<template>
  <view class="uni-numbox">
    <v-btn
      icon="mdi-minus" 
      size="x-small" 
      :disabled="inputValue <= min || disabled" 
      @click="_calcValue('minus')"
    ></v-btn>
    <input
      :disabled="disabled"
      @focus="_onFocus"
      @blur="_onBlur"
      class="uni-numbox__value inputItem mx-2"
      type="number"
      v-model="inputValue"
      :style="{ color }"
    />
    <v-btn
      icon="mdi-plus" 
      size="x-small" 
      :disabled="inputValue >= max || disabled" 
      @click="_calcValue('plus')"
    ></v-btn>
    <div class="ml-3" style="color: #b7b7b7; font-size: 14px;">库存：{{ totalStock }}</div>
  </view>
</template>
<script>
  /**
   * NumberBox 数字输入框
   * @description 带加减按钮的数字输入框
   * @tutorial https://ext.dcloud.net.cn/plugin?id=31
   * @property {Number} value 输入框当前值
   * @property {Number} min 最小值
   * @property {Number} max 最大值
   * @property {Number} step 每次点击改变的间隔大小
   * @property {String} background 背景色
   * @property {String} color 字体颜色（前景色）
   * @property {Boolean} disabled = [true|false] 是否为禁用状态
   * @event {Function} change 输入框值改变时触发的事件，参数为输入框当前的 value
   * @event {Function} focus 输入框聚焦时触发的事件，参数为 event 对象
   * @event {Function} blur 输入框失焦时触发的事件，参数为 event 对象
   */

  export default {
    name: 'UniNumberBox',
    emits: ['change', 'input', 'update:modelValue', 'blur', 'focus'],
    props: {
      value: {
        type: [Number, String],
        default: 1,
      },
      modelValue: {
        type: [Number, String],
        default: 1,
      },
      min: {
        type: Number,
        default: 0,
      },
      max: {
        type: Number,
        default: 100,
      },
      totalStock: {
        type: Number,
        default: 0,
      },
      step: {
        type: Number,
        default: 1,
      },
      background: {
        type: String,
        default: '#f5f5f5',
      },
      color: {
        type: String,
        default: '#333',
      },
      disabled: {
        type: Boolean,
        default: false,
      },
      activity: {
        type: String,
        default: 'none',
      },
    },
    data() {
      return {
        inputValue: 0,
        stock: 0,
      };
    },
    watch: {
      value(val) {
        this.inputValue = +val;
      },
      modelValue(val) {
        this.inputValue = +val;
      },
      max(val) {
        this.inputValue = this.inputValue-0 > + val ? + val : this.inputValue;
      },
    },
    created() {
      if (this.value === 1) {
        this.inputValue = +this.modelValue;
      }
      if (this.modelValue === 1) {
        this.inputValue = +this.value;
      }
    },
    methods: {
      _calcValue(type) {
        if (this.disabled) {
          return;
        }
        const scale = this._getDecimalScale();
        let value = this.inputValue * scale;
        let step = this.step * scale;
        if (type === 'minus') {
          value -= step;
          if (value < this.min * scale) {
            return;
          }
          if (value > this.max * scale) {
            value = this.max * scale;
          }
        }

        if (type === 'plus') {
          value += step;
          if (value > this.max * scale) {
            return;
          }
          if (value < this.min * scale) {
            value = this.min * scale;
          }
        }

        this.inputValue = (value / scale).toFixed(String(scale).length - 1);
        this.$emit('change', +this.inputValue);
        // TODO vue2 兼容
        this.$emit('input', +this.inputValue);
        // TODO vue3 兼容
        this.$emit('update:modelValue', +this.inputValue);
      },
      _getDecimalScale() {
        let scale = 1;
        // 浮点型
        if (~~this.step !== this.step) {
          scale = Math.pow(10, String(this.step).split('.')[1].length);
        }
        return scale;
      },
      _onBlur(event) {
        let value = this.inputValue;
        this.$emit('blur', value);
        value = +value;
        if (value > this.max) {
          value = this.max;
        } else if (value < this.min) {
          value = this.min;
        }
        const scale = this._getDecimalScale();
        this.inputValue = value.toFixed(String(scale).length - 1);
        this.$emit('change', +this.inputValue);
        this.$emit('input', +this.inputValue);
      },
      _onFocus(event) {
        this.$emit('focus', event);
      },
    },
  };
</script>
<style lang="scss" scoped>
input::-webkit-outer-spin-button, input::-webkit-inner-spin-button{
  -webkit-appearance: none !important;
  margin: 0; 
}
.inputItem {
  width: 70px; 
  border: 1px solid #eee; 
  padding: 2px 5px; 
  text-align: center;
}
</style>
