/**
 * Plugin that highlights matched word partials in a given element.
 * TODO: Add a function for restoring the previous text.
 * TODO: Accept mappings for converting shortcuts like WP: to Wikipedia:.
 */
( function ( $ ) {

	$.highlightText = {

		// Split our pattern string at spaces and run our highlight function on the results
		splitAndHighlight: function ( node, pat ) {
			var i,
				patArray = pat.split( ' ' );
			for ( i = 0; i < patArray.length; i++ ) {
				if ( patArray[i].length === 0 ) {
					continue;
				}
				$.highlightText.innerHighlight( node, patArray[i] );
			}
			return node;
		},

		// scans a node looking for the pattern and wraps a span around each match
		innerHighlight: function ( node, pat ) {
			var i, match, pos, spannode, middlebit, middleclone;
			// if this is a text node
			if ( node.nodeType === 3 ) {
				// TODO - need to be smarter about the character matching here.
				// non latin characters can make regex think a new word has begun: do not use \b
				// http://stackoverflow.com/questions/3787072/regex-wordwrap-with-utf8-characters-in-js
				// look for an occurrence of our pattern and store the starting position
				match = node.data.match( new RegExp( '(^|\\s)' + $.escapeRE( pat ), 'i' ) );
				if ( match ) {
					pos = match.index + match[1].length; // include length of any matched spaces
					// create the span wrapper for the matched text
					spannode = document.createElement( 'span' );
					spannode.className = 'highlight';
					// shave off the characters preceding the matched text
					middlebit = node.splitText( pos );
					// shave off any unmatched text off the end
					middlebit.splitText( pat.length );
					// clone for appending to our span
					middleclone = middlebit.cloneNode( true );
					// append the matched text node to the span
					spannode.appendChild( middleclone );
					// replace the matched node, with our span-wrapped clone of the matched node
					middlebit.parentNode.replaceChild( spannode, middlebit );
				}
			// if this is an element with childnodes, and not a script, style or an element we created
			} else if ( node.nodeType === 1
				&& node.childNodes
				&& !/(script|style)/i.test( node.tagName )
				&& !( node.tagName.toLowerCase() === 'span'
					&& node.className.match( /\bhighlight/ )
				)
			) {
				for ( i = 0; i < node.childNodes.length; ++i ) {
					// call the highlight function for each child node
					$.highlightText.innerHighlight( node.childNodes[i], pat );
				}
			}
		}
	};

	$.fn.highlightText = function ( matchString ) {
		return this.each( function () {
			var $el = $( this );
			$el.data( 'highlightText', { originalText: $el.text() } );
			$.highlightText.splitAndHighlight( this, matchString );
		} );
	};

}( jQuery ) );
