/*
 * Copyright 2007-2009 by Tobia Conforto <tobia.conforto@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General
 * Public License as published by the Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Versions: 0.1    2007-08-19  Initial release
 *                  2008-08-21  Re-released under GPL v2
 *           0.1.1  2008-09-18  Compatibility with prototype.js
 *           0.2    2008-10-15  Linkable images, contributed by Tim Rainey <tim@zmlabs.com>
 *           0.3    2008-10-22  Added option to repeat the animation a number of times, then stop
 *           0.3.1  2008-11-11  Better error messages
 *           0.3.2  2008-11-11  Fixed a couple of CSS bugs, contributed by Erwin Bot <info@ixgcms.nl>
 *           0.3.3  2008-12-14  Added onclick option
 *           0.3.4  2009-03-12  Added shuffle option, contributed by Ralf Santbergen <ralf_santbergen@hotmail.com>
 *           0.3.5  2009-03-12  Fixed usage of href parameter in 'Ken Burns' mode
 *           0.3.6  2009-04-16  Added alt option
 *           0.3.7  2009-05-14  Fixed bug when container div doesn't have a position CSS attribute
 */
jQuery.fn.crossSlide = function(opts, plan){
    var self = this, self_width = this.width(), self_height = this.height();
    
    // generic utilities
    function format(str){
        for (var i = 1; i < arguments.length; i++) 
            str = str.replace(new RegExp('\\{' + (i - 1) + '}', 'g'), arguments[i]);
        return str;
    }
    
    function abort(){
        arguments[0] = 'crossSlide: ' + arguments[0];
        throw format.apply(null, arguments);
    }
    
    // first preload all the images, while getting their actual width and height
    (function(proceed){
    
        var n_loaded = 0;
        function loop(i, img){
            // for (i = 0; i < plan.length; i++) but with independent var i, img (for the closures)
            img.onload = function(e){
                n_loaded++;
                plan[i].width = img.width;
                plan[i].height = img.height;
                if (n_loaded == plan.length) 
                    proceed();
            }
            img.src = plan[i].src;
            if (i + 1 < plan.length) 
                loop(i + 1, new Image());
        }
        loop(0, new Image());
        
    })(function(){ // then proceed
        // utility to parse "from" and "to" parameters
        function parse_position_param(param){
            var zoom = 1;
            var tokens = param.replace(/^\s*|\s*$/g, '').split(/\s+/);
            if (tokens.length > 3) 
                throw new Error();
            if (tokens[0] == 'center') 
                if (tokens.length == 1) 
                    tokens = ['center', 'center'];
                else 
                    if (tokens.length == 2 && tokens[1].match(/^[\d.]+x$/i)) 
                        tokens = ['center', 'center', tokens[1]];
            if (tokens.length == 3) 
                zoom = parseFloat(tokens[2].match(/^([\d.]+)x$/i)[1]);
            var pos = tokens[0] + ' ' + tokens[1];
            if (pos == 'left top' || pos == 'top left') 
                return {
                    xrel: 0,
                    yrel: 0,
                    zoom: zoom
                };
            if (pos == 'left center' || pos == 'center left') 
                return {
                    xrel: 0,
                    yrel: .5,
                    zoom: zoom
                };
            if (pos == 'left bottom' || pos == 'bottom left') 
                return {
                    xrel: 0,
                    yrel: 1,
                    zoom: zoom
                };
            if (pos == 'center top' || pos == 'top center') 
                return {
                    xrel: .5,
                    yrel: 0,
                    zoom: zoom
                };
            if (pos == 'center center') 
                return {
                    xrel: .5,
                    yrel: .5,
                    zoom: zoom
                };
            if (pos == 'center bottom' || pos == 'bottom center') 
                return {
                    xrel: .5,
                    yrel: 1,
                    zoom: zoom
                };
            if (pos == 'right top' || pos == 'top right') 
                return {
                    xrel: 1,
                    yrel: 0,
                    zoom: zoom
                };
            if (pos == 'right center' || pos == 'center right') 
                return {
                    xrel: 1,
                    yrel: .5,
                    zoom: zoom
                };
            if (pos == 'right bottom' || pos == 'bottom right') 
                return {
                    xrel: 1,
                    yrel: 1,
                    zoom: zoom
                };
            return {
                xrel: parseInt(tokens[0].match(/^(\d+)%$/)[1]) / 100,
                yrel: parseInt(tokens[1].match(/^(\d+)%$/)[1]) / 100,
                zoom: zoom
            };
        }
        
