<template>
  <div class="calculator">
 
    <!-- 當前運算過程顯示區(qū)域 -->
    <div class="expression">{{ currentExpression }}</div>
 
    <!-- 計算器顯示屏 -->
    <div class="display">{{ displayValue }}</div>
 
    <!-- 按鈕區(qū)域 -->
    <div class="buttons">
      <el-button @click="clear">AC</el-button>
      <el-button @click="toggleSign">+/-</el-button>
      <el-button @click="inputPercent">%</el-button>
      <el-button @click="inputOperator('÷')" style="font-size: 22px;">÷</el-button>
 
      <el-button @click="inputDigit(7)">7</el-button>
      <el-button @click="inputDigit(8)">8</el-button>
      <el-button @click="inputDigit(9)">9</el-button>
      <el-button @click="inputOperator('*')">*</el-button>
 
      <el-button @click="inputDigit(4)">4</el-button>
      <el-button @click="inputDigit(5)">5</el-button>
      <el-button @click="inputDigit(6)">6</el-button>
      <el-button @click="inputOperator('-')">-</el-button>
 
      <el-button @click="inputDigit(1)">1</el-button>
      <el-button @click="inputDigit(2)">2</el-button>
      <el-button @click="inputDigit(3)">3</el-button>
      <el-button @click="inputOperator('+')">+</el-button>
 
      <el-button @click="inputDigit(0)" class="zero">0</el-button>
      <el-button @click="inputDot">.</el-button>
      <el-button @click="calculate">=</el-button>
    </div>
  </div>
</template>
 
<script>
  export default {
    data() {
      return {
        displayValue: '0', // 顯示的值
        firstOperand: null, // 第一個操作數(shù)
        waitingForSecondOperand: false, // 是否等待第二個操作數(shù)
        operator: null, // 當前的操作符
        currentExpression: '' // 用于存儲當前運算過程
      };
    },
    methods: {
      // 輸入數(shù)字
      inputDigit(digit) {
        // 如果運算結束并開始輸入新數(shù)字，清空計算過程和顯示屏
        if (this.firstOperand !== null && this.operator === null) {
          this.displayValue = String(digit);
          this.currentExpression = ''; // 清空當前運算過程
          this.firstOperand = null; // 重置操作數(shù)
        } else if (this.waitingForSecondOperand) {
          this.displayValue = String(digit);
          this.waitingForSecondOperand = false;
        } else {
          this.displayValue = this.displayValue === '0' ? String(digit) : this.displayValue + String(digit);
        }
        this.updateExpression();
      },
      // 輸入小數(shù)點
      inputDot() {
        if (!this.displayValue.includes('.')) {
          this.displayValue += '.';
        }
        this.updateExpression();
      },
      // 處理運算符
      inputOperator(nextOperator) {
        const inputValue = parseFloat(this.displayValue);
 
        if (this.operator && this.waitingForSecondOperand) {
          this.operator = nextOperator;
          this.updateExpression();
          return;
        }
 
        if (this.firstOperand === null) {
          this.firstOperand = inputValue;
        } else if (this.operator) {
          const result = this.performCalculation(this.firstOperand, inputValue, this.operator);
          this.displayValue = String(result);
          this.firstOperand = result;
        }
 
        this.waitingForSecondOperand = true;
        this.operator = nextOperator;
        this.updateExpression();
      },
      // 執(zhí)行計算
      performCalculation(firstOperand, secondOperand, operator) {
        switch (operator) {
          case '+':
            return firstOperand + secondOperand;
          case '-':
            return firstOperand - secondOperand;
          case '*':
            return firstOperand * secondOperand;
          case '÷':
            return firstOperand / secondOperand;
          default:
            return secondOperand;
        }
      },
      // 計算結果
      calculate() {
        // 如果未輸入第二個操作數(shù)，直接返回，不執(zhí)行計算
        if (this.operator && this.waitingForSecondOperand) {
          return;
        }
        if (this.operator) {
          const inputValue = parseFloat(this.displayValue);
          const secondOperand = this.waitingForSecondOperand ? this.firstOperand : inputValue; // 如果沒有第二個操作數(shù)，則使用第一個操作數(shù)
 
          const result = this.performCalculation(this.firstOperand, secondOperand, this.operator);
 
          // 完整地記錄本次運算過程
          this.currentExpression = `${this.firstOperand} ${this.operator} ${secondOperand} = ${result}`;
 
          this.displayValue = String(result);
          this.firstOperand = result;
          this.operator = null;
          this.waitingForSecondOperand = false;
        }
      },
      // 清除
      clear() {
        this.displayValue = '0';
        this.firstOperand = null;
        this.operator = null;
        this.waitingForSecondOperand = false;
        this.currentExpression = ''; // 清空當前運算過程
      },
      // 刪除最后一個輸入的字符
      deleteLast() {
        this.displayValue = this.displayValue.length > 1 ? this.displayValue.slice(0, -1) : '0';
        this.updateExpression();
      },
      // 改變符號
      toggleSign() {
        this.displayValue = String(parseFloat(this.displayValue) * -1);
        this.updateExpression();
      },
      // 處理百分比
      inputPercent() {
        this.displayValue = String(parseFloat(this.displayValue) / 100);
        this.updateExpression();
      },
      // 更新當前運算過程的顯示內(nèi)容
      updateExpression() {
        if (this.firstOperand !== null && this.operator) {
          // 如果還未輸入第二個操作數(shù)，不顯示 displayValue
          this.currentExpression = this.waitingForSecondOperand ?
            `${this.firstOperand} ${this.operator}` :
            `${this.firstOperand} ${this.operator} ${this.displayValue}`;
        } else {
          this.currentExpression = this.displayValue;
        }
        console.log('this.currentExpression', this.currentExpression)
      }
    }
  };
</script>
 
<style scoped>
  .calculator {
    width: 400px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f1f1f1;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  }
 
  .expression {
    min-height: 30px;
    color: #888;
    text-align: right;
    font-size: 16px;
    margin-bottom: 5px;
  }
 
  .display {
    width: 100%;
    min-height: 60px;
    background-color: #333;
    color: white;
    text-align: right;
    padding: 10px;
    font-size: 24px;
    border-radius: 5px;
    margin-bottom: 10px;
    word-wrap: break-word;
  }
 
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
  }
 
  button {
    width: 100%;
    font-size: 18px;
    border-radius: 5px;
    background-color: #fff;
    border: 1px solid #ccc;
  }
 
  .zero {
    grid-column: span 2;
  }
 
  >>>.el-button+.el-button {
    margin-left: 0;
  }
</style>

import Calculator from '@/components/common/calculator'
 
export default {
    components:{
        Calculator
    },
}

<Calculator></Calculator>