import PropTypes from '../../../_util/vue-types'
import BaseMixin from '../../../_util/BaseMixin'
import { getOptionProps } from '../../../_util/props-util'
import MonthPanel from '../month/MonthPanel'
import YearPanel from '../year/YearPanel'
import DecadePanel from '../decade/DecadePanel'
function noop () {}
function goMonth (direction) {
  const next = this.value.clone()
  next.add(direction, 'months')
  this.__emit('valueChange', next)
}

function goYear (direction) {
  const next = this.value.clone()
  next.add(direction, 'years')
  this.__emit('valueChange', next)
}

function showIf (condition, el) {
  return condition ? el : null
}

const CalendarHeader = {
  mixins: [BaseMixin],
  props: {
    prefixCls: PropTypes.string,
    value: PropTypes.object,
    // onValueChange: PropTypes.func,
    showTimePicker: PropTypes.bool,
    // onPanelChange: PropTypes.func,
    locale: PropTypes.object,
    enablePrev: PropTypes.any.def(1),
    enableNext: PropTypes.any.def(1),
    disabledMonth: PropTypes.func,
    mode: PropTypes.any,
    monthCellRender: PropTypes.func,
    monthCellContentRender: PropTypes.func,
  },
  data () {
    this.nextMonth = goMonth.bind(this, 1)
    this.previousMonth = goMonth.bind(this, -1)
    this.nextYear = goYear.bind(this, 1)
    this.previousYear = goYear.bind(this, -1)
    return {
      yearPanelReferer: null,
    }
  },
  methods: {
    onMonthSelect (value) {
      this.__emit('panelChange', value, 'date')
      if (this.$listeners.monthSelect) {
        this.__emit('monthSelect', value)
      } else {
        this.__emit('valueChange', value)
      }
    },

    onYearSelect (value) {
      const referer = this.yearPanelReferer
      this.setState({ yearPanelReferer: null })
      this.__emit('panelChange', value, referer)
      this.__emit('valueChange', value)
    },

    onDecadeSelect (value) {
      this.__emit('panelChange', value, 'year')
      this.__emit('valueChange', value)
    },

    monthYearElement (showTimePicker) {
      const props = this.$props
      const prefixCls = props.prefixCls
      const locale = props.locale
      const value = props.value
      const localeData = value.localeData()
      const monthBeforeYear = locale.monthBeforeYear
      const selectClassName = `${prefixCls}-${monthBeforeYear ? 'my-select' : 'ym-select'}`
      const year = (<a
        class={`${prefixCls}-year-select`}
        role='button'
        onClick={showTimePicker ? noop : () => this.showYearPanel('date')}
        title={locale.yearSelect}
      >
        {value.format(locale.yearFormat)}
      </a>)
      const month = (<a
        class={`${prefixCls}-month-select`}
        role='button'
        onClick={showTimePicker ? noop : this.showMonthPanel}
        title={locale.monthSelect}
      >
        {locale.monthFormat ? value.format(locale.monthFormat) : localeData.monthsShort(value)}
      </a>)
      let day
      if (showTimePicker) {
        day = (<a
          class={`${prefixCls}-day-select`}
          role='button'
        >
          {value.format(locale.dayFormat)}
        </a>)
      }
      let my = []
      if (monthBeforeYear) {
        my = [month, day, year]
      } else {
        my = [year, month, day]
      }
      return (<span class={selectClassName}>
        {my}
      </span>)
    },

    showMonthPanel () {
    // null means that users' interaction doesn't change value
      this.__emit('panelChange', null, 'month')
    },

    showYearPanel (referer) {
      this.setState({ yearPanelReferer: referer })
      this.__emit('panelChange', null, 'year')
    },

    showDecadePanel () {
      this.__emit('panelChange', null, 'decade')
    },
  },

  render () {
    const props = getOptionProps(this)
    const {
      prefixCls,
      locale,
      mode,
      value,
      showTimePicker,
      enableNext,
      enablePrev,
      disabledMonth,
    } = props

    let panel = null
    if (mode === 'month') {
      panel = (
        <MonthPanel
          locale={locale}
          defaultValue={value}
          rootPrefixCls={prefixCls}
          onSelect={this.onMonthSelect}
          onYearPanelShow={() => this.showYearPanel('month')}
          disabledDate={disabledMonth}
          cellRender={props.monthCellRender}
          contentRender={props.monthCellContentRender}
        />
      )
    }
    if (mode === 'year') {
      panel = (
        <YearPanel
          locale={locale}
          defaultValue={value}
          rootPrefixCls={prefixCls}
          onSelect={this.onYearSelect}
          onDecadePanelShow={this.showDecadePanel}
        />
      )
    }
    if (mode === 'decade') {
      panel = (
        <DecadePanel
          locale={locale}
          defaultValue={value}
          rootPrefixCls={prefixCls}
          onSelect={this.onDecadeSelect}
        />
      )
    }

    return (<div class={`${prefixCls}-header`}>
      <div style={{ position: 'relative' }}>
        {showIf(enablePrev && !showTimePicker,
          <a
            class={`${prefixCls}-prev-year-btn`}
            role='button'
            onClick={this.previousYear}
            title={locale.previousYear}
          />)}
        {showIf(enablePrev && !showTimePicker,
          <a
            class={`${prefixCls}-prev-month-btn`}
            role='button'
            onClick={this.previousMonth}
            title={locale.previousMonth}
          />)}
        {this.monthYearElement(showTimePicker)}
        {showIf(enableNext && !showTimePicker,
          <a
            class={`${prefixCls}-next-month-btn`}
            onClick={this.nextMonth}
            title={locale.nextMonth}
          />)}
        {showIf(enableNext && !showTimePicker,
          <a
            class={`${prefixCls}-next-year-btn`}
            onClick={this.nextYear}
            title={locale.nextYear}
          />)}
      </div>
      {panel}
    </div>)
  },
}

export default CalendarHeader