script.js

/**
 * @license
 * Copyright © 2026 Ashraf Morningstar
 * https://github.com/AshrafMorningstar
 * 
 * Licensed under the MIT License.
 * This is a personal educational recreation.
 * Original project concepts remain property of their respective creators.
 */

/*
 Copyright (c) 2026 Ashraf Morningstar
 These are personal recreations of existing projects, developed by Ashraf Morningstar
 for learning and skill development.
 Original project concepts remain the intellectual property of their respective creators.
 Repository: https://github.com/AshrafMorningstar
*/

// Screen element reference
const screen = document.getElementById('displayResult');
screen.value = '0';

// Limit for input length
const INPUT_LIMIT = 20;

// Counter for open parentheses
let openParentheses = 0;

function handleInput(input) {
    if (screen.value === 'Error') {
        resetScreen();
    }

    // Handle special cases for math functions
    if (typeof input === 'string' && input.startsWith('Math.')) {
        if (screen.value === '0') {
            screen.value = input;
        } else {
            screen.value += input;
        }
        if (input.endsWith('(')) {
            openParentheses++;
        }
        return;
    }

    // Prevent multiple decimal points in a number
    if (input === '.' && screen.value.split(/[\+\-\*\/]/).pop().includes('.')) {
        return;
    }

    // Enforce input length limit
    if (screen.value.length >= INPUT_LIMIT) {
        return;
    }

    if (screen.value === '0' && input !== '.') {
        screen.value = input;
    } else {
        screen.value += input;
    }
}

function resetScreen() {
    screen.value = '0';
    openParentheses = 0;
}

function removeLastChar() {
    if (screen.value === 'Error') {
        resetScreen();
        return;
    }

    if (screen.value.length > 1) {
        // Adjust parentheses counter when removing parentheses
        if (screen.value.endsWith('(')) {
            openParentheses--;
        } else if (screen.value.endsWith(')')) {
            openParentheses++;
        }
        screen.value = screen.value.slice(0, -1);
    } else {
        screen.value = '0';
    }
}

function evaluateExpression() {
    try {
        // Auto-close any unclosed parentheses
        let expr = screen.value;
        while (openParentheses > 0) {
            expr += ')';
            openParentheses--;
        }

        // Replace symbols for multiplication and division
        expr = expr.replace(/×/g, '*').replace(/÷/g, '/');

        // Validate the expression
        if (!/^[0-9+\-*/(). Math\w]+$/.test(expr)) {
            throw new Error('Invalid input');
        }

        // Evaluate and format the result
        let result = eval(expr);

        // Handle division by zero
        if (!isFinite(result)) {
            throw new Error('Cannot divide by zero');
        }

        // Format the result
        if (Number.isInteger(result)) {
            screen.value = result.toString();
        } else {
            screen.value = parseFloat(result.toFixed(8)).toString();
        }
    } catch (err) {
        screen.value = 'Error';
        setTimeout(resetScreen, 2000);
    }
}

// Add keyboard functionality
document.addEventListener('keydown', (e) => {
    const key = e.key;

    // Prevent default actions for calculator keys
    if (key.match(/[\d+\-*/.=Enter]/) || key === 'Backspace' || key === 'Escape') {
        e.preventDefault();
    }

    // Handle input keys
    if (key.match(/[\d.]/)) {
        handleInput(key);
    } else if (key.match(/[+\-*\/]/)) {
        handleInput(key);
    } else if (key === 'Enter' || key === '=') {
        evaluateExpression();
    } else if (key === 'Backspace') {
        removeLastChar();
    } else if (key === 'Escape') {
        resetScreen();
    }
});

// These are personal recreations of existing projects, developed by Ashraf Morningstar for learning and skill development. Original project concepts remain the intellectual property of their respective creators.
https://github.com/AshrafMorningstar