/**
 * 选择列表插件
 * varstion 2.0.0
 * by Houfeng
 * Houfeng@DCloud.io
 */

(function($, window, document, undefined) {

    var MAX_EXCEED = 30;
    var VISIBLE_RANGE = 90;
    var DEFAULT_ITEM_HEIGHT = 40;
    var BLUR_WIDTH = 10;

    var rad2deg = $.rad2deg = function(rad) {
        return rad / (Math.PI / 180);
    };

    var deg2rad = $.deg2rad = function(deg) {
        return deg * (Math.PI / 180);
    };

    var platform = navigator.platform.toLowerCase();
    var userAgent = navigator.userAgent.toLowerCase();
    var isIos = (userAgent.indexOf('iphone') > -1 ||
            userAgent.indexOf('ipad') > -1 ||
            userAgent.indexOf('ipod') > -1) &&
        (platform.indexOf('iphone') > -1 ||
            platform.indexOf('ipad') > -1 ||
            platform.indexOf('ipod') > -1);
    //alert(isIos);

    var Picker = $.Picker = function(holder, options) {
        var self = this;
        self.holder = holder;
        self.options = options || {};
        self.init();
        self.initInertiaParams();
        self.calcElementItemPostion(true);
        self.bindEvent();
    };

    Picker.prototype.findElementItems = function() {
        var self = this;
        self.elementItems = [].slice.call(self.holder.querySelectorAll('li'));
        return self.elementItems;
    };

    Picker.prototype.init = function() {
        var self = this;
        self.list = self.holder.querySelector('ul');
        self.findElementItems();
        self.height = self.holder.offsetHeight;
        self.r = self.height / 2 - BLUR_WIDTH;
        self.d = self.r * 2;
        self.itemHeight = self.elementItems.length > 0 ? self.elementItems[0].offsetHeight : DEFAULT_ITEM_HEIGHT;
        self.itemAngle = parseInt(self.calcAngle(self.itemHeight * 0.8));
        self.hightlightRange = self.itemAngle / 2;
        self.visibleRange = VISIBLE_RANGE;
        self.beginAngle = 0;
        self.beginExceed = self.beginAngle - MAX_EXCEED;
        self.list.angle = self.beginAngle;
        if (isIos) {
            self.list.style.webkitTransformOrigin = "center center " + self.r + "px";
        }
    };

    Picker.prototype.calcElementItemPostion = function(andGenerateItms) {
        var self = this;
        if (andGenerateItms) {
            self.items = [];
        }
        self.elementItems.forEach(function(item) {
            var index = self.elementItems.indexOf(item);
            self.endAngle = self.itemAngle * index;
            item.angle = self.endAngle;
            item.style.webkitTransformOrigin = "center center -" + self.r + "px";
            item.style.webkitTransform = "translateZ(" + self.r + "px) rotateX(" + (-self.endAngle) + "deg)";
            if (andGenerateItms) {
                var dataItem = {};
                dataItem.text = item.innerHTML || '';
                dataItem.value = item.getAttribute('data-value') || dataItem.text;
                self.items.push(dataItem);
            }
        });
        self.endExceed = self.endAngle + MAX_EXCEED;
        self.calcElementItemVisibility(self.beginAngle);
    };

    Picker.prototype.calcAngle = function(c) {
        var self = this;
        var a = parseFloat(self.r);
        var b = parseFloat(self.r)
            //直径的整倍数部分直接乘以 180
        c = Math.abs(c); //只算角度不关心正否值
        var intDeg = parseInt(c / self.d) * 180;
        c = c % self.d;
        //余弦
        var cosC = (a * a + b * b - c * c) / (2 * a * b);
        var angleC = intDeg + rad2deg(Math.acos(cosC));
        return angleC;
    };

    Picker.prototype.calcElementItemVisibility = function(angle) {
        var self = this;
        self.elementItems.forEach(function(item) {
            var difference = Math.abs(item.angle - angle);
            if (difference < self.hightlightRange) {
                item.classList.add('highlight');
            } else if (difference < self.visibleRange) {
                item.classList.add('visible');
                item.classList.remove('highlight');
            } else {
                item.classList.remove('highlight');
                item.classList.remove('visible');
            }
        });
    };

    Picker.prototype.setAngle = function(angle) {
        var self = this;
        self.list.angle = angle;
        self.list.style.webkitTransform = "perspective(1000px) rotateY(0deg) rotateX(" + angle + "deg)";
        self.calcElementItemVisibility(angle);
    };

