/**
 * jQuery ticker plugin
 *
 * By Andrew Betts <andrew.betts@assanka.net>
 *
 * Copyright (c) 2010 Assanka Limited
 *
 * -----------
 *
 * Licenced under the terms of the MIT licence, reproduced below:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * -----------
 *
 * A ticker tape animation plugin, designed to emulate continuous tickers of the
 * type typically seen on 24 hour news channels. Requires native CSS3 
 * transitions which are currently only available in webkit based browsers.
 *
 * Features:
 *
 * + When the ticker reaches the end of the text, the text
 *   at the beginning of the ticker follows on immediately,
 *   creating a continuous loop
 *
 * + Changes to the contents of the ticker are reflected
 *   seamlessly - content is never added or removed in the
 *   visible portion of the ticker
 *
 * @author     Andrew Betts <andrew.betts@assanka.net>
 * @copyright  Assanka Limited
 * @licence    http://www.opensource.org/licenses/mit-license.php
 */
(function ($){

	$.fn.ticker = function(options) {
		settings = jQuery.extend({
			pxpersec: 30
		}, options);
		if (this.length != 1) throw "Ticker can only be attached to a single element";
		if (this.children('ul').length != 1) throw "Ticker container must contain a UL, eg <div id='ticker'><ul></ul></div>";
		return new $.ticker(this, settings);
	}
	
	$.ticker = function(el, settings) {
	
		var addqueue = [];
		var removequeue = [];
		var numsegs;
		var updatecount = 0;
		var thisticker = this;
		var msgwidth = 0;
		var isscrolling = 0;
	
		var elcont = el;
		var eltape = el.children().first();
		eltape.css({"margin":0, "padding":0, "listStyleType":'none', "whiteSpace":'nowrap', 'float':'left', "position":'absolute', "right":0, "oTransition":'right 0s linear 0', "webkitTransition":'right 0s linear 0', "mozTransition":'right 0s linear 0', "transition":'right 0s linear 0'});
		elcont.css({overflow:'hidden'});
		if (!elcont.css('float') || elcont.css('float') == 'none') elcont.css('display', 'block');
	
		if (eltape.children('li').length) initTape();
	
	
		/* Private methods */
	
		function initTape() {
			
			numsegs = 1;
		
			// Mark each message in the list
			if (!eltape.children('li').length) throw "Cannot initialise ticker: Nothing in it";
			eltape.children('li').each(function() {
				if (!$(this).attr('id')) $(this).attr('id', 'msg'+Math.ceil(Math.random()*99999999));
				$(this).addClass('seg1').attr('seg', 1);
			});
						
			// Apply transiton CSS to the tape
			isscrolling = 1;
			updatecount = 1;
			eltape.bind('webkitTransitionEnd', slide);
			eltape.bind('oTransitionEnd', slide);
			eltape.bind('mozTransitionEnd', slide);
			eltape.bind('transitionEnd', slide);
			slide();
		}
		
		function slide(e) {
		
			// Copy each segment over the one preceding it
			if (updatecount) {
				if (numsegs > 1) {
					for (var i=(numsegs-1); i>=1; i--) {
						eltape.find('.seg'+(i+1)).remove();
						eltape.find('.seg'+i).clone().removeClass('seg'+i).removeAttr('id').addClass('seg'+(i+1)).attr('seg', (i+1)).insertBefore(eltape.find('.seg'+i).first());
					}
				}

				// If the ticker is now empty, delete all shadow segments and stop
				if (eltape.find('.empty').length) {
					eltape.unbind().css({webkitTransitionDuration:'0s'}).children().remove();
					isscrolling = 0;
					return;
				}
				
