const crypto = require('crypto');

class RSAAESEncryption {
    static generateRSAKeyPair(keySize) {
        return new Promise((resolve, reject) => {
            crypto.generateKeyPair('rsa', {
                modulusLength: keySize,
                publicKeyEncoding: { type: 'spki', format: 'pem' },
                privateKeyEncoding: { type: 'pkcs8', format: 'pem' }
            }, (err, publicKey, privateKey) => {
                if (err) {
                    reject(err);
                } else {
                    resolve({ publicKey, privateKey });
                }
            });
        });
    }

    static encryptLargeDataWithRSA(data, publicKeyPEM) {
        const publicKey = crypto.createPublicKey(publicKeyPEM);
        const aesKey = crypto.randomBytes(32); // 256 bits for AES-256

        const encryptedAESKey = crypto.publicEncrypt({
            key: publicKey,
            padding: crypto.constants.RSA_PKCS1_OAEP_PADDING
        }, aesKey);

        const iv = crypto.randomBytes(16); // Initialization Vector for AES
        const cipher = crypto.createCipheriv('aes-256-cbc', aesKey, iv);

        const encryptedData = Buffer.concat([iv, cipher.update(data), cipher.final()]);

        return Buffer.concat([encryptedAESKey, encryptedData]);
    }

    static decryptLargeDataWithRSA(encryptedData, privateKeyPEM) {
        const privateKey = crypto.createPrivateKey(privateKeyPEM);
        const encryptedAESKey = encryptedData.slice(0, 16);
        const encryptedDataOnly = encryptedData.slice(16);
        console.log(encryptedAESKey)

        const aesKey = crypto.privateDecrypt({
            key: privateKey,
            padding: crypto.constants.RSA_PKCS1_OAEP_PADDING
        }, encryptedAESKey);

        const iv = encryptedDataOnly.slice(0, 16);
        const ciphertext = encryptedDataOnly.slice(16);

        const decipher = crypto.createDecipheriv('aes-256-cbc', aesKey, iv);

        return Buffer.concat([decipher.update(ciphertext), decipher.final()]);
    }
}

const privateKeyPEM = `
-----BEGIN RSA PRIVATE KEY-----
MIICXQIBAAKBgQDPtNZz3MCyxGGE5yWqq6r8BUAWIUhHH7UNJ4mrfzOpc9ojRxcNkqq1mgyGetoFHgRWYbU6z/Me1yO5ucgV9FaYU1PnPtX4XlJifor+BzdnzDjCB4VXNFR00brcmrsflDd21aCJlqEpRJhn4d03mm1CspcVDNnEQp4ETBkr0+wymQIDAQABAoGAAYJxmBV5cRq+WjkDXbZtIfnzNpbNkkrdIog4pgo1HPpwc+fJ5rHkOgM02rPuof73k3HuekvT18nQTpBCcvIVLDrObui+HzrUlaZ8AAmhdIYlEkp9pwq4FuShc0EIfGN4GM/nYo9GZBsmvr6ndBAhlQwmxnn+ZAxnsIRuialCB7UCQQDqLPtk41K7i547OPmelbjuFAglKCRf74i5Cik0BkzDwOHauFO0k4Fy7/cKftCChQNGjooryl2Fz3hAaWcLANE1AkEA4xBYP6evLF0CBW4Yb+Qu2IiW2CIH1k+W3c0HlNBySpHFbhpy0H3ht02CDyqlaLRrfxwkF13kZ2PviIN0eL9MVQJBAM7WWF4uI38fvO0WT/Twzd0LuH4JTMen7R1zih03i0pD7bmgod6XgvkgVxXgGQ+PqOsDL6uqHJz6OX67GpavbBkCQQDTJ3L5lyVmuwNTK2PcQbVyteqZCWSCXrcsgisnr4RpZg/UaRIWYsnRnWlyUzVJHmbM6M2DUVRC9YNeTui0FSmVAkAzhKth6fPxOAELHVSf3xf98PXKcAvch52uIm+/2oNGNpJLjd/EpU8vn+x7PoZH0SU4Ll5l27MQw+ulRB3EWolh
-----END RSA PRIVATE KEY-----
`

const encryptedData = Buffer.from("eVEOnrU86BNgEzXE9tMKWJxbjEHRNLTrtH/6uv6+YDekUo+hjBCTY/pnKpgn1AmG4dH5+gQKbEmtZKtT/m584siNefANMhwjIAOIZLo07mqDy8EyY6Rt52xdY0Uy7qq0aTN42vbXbPdAadWyohh7OuhimyDc7J8WP4c+g5h1VlLOUnvzGYdw0KpPnXodvhWVfwY4M607b1pACrnjoAHsPg==", 'base64') 
const decryptedData = RSAAESEncryption.decryptLargeDataWithRSA(encryptedData, privateKeyPEM);
console.log(decryptedData)

// Example usage
// (async () => {
//     try {
//         const keySize = 1024; // Choose an appropriate key size
//         const { publicKey, privateKey } = await RSAAESEncryption.generateRSAKeyPair(keySize);

//         const plaintext = 'Hello, RSA and AES encryption in JavaScript!';
//         const encryptedData = RSAAESEncryption.encryptLargeDataWithRSA(Buffer.from(plaintext), publicKey);

//         console.log('Encrypted Data:', encryptedData.toString('base64'));

//         const decryptedData = RSAAESEncryption.decryptLargeDataWithRSA(encryptedData, privateKey);
//         console.log('Decrypted Data:', decryptedData.toString('utf8'));
//     } catch (error) {
//         console.error('Error:', error);
//     }
// })();