        // utility to compute the css for a given phase between p.from and p.to
        // phase = 1: begin fade-in,  2: end fade-in,  3: begin fade-out,  4: end fade-out
        function position_to_css(p, phase){
            switch (phase) {
                case 1:
                    var pos = 0;
                    break;
                case 2:
                    var pos = fade_ms / (p.time_ms + 2 * fade_ms);
                    break;
                case 3:
                    var pos = 1 - fade_ms / (p.time_ms + 2 * fade_ms);
                    break;
                case 4:
                    var pos = 1;
                    break;
            }
            return {
                left: Math.round(p.from.left + pos * (p.to.left - p.from.left)),
                top: Math.round(p.from.top + pos * (p.to.top - p.from.top)),
                width: Math.round(p.from.width + pos * (p.to.width - p.from.width)),
                height: Math.round(p.from.height + pos * (p.to.height - p.from.height))
            };
        }
        
        // check global params
        if (!opts.fade) 
            abort('missing fade parameter.');
        if (opts.speed && opts.sleep) 
            abort('you cannot set both speed and sleep at the same time.');
        // conversion from sec to ms; from px/sec to px/ms
        var fade_ms = Math.round(opts.fade * 1000);
        if (opts.sleep) 
            var sleep = Math.round(opts.sleep * 1000);
        if (opts.speed) 
            var speed = opts.speed / 1000, fade_px = Math.round(fade_ms * speed);
        
        // set container css
        self.empty().css({
            overflow: 'hidden',
            padding: 0
        });
        if (!/^(absolute|relative|fixed)$/.test(self.css('position'))) 
            self.css({
                position: 'relative'
            });
        if (!self.width() || !self.height()) 
            abort('container element does not have its own width and height');
        
        // random sorting
        if (opts.shuffle) 
            plan.sort(function(){
                return Math.random() - 0.5;
            });
        
        // prepare each image
        for (var i = 0; i < plan.length; ++i) {
        
            var p = plan[i];
            if (!p.src) 
                abort('missing src parameter in picture {0}.', i + 1);
            
            if (speed) { // speed/dir mode
                // check parameters and translate speed/dir mode into full mode (from/to/time)
                switch (p.dir) {
                    case 'up':
                        p.from = {
                            xrel: .5,
                            yrel: 0,
                            zoom: 1
                        };
                        p.to = {
                            xrel: .5,
                            yrel: 1,
                            zoom: 1
                        };
                        var slide_px = p.height - self_height - 2 * fade_px;
                        break;
                    case 'down':
                        p.from = {
                            xrel: .5,
                            yrel: 1,
                            zoom: 1
                        };
                        p.to = {
                            xrel: .5,
                            yrel: 0,
                            zoom: 1
                        };
                        var slide_px = p.height - self_height - 2 * fade_px;
                        break;
                    case 'left':
                        p.from = {
                            xrel: 0,
                            yrel: .5,
                            zoom: 1
                        };
                        p.to = {
                            xrel: 1,
                            yrel: .5,
                            zoom: 1
                        };
                        var slide_px = p.width - self_width - 2 * fade_px;
                        break;
                    case 'right':
                        p.from = {
                            xrel: 1,
                            yrel: .5,
                            zoom: 1
                        };
                        p.to = {
                            xrel: 0,
                            yrel: .5,
                            zoom: 1
                        };
                        var slide_px = p.width - self_width - 2 * fade_px;
                        break;
                    default:
                        abort('missing or malformed "dir" parameter in picture {0}.', i + 1);
                }
                if (slide_px <= 0) 
                    abort('picture number {0} is too short for the desired fade duration.', i + 1);
                p.time_ms = Math.round(slide_px / speed);
                
            }
            else 
                if (!sleep) { // full mode
                    // check and parse parameters
                    if (!p.from || !p.to || !p.time) 
                        abort('missing either speed/sleep option, or from/to/time params in picture {0}.', i + 1);
                    try {
                        p.from = parse_position_param(p.from)
                    } 
                    catch (e) {
                        abort('malformed "from" parameter in picture {0}.', i + 1);
                    }
                    try {
                        p.to = parse_position_param(p.to)
                    } 
                    catch (e) {
                        abort('malformed "to" parameter in picture {0}.', i + 1);
                    }
                    if (!p.time) 
                        abort('missing "time" parameter in picture {0}.', i + 1);
                    p.time_ms = Math.round(p.time * 1000)
                }
            
