<template>
  <div ref="outerWrapper" :class="wrapperClasses">
    <div v-if="isHorizontal" :class="`${prefix}-horizontal`">
      <div :style="{right: `${anotherOffset}%`}" :class="[`${prefix}-pane`, 'left-pane']"><slot name="left"/></div>
      <div :class="`${prefix}-trigger-con`" :style="{left: `${offset}%`}" @mousedown="handleMousedown">
        <slot name="trigger">
          <trigger mode="vertical"/>
        </slot>
      </div>
      <div :style="{left: `${offset}%`}" :class="[`${prefix}-pane`, 'right-pane']"><slot name="right"/></div>
    </div>
    <div v-else :class="`${prefix}-vertical`">
      <div :style="{bottom: `${anotherOffset}%`}" :class="[`${prefix}-pane`, 'top-pane']"><slot name="top"/></div>
     <div :class="`${prefix}-trigger-con`" :style="{top: `${offset}%`}" @mousedown="handleMousedown">
        <slot name="trigger">
          <trigger mode="horizontal"/>
        </slot>
      </div>
      <div :style="{top: `${offset}%`}" :class="[`${prefix}-pane`, 'bottom-pane']"><slot name="bottom"/></div>
    </div>
  </div>
</template>

<script>
import { oneOf } from '../../utils/assist';
import { on, off } from '../../utils/dom';
import Trigger from './trigger.vue'
export default {
  name: 'Split',
  components: {
    Trigger
  },
  props: {
    value: {
      type: [Number, String],
      default: 0.5
    },
    mode: {
      validator (value) {
        return oneOf(value, ['horizontal', 'vertical'])
      },
      default: 'horizontal'
    },
    min: {
      type: [Number, String],
      default: '40px'
    },
    max: {
      type: [Number, String],
      default: '40px'
    }
  },
  /**
   * Events
   * @on-move-start
   * @on-moving 返回值：事件对象，但是在事件对象中加入了两个参数：atMin(当前是否在最小值处), atMax(当前是否在最大值处)
   * @on-move-end
   */
  data () {
    return {
      prefix: 'ivu-split',
      offset: 0,
      oldOffset: 0,
      isMoving: false
    }
  },
  computed: {
    wrapperClasses () {
      return [
        `${this.prefix}-wrapper`,
        this.isMoving ? 'no-select' : ''
      ]
    },
    isHorizontal () {
      return this.mode === 'horizontal'
    },
    anotherOffset () {
      return 100 - this.offset
    },
    valueIsPx () {
      return typeof this.value === 'string'
    },
    offsetSize () {
      return this.isHorizontal ? 'offsetWidth' : 'offsetHeight'
    },
    computedMin () {
      return this.getComputedThresholdValue('min')
    },
    computedMax () {
      return this.getComputedThresholdValue('max')
    }
  },
  methods: {
    px2percent (numerator, denominator) {
      return parseFloat(numerator) / parseFloat(denominator)
    },
    getComputedThresholdValue (type) {
      let size = this.$refs.outerWrapper[this.offsetSize]
      if (this.valueIsPx) return typeof this[type] === 'string' ? this[type] : size * this[type]
      else return typeof this[type] === 'string' ? this.px2percent(this[type], size) : this[type]
    },
    getMin (value1, value2) {
      if (this.valueIsPx) return `${Math.min(parseFloat(value1), parseFloat(value2))}px`
      else return Math.min(value1, value2)
    },
    getMax (value1, value2) {
      if (this.valueIsPx) return `${Math.max(parseFloat(value1), parseFloat(value2))}px`
      else return Math.max(value1, value2)
    },
    getAnotherOffset (value) {
      let res = 0
      if (this.valueIsPx) res = `${this.$refs.outerWrapper[this.offsetSize] - parseFloat(value)}px`
      else res = 1 - value
      return res
    },
    handleMove (e) {
      let pageOffset = this.isHorizontal ? e.pageX : e.pageY
      let offset = pageOffset - this.initOffset
      let outerWidth = this.$refs.outerWrapper[this.offsetSize]
      let value = this.valueIsPx ? `${parseFloat(this.oldOffset) + offset}px` : (this.px2percent(outerWidth * this.oldOffset + offset, outerWidth))
      let anotherValue = this.getAnotherOffset(value)
      if (parseFloat(value) <= parseFloat(this.computedMin)) value = this.getMax(value, this.computedMin)
      if (parseFloat(anotherValue) <= parseFloat(this.computedMax)) value = this.getAnotherOffset(this.getMax(anotherValue, this.computedMax))
      e.atMin = this.value === this.computedMin
      e.atMax = this.valueIsPx ? this.getAnotherOffset(this.value) === this.computedMax : this.getAnotherOffset(this.value).toFixed(5) === this.computedMax.toFixed(5)
      this.$emit('input', value)
      this.$emit('on-moving', e)
    },
    handleUp () {
      this.isMoving = false
      off(document, 'mousemove', this.handleMove)
      off(document, 'mouseup', this.handleUp)
      this.$emit('on-move-end')
    },
    handleMousedown (e) {
      this.initOffset = this.isHorizontal ? e.pageX : e.pageY
      this.oldOffset = this.value
      this.isMoving = true
      on(document, 'mousemove', this.handleMove)
      on(document, 'mouseup', this.handleUp)
      this.$emit('on-move-start')
    }
  },
  watch: {
    value () {
      this.offset = (this.valueIsPx ? this.px2percent(this.value, this.$refs.outerWrapper[this.offsetSize]) : this.value) * 10000 / 100
    }
  },
  mounted () {
    this.$nextTick(() => {
      this.offset = (this.valueIsPx ? this.px2percent(this.value, this.$refs.outerWrapper[this.offsetSize]) : this.value) * 10000 / 100
    })
  }
}
</script>
