// pages/calculator/calculator.ts
Page({
  data: {
    displayValue: '0',
    history: '',
    operator: null as string | null,
    firstOperand: null as number | null,
    waitingForSecondOperand: false,
  },

  onLoad() {
  },

  onDigit(e: any) {
    const digit = e.currentTarget.dataset.digit;
    const { displayValue, waitingForSecondOperand } = this.data;

    if (waitingForSecondOperand) {
      this.setData({
        displayValue: digit,
        waitingForSecondOperand: false
      });
    } else {
      this.setData({
        displayValue: displayValue === '0' ? digit : displayValue + digit
      });
    }
  },

  onDot() {
    const { displayValue, waitingForSecondOperand } = this.data;
    if (waitingForSecondOperand) {
      this.setData({
        displayValue: '0.',
        waitingForSecondOperand: false
      });
    } else if (displayValue.indexOf('.') === -1) {
      this.setData({
        displayValue: displayValue + '.'
      });
    }
  },

  onClear() {
    this.setData({
      displayValue: '0',
      history: '',
      operator: null,
      firstOperand: null,
      waitingForSecondOperand: false
    });
  },

  onDelete() {
    const { displayValue } = this.data;
    this.setData({
      displayValue: displayValue.length > 1 ? displayValue.slice(0, -1) : '0'
    });
  },

  onOperator(e: any) {
    const nextOperator = e.currentTarget.dataset.op;
    const { displayValue, operator, firstOperand } = this.data;
    const inputValue = parseFloat(displayValue);

    if (operator && this.data.waitingForSecondOperand) {
      this.setData({ 
        operator: nextOperator,
        history: `${firstOperand} ${nextOperator}`
      });
      return;
    }

    let newFirstOperand = firstOperand;

    if (firstOperand == null) {
      newFirstOperand = inputValue;
    } else if (operator) {
      const result = this.performCalculation(operator, firstOperand, inputValue);
      newFirstOperand = result;
      this.setData({
        displayValue: String(result),
      });
    }

    this.setData({
      firstOperand: newFirstOperand,
      waitingForSecondOperand: true,
      operator: nextOperator,
      history: `${newFirstOperand} ${nextOperator}`
    });
  },

  onEqual() {
    const { displayValue, operator, firstOperand } = this.data;
    const inputValue = parseFloat(displayValue);

    if (operator && firstOperand != null) {
      const result = this.performCalculation(operator, firstOperand, inputValue);
      this.setData({
        displayValue: String(result),
        firstOperand: null,
        operator: null,
        waitingForSecondOperand: true,
        history: ''
      });
    }
  },

  performCalculation(operator: string, firstOperand: number, secondOperand: number) {
    switch (operator) {
      case '+':
        return firstOperand + secondOperand;
      case '-':
        return firstOperand - secondOperand;
      case '*':
        return firstOperand * secondOperand;
      case '/':
        return firstOperand / secondOperand;
      case '%':
        return firstOperand % secondOperand;
      default:
        return secondOperand;
    }
  }
});