/**
 * dropload
 * 西門(http://ons.me/526.html)
 * 0.9.0(160215)
 */

; (function ($) {
    'use strict';
    var win = window;
    var doc = document;
    var $win = $(win);
    var $doc = $(doc);
    $.fn.dropload = function (options) {
        console.log('this', this);
        return new MyDropLoad(this, options);
    };
    var MyDropLoad = function (element, options) {
        var me = this;
        me.$element = element;
        // 上方是否插入DOM
        me.upInsertDOM = false;
        // loading狀態
        me.loading = false;
        // 是否鎖定
        me.isLockUp = false;
        me.isLockDown = false;
        // 是否有數據
        me.isData = true;
        me._scrollTop = 0;
        me._threshold = 0;
        me.init(options);
        console.log('element', element);

    };

    // 初始化
    MyDropLoad.prototype.init = function (options) {
        var me = this;
        me.opts = $.extend(true, {}, {
            scrollArea: me.$element,                                            // 滑動區域
            domUp: {                                                            // 上方DOM
                domClass: 'dropload-up',
                domRefresh: '<div class="dropload-refresh">↓下拉刷新</div>',
                domUpdate: '<div class="dropload-update">↑釋放更新</div>',
                domLoad: '<div class="dropload-load"><span class="loading"></span>加載中...</div>'
            },
            domDown: {                                                          // 下方DOM
                domClass: 'dropload-down',
                domRefresh: '<div class="dropload-refresh">↑上拉加載更多</div>',
                domLoad: '<div class="dropload-load"><span class="loading"></span>加載中...</div>',
                domNoData: '<div class="dropload-noData">沒有更多了</div>'
            },
            autoLoad: true,                                                     // 自動加載
            distance: 50,                                                       // 拉動距離
            threshold: '',                                                      // 提前加載距離
            loadUpFn: '',                                                       // 上方function
            loadDownFn: ''                                                      // 下方function
        }, options);

        // 如果加載下方，事先在下方插入DOM
        if (me.opts.loadDownFn != '') {
            me.$element.append('<div class="' + me.opts.domDown.domClass + '">' + me.opts.domDown.domRefresh + '</div>');
            me.$domDown = $('.' + me.opts.domDown.domClass);
        }

        // 計算提前加載距離
        if (!!me.$domDown && me.opts.threshold === '') {
            // 默認滑到加載區2/3處時加載
            me._threshold = Math.floor(me.$domDown.height() * 1 / 3);
        } else {
            me._threshold = me.opts.threshold;
        }

        // 判斷滾動區域
        if (me.opts.scrollArea == win) {
            me.$scrollArea = $win;
            // 獲取文檔高度
            me._scrollContentHeight = $doc.height();
            // 獲取win顯示區高度  —— 這裏有坑
            me._scrollWindowHeight = doc.documentElement.clientHeight;
        } else {
            me.$scrollArea = me.opts.scrollArea;
            me._scrollContentHeight = me.$element[0].scrollHeight;
            me._scrollWindowHeight = me.$element.height();
        }
        fnAutoLoad(me);

        // 窗口調整
        $win.on('resize', function () {
            if (me.opts.scrollArea == win) {
                // 重新獲取win顯示區高度
                me._scrollWindowHeight = win.innerHeight;
            } else {
                me._scrollWindowHeight = me.$element.height();
            }
        });

        // 綁定觸摸
        me.$element.on('touchstart', function (e) {
            if (!me.loading) {
                fnTouches(e);
                fnTouchstart(e, me);
            }
        });
        me.$element.on('touchmove', function (e) {
            if (!me.loading) {
                fnTouches(e, me);
                fnTouchmove(e, me);
            }
        });
        me.$element.on('touchend', function () {
            if (!me.loading) {
                fnTouchend(me);
            }
        });

        // 加載下方
        me.$scrollArea.on('scroll', function () {
            me._scrollTop = me.$scrollArea.scrollTop();

            // 滾動頁面觸發加載數據
            if (me.opts.loadDownFn != '' && !me.loading && !me.isLockDown && (me._scrollContentHeight - me._threshold) <= (me._scrollWindowHeight + me._scrollTop)) {
                loadDown(me);
            }
        });
    };

    // touches
    function fnTouches (e) {
        if (!e.touches) {
            e.touches = e.originalEvent.touches;
        }
    }

    // touchstart
    function fnTouchstart (e, me) {
        me._startY = e.touches[0].pageY;
        // 記住觸摸時的scrolltop值
        me.touchScrollTop = me.$scrollArea.scrollTop();
    }

    // touchmove
    function fnTouchmove (e, me) {
        me._curY = e.touches[0].pageY;
        me._moveY = me._curY - me._startY;

        if (me._moveY > 0) {
            me.direction = 'down';
        } else if (me._moveY < 0) {
            me.direction = 'up';
        }

        var _absMoveY = Math.abs(me._moveY);

