var DatePicker = (function () {

  /**
   * 日历组件
   * @param config {target: DOM, defaultDate: '2017-04-15', selectInterval: [2000, 2020]}
   * @constructor
   */
  function Calendar(config) {

    this.target = function () {
      if (config.el) {
        return config.el;
      } else {
        throw "The el option is required";
      }
    }();
    this.trigger = function () {
      if (config.trigger) {
        return config.trigger;
      } else {
        throw "The trigger option is required";
      }
    }();
    this.defaultDate = config.default || 'today';
    this.isRadio = !!(config.isRadio);
    this.lang = (config.lang == 'CN') ? config.lang : 'EN';
    this.position = config.position || 'bottom';
    this.selectInterval = config.interval || [1970, 2030];
    this.isShow = true;

    this.showFn = config.showFn || function () {
      };
    this.hideFn = config.hideFn || function () {
      };
    this.onchange = config.onchange || function () {
      };
    // 当前日历数据
    this.nonceYear = 0;
    this.nonceMonth = 0;
    this.nonceDay = 0;

    // 选中的数据
    this.selectedDate = {
      begin: {
        year: 0,
        month: 0,
        day: 0
      },
      end: {
        year: 0,
        month: 0,
        day: 0
      }
    };
    // 日期数组
    this.renderDate = [];
    this.init();
  }

  // DatePicker = Calendar;
  var utils = {
    // 惰性载入
    bind: function (el, event, listener) {
      if (el.addEventListener) {
        this.bind = function (el, event, listener) {
          el.addEventListener(event, listener);
        }
      } else if (el.attachEvent) {
        this.bind = function (el, event, listener) {
          el.attachEvent.call(el, event, listener);
        }
      } else {
        this.bind = function (el, event, listener) {
          el.on[event] = listener;
        }
      }
      return this.bind.apply(this, arguments);
    },
    delegates: function (tagName, fn) {
      return function (e) {
        var event = e || window.event,
          target = event.target || event.srcElement;
        if (target.tagName.toLowerCase() === tagName) {
          fn.call(null, target);
        }
      }
    },

    addClass: function (el, className) {

      var ol = el.className;
      if (ol.split(' ').indexOf(className) === -1) {
        el.className = ol + " " + className;
      }

    },

    removeClass: function (el, className) {
      ([]).forEach.call(el, function (ele) {

        var ol = ele.className,
          reg = new RegExp("(\\s)*" + className);
        ele.className = ol.replace(reg, '');
      });


    }
  }

  Calendar.prototype = {
    constructor: Calendar,

    show: function () {
      this.target.style.display = 'inline-block';
      this.isShow = true;
      this.target.style.position = 'absolute';

      var triggerW = this.trigger.offsetWidth,
        triggerH = this.trigger.offsetHeight,
        offTop = this.trigger.offsetTop,
        offLeft = this.trigger.offsetLeft;

      var targetW = this.target.offsetWidth,
        targetH = this.target.offsetHeight;
      var leftAttr, topAttr;
      if (this.position == 'top') {
        leftAttr = offLeft;
        topAttr = offTop - targetH;
      } else if (this.position == 'right') {
        leftAttr = offLeft + triggerW;
        topAttr = offTop;
      } else if (this.position == 'left') {
        leftAttr = offLeft - targetW;
        topAttr = offTop;
      } else {
        leftAttr = offLeft;
        topAttr = offTop + triggerH;
      }
      this.target.style.left = leftAttr + 'px';
      this.target.style.top = topAttr + 'px';
      this.showFn();
    },

    hide: function () {
      this.target.style.display = 'none';
      this.isShow = false;
      this.hideFn();
    },

    get: function () {
      var self = this;

      function format(attr) {
        // 结束日期为空时，不显示
        if (attr == 'end'
          && !self.selectedDate[attr].year) {
          return;
        }
        return self.selectedDate[attr].year +
          '-' +
          (self.selectedDate[attr].month + 1) +
          '-' +
          self.selectedDate[attr].day;
      }

