<template>
  <transition name="el-zoom-in-top" @after-leave="$emit('dodestroy')">
    <div
      v-show="visible"
      class="el-picker-panel el-date-range-picker el-popper"
      :class="[
        {
          'has-sidebar': $slots.sidebar || shortcuts
        },
        popperClass
      ]"
    >
      <div class="el-picker-panel__body-wrapper">
        <slot name="sidebar" class="el-picker-panel__sidebar"></slot>
        <div class="el-picker-panel__sidebar" v-if="shortcuts">
          <button
            type="button"
            class="el-picker-panel__shortcut"
            v-for="(shortcut, key) in shortcuts"
            :key="key"
            @click="handleShortcutClick(shortcut)"
          >
            {{ shortcut.text }}
          </button>
        </div>
        <div class="el-picker-panel__body">
          <div
            class="el-picker-panel__content el-date-range-picker__content is-left"
          >
            <div class="el-date-range-picker__header">
              <button
                type="button"
                @click="leftPrevYear"
                class="el-picker-panel__icon-btn el-icon-d-arrow-left"
              ></button>
              <button
                type="button"
                v-if="unlinkPanels"
                @click="leftNextYear"
                :disabled="!enableYearArrow"
                :class="{ 'is-disabled': !enableYearArrow }"
                class="el-picker-panel__icon-btn el-icon-d-arrow-right"
              ></button>
              <div>{{ leftLabel }}</div>
            </div>
            <month-table
              selection-mode="range"
              :date="leftDate"
              :default-value="defaultValue"
              :min-date="minDate"
              :max-date="maxDate"
              :range-state="rangeState"
              :disabled-date="disabledDate"
              @changerange="handleChangeRange"
              @pick="handleRangePick"
            >
            </month-table>
          </div>
          <div
            class="el-picker-panel__content el-date-range-picker__content is-right"
          >
            <div class="el-date-range-picker__header">
              <button
                type="button"
                v-if="unlinkPanels"
                @click="rightPrevYear"
                :disabled="!enableYearArrow"
                :class="{ 'is-disabled': !enableYearArrow }"
                class="el-picker-panel__icon-btn el-icon-d-arrow-left"
              ></button>
              <button
                type="button"
                @click="rightNextYear"
                class="el-picker-panel__icon-btn el-icon-d-arrow-right"
              ></button>
              <div>{{ rightLabel }}</div>
            </div>
            <month-table
              selection-mode="range"
              :date="rightDate"
              :default-value="defaultValue"
              :min-date="minDate"
              :max-date="maxDate"
              :range-state="rangeState"
              :disabled-date="disabledDate"
              @changerange="handleChangeRange"
              @pick="handleRangePick"
            >
            </month-table>
          </div>
        </div>
      </div>
    </div>
  </transition>
</template>

<script type="text/babel">
import {
  isDate,
  modifyWithTimeString,
  prevYear,
  nextYear,
  nextMonth
} from '../../../../src/utils/date-util'
import Clickoutside from '../../../../src/directives/clickoutside'
import Locale from '../../../../src/mixins/locale'
import MonthTable from '../basic/month-table'
import { ElInput } from '../../../../src/components/Input'
import { ElButton } from '../../../../src/components/Button'
import { useDateEmitter } from '../../index'

const calcDefaultValue = (defaultValue) => {
  if (Array.isArray(defaultValue)) {
    return [new Date(defaultValue[0]), new Date(defaultValue[1])]
  } else if (defaultValue) {
    return [new Date(defaultValue), nextMonth(new Date(defaultValue))]
  } else {
    return [new Date(), nextMonth(new Date())]
  }
}
export default {
  mixins: [Locale],

  directives: { Clickoutside },

  computed: {
    btnDisabled() {
      return !(
        this.minDate &&
        this.maxDate &&
        !this.selecting &&
        this.isValidValue([this.minDate, this.maxDate])
      )
    },

    leftLabel() {
      return this.leftDate.getFullYear() + ' ' + this.t('el.datepicker.year')
    },

    rightLabel() {
      return this.rightDate.getFullYear() + ' ' + this.t('el.datepicker.year')
    },

    leftYear() {
      return this.leftDate.getFullYear()
    },

    rightYear() {
      return this.rightDate.getFullYear() === this.leftDate.getFullYear()
        ? this.leftDate.getFullYear() + 1
        : this.rightDate.getFullYear()
    },

    enableYearArrow() {
      return this.unlinkPanels && this.rightYear > this.leftYear + 1
    }
  },

  data() {
    return {
      popperClass: '',
      value: [],
      defaultValue: null,
      defaultTime: null,
      minDate: '',
      maxDate: '',
      leftDate: new Date(),
      rightDate: nextYear(new Date()),
      rangeState: {
        endDate: null,
        selecting: false,
        row: null,
        column: null
      },
      shortcuts: '',
      visible: '',
      disabledDate: '',
      format: '',
      arrowControl: false,
      unlinkPanels: false
    }
  },

