import crypto, { createCipheriv, createDecipheriv, randomBytes } from "node:crypto";

export async function generateKeypair() {
  return crypto.generateKeyPairSync("rsa", {
    modulusLength: 2048,
    publicKeyEncoding: { type: "pkcs1", format: "pem" },
    privateKeyEncoding: { type: "pkcs1", format: "pem" },
  });
}

export async function encrypt(plaintext: string, hexKey: string): Promise<string> {
  const key = Buffer.from(hexKey, "hex");
  const algorithm = "aes-256-cbc"; // Encryption algorithm
  const iv = randomBytes(16); // Initialization vector

  const cipher = createCipheriv(algorithm, key, iv);
  let encrypted = cipher.update(plaintext, "utf8", "hex");
  encrypted += cipher.final("hex");

  // Combine IV and encrypted text
  return iv.toString("hex") + ":" + encrypted;
}

// Decrypt function
export async function decrypt(encryptedText: string, hexKey: string): Promise<string> {
  const key = Buffer.from(hexKey, "hex");
  const algorithm = "aes-256-cbc";
  const textParts = encryptedText.split(":");
  const iv = Buffer.from(textParts[0], "hex");
  const encrypted = textParts[1];

  const decipher = createDecipheriv(algorithm, key, iv);
  let decrypted = decipher.update(encrypted, "hex", "utf8");
  decrypted += decipher.final("utf8");

  return decrypted;
}