      var currBegin = format('begin')
        , currEnd = format('end');
      if (this.isRadio) {
        return currBegin;
      } else {
        return [currBegin, currEnd];
      }
    },
    /**
     * 初始化
     */
    init: function () {
      this.hide();
      // compute select year
      var yearOpts = this._productOptions(this.selectInterval, this.lang == 'CN' ? '年' : '');
      var dateOpts = this._productOptions([1, 12], this.lang == 'CN' ? '月' : '');
      // 初始化布局
      var navTop = "<div class='calendar-wrapper'>" +
        "<div class='calendar-header'>" +
        "<span class='leftArrow'></span>" +
        "<div class='calendar-mid'>" +
        "<select class='year'>" +
        yearOpts +
        "</select>" +
        "<select class='date'>" +
        dateOpts +
        "</select>" +
        "</div>" +
        "<span class='rightArrow'></span>" +
        "</div>" +
        "</div>";

      this.target.innerHTML = navTop;

      this._setDefault();

      this.eventListener();
    },
    /**
     * 生成选项
     * @param between
     * @param concat
     * @returns {string}
     * @private
     */
    _productOptions: function (between, concat) {
      var opts = "";
      for (var i = between[0]; i <= between[1]; i++) {
        opts += "<option value='" + i + "'>" +
          i + concat +
          "</option>";
      }
      return opts;
    },
    /**
     * 设置默认的日期
     * @private
     */
    _setDefault: function () {
      var defaultD = this.defaultDate,
        self = this;
      if (defaultD === 'today') {
        var d = new Date();
        self.nonceYear = d.getFullYear();
        self.nonceMonth = d.getMonth();
        self.nonceDay = d.getDate();
      } else {
        var relate = defaultD.split('-');
        if (relate.length <= 1)
          throw "default option is invalid, please check the options and reset `YYYY-mm-dd` or `YYYY-mm`";
        else {
          self.nonceYear = relate[0];
          self.nonceMonth = +relate[1] - 1;
          self.nonceDay = relate[2] || 1;
        }
      }
      // 设置选中的默认年份与月份
      self.selectedDate.begin.year = self.nonceYear;
      self.selectedDate.begin.month = self.nonceMonth;
      self._setDateList();


    },

    /**
     *  处理日期数组
     * @returns {Array}
     * @private
     */
    _setDateList: function () {
      /*一个月的第一天星期几*/
      var whatday = new Date(this.nonceYear, this.nonceMonth, 1).getDay();

      var monthMuchDay = [31,
        (this.nonceYear % 4 === 0 && (this.nonceYear % 100 !== 0 || this.nonceYear % 400 === 0))
          ? 29 : 28
        , 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

      var renderList = [],
        /*4/16 Fixed 当前月为1月份，手动设置上一个月为12月份*/
        prevMonthDays = this.nonceMonth - 1 > 0 ? monthMuchDay[this.nonceMonth - 1] : 31,
        nonceMonthDays = monthMuchDay[this.nonceMonth];
      /*一个月的最后一天星期几*/
      var monthLastDay = new Date(this.nonceYear, this.nonceMonth, nonceMonthDays).getDay();

      /*前置补空*/
      var prevOnce = whatday, obj;
      while (prevOnce > 0) {
        obj = {
          isInner: false,
          num: prevMonthDays--
        };
        prevOnce--;
        renderList.unshift(obj);
      }
      /*当前月天数*/
      for (var i = 1; i <= nonceMonthDays; i++) {
        obj = {
          isInner: true,
          num: i
        };
        renderList.push(obj);
      }
      /*后置补空*/
      for (var i = 1; monthLastDay < 6; monthLastDay++, i++) {
        obj = {
          isInner: false,
          num: i
        };
        renderList.push(obj);
      }
      this.renderDate = renderList;

      this._doRender(renderList);
    },
    /**
     * 根据日期数组渲染DOM
     * @param arr
     * @private
     */
    _doRender: function (arr) {