  watch: {
    value(newVal) {
      if (!newVal) {
        this.minDate = null
        this.maxDate = null
      } else if (Array.isArray(newVal)) {
        this.minDate = isDate(newVal[0]) ? new Date(newVal[0]) : null
        this.maxDate = isDate(newVal[1]) ? new Date(newVal[1]) : null
        if (this.minDate) {
          this.leftDate = this.minDate
          if (this.unlinkPanels && this.maxDate) {
            const minDateYear = this.minDate.getFullYear()
            const maxDateYear = this.maxDate.getFullYear()
            this.rightDate =
              minDateYear === maxDateYear
                ? nextYear(this.maxDate)
                : this.maxDate
          } else {
            this.rightDate = nextYear(this.leftDate)
          }
        } else {
          this.leftDate = calcDefaultValue(this.defaultValue)[0]
          this.rightDate = nextYear(this.leftDate)
        }
      }
    },

    defaultValue(val) {
      if (!Array.isArray(this.value)) {
        const [left, right] = calcDefaultValue(val)
        this.leftDate = left
        this.rightDate =
          val &&
          val[1] &&
          left.getFullYear() !== right.getFullYear() &&
          this.unlinkPanels
            ? right
            : nextYear(this.leftDate)
      }
    }
  },

  methods: {
    handleClear() {
      this.minDate = null
      this.maxDate = null
      this.leftDate = calcDefaultValue(this.defaultValue)[0]
      this.rightDate = nextYear(this.leftDate)
      this.trigger('pick', null)
    },

    handleChangeRange(val) {
      this.minDate = val.minDate
      this.maxDate = val.maxDate
      this.rangeState = val.rangeState
    },

    handleRangePick(val, close = true) {
      const defaultTime = this.defaultTime || []
      const minDate = modifyWithTimeString(val.minDate, defaultTime[0])
      const maxDate = modifyWithTimeString(val.maxDate, defaultTime[1])
      if (this.maxDate === maxDate && this.minDate === minDate) {
        return
      }
      this.onPick && this.onPick(val)
      this.maxDate = maxDate
      this.minDate = minDate

      // workaround for https://github.com/ElemeFE/element/issues/7539, should remove this block when we don't have to care about Chromium 55 - 57
      setTimeout(() => {
        this.maxDate = maxDate
        this.minDate = minDate
      }, 10)
      if (!close) return
      this.handleConfirm()
    },

    handleShortcutClick(shortcut) {
      if (shortcut.onClick) {
        shortcut.onClick(this)
      }
    },

    // leftPrev*, rightNext* need to take care of `unlinkPanels`
    leftPrevYear() {
      this.leftDate = prevYear(this.leftDate)
      if (!this.unlinkPanels) {
        this.rightDate = prevYear(this.rightDate)
      }
    },

    rightNextYear() {
      if (!this.unlinkPanels) {
        this.leftDate = nextYear(this.leftDate)
      }
      this.rightDate = nextYear(this.rightDate)
    },

    // leftNext*, rightPrev* are called when `unlinkPanels` is true
    leftNextYear() {
      this.leftDate = nextYear(this.leftDate)
    },

    rightPrevYear() {
      this.rightDate = prevYear(this.rightDate)
    },

    handleConfirm(visible = false) {
      if (this.isValidValue([this.minDate, this.maxDate])) {
        this.trigger('pick', [this.minDate, this.maxDate], visible)
      }
    },

    isValidValue(value) {
      return (
        Array.isArray(value) &&
        value &&
        value[0] &&
        value[1] &&
        isDate(value[0]) &&
        isDate(value[1]) &&
        value[0].getTime() <= value[1].getTime() &&
        (typeof this.disabledDate === 'function'
          ? !this.disabledDate(value[0]) && !this.disabledDate(value[1])
          : true)
      )
    },

    resetView() {
      // NOTE: this is a hack to reset {min, max}Date on picker open.
      // TODO: correct way of doing so is to refactor {min, max}Date to be dependent on value and internal selection state
      //       an alternative would be resetView whenever picker becomes visible, should also investigate date-panel's resetView
      this.minDate =
        this.value && isDate(this.value[0]) ? new Date(this.value[0]) : null
      this.maxDate =
        this.value && isDate(this.value[0]) ? new Date(this.value[1]) : null
    }
  },

  // eslint-disable-next-line vue/no-unused-components
  components: { MonthTable, ElInput, ElButton },
  setup() {
    const { trigger, on } = useDateEmitter()
    return { trigger, on }
  }
}
</script>
