Enable line numbering only on configured namespaces

Introduces a new config variable `CodeMirrorLineNumberingNamespaces`
that can restrict line numbering to only appear for specified
namespaces.  Setting to null enables everywhere.

This takes some liberties with the `lib` module, turning it into a
container for shared functionality.  This can be pursued in later
work, by cleaning up duplicated code in this repo.

FIXME: failed to deduplicate the code for now.

Bug: T267911
Change-Id: Ida2b33eef38edc57d29756ec472c6f2c83bd7b11

extension.json

@@ -24,6 +24,11 @@
 			"value": false,
 			"description": "Temporary feature flag for accessibility colors.",
 			"public": true
+		},
+		"CodeMirrorLineNumberingNamespaces": {
+			"value": [ 10 ],
+			"description": "List of namespace IDs where line numbering should be enabled, or `null` to enable for all namespaces.  Defaults to the `Template` namespace.",
+			"public": true
 		}
 	},
 	"MessagesDirs": {

includes/CodeMirrorHooks.php

@@ -49,6 +49,8 @@ class CodeMirrorHooks {
 	/**
 	 * Hook handler for enabling bracket matching.
 	 *
+	 * TODO: restrict to pages where codemirror might be enabled.
+	 *
 	 * @param array &$vars Array of variables to be added into the output of the startup module
 	 */
 	public static function onResourceLoaderGetConfigVars( array &$vars ) {
@@ -61,6 +63,8 @@ class CodeMirrorHooks {
 				->getCookie( '-codemirror-bracket-matching-test', 'mw' );
 
 		$vars['wgCodeMirrorAccessibilityColors'] = $config->get( 'CodeMirrorAccessibilityColors' );
+
+		$vars['wgCodeMirrorLineNumberingNamespaces'] = $config->get( 'CodeMirrorLineNumberingNamespaces' );
 	}
 
 	/**

resources/ext.CodeMirror.js

@@ -87,6 +87,21 @@
 		mw.user.options.set( 'usecodemirror', prefValue ? 1 : 0 );
 	}
 
+	/**
+	 * TODO: remove once line numbering is fully deployed. (TBD: task)
+	 *
+	 * @return bool
+	 */
+	function isLineNumbering() {
+		var lineNumberingNamespaces = mw.config.get( 'wgCodeMirrorLineNumberingNamespaces' );
+
+		if ( lineNumberingNamespaces === null ) {
+			return true;
+		} else {
+			return lineNumberingNamespaces.indexOf( mw.config.get( 'wgNamespaceNumber' ) ) !== -1;
+		}
+	}
+
 	/**
 	 * Replaces the default textarea with CodeMirror
 	 */
@@ -113,7 +128,7 @@
 				mwConfig: config,
 				// styleActiveLine: true, // disabled since Bug: T162204, maybe should be optional
 				lineWrapping: true,
-				lineNumbers: true,
+				lineNumbers: isLineNumbering(),
 				readOnly: $textbox1[ 0 ].readOnly,
 				// select mediawiki as text input mode
 				mode: 'text/mediawiki',

resources/modules/ve-cm/ve.ui.CodeMirrorAction.js

@@ -32,6 +32,21 @@ ve.ui.CodeMirrorAction.static.methods = [ 'toggle' ];
 
 /* Methods */
 
+/**
+ * TODO: remove once line numbering is fully deployed. (TBD: task)
+ *
+ * @return bool
+ */
+ve.ui.CodeMirrorAction.static.isLineNumbering = function () {
+	var lineNumberingNamespaces = mw.config.get( 'wgCodeMirrorLineNumberingNamespaces' );
+
+	if ( lineNumberingNamespaces === null ) {
+		return true;
+	} else {
+		return lineNumberingNamespaces.indexOf( mw.config.get( 'wgNamespaceNumber' ) ) !== -1;
+	}
+};
+
 /**
  * @method
  * @param {boolean} [enable] State to force toggle to, inverts current state if undefined
@@ -71,15 +86,7 @@ ve.ui.CodeMirrorAction.prototype.toggle = function ( enable ) {
 					mwConfig: config,
 					readOnly: 'nocursor',
 					lineWrapping: true,
-					// Set up a special "padding" gutter to create space between the line numbers
-					// and page content.  The first column name is a magic constant which causes
-					// the built-in line number gutter to appear in the desired, leftmost position.
-					gutters: [
-						'CodeMirror-linenumbers',
-						'CodeMirror-linenumber-padding'
-					],
 					scrollbarStyle: 'null',
-					lineNumbers: true,
 					specialChars: /^$/,
 					viewportMargin: 5,
 					tabSize: tabSizeValue ? +tabSizeValue : 8,
@@ -98,6 +105,19 @@ ve.ui.CodeMirrorAction.prototype.toggle = function ( enable ) {
 					};
 				}
 
+				if ( ve.ui.CodeMirrorAction.static.isLineNumbering() ) {
+					$.extend( cmOptions, {
+						// Set up a special "padding" gutter to create space between the line numbers
+						// and page content.  The first column name is a magic constant which causes
+						// the built-in line number gutter to appear in the desired, leftmost position.
+						gutters: [
+							'CodeMirror-linenumbers',
+							'CodeMirror-linenumber-padding'
+						],
+						lineNumbers: true
+					} );
+				}
+
 				surface.mirror = CodeMirror( surfaceView.$element[ 0 ], cmOptions );
 
 				// The VE/CM overlay technique only works with monospace fonts (as we use width-changing bold as a highlight)