// Credentials encryption/decryption using Web Crypto API
document.addEventListener('DOMContentLoaded', function() {
    const decryptButtons = document.querySelectorAll('.decrypt-btn');

    decryptButtons.forEach(button => {
        button.addEventListener('click', async function() {
            const id = this.dataset.id;
            const encryptedDiv = document.getElementById('encrypted-' + id);
            const decryptedDiv = document.getElementById('decrypted-' + id);

            // Get master password
            const password = prompt('Введите мастер-пароль:');
            if (!password) return;

            try {
                const encryptedBase64 = encryptedDiv.textContent.trim();
                const decrypted = await decrypt(encryptedBase64, password);

                // Parse and display decrypted content
                const data = JSON.parse(decrypted);

                let html = '';
                for (const [key, value] of Object.entries(data)) {
                    const label = formatLabel(key);
                    html += `<div class="field-row">
                        <span class="field-label">${label}:</span>
                        <span class="field-value">${value}</span>
                    </div>`;
                }

                decryptedDiv.innerHTML = html;
                decryptedDiv.style.display = 'block';
                encryptedDiv.style.display = 'none';
                this.textContent = 'Скрыть';
                this.classList.remove('btn-primary');
                this.classList.add('btn-secondary');

                // Change button to toggle
                this.onclick = function() {
                    if (decryptedDiv.style.display === 'none') {
                        decryptedDiv.style.display = 'block';
                        encryptedDiv.style.display = 'none';
                        this.textContent = 'Скрыть';
                    } else {
                        decryptedDiv.style.display = 'none';
                        encryptedDiv.style.display = 'block';
                        this.textContent = 'Расшифровать';
                    }
                };
            } catch (error) {
                console.error('Decryption error:', error);
                alert('Ошибка расшифровки. Проверьте мастер-пароль.');
            }
        });
    });
});

function formatLabel(key) {
    const labels = {
        'user': 'Пользователь',
        'password': 'Пароль',
        'host': 'Хост',
        'port': 'Порт',
        'database': 'База данных',
        'notes': 'Заметки',
        'ip': 'IP',
        'auth': 'Авторизация',
        'vpn': 'VPN'
    };
    return labels[key] || key;
}

// Derive encryption key from password using PBKDF2
async function deriveKey(password, salt) {
    const encoder = new TextEncoder();
    const keyMaterial = await crypto.subtle.importKey(
        'raw',
        encoder.encode(password),
        { name: 'PBKDF2' },
        false,
        ['deriveBits', 'deriveKey']
    );

    return crypto.subtle.deriveKey(
        {
            name: 'PBKDF2',
            salt: salt,
            iterations: 100000,
            hash: 'SHA-256'
        },
        keyMaterial,
        { name: 'AES-GCM', length: 256 },
        false,
        ['encrypt', 'decrypt']
    );
}

// Decrypt data
async function decrypt(encryptedBase64, password) {
    const encryptedData = Uint8Array.from(atob(encryptedBase64), c => c.charCodeAt(0));

    // Extract salt (first 16 bytes), IV (next 12 bytes), and ciphertext
    const salt = encryptedData.slice(0, 16);
    const iv = encryptedData.slice(16, 28);
    const ciphertext = encryptedData.slice(28);

    const key = await deriveKey(password, salt);

    const decrypted = await crypto.subtle.decrypt(
        { name: 'AES-GCM', iv: iv },
        key,
        ciphertext
    );

    return new TextDecoder().decode(decrypted);
}

// Encrypt data (for creating new credentials)
async function encrypt(plaintext, password) {
    const encoder = new TextEncoder();
    const salt = crypto.getRandomValues(new Uint8Array(16));
    const iv = crypto.getRandomValues(new Uint8Array(12));

    const key = await deriveKey(password, salt);

    const ciphertext = await crypto.subtle.encrypt(
        { name: 'AES-GCM', iv: iv },
        key,
        encoder.encode(plaintext)
    );

    // Combine salt + iv + ciphertext
    const combined = new Uint8Array(16 + 12 + ciphertext.byteLength);
    combined.set(salt, 0);
    combined.set(iv, 16);
    combined.set(new Uint8Array(ciphertext), 28);

    return btoa(String.fromCharCode(...combined));
}

// Utility function for encrypting credentials (can be used in console)
window.encryptCreds = async function(data, password) {
    const json = JSON.stringify(data);
    return await encrypt(json, password);
};