/*
 * 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;
};