Add link target options to $g_html_make_links

- Replace "magic numbers" with constants defined in constants_inc.php
- Update manual and config_defaults_inc.php with revised constants

Fixes #20694

Signed-off-by: Damien Regad <dregad@mantisbt.org>

Changes from original submission:
- commits squashed;
- reworded and reformatted the documentation for the new constants;
- referenced the equivalence between LINKS_SAME_WINDOW and ON;
- simplify the code in string_insert_hrefs().

config_defaults_inc.php

@@ -1781,12 +1781,16 @@
 ##########################
 
 /**
- * html tags
- * Set this flag to automatically convert www URLs and
- * email addresses into clickable links
+ * Convert URLs and e-mail addresses to html links.
+ * This flag controls whether www URLs and email addresses are automatically
+ * converted to clickable links as well as where the www links open when
+ * clicked. Valid options are:
+ * - OFF                Do not convert URLs or emails
+ * - LINKS_SAME_WINDOW  Convert to links that open in the current window (DEFAULT)
+ * - LINKS_NEW_WINDOW   Convert to links that open in a new window
  * @global integer $g_html_make_links
  */
-$g_html_make_links = ON;
+$g_html_make_links = LINKS_SAME_WINDOW;
 
 /**
  * These are the valid html tags for multi-line fields (e.g. description)

core/constant_inc.php

@@ -593,6 +593,10 @@
 
 define( 'SECONDS_PER_DAY', 86400 );
 
+# Auto-generated link targets
+define( 'LINKS_SAME_WINDOW', 1 );
+define( 'LINKS_NEW_WINDOW', 2 );
+
 # Obsolete / deprecated constants
 # Defined below for backwards-compatibility purposes -- Do not use them
 #        Constant                                   # Replaced by

core/string_api.php

@@ -503,12 +503,17 @@ function string_insert_hrefs( $p_string ) {
 		$s_email_regex = substr_replace( email_regex_simple(), '(?:mailto:)?', 1, 0 );
 	}
 
-	# Find any URL in a string and replace it by a clickable link
+	# Find any URL in a string and replace it with a clickable link
 	$p_string = preg_replace_callback(
 		$s_url_regex,
 		function ( $p_match ) {
 			$t_url_href = 'href="' . rtrim( $p_match[1], '.' ) . '"';
-			return "<a ${t_url_href}>${p_match[1]}</a> [<a ${t_url_href} target=\"_blank\">^</a>]";
+			if( config_get( 'html_make_links' ) == LINKS_NEW_WINDOW ) {
+				$t_url_target = ' target="_blank"';
+			} else {
+				$t_url_target = '';
+			}
+			return "<a ${t_url_href}${t_url_target}>${p_match[1]}</a>";
 		},
 		$p_string
 	);

docbook/Admin_Guide/en-US/config/html.xml

@@ -6,6 +6,34 @@
 	<title>HTML</title>
 
 	<variablelist>
+		<varlistentry>
+			<term>$g_html_make_links</term>
+			<listitem>
+				<para>This flag controls whether www URLs and email addresses are
+					automatically converted into clickable links as well as where
+					the www links open when clicked. The options are:
+					<itemizedlist>
+						<listitem>
+							<para><emphasis>OFF</emphasis> - do not convert URLs or emails
+							</para>
+						</listitem>
+						<listitem>
+							<para><emphasis>LINKS_SAME_WINDOW</emphasis> -
+								convert to links that open in current tab/window.
+								NOTE: for backwards-compatibility, this is
+								equivalent to <emphasis>ON</emphasis>.
+							</para>
+						</listitem>
+						<listitem>
+							<para><emphasis>LINKS_NEW_WINDOW</emphasis> -
+								convert to links that open in a new tab/window
+							</para>
+						</listitem>
+					</itemizedlist>
+					Default is <emphasis>LINKS_SAME_WINDOW</emphasis>.
+				</para>
+			</listitem>
+		</varlistentry>
 		<varlistentry>
 			<term>$g_html_valid_tags</term>
 			<listitem>