(function($) {

$.fn.spriteshow = function(options) {
  options = options || {};
  return $(this).each(function() {
    var spriteshow = $(this).data('spriteshow');
		if (!spriteshow) {
		  spriteshow = new Spriteshow($(this), options);
			$(this).data('spriteshow', spriteshow);
		}
  });
};

function Spriteshow($elem, options) {
	this.$elem = $elem;
  this.options = options;

  this.$target = this.options.target || $elem;
  if(this.options.sprite_orientation && this.options.sprite_orientation == 'horizontal') {
    this.offset = this.$target.width();
  } else {
    this.offset = this.$target.height();
  }
  this.index = 0;
  this.playing = true;

  if(this.options.index_control) {
    this.$index_control_children = this.options.index_control.children();
  } else {
    this.$index_control_children = $([]);
  }

  if(!this.options.should_autoadvance_callback) {
    this.options.should_autoadvance_callback = function() { return true;};
  }

  this.number = this.options.number || this.$index_control_children.length;

  this.update_offset();
  this._attach();

  var _this = this;
  if(options.play_delay) this.playing_timer();
}

$.extend(Spriteshow.prototype, {
  _attach: function() {
    var _this = this;
    this.$index_control_children.click(function(e) {
      e.preventDefault();
      _this.set_index($(this).index());
      _this.pause();
    });
    if(this.options.controls) {
      this.options.controls.children('.left').click(function(e) {
        e.preventDefault();
        _this.page_left();
        _this.pause();
      });
      this.options.controls.children('.right').click(function(e) {
        e.preventDefault();
        _this.page_right();
        _this.pause();
      });
      this.options.controls.children('.play-pause').click(function(e) {
        if(_this.playing) {
          _this.pause();
        } else {
          _this.play();
        }
      });
    }
  },
  update_offset: function() {
    var _this = this;
    if (this.options.effect == 'fade') {
      var $new_image = this.$target.clone();
      this.$target.css('position', 'absolute');
      this.$target.after($new_image);
      this.$target.fadeOut(function() {
        $(this).remove();
      });
      this.$target = $new_image;
    }

    this.current_offset = this.index * this.offset;
    if(this.options.sprite_orientation && this.options.sprite_orientation == 'horizontal') {
      this.$target.css('background-position', '-' + this.current_offset + 'px 0');
    } else {
      this.$target.css('background-position', '0 -' + this.current_offset + 'px');
    }
  },
  set_index: function(index) {
    this.index = index;
    this.$index_control_children.removeClass('selected');
    this.$index_control_children.filter(':eq(' + index + ')').addClass('selected');
    this.$target.trigger('spriteshow:index', [index]);
    this.update_offset();
  },
  page_left: function() {
    var target_index = this.index - 1;
    if(target_index < 0) target_index = this.number - 1;
    this.set_index(target_index);
  },
  page_right: function() {
    var target_index = this.index + 1;
    if(target_index >= this.number) target_index = 0;
    this.set_index(target_index);
  },
  playing_timer: function() {
    var _this = this;
    this.play_timeout = setTimeout(function() {
      if(_this.playing && _this.options.should_autoadvance_callback()) _this.page_right();
      if(_this.options.pause_when_behind_by) {
        var right_now = (new Date()).getTime();
        if(_this.last_play_date && Math.abs(_this.last_play_date - right_now - _this.options.play_delay) > _this.options.pause_when_behind_by) {
          if(!_this.slow_strikes) {
            _this.slow_strikes = 0;
          } else {
            _this.slow_strikes += 1;
          }
          if(_this.slow_strikes > 3) {
            _this.pause();
          }
        } else {
          _this.slow_strikes = 0;
        }
        _this.last_play_date = right_now;
      }
      _this.playing_timer();
    }, this.options.play_delay);
  },
  play: function() {
    this.playing = true;
    if(this.options.controls) {
      this.options.controls.children('.play-pause').removeClass('spriteshow-play').addClass('spriteshow-pause');
    }
  },
  pause: function() {
    this.playing = false;
    if(this.options.controls) {
      this.options.controls.children('.play-pause').removeClass('spriteshow-pause').addClass('spriteshow-play');
    }
  }
});

})(jQuery);