            // precalculate left/top/width/height bounding values
            if (p.from) 
                jQuery.each([p.from, p.to], function(i, from_to){
                    from_to.width = Math.round(p.width * from_to.zoom);
                    from_to.height = Math.round(p.height * from_to.zoom);
                    from_to.left = Math.round((self_width - from_to.width) * from_to.xrel);
                    from_to.top = Math.round((self_height - from_to.height) * from_to.yrel);
                });
            
            // append the image (or anchor) element to the container
            var elm;
            if (p.href) 
                elm = jQuery(format('<a href="{0}"><img src="{1}"/></a>', p.href, p.src));
            else 
                elm = jQuery(format('<img src="{0}"/>', p.src));
            if (p.onclick) 
                elm.click(p.onclick);
            if (p.alt) 
                elm.find('img').attr('alt', p.alt);
            elm.appendTo(self);
        }
        speed = undefined; // speed mode has now been translated to full mode
        // find images to animate and set initial css attributes
        var imgs = self.find('img').css({
            position: 'absolute',
            visibility: 'hidden',
            top: 0,
            left: 0,
            border: 0
        });
        
        // show first image
        imgs.eq(0).css({
            visibility: 'visible'
        });
        if (!sleep) 
            imgs.eq(0).css(position_to_css(plan[0], 2));
        
        // create animation chain
        var countdown = opts.loop;
        function create_chain(i, chainf){
            // building the chain backwards, or inside out
            
            if (i % 2 == 0) {
                if (sleep) {
                
                    // still image sleep
                    
                    var i_sleep = i / 2, i_hide = (i_sleep - 1 + plan.length) % plan.length, img_sleep = imgs.eq(i_sleep), img_hide = imgs.eq(i_hide);
                    
                    var newf = function(){
                        img_hide.css('visibility', 'hidden');
                        setTimeout(chainf, sleep);
                    };
                    
                }
                else {
                
                    // single image slide
                    
                    var i_slide = i / 2, i_hide = (i_slide - 1 + plan.length) % plan.length, img_slide = imgs.eq(i_slide), img_hide = imgs.eq(i_hide), time = plan[i_slide].time_ms, slide_anim = position_to_css(plan[i_slide], 3);
                    
                    var newf = function(){
                        img_hide.css('visibility', 'hidden');
                        img_slide.animate(slide_anim, time, 'linear', chainf);
                    };
                    
                }
            }
            else {
                if (sleep) {
                
                    // still image cross-fade
                    
                    var i_from = Math.floor(i / 2), i_to = Math.ceil(i / 2) % plan.length, img_from = imgs.eq(i_from), img_to = imgs.eq(i_to), from_anim = {}, to_init = {
                        visibility: 'visible'
                    }, to_anim = {};
                    
                    if (i_to > i_from) {
                        to_init.opacity = 0;
                        to_anim.opacity = 1;
                    }
                    else {
                        from_anim.opacity = 0;
                    }
                    
                    var newf = function(){
                        img_to.css(to_init);
                        if (from_anim.opacity != undefined) 
                            img_from.animate(from_anim, fade_ms, 'linear', chainf);
                        else 
                            img_to.animate(to_anim, fade_ms, 'linear', chainf);
                    };
                    
                }
                else {
                
                    // cross-slide + cross-fade
                    
                    var i_from = Math.floor(i / 2), i_to = Math.ceil(i / 2) % plan.length, img_from = imgs.eq(i_from), img_to = imgs.eq(i_to), from_anim = position_to_css(plan[i_from], 4), to_init = position_to_css(plan[i_to], 1), to_anim = position_to_css(plan[i_to], 2);
                    
                    if (i_to > i_from) {
                        to_init.opacity = 0;
                        to_anim.opacity = 1;
                    }
                    else {
                        from_anim.opacity = 0;
                    }
                    to_init.visibility = 'visible';
                    
                    var newf = function(){
                        img_from.animate(from_anim, fade_ms, 'linear');
                        img_to.css(to_init);
                        img_to.animate(to_anim, fade_ms, 'linear', chainf);
                    };
                    
                }
            }
            
            // if the loop option was requested, push a countdown check
            if (opts.loop && i == plan.length * 2 - 2) {
                var newf_orig = newf;
                newf = function(){
                    if (--countdown) 
                        newf_orig();
                }
            }
            
            if (i > 0) 
                return create_chain(i - 1, newf);
            else 
                return newf;
        }
        var animation = create_chain(plan.length * 2 - 1, function(){
            return animation();
        });
        
        // start animation
        animation();
        
    });
    
    return self;
};