      var self = this,
        lang = {
          'EN': ['Sun', 'Mon', 'Tue', 'Wed', 'Thur', 'Fri', 'Sat'],
          'CN': ['日', '一', '二', '三', '四', '五', '六']
        },
        label = lang[self.lang].map(function (ele, i) {
          if (i == 0 || lang.length - 1) {
            return "<li class='weekend'>" + ele + "</li>"
          } else {
            return "<li>" + ele + "</li>"
          }
        }),
        selectedBgTs = +new Date(self.selectedDate.begin.year,
          self.selectedDate.begin.month,
          self.selectedDate.begin.day),
        selectedEndTs = +new Date(self.selectedDate.end.year,
          self.selectedDate.end.month,
          self.selectedDate.end.day);

      var date = "<ul class='weekTip'>" +
        label.join('') +
        "</ul>";

      date += "<ul class='date'>";


      arr.forEach(function (ele, ind) {
        var line = Math.floor(ind / 6)
          , currTs = +new Date(self.nonceYear, self.nonceMonth, ele.num);
        // 非这个月的日子
        if (!ele.isInner)
          date += "<li class='disabled'>" + ele.num + "</li>";
        // 选中的开始日子
        else if (ele.num === self.selectedDate.begin.day &&
          self.nonceMonth === self.selectedDate.begin.month &&
          self.nonceYear === self.selectedDate.begin.year)
          date += "<li class='abled active'>" + ele.num + "</li>";
        // 选中的结束日子
        else if (ele.num === self.selectedDate.end.day &&
          self.nonceMonth === self.selectedDate.end.month &&
          self.nonceYear === self.selectedDate.end.year)
          date += "<li class='abled active'>" + ele.num + "</li>";
        // 间隔的日子
        else if (currTs > selectedBgTs && currTs < selectedEndTs)
          date += "<li class='abled across'>" + ele.num + "</li>";
        // 周末的日子
        else if (!(ind % 7) || ind === line * 6 + line - 1)
          date += "<li class='weekend'>" + ele.num + "</li>";
        // 未选中的日子
        else
          date += "<li class='abled'>" + ele.num + "</li>";
      });

      date += "</ul>";

      var dateContainer = document.createElement('div');
      dateContainer.className = 'dateWrap';
      dateContainer.innerHTML = date;

      var header = this.target.querySelector(" .calendar-header");
      // add
      var fload;
      if (fload = (header.nextElementSibling)) {
        header.parentNode.replaceChild(dateContainer, fload);
      } else {
        header.parentNode.insertBefore(dateContainer, null);
      }

      this._selected(" .year option", this.nonceYear);
      this._selected(" .date option", this.nonceMonth + 1);
    },
    /**
     *  默认选中年份和月份选择框
     *  2017/07/21 fixed
     *  `<option selected>2012</option>
     *  <option>2013</option>`
     *  先removeAttribute(2012)，再setAttribute(2013)。2013不能被选中，改用opt.select=Boolean
     * @param selector
     * @param tag
     * @private
     */
    _selected: function (selector, tag) {
      var options = this.target.querySelectorAll(selector);
      ([]).forEach.call(options, function (opt) {
        opt.selected = opt.value === tag.toString()
      });
    },

    /**
     * 上一个月的操作
     * @private
     */
    _prevMonth: function () {
      if (this.nonceMonth === 0) {
        this.nonceYear--;
        this.nonceMonth = 11;
      } else {
        this.nonceMonth--;
      }
      this._setDateList();
    },

    /**
     * 下一个月的操作
     * @private
     */
    _nextMonth: function () {
      if (this.nonceMonth === 11) {
        this.nonceYear++;
        this.nonceMonth = 0;
      } else {
        this.nonceMonth++;
      }
      this._setDateList();
    },

