<template>
  <div @dragstart.prevent :class="['el-input-number', inputNumberSize ? 'el-input-number--' + inputNumberSize : '', { 'is-disabled': inputNumberDisabled }, { 'is-without-controls': !controls }, { 'is-controls-right': controlsAtRight }]">
    <span class="el-input-number__decrease" role="button" v-if="controls" v-repeat-click="decrease" :class="{ 'is-disabled': minDisabled }" @keydown.enter="decrease">
      <i :class="`el-icon-${controlsAtRight ? 'arrow-down' : 'minus'}`"></i>
    </span>
    <span class="el-input-number__increase" role="button" v-if="controls" v-repeat-click="increase" :class="{ 'is-disabled': maxDisabled }" @keydown.enter="increase">
      <i :class="`el-icon-${controlsAtRight ? 'arrow-up' : 'plus'}`"></i>
    </span>
    <el-input ref="input" :value="currentInputValue" :disabled="inputNumberDisabled" :size="inputNumberSize" :max="max" :min="min" :name="name" :label="label" @keydown.up.native.prevent="increase" @keydown.down.native.prevent="decrease" @blur="handleBlur" @focus="handleFocus" @change="handleInputChange"> </el-input>
  </div>
</template>
<script>
import ElInput from 'element-ui/packages/input';
import Focus from 'element-ui/src/mixins/focus';
import RepeatClick from 'element-ui/src/directives/repeat-click';

export default {
  name: 'ElInputNumber',
  mixins: [Focus('input')],
  inject: {
    elForm: {
      default: ''
    },
    elFormItem: {
      default: ''
    }
  },
  directives: {
    repeatClick: RepeatClick
  },
  components: {
    ElInput
  },
  props: {
    step: {
      type: Number,
      default: 1
    },
    max: {
      type: Number,
      default: Infinity
    },
    min: {
      type: Number,
      default: -Infinity
    },
    value: {},
    disabled: Boolean,
    size: String,
    controls: {
      type: Boolean,
      default: true
    },
    controlsPosition: {
      type: String,
      default: ''
    },
    name: String,
    label: String,
    precision: {
      type: Number,
      validator(val) {
        return val >= 0 && val === parseInt(val, 10);
      }
    }
  },
  data() {
    return {
      currentValue: ''
    };
  },
  watch: {
    value: {
      immediate: true,
      handler(value) {
        let newVal = value === undefined || value === -1 ? value : Number(value);
        if (newVal !== undefined) {
          if (isNaN(newVal)) {
            return;
          }
          if (this.precision !== undefined) {
            newVal = this.toPrecision(newVal, this.precision);
          }
        }
        if (newVal >= this.max) newVal = this.max;
        if (newVal <= this.min) {
          if (newVal == -1) {
            newVal = undefined;
          } else {
            newVal = this.min;
          }
        }
        this.currentValue = newVal;
        this.$emit('input', newVal);
      }
    }
  },
  computed: {
    minDisabled() {
      return this._decrease(this.value, this.step) < this.min;
    },
    maxDisabled() {
      return this._increase(this.value, this.step) > this.max;
    },
    numPrecision() {
      const { value, step, getPrecision, precision } = this;
      const stepPrecision = getPrecision(step);
      if (precision !== undefined) {
        if (stepPrecision > precision) {
          // console.warn('[Element Warn][InputNumber]precision should not be less than the decimal places of step');
        }
        return precision;
      } else {
        return Math.max(getPrecision(value), stepPrecision);
      }
    },
    controlsAtRight() {
      return this.controlsPosition === 'right';
    },
    _elFormItemSize() {
      return (this.elFormItem || {}).elFormItemSize;
    },
    inputNumberSize() {
      return this.size || this._elFormItemSize || (this.$ELEMENT || {}).size;
    },
    inputNumberDisabled() {
      return this.disabled || (this.elForm || {}).disabled;
    },
    currentInputValue() {
      const currentValue = this.currentValue;
      if (typeof currentValue === 'number' && this.precision !== undefined) {
        return currentValue.toFixed(this.precision);
      } else {
        return currentValue;
      }
    }
  },
  methods: {
    toPrecision(num, precision) {
      if (precision === undefined) precision = this.numPrecision;
      return parseFloat(parseFloat(Number(num).toFixed(precision)));
    },
    getPrecision(value) {
      if (value === undefined) return 0;
      const valueString = value.toString();
      const dotPosition = valueString.indexOf('.');
      let precision = 0;
      if (dotPosition !== -1) {
        precision = valueString.length - dotPosition - 1;
      }
      return precision;
    },
    _increase(val, step) {
      if (typeof val !== 'number' && val !== undefined) return this.currentValue;

      const precisionFactor = Math.pow(10, this.numPrecision);
      // Solve the accuracy problem of JS decimal calculation by converting the value to integer.
      return this.toPrecision((precisionFactor * val + precisionFactor * step) / precisionFactor);
    },
    _decrease(val, step) {
      if (typeof val !== 'number' && val !== undefined) return this.currentValue;

      const precisionFactor = Math.pow(10, this.numPrecision);

      return this.toPrecision((precisionFactor * val - precisionFactor * step) / precisionFactor);
    },
    increase() {
      if (this.inputNumberDisabled || this.maxDisabled) return;
      const value = this.value || 0;
      const newVal = this._increase(value, this.step);
      this.setCurrentValue(newVal);
    },
    decrease() {
      if (this.inputNumberDisabled || this.minDisabled) return;
      const value = this.value || 0;
      const newVal = this._decrease(value, this.step);
      this.setCurrentValue(newVal);
    },
    handleBlur(event) {
      this.$emit('blur', event);
      this.$refs.input.setCurrentValue(this.currentInputValue);
    },
    handleFocus(event) {
      this.$emit('focus', event);
    },
    setCurrentValue(newVal) {
      const oldVal = this.currentValue;
      if (typeof newVal === 'number' && this.precision !== undefined) {
        newVal = this.toPrecision(newVal, this.precision);
      }
      if (newVal >= this.max) newVal = this.max;
      if (newVal <= this.min) newVal = this.min;
      if (oldVal === newVal) {
        this.$refs.input.setCurrentValue(this.currentInputValue);
        return;
      }
      this.$emit('input', newVal);
      this.$emit('change', newVal, oldVal);
      this.currentValue = newVal;
    },
    handleInputChange(value) {
      const newVal = value === '' ? undefined : Number(value);
      if (!isNaN(newVal) || value === '') {
        this.setCurrentValue(newVal);
      }
    }
  },
  mounted() {
    let innerInput = this.$refs.input.$refs.input;
    innerInput.setAttribute('role', 'spinbutton');
    innerInput.setAttribute('aria-valuemax', this.max);
    innerInput.setAttribute('aria-valuemin', this.min);
    innerInput.setAttribute('aria-valuenow', this.currentValue);
    innerInput.setAttribute('aria-disabled', this.inputNumberDisabled);
  },
  updated() {
    if (!this.$refs || !this.$refs.input) return;
    const innerInput = this.$refs.input.$refs.input;
    innerInput.setAttribute('aria-valuenow', this.currentValue);
  }
};
</script>
