import argon2 from 'argon2';

// Hash a password
export async function hashPassword(password: string): Promise<string> {
  return argon2.hash(password, {
    type: argon2.argon2id,
    memoryCost: 65536,   // 64 MB
    timeCost: 3,
    parallelism: 1,
  });
}

// Verify a password
export async function verifyPassword(hash: string, password: string): Promise<boolean> {
  return argon2.verify(hash, password);
}

// bcrypt fallback (cost 12+ required in production)
import bcrypt from 'bcrypt';

const SALT_ROUNDS = 12;

export async function hashPassword(password: string): Promise<string> {
  return bcrypt.hash(password, SALT_ROUNDS);
}

export async function verifyPassword(hash: string, password: string): Promise<boolean> {
  return bcrypt.compare(password, hash);
}

import { randomBytes, createCipheriv, createDecipheriv } from 'crypto';

const ALGORITHM = 'aes-256-gcm';
const KEY_LENGTH = 32; // 256 bits
const IV_LENGTH = 12;  // 96 bits - recommended for GCM
const TAG_LENGTH = 16; // 128 bits

export function encrypt(plaintext: string, key: Buffer): {
  ciphertext: string;
  iv: string;
  tag: string;
} {
  const iv = randomBytes(IV_LENGTH);
  const cipher = createCipheriv(ALGORITHM, key, iv, { authTagLength: TAG_LENGTH });

  const encrypted = Buffer.concat([
    cipher.update(plaintext, 'utf8'),
    cipher.final(),
  ]);

  return {
    ciphertext: encrypted.toString('base64'),
    iv: iv.toString('base64'),
    tag: cipher.getAuthTag().toString('base64'),
  };
}

export function decrypt(
  ciphertext: string,
  iv: string,
  tag: string,
  key: Buffer
): string {
  const decipher = createDecipheriv(
    ALGORITHM,
    key,
    Buffer.from(iv, 'base64'),
    { authTagLength: TAG_LENGTH }
  );

  decipher.setAuthTag(Buffer.from(tag, 'base64'));

  return Buffer.concat([
    decipher.update(Buffer.from(ciphertext, 'base64')),
    decipher.final(),