    /**
     * 各种事件监听
     */
    eventListener: function () {
      var self = this;
      /**
       * 左箭头监听
       */
      utils.bind(self.target.querySelector(".leftArrow"),
        'click',
        function () {
          self._prevMonth();
        });

      /**
       * 右箭头监听
       */
      utils.bind(self.target.querySelector(".rightArrow"),
        'click',
        function () {
          self._nextMonth();
        });

      /**
       * 日期点击监听
       * 2017/4/14 fixed：用事件冒泡的方式监听动态添加元素的绑定事件
       */
      utils.bind(document,
        'click',
        utils.delegates(
          'li',
          function (t) {
            // 父元素不是ul.date时跳出
            if (!t.parentNode.classList.contains('date')) return;

            if (self.isRadio) {
              selectRadio(self, 'begin', t);
            } else {
              selectRange(self, t);
            }

            self._setDateList();

            self.onchange(self.get());

            // 判断是否为范围选择
            if (!self.isRadio && self.selectedDate.end.year) {
              self.hide();
            } else if (self.isRadio) {
              self.hide();
            }
          }
        )
      );

      // 选一个日期时
      function selectRadio(oDate, type, target) {
        oDate.selectedDate[type].day = +(target.innerHTML);
        // 点击的是非本月的日期
        var clkId = [].indexOf.call(target.parentElement.children, target);
        if (!oDate.renderDate[clkId].isInner) {
          if (oDate.selectedDate[type].day > 15) {
            oDate.selectedDate[type].month = (oDate.nonceMonth - 1 < 0) ? 11 : oDate.nonceMonth - 1;
            oDate._prevMonth();
          } else {
            oDate.selectedDate[type].month = (oDate.nonceMonth + 1 >= 12) ? 0 : oDate.nonceMonth + 1;
            oDate._nextMonth();
          }
        } else {
          oDate.selectedDate[type].month = oDate.nonceMonth;
        }

        oDate.selectedDate[type].year = oDate.nonceYear;
      }

      // 选日期范围
      function selectRange(oDate, target) {
        var oSelected = self.selectedDate
          , isSelEnd = (!!oSelected.end.year)
          , isSelBg = (!!oSelected.begin.day)
          , day = +(target.innerHTML);

        // 选中的日期是否在开始日期前面
        function isSelFront() {
          // 选择下一个月的日期时
          if (/disabled/.test(target.className)) {
            return !(day < 15);
          } else {
            return (
              +new Date(self.nonceYear, self.nonceMonth, day)
              < +new Date(oSelected.begin.year, oSelected.begin.month, oSelected.begin.day)
            )
          }
        }

        // 未选择起始时间 || 将选择的时间在begin前面
        if (!isSelBg || (!isSelEnd && isSelFront())) {
          selectRadio.call(null, oDate, 'begin', target)
        }
        // 未选择截止时间
        else if (isSelBg && !isSelEnd) {
          selectRadio.call(null, oDate, 'end', target)
        } else {
          selectRadio.call(null, oDate, 'begin', target)
          oSelected.end.year = 0;
        }

      }

      /**
       * 年份选择框监听
       */
      utils.bind(self.target.querySelector("select.year"),
        'change',
        function (e) {
          self.nonceYear = e.target.value;
          self._setDateList();

        });

      /**
       * 月份选择框监听
       */
      utils.bind(self.target.querySelector("select.date"),
        'change',
        function (e) {
          self.nonceMonth = e.target.value - 1;
          self._setDateList();

        });

      /**
       * 点击非日历处隐藏日历
       */
      utils.bind(document,
        'click',
        function (e) {
          var showDP = self.isShow,
            t = e.target,
            breakReg = /dateWrap|calendar\-wrapper/;
          while (t) {
            if (t == self.trigger || t.className && t.className.search(breakReg) != -1) {
              showDP = false;
              break;
            }
            t = t.parentNode
          }
          if (showDP) {
            self.hide();
            return true;
          }
        })
    }
  }
  return Calendar;
})();

!window.DatePicker && (window.DatePicker = DatePicker);