/*global jQuery */
/*!
 * jQuery Scrollbox
 * (c) 2009-2013 Hunter Wu <hunter.wu@gmail.com>
 * MIT Licensed.
 *
 * http://github.com/wmh/jquery-scrollbox
 */

(function ($) {

    $.fn.scrollbox = function (config) {
        //default config
        var defConfig = {
            linear: false,          // Scroll method
            startDelay: 2,          // Start delay (in seconds)
            delay: 3,               // Delay after each scroll event (in seconds)
            step: 5,                // Distance of each single step (in pixels)
            speed: 32,              // Delay after each single step (in milliseconds)
            switchItems: 1,         // Items to switch after each scroll event
            direction: 'vertical',
            distance: 'auto',
            autoPlay: true,
            onMouseOverPause: true,
            paused: false,
            queue: null,
            listElement: 'ul',
            listItemElement: 'li'
        };
        config = $.extend(defConfig, config);
        config.scrollOffset = config.direction === 'vertical' ? 'scrollTop' : 'scrollLeft';
        if (config.queue) {
            config.queue = $('#' + config.queue);
        }

        return this.each(function () {
            var container = $(this),
                containerUL,
                scrollingId = null,
                nextScrollId = null,
                paused = false,
                backward,
                forward,
                resetClock,
                scrollForward,
                scrollBackward,
                forwardHover,
                pauseHover;

            if (config.onMouseOverPause) {
                container.bind('mouseover', function () { paused = true; });
                container.bind('mouseout', function () { paused = false; });
            }
            containerUL = container.children(config.listElement + ':first-child');

            scrollForward = function () {
                if (paused) {
                    return;
                }
                var curLi,
                    i,
                    newScrollOffset,
                    scrollDistance,
                    theStep;

                curLi = containerUL.children(config.listItemElement + ':first-child');

                scrollDistance = config.distance !== 'auto' ? config.distance :
                  config.direction === 'vertical' ? curLi.outerHeight(true) : curLi.outerWidth(true);

                // offset
                if (!config.linear) {
                    theStep = Math.max(3, parseInt((scrollDistance - container[0][config.scrollOffset]) * 0.3, 10));
                    newScrollOffset = Math.min(container[0][config.scrollOffset] + theStep, scrollDistance);
                } else {
                    newScrollOffset = Math.min(container[0][config.scrollOffset] + config.step, scrollDistance);
                }
                container[0][config.scrollOffset] = newScrollOffset;

                if (newScrollOffset >= scrollDistance) {
                    for (i = 0; i < config.switchItems; i++) {
                        if (config.queue && config.queue.find(config.listItemElement).length > 0) {
                            containerUL.append(config.queue.find(config.listItemElement)[0]);
                            containerUL.children(config.listItemElement + ':first-child').remove();
                        } else {
                            containerUL.append(containerUL.children(config.listItemElement + ':first-child'));
                        }
                    }
                    container[0][config.scrollOffset] = 0;
                    clearInterval(scrollingId);
                    if (config.autoPlay) {
                        nextScrollId = setTimeout(forward, config.delay * 1000);
                    }
                }
            };

            // Backward
            // 1. If forwarding, then reverse
            // 2. If stoping, then backward once
            scrollBackward = function () {
                if (paused) {
                    return;
                }
                var curLi,
                    i,
                    liLen,
                    newScrollOffset,
                    scrollDistance,
                    theStep;

                // init
                if (container[0][config.scrollOffset] === 0) {
                    liLen = containerUL.children(config.listItemElement).length;
                    for (i = 0; i < config.switchItems; i++) {
                        containerUL.children(config.listItemElement + ':last-child').insertBefore(containerUL.children(config.listItemElement + ':first-child'));
                    }

                    curLi = containerUL.children(config.listItemElement + ':first-child');
                    scrollDistance = config.distance !== 'auto' ?
                        config.distance :
                        config.direction === 'vertical' ? curLi.height() : curLi.width();
                    container[0][config.scrollOffset] = scrollDistance;
                }

                // new offset
                if (!config.linear) {
                    theStep = Math.max(3, parseInt(container[0][config.scrollOffset] * 0.3, 10));
                    newScrollOffset = Math.max(container[0][config.scrollOffset] - theStep, 0);
                } else {
                    newScrollOffset = Math.max(container[0][config.scrollOffset] - config.step, 0);
                }
                container[0][config.scrollOffset] = newScrollOffset;

                if (newScrollOffset === 0) {
                    clearInterval(scrollingId);
                    if (config.autoPlay) {
                        nextScrollId = setTimeout(forward, config.delay * 1000);
                    }
                }
            };

            forward = function () {
                clearInterval(scrollingId);
                scrollingId = setInterval(scrollForward, config.speed);
            };

            // Implements mouseover function.
            forwardHover = function () {
                config.autoPlay = true;
                paused = false;
                clearInterval(scrollingId);
                scrollingId = setInterval(scrollForward, config.speed);
            };
            pauseHover = function () {
                paused = true;
            };

            backward = function () {
                clearInterval(scrollingId);
                scrollingId = setInterval(scrollBackward, config.speed);
            };

            resetClock = function (delay) {
                config.delay = delay || config.delay;
                clearTimeout(nextScrollId);
                if (config.autoPlay) {
                    nextScrollId = setTimeout(forward, config.delay * 1000);
                }
            };

            if (config.autoPlay) {
                nextScrollId = setTimeout(forward, config.startDelay * 1000);
            }

            // bind events for container
            container.bind('resetClock', function (delay) { resetClock(delay); });
            container.bind('forward', function () { clearTimeout(nextScrollId); forward(); });
            container.bind('pauseHover', function () { pauseHover(); });
            container.bind('forwardHover', function () { forwardHover(); });
            container.bind('backward', function () { clearTimeout(nextScrollId); backward(); });
            container.bind('speedUp', function (speed) {
                if (typeof speed === 'undefined') {
                    speed = Math.max(1, parseInt(config.speed / 2, 10));
                }
                config.speed = speed;
            });

            container.bind('speedDown', function (speed) {
                if (typeof speed === 'undefined') {
                    speed = config.speed * 2;
                }
                config.speed = speed;
            });

            container.bind('updateConfig', function (event, options) {
                config = $.extend(config, options);
            });

        });
    };

}(jQuery));