bug->project_id );
+	if( !access_has_project_level( $t_show_user_email_threshold, $t_bug->project_id ) ) {
+		if( $p_show_as_text && $p_text ) {
+			echo $t_tooltip ? '<a' . $t_tooltip . '>' . $p_text . '</a>' : $p_text;
+		}
 		return;
 	}
 
-	$t_subject = email_build_subject( $p_bug_id );
-
 	# If we apply string_url() to the whole mailto: link then the @
 	# gets turned into a %40 and you can't right click in browsers to
 	# do Copy Email Address.  If we don't apply string_url() to the
 	# subject text then an ampersand (for example) will truncate the text
-	$t_subject = string_url( $t_subject );
+	$t_subject = string_url( email_build_subject( $p_bug_id ) );
 	$t_email = string_url( $p_email );
 	$t_mailto = string_attribute( 'mailto:' . $t_email . '?subject=' . $t_subject );
 	$t_text = string_display( $p_text );
 
-	echo '<a href="' . $t_mailto . '"' . $t_tooltip . '>' . $t_text . '</a>';
+	if( $p_show_as_text ) {
+		$t_class = '';
+	} else {
+		$t_class = ' class="btn btn-primary btn-white btn-round btn-xs"';
+		$t_text = '<i class="fa fa-envelope-o"></i>' . ( $t_text ? "&nbsp;$t_text" : '' );
+	}
+
+	printf( '<a href="%s"%s%s>%s</a>',
+		$t_mailto,
+		$t_tooltip,
+		$t_class,
+		$t_text
+	);
 }
 
 /**