/**
 * Simple Placeholder-based Localization
 *
 * Call on a selection of HTML which contains <html:msg key="message-key" /> elements or elements
 * with title-msg="message-key", alt-msg="message-key" or placeholder-msg="message-key" attributes.
 * <html:msg /> elements will be replaced with localized text, *-msg attributes will be replaced
 * with attributes that do not have the "-msg" suffix and contain a localized message.
 *
 * Example:
 *     // Messages: { 'title': 'Awesome', 'desc': 'Cat doing backflip' 'search' contains 'Search' }
 *     var html = '\
 *         <p>\
 *             <html:msg key="title" />\
 *             <img src="something.jpg" title-msg="title" alt-msg="desc" />\
 *             <input type="text" placeholder-msg="search" />\
 *         </p>';
 *     $( 'body' ).append( $( html ).localize() );
 *
 * Appends something like this to the body...
 *     <p>
 *         Awesome
 *         <img src="something.jpg" title="Awesome" alt="Cat doing backflip" />
 *         <input type="text" placeholder="Search" />
 *     </p>
 *
 * Arguments can be passed into uses of a message using the params property of the options object
 * given to .localize(). Multiple messages can be given parameters, because the params property is
 * an object keyed by the message key to apply the parameters to, each containing an array of
 * parameters to use. The limitation is that you can not use different parameters to individual uses
 * of a message in the same selection being localized - they will all recieve the same parameters.
 *
 * Example:
 *     // Messages: { 'easy-as': 'Easy as $1 $2 $3.' }
 *     var html = '<p><html:msg key="easy-as" /></p>';
 *     $( 'body' ).append( $( html ).localize( { 'params': { 'easy-as': ['a', 'b', 'c'] } } ) );
 *
 * Appends something like this to the body...
 *     <p>Easy as a, b, c</p>
 *
 * Raw HTML content can be used, instead of it being escaped as text. To do this, just use the raw
 * attribute on a msg element.
 *
 * Example:
 *     // Messages: { 'hello': '<b><i>Hello</i> $1!</b>' }
 *     var html = '\
 *         <p>\
 *             <!-- escaped: --><html:msg key="hello" />\
 *             <!-- raw: --><html:msg key="hello" raw />\
 *         </p>';
 *     $( 'body' ).append( $( html ).localize( { 'params': { 'hello': ['world'] } } ) );
 *
 * Appends something like this to the body...
 *     <p>
 *         <!-- escaped: -->&lt;b&gt;&lt;i&gt;Hello&lt;/i&gt; world!&lt;/b&gt;
 *         <!-- raw: --><b><i>Hello</i> world!</b>
 *     </p>
 *
 * Message keys can also be remapped, allowing the same generic template to be used with a variety
 * of messages. This is important for improving re-usability of templates.
 *
 * Example:
 *     // Messages: { 'good-afternoon': 'Good afternoon' }
 *     var html = '<p><html:msg key="greeting" /></p>';
 *     $( 'body' ).append( $( html ).localize( { 'keys': { 'greeting': 'good-afternoon' } } ) );
 *
 * Appends something like this to the body...
 *     <p>Good afternoon</p>
 *
 * Message keys can also be prefixed globally, which is handy when writing extensions, where by
 * convention all messages are prefixed with the extension's name.
 *
 * Example:
 *     // Messages: { 'teleportation-warning': 'You may not get there all in one piece.' }
 *     var html = '<p><html:msg key="warning" /></p>';
 *     $( 'body' ).append( $( html ).localize( { 'prefix': 'teleportation-' } ) );
 *
 * Appends something like this to the body...
 *     <p>You may not get there all in one piece.</p>
 *
 */
( function ( $, mw ) {

/**
 * Gets a localized message, using parameters from options if present.
 *
 * @function
 * @param {String} key Message key to get localized message for
 * @returns {String} Localized message
 */
function msg( options, key ) {
	var args = options.params[key] || [];
	// Format: mw.msg( key [, p1, p2, ...] )
	args.unshift( options.prefix + ( options.keys[key] || key ) );
	return mw.msg.apply( mw, args );
}

/**
 * Localizes a DOM selection by replacing <html:msg /> elements with localized text and adding
 * localized title and alt attributes to elements with title-msg and alt-msg attributes
 * respectively.
 *
 * @method
 * @param {Object} options Map of options to be used while localizing
 * @param {String} options.prefix String to prepend to all message keys
 * @param {Object} options.keys Message key aliases, used for remapping keys to a template
 * @param {Object} options.params Lists of parameters to use with certain message keys
 * @returns {jQuery} This selection
 */
$.fn.localize = function ( options ) {
	var $target = this,
		attributes = ['title', 'alt', 'placeholder'];

	// Extend options
	options = $.extend( {
		prefix: '',
		keys: {},
		params: {}
	}, options );

	// Elements
	// Ok, so here's the story on this selector. In IE 6/7, searching for 'msg' turns up the
	// 'html:msg', but searching for 'html:msg' doesn't. In later IE and other browsers, searching
	// for 'html:msg' turns up the 'html:msg', but searching for 'msg' doesn't. So searching for
	// both 'msg' and 'html:msg' seems to get the job done. This feels pretty icky, though.
	$target.find( 'msg,html\\:msg' ).each( function () {
		var $el = $(this);
		// Escape by default
		if ( $el.attr( 'raw' ) ) {
			$el.html( msg( options, $el.attr( 'key' ) ) );
		} else {
			$el.text( msg( options, $el.attr( 'key' ) ) );
		}
		// Remove wrapper
		$el.replaceWith( $el.html() );
	} );

	// Attributes
	// Note: there's no way to prevent escaping of values being injected into attributes, this is
	// on purpose, not a design flaw.
	$.each( attributes, function ( i, attr ) {
		var msgAttr = attr + '-msg';
		$target.find( '[' + msgAttr + ']' ).each( function () {
			var $el = $(this);
			$el.attr( attr, msg( options, $el.attr( msgAttr ) ) ).removeAttr( msgAttr );
		} );
	} );

	// HTML, Text for elements which cannot have children e.g. OPTION
	$target.find( '[data-msg-text]' ).each( function() {
		var $el = $( this );
		$el.text( msg( options, $el.attr( 'data-msg-text' ) ) );
	} );

	$target.find( '[data-msg-html]' ).each( function() {
		var $el = $( this );
		$el.html( msg( options, $el.attr( 'data-msg-html' ) ) );
	} );

	return $target;
};

// Let IE know about the msg tag before it's used...
document.createElement( 'msg' );

}( jQuery, mediaWiki ) );
