<template>
  <div class="el-rate">
    <span
      v-for="item in max"
      class="el-rate__item"
      @mousemove="setCurrentValue(item, $event)"
      @mouseleave="resetCurrentValue"
      @click="selectValue(item)"
      :style="{ cursor: disabled ? 'auto' : 'pointer' }">
      <i
        :class="[classes[item - 1], { 'hover': hoverIndex === item }]"
        class="el-rate__icon"
        :style="getIconStyle(item)">
        <i
          v-if="showDecimalIcon(item)"
          :class="decimalIconClass"
          :style="decimalStyle"
          class="el-rate__decimal">
        </i>
      </i>
    </span>
    <span v-if="showText" class="el-rate__text" :style="{ color: textColor }">{{ text }}</span>
  </div>
</template>

<script type="text/babel">
  import { hasClass } from 'element-ui/src/utils/dom';

  export default {
    name: 'ElRate',

    data() {
      return {
        classMap: {},
        pointerAtLeftHalf: true,
        currentValue: this.value,
        hoverIndex: -1
      };
    },

    props: {
      value: {
        type: Number,
        default: 0
      },
      lowThreshold: {
        type: Number,
        default: 2
      },
      highThreshold: {
        type: Number,
        default: 4
      },
      max: {
        type: Number,
        default: 5
      },
      colors: {
        type: Array,
        default() {
          return ['#F7BA2A', '#F7BA2A', '#F7BA2A'];
        }
      },
      voidColor: {
        type: String,
        default: '#C6D1DE'
      },
      disabledVoidColor: {
        type: String,
        default: '#EFF2F7'
      },
      iconClasses: {
        type: Array,
        default() {
          return ['el-icon-star-on', 'el-icon-star-on', 'el-icon-star-on'];
        }
      },
      voidIconClass: {
        type: String,
        default: 'el-icon-star-off'
      },
      disabledVoidIconClass: {
        type: String,
        default: 'el-icon-star-on'
      },
      disabled: {
        type: Boolean,
        default: false
      },
      allowHalf: {
        type: Boolean,
        default: false
      },
      showText: {
        type: Boolean,
        default: false
      },
      textColor: {
        type: String,
        default: '#1f2d3d'
      },
      texts: {
        type: Array,
        default() {
          return ['极差', '失望', '一般', '满意', '惊喜'];
        }
      },
      textTemplate: {
        type: String,
        default: '{value}'
      }
    },

    computed: {
      text() {
        let result = '';
        if (this.disabled) {
          result = this.textTemplate.replace(/\{\s*value\s*\}/, this.value);
        } else {
          result = this.texts[Math.ceil(this.currentValue) - 1];
        }
        return result;
      },

      decimalStyle() {
        let width = '';
        if (this.disabled) {
          width = `${ this.valueDecimal < 50 ? 0 : 50 }%`;
        }
        if (this.allowHalf) {
          width = '50%';
        }
        return {
          color: this.activeColor,
          width
        };
      },

      valueDecimal() {
        return this.value * 100 - Math.floor(this.value) * 100;
      },

      decimalIconClass() {
        return this.getValueFromMap(this.value, this.classMap);
      },

      voidClass() {
        return this.disabled ? this.classMap.disabledVoidClass : this.classMap.voidClass;
      },

      activeClass() {
        return this.getValueFromMap(this.currentValue, this.classMap);
      },

      colorMap() {
        return {
          lowColor: this.colors[0],
          mediumColor: this.colors[1],
          highColor: this.colors[2],
          voidColor: this.voidColor,
          disabledVoidColor: this.disabledVoidColor
        };
      },

      activeColor() {
        return this.getValueFromMap(this.currentValue, this.colorMap);
      },

      classes() {
        let result = [];
        let i = 0;
        let threshold = this.currentValue;
        if (this.allowHalf && this.currentValue !== Math.floor(this.currentValue)) {
          threshold--;
        }
        for (; i < threshold; i++) {
          result.push(this.activeClass);
        }
        for (; i < this.max; i++) {
          result.push(this.voidClass);
        }
        return result;
      }
    },

    watch: {
      value(val) {
        this.$emit('change', val);
        this.currentValue = val;
        this.pointerAtLeftHalf = this.value !== Math.floor(this.value);
      }
    },

    methods: {
      getValueFromMap(value, map) {
        let result = '';
        if (value <= this.lowThreshold) {
          result = map.lowColor || map.lowClass;
        } else if (value >= this.highThreshold) {
          result = map.highColor || map.highClass;
        } else {
          result = map.mediumColor || map.mediumClass;
        }
        return result;
      },

      showDecimalIcon(item) {
        let showWhenDisabled = this.disabled && this.valueDecimal > 0 && item - 1 < this.value && item > this.value;
        /* istanbul ignore next */
        let showWhenAllowHalf = this.allowHalf &&
          this.pointerAtLeftHalf &&
          item - 0.5 <= this.currentValue &&
          item > this.currentValue;
        return showWhenDisabled || showWhenAllowHalf;
      },

      getIconStyle(item) {
        const voidColor = this.disabled ? this.colorMap.disabledVoidColor : this.colorMap.voidColor;
        return {
          color: item <= this.currentValue ? this.activeColor : voidColor
        };
      },

      selectValue(value) {
        if (this.disabled) {
          return;
        }
        if (this.allowHalf && this.pointerAtLeftHalf) {
          this.$emit('input', this.currentValue);
        } else {
          this.$emit('input', value);
        }
      },

      setCurrentValue(value, event) {
        if (this.disabled) {
          return;
        }
        /* istanbul ignore if */
        if (this.allowHalf) {
          let target = event.target;
          if (hasClass(target, 'el-rate__item')) {
            target = target.querySelector('.el-rate__icon');
          }
          if (hasClass(target, 'el-rate__decimal')) {
            target = target.parentNode;
          }
          this.pointerAtLeftHalf = event.offsetX * 2 <= target.clientWidth;
          this.currentValue = this.pointerAtLeftHalf ? value - 0.5 : value;
        } else {
          this.currentValue = value;
        }
        this.hoverIndex = value;
      },

      resetCurrentValue() {
        if (this.disabled) {
          return;
        }
        if (this.allowHalf) {
          this.pointerAtLeftHalf = this.value !== Math.floor(this.value);
        }
        this.currentValue = this.value;
        this.hoverIndex = -1;
      }
    },

    created() {
      if (!this.value) {
        this.$emit('input', 0);
      }
      this.classMap = {
        lowClass: this.iconClasses[0],
        mediumClass: this.iconClasses[1],
        highClass: this.iconClasses[2],
        voidClass: this.voidIconClass,
        disabledVoidClass: this.disabledVoidIconClass
      };
    }
  };
</script>