        // 加載上方
        if (me.opts.loadUpFn != '' && me.touchScrollTop <= 0 && me.direction == 'down' && !me.isLockUp) {
            e.preventDefault();

            me.$domUp = $('.' + me.opts.domUp.domClass);
            // 如果加載區沒有DOM
            if (!me.upInsertDOM) {
                me.$element.prepend('<div class="' + me.opts.domUp.domClass + '"></div>');
                me.upInsertDOM = true;
            }

            fnTransition(me.$domUp, 0);

            // 下拉
            if (_absMoveY <= me.opts.distance) {
                me._offsetY = _absMoveY;
                // todo：move時會不斷清空、增加dom，有可能影響性能，下同
                me.$domUp.html(me.opts.domUp.domRefresh);
                // 指定距離 < 下拉距離 < 指定距離*2
            } else if (_absMoveY > me.opts.distance && _absMoveY <= me.opts.distance * 2) {
                me._offsetY = me.opts.distance + (_absMoveY - me.opts.distance) * 0.5;
                me.$domUp.html(me.opts.domUp.domUpdate);
                // 下拉距離 > 指定距離*2
            } else {
                me._offsetY = me.opts.distance + me.opts.distance * 0.5 + (_absMoveY - me.opts.distance * 2) * 0.2;
            }

            me.$domUp.css({ 'height': me._offsetY });
        }
    }

    // touchend
    function fnTouchend (me) {
        var _absMoveY = Math.abs(me._moveY);
        if (me.opts.loadUpFn != '' && me.touchScrollTop <= 0 && me.direction == 'down' && !me.isLockUp) {
            fnTransition(me.$domUp, 300);

            if (_absMoveY > me.opts.distance) {
                me.$domUp.css({ 'height': me.$domUp.children().height() });
                me.$domUp.html(me.opts.domUp.domLoad);
                me.loading = true;
                me.opts.loadUpFn(me);
            } else {
                me.$domUp.css({ 'height': '0' }).on('webkitTransitionEnd mozTransitionEnd transitionend', function () {
                    me.upInsertDOM = false;
                    $(this).remove();
                });
            }
            me._moveY = 0;
        }
    }

    // 如果文檔高度不大於窗口高度，數據較少，自動加載下方數據
    function fnAutoLoad (me) {
        if (me.opts.autoLoad) {
            if ((me._scrollContentHeight - me._threshold) <= me._scrollWindowHeight) {
                loadDown(me);
            }
        }
    }

    // 重新獲取文檔高度
    function fnRecoverContentHeight (me) {
        if (me.opts.scrollArea == win) {
            me._scrollContentHeight = $doc.height();
        } else {
            me._scrollContentHeight = me.$element[0].scrollHeight;
        }
    }

    // 加載下方
    function loadDown (me) {
        me.direction = 'up';
        me.$domDown.html(me.opts.domDown.domLoad);
        me.loading = true;
        me.opts.loadDownFn(me);
    }

    // 鎖定
    MyDropLoad.prototype.lock = function (direction) {
        var me = this;
        // 如果不指定方向
        if (direction === undefined) {
            // 如果操作方向向上
            if (me.direction == 'up') {
                me.isLockDown = true;
                // 如果操作方向向下
            } else if (me.direction == 'down') {
                me.isLockUp = true;
            } else {
                me.isLockUp = true;
                me.isLockDown = true;
            }
            // 如果指定鎖上方
        } else if (direction == 'up') {
            me.isLockUp = true;
            // 如果指定鎖下方
        } else if (direction == 'down') {
            me.isLockDown = true;
            // 為了解決DEMO5中tab效果bug，因為滑動到下面，再滑上去點tab，direction=down，所以有bug
            me.direction = 'up';
        }
    };

    // 解鎖
    MyDropLoad.prototype.unlock = function () {
        var me = this;
        // 簡單粗暴解鎖
        me.isLockUp = false;
        me.isLockDown = false;
        // 為了解決DEMO5中tab效果bug，因為滑動到下面，再滑上去點tab，direction=down，所以有bug
        me.direction = 'up';
    };

    // 無數據
    MyDropLoad.prototype.noData = function (flag) {
        var me = this;
        if (flag === undefined || flag == true) {
            me.isData = false;
        } else if (flag == false) {
            me.isData = true;
        }
    };

    // 重置
    MyDropLoad.prototype.resetload = function () {
        var me = this;
        if (me.direction == 'down' && me.upInsertDOM) {
            me.$domUp.css({ 'height': '0' }).on('webkitTransitionEnd mozTransitionEnd transitionend', function () {
                me.loading = false;
                me.upInsertDOM = false;
                $(this).remove();
                fnRecoverContentHeight(me);
            });
        } else if (me.direction == 'up') {
            me.loading = false;
            // 如果有數據
            if (me.isData) {
                // 加載區修改樣式
                me.$domDown.html(me.opts.domDown.domRefresh);
                fnRecoverContentHeight(me);
                fnAutoLoad(me);
            } else {
                // 如果沒數據
                me.$domDown.html(me.opts.domDown.domNoData);
            }
        }
    };

    // css過渡
    function fnTransition (dom, num) {
        dom.css({
            '-webkit-transition': 'all ' + num + 'ms',
            'transition': 'all ' + num + 'ms'
        });
    }
})(window.Zepto || window.jQuery);