				// Add or remove segments as necessary
				var widths = calcWidths();
				if (widths.total < (elcont.width()+widths.seg1)) {
					var content = eltape.children('.seg'+numsegs);
					var content = content.clone().removeAttr('id').removeClass('seg'+numsegs);
					if (!widths['seg'+numsegs]) throw "Ticker is zero-width"
					var numrequired = Math.ceil((elcont.width()+widths.seg1-widths.total)/widths['seg'+numsegs]);
					for (var i=1; i<=numrequired; i++) {
						numsegs++;
						eltape.prepend(content.clone().addClass('seg'+numsegs).attr('seg',numsegs));
						widths['seg'+numsegs] = widths['seg'+(numsegs-1)];
						widths.total += widths['seg'+numsegs];
					}
				}
				if (widths.total > (elcont.width()+(widths.seg1*2))) {
					eltape.find('.seg'+numsegs).remove();
					numsegs--;
					widths.total -= widths['seg'+(numsegs+1)];
					delete widths['seg'+(numsegs+1)];
				}
				
				msgwidth = widths.seg1;
				eltape.width(widths.total);
				updatecount--;
			}
			
			// Modify the last segment to add/remove queued elements
			if (removequeue.length || addqueue.length) {
				if (removequeue.length) {
					for (var i=removequeue.length-1; i>=0; i--) $(removequeue[i]).remove();
					removequeue = [];
					
					// If master segment is now zero-width, add a .empty message that is the width of the parent container
					if (!eltape.find('.seg1').length) $('<li class="seg1 empty"></li>').width(elcont.width()).appendTo(eltape);
				}
				if (addqueue.length) {
					for (var i=addqueue.length-1; i>=0; i--) {
						$(addqueue[i]).addClass('seg1').attr('seg', 1).appendTo(eltape);
					}
					addqueue = [];
					
					// Remove any .empty messages
					eltape.find('.seg1').filter('.empty').remove();
				}
				
				// Recalculate widths
				var widths = calcWidths();
				msgwidth = widths.seg1;
				eltape.width(widths.total);
				
				// Start cascade
				updatecount = numsegs;
			}
						
			// Reposition the tape to move the last segment just off the right side of the screen
			eltape.css({"webkitTransitionDuration":'0s', "mozTransitionDuration":'0s', "oTransitionDuration":'0s', "transitionDuration":'0s'});
			eltape.css({"right":'-'+msgwidth+'px'});
	
			// Calculate duration of animation to achieve desired speed, resume scrolling
			dur = Math.floor(msgwidth/settings.pxpersec);
			setTimeout(function() {
				eltape.css({"webkitTransitionDuration":dur+'s', "mozTransitionDuration":dur+'s', "oTransitionDuration":dur+'s', "transitionDuration":'0s'});
				eltape.css({right:0+'px'});
			}, 0);
		}


		/* Private methods */
	
		function calcWidths() {
			var widths = {total:0}
			eltape.children().each(function() {
				if (typeof widths['seg'+$(this).attr('seg')] == 'undefined') widths['seg'+$(this).attr('seg')] = 0;
				widths['seg'+$(this).attr('seg')] += $(this).outerWidth();
				widths.total += $(this).outerWidth();
			});
			return widths;
		}
	
	
		/* Public methods */
		
		// Add a new item to the ticker.  Pass a reference to an LI that is to be added to the ticker
		this.addMsg = function(el) {
			if (typeof el == 'string') el = $('<li>'+el+'</li>');
			if (!el.attr('id')) el.attr('id', 'msg'+Math.ceil(Math.random()*99999999));
			if (isscrolling) {
				addqueue.push(el);
			} else {
				eltape.append(el);
			}
			return el.attr('id');
		}
		
		// Remove an item from the ticker.  Pass a reference to an LI in segment 1.
		this.removeMsg = function(el) {
			if (typeof el == 'string') el = $('#'+el);
			removequeue.push(el);
		}

		// Start if not already running
		this.start = function() {
			if (!isscrolling) initTape();
		}

		// Report current status of ticker
		this.isScrolling = function() {
			return (isscrolling == true);
		}
	}
})(jQuery);