    Picker.prototype.bindEvent = function() {
        var self = this;
        var lastAngle = 0;
        var startY = null;
        var isPicking = false;
        self.holder.addEventListener($.EVENT_START, function(event) {
            isPicking = true;
            event.preventDefault();
            self.list.style.webkitTransition = '';
            startY = (event.changedTouches ? event.changedTouches[0] : event).pageY;
            lastAngle = self.list.angle;
            self.updateInertiaParams(event, true);
        }, false);
        self.holder.addEventListener($.EVENT_END, function(event) {
            isPicking = false;
            event.preventDefault();
            self.startInertiaScroll(event);
        }, false);
        self.holder.addEventListener($.EVENT_CANCEL, function(event) {
            isPicking = false;
            event.preventDefault();
            self.startInertiaScroll(event);
        }, false);
        self.holder.addEventListener($.EVENT_MOVE, function(event) {
            if (!isPicking) {
                return;
            }
            event.preventDefault();
            var endY = (event.changedTouches ? event.changedTouches[0] : event).pageY;
            var dragRange = endY - startY;
            var dragAngle = self.calcAngle(dragRange);
            var newAngle = dragRange > 0 ? lastAngle - dragAngle : lastAngle + dragAngle;
            if (newAngle > self.endExceed) {
                newAngle = self.endExceed
            }
            if (newAngle < self.beginExceed) {
                newAngle = self.beginExceed
            }
            self.setAngle(newAngle);
            self.updateInertiaParams(event);
        }, false);
        //--
        self.list.addEventListener('tap', function(event) {
            elementItem = event.target;
            if (elementItem.tagName == 'LI') {
                self.setSelectedIndex(self.elementItems.indexOf(elementItem), 200);
            }
        }, false);
    };

    Picker.prototype.initInertiaParams = function() {
        var self = this;
        self.lastMoveTime = 0;
        self.lastMoveStart = 0;
        self.stopInertiaMove = false;
    };

    Picker.prototype.updateInertiaParams = function(event, isStart) {
        var self = this;
        var point = event.changedTouches ? event.changedTouches[0] : event;
        if (isStart) {
            self.lastMoveStart = point.pageY;
            self.lastMoveTime = event.timeStamp || Date.now();
            self.startAngle = self.list.angle;
        } else {
            var nowTime = event.timeStamp || Date.now();
            if (nowTime - self.lastMoveTime > 300) {
                self.lastMoveTime = nowTime;
                self.lastMoveStart = point.pageY;
            }
        }
        self.stopInertiaMove = true;
    };

    Picker.prototype.startInertiaScroll = function(event) {
        var self = this;
        var point = event.changedTouches ? event.changedTouches[0] : event;
        /** 
         * 缓动代码
         */
        var nowTime = event.timeStamp || Date.now();
        var v = (point.pageY - self.lastMoveStart) / (nowTime - self.lastMoveTime); //最后一段时间手指划动速度  
        var dir = v > 0 ? -1 : 1; //加速度方向  
        var deceleration = dir * 0.0006 * -1;
        var duration = Math.abs(v / deceleration); // 速度消减至0所需时间  
        var dist = v * duration / 2; //最终移动多少 
        var startAngle = self.list.angle;
        var distAngle = self.calcAngle(dist) * dir;
        //----
        var srcDistAngle = distAngle;
        if (startAngle + distAngle < self.beginExceed) {
            distAngle = self.beginExceed - startAngle;
            duration = duration * (distAngle / srcDistAngle) * 0.6;
        }
        if (startAngle + distAngle > self.endExceed) {
            distAngle = self.endExceed - startAngle;
            duration = duration * (distAngle / srcDistAngle) * 0.6;
        }
        //----
        if (distAngle == 0) {
            self.endScroll();
            return;
        }
        self.scrollDistAngle(nowTime, startAngle, distAngle, duration);
    };

    Picker.prototype.scrollDistAngle = function(nowTime, startAngle, distAngle, duration) {
        var self = this;
        self.stopInertiaMove = false;
        (function(nowTime, startAngle, distAngle, duration) {
            var frameInterval = 13;
            var stepCount = duration / frameInterval;
            var stepIndex = 0;
            (function inertiaMove() {
                if (self.stopInertiaMove) return;
                var newAngle = self.quartEaseOut(stepIndex, startAngle, distAngle, stepCount);
                self.setAngle(newAngle);
                stepIndex++;
                if (stepIndex > stepCount - 1 || newAngle < self.beginExceed || newAngle > self.endExceed) {
                    self.endScroll();
                    return;
                }
                setTimeout(inertiaMove, frameInterval);
            })();
        })(nowTime, startAngle, distAngle, duration);
    };

    Picker.prototype.quartEaseOut = function(t, b, c, d) {
        return -c * ((t = t / d - 1) * t * t * t - 1) + b;
    };

    Picker.prototype.endScroll = function() {
        var self = this;
        if (self.list.angle < self.beginAngle) {
            self.list.style.webkitTransition = "150ms ease-out";
            self.setAngle(self.beginAngle);
        } else if (self.list.angle > self.endAngle) {
            self.list.style.webkitTransition = "150ms ease-out";
            self.setAngle(self.endAngle);
        } else {
            var index = parseInt((self.list.angle / self.itemAngle).toFixed(0));
            self.list.style.webkitTransition = "100ms ease-out";
            self.setAngle(self.itemAngle * index);
        }
        self.triggerChange();
    };

    Picker.prototype.triggerChange = function(force) {
        var self = this;
        setTimeout(function() {
            var index = self.getSelectedIndex();
            var item = self.items[index];
            if ($.trigger && (index != self.lastIndex || force === true)) {
                $.trigger(self.holder, 'change', {
                    "index": index,
                    "item": item
                });
                //console.log('change:' + index);
            }
            self.lastIndex = index;
            typeof force === 'function' && force();
        }, 0);
    };

    Picker.prototype.correctAngle = function(angle) {
        var self = this;
        if (angle < self.beginAngle) {
            return self.beginAngle;
        } else if (angle > self.endAngle) {
            return self.endAngle;
        } else {
            return angle;
        }
    };

    Picker.prototype.setItems = function(items) {
        var self = this;
        self.items = items || [];
        var buffer = [];
        self.items.forEach(function(item) {
            if (item !== null && item !== undefined) {
                buffer.push('<li>' + (item.text || item) + '</li>');
            }
        });
        self.list.innerHTML = buffer.join('');
        self.findElementItems();
        self.calcElementItemPostion();
        self.setAngle(self.correctAngle(self.list.angle));
        self.triggerChange(true);
    };

    Picker.prototype.getItems = function() {
        var self = this;
        return self.items;
    };

    Picker.prototype.getSelectedIndex = function() {
        var self = this;
        return parseInt((self.list.angle / self.itemAngle).toFixed(0));
    };

    Picker.prototype.setSelectedIndex = function(index, duration, callback) {
        var self = this;
        self.list.style.webkitTransition = '';
        var angle = self.correctAngle(self.itemAngle * index);
        if (duration && duration > 0) {
            var distAngle = angle - self.list.angle;
            self.scrollDistAngle(Date.now(), self.list.angle, distAngle, duration);
        } else {
            self.setAngle(angle);
        }
        self.triggerChange(callback);
    };

    Picker.prototype.getSelectedItem = function() {
        var self = this;
        return self.items[self.getSelectedIndex()];
    };

    Picker.prototype.getSelectedValue = function() {
        var self = this;
        return (self.items[self.getSelectedIndex()] || {}).value;
    };

    Picker.prototype.getSelectedText = function() {
        var self = this;
        return (self.items[self.getSelectedIndex()] || {}).text;
    };

    Picker.prototype.setSelectedValue = function(value, duration, callback) {
        var self = this;
        for (var index in self.items) {
            var item = self.items[index];
            if (item.value == value) {
                self.setSelectedIndex(index, duration, callback);
                return;
            }
        }
    };

    if ($.fn) {
        $.fn.picker = function(options) {
            //遍历选择的元素
            this.each(function(i, element) {
                if (element.picker) return;
                if (options) {
                    element.picker = new Picker(element, options);
                } else {
                    var optionsText = element.getAttribute('data-picker-options');
                    var _options = optionsText ? JSON.parse(optionsText) : {};
                    element.picker = new Picker(element, _options);
                }
            });
            return this[0] ? this[0].picker : null;
        };

        //自动初始化
        $.ready(function() {
            $('.mui-picker').picker();
        });
    }

})(window.mui || window, window, document, undefined);
//end
