script.js

const passwordOutput = document.getElementById('password-output');
const copyBtn = document.getElementById('copy-btn');
const strengthBar = document.getElementById('strength-bar');
const strengthText = document.getElementById('strength-text');

const lengthSlider = document.getElementById('length-slider');
const lengthVal = document.getElementById('length-val');

const uppercaseToggle = document.getElementById('uppercase');
const lowercaseToggle = document.getElementById('lowercase');
const numbersToggle = document.getElementById('numbers');
const symbolsToggle = document.getElementById('symbols');
const excludeAmbiguousToggle = document.getElementById('exclude-ambiguous');

const generateBtn = document.getElementById('generate-btn');

// Character sets
const CHARS = {
    uppercase: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
    lowercase: 'abcdefghijklmnopqrstuvwxyz',
    numbers: '0123456789',
    symbols: '!@#$%^&*()_+~`|}{[]:;?><,./-=',
    ambiguous: 'il1Oo0I'
};

// Sync length slider value
lengthSlider.addEventListener('input', (e) => {
    lengthVal.textContent = e.target.value;
});

// Secure Random Generation
function secureRandomIndex(max) {
    const array = new Uint32Array(1);
    window.crypto.getRandomValues(array);
    return array[0] % max;
}

function calculateEntropy(length, poolSize) {
    if (poolSize === 0) return 0;
    return length * Math.log2(poolSize);
}

function updateStrengthMeter(entropy) {
    let strength = 0;
    let text = 'Very Weak';
    let colorClass = '';

    if (entropy <= 0) {
        strength = 0;
        text = 'None';
    } else if (entropy < 40) {
        strength = 1;
        text = 'Weak';
    } else if (entropy < 60) {
        strength = 2;
        text = 'Fair';
    } else if (entropy < 80) {
        strength = 3;
        text = 'Good';
    } else {
        strength = 4;
        text = 'Strong';
    }

    strengthBar.setAttribute('data-strength', strength);
    strengthText.textContent = text;
    
    // Change text color based on strength
    const colors = ['var(--text-secondary)', 'var(--danger)', 'var(--warning)', '#a371f7', 'var(--success)'];
    strengthText.style.color = colors[strength];
}

function generatePassword() {
    let pool = '';
    const length = parseInt(lengthSlider.value, 10);
    
    const useUpper = uppercaseToggle.checked;
    const useLower = lowercaseToggle.checked;
    const useNums = numbersToggle.checked;
    const useSyms = symbolsToggle.checked;
    const excludeAmbiguous = excludeAmbiguousToggle.checked;

    if (useUpper) pool += CHARS.uppercase;
    if (useLower) pool += CHARS.lowercase;
    if (useNums) pool += CHARS.numbers;
    if (useSyms) pool += CHARS.symbols;

    if (excludeAmbiguous) {
        const ambiguousRegex = new RegExp(`[${CHARS.ambiguous}]`, 'g');
        pool = pool.replace(ambiguousRegex, '');
    }

    if (pool.length === 0) {
        passwordOutput.value = '';
        updateStrengthMeter(0);
        return;
    }

    let password = '';
    
    // Ensure at least one character from each selected pool if length permits
    const guaranteedChars = [];
    if (useUpper) {
        let uPool = CHARS.uppercase;
        if (excludeAmbiguous) uPool = uPool.replace(new RegExp(`[${CHARS.ambiguous}]`, 'g'), '');
        if (uPool.length > 0) guaranteedChars.push(uPool[secureRandomIndex(uPool.length)]);
    }
    if (useLower) {
        let lPool = CHARS.lowercase;
        if (excludeAmbiguous) lPool = lPool.replace(new RegExp(`[${CHARS.ambiguous}]`, 'g'), '');
        if (lPool.length > 0) guaranteedChars.push(lPool[secureRandomIndex(lPool.length)]);
    }
    if (useNums) {
        let nPool = CHARS.numbers;
        if (excludeAmbiguous) nPool = nPool.replace(new RegExp(`[${CHARS.ambiguous}]`, 'g'), '');
        if (nPool.length > 0) guaranteedChars.push(nPool[secureRandomIndex(nPool.length)]);
    }
    if (useSyms) {
        let sPool = CHARS.symbols;
        // usually symbols don't have ambiguous chars, but just in case
        if (sPool.length > 0) guaranteedChars.push(sPool[secureRandomIndex(sPool.length)]);
    }

    // Fill the rest
    for (let i = guaranteedChars.length; i < length; i++) {
        password += pool[secureRandomIndex(pool.length)];
    }

    // Shuffle the result including guaranteed characters
    const passwordArray = [...guaranteedChars, ...password.split('')];
    for (let i = passwordArray.length - 1; i > 0; i--) {
        const j = secureRandomIndex(i + 1);
        [passwordArray[i], passwordArray[j]] = [passwordArray[j], passwordArray[i]];
    }

    const finalPassword = passwordArray.join('');
    // Truncate if guaranteed chars pushed it over length, which shouldn't happen for length > 4
    passwordOutput.value = finalPassword.slice(0, length);

    // Calculate strength based on entropy
    const entropy = calculateEntropy(length, pool.length);
    updateStrengthMeter(entropy);
}

// Copy to Clipboard
async function copyToClipboard() {
    const password = passwordOutput.value;
    if (!password || password === "Click 'Generate'") return;

    try {
        await navigator.clipboard.writeText(password);
        
        // UI feedback
        copyBtn.innerHTML = '<i class="fa-solid fa-check"></i>';
        copyBtn.classList.add('copied');
        
        setTimeout(() => {
            copyBtn.innerHTML = '<i class="fa-regular fa-copy"></i>';
            copyBtn.classList.remove('copied');
        }, 2000);
    } catch (err) {
        console.error('Failed to copy text: ', err);
        // Fallback for older browsers
        passwordOutput.select();
        document.execCommand('copy');
    }
}

// Event Listeners
generateBtn.addEventListener('click', generatePassword);
copyBtn.addEventListener('click', copyToClipboard);

// Auto-generate on toggle change
const toggles = [
    lengthSlider, uppercaseToggle, lowercaseToggle, 
    numbersToggle, symbolsToggle, excludeAmbiguousToggle
];

toggles.forEach(toggle => {
    toggle.addEventListener('change', () => {
        // Only auto-generate if a password has already been generated once or is empty
        if (passwordOutput.value !== "Click 'Generate'") {
            generatePassword();
        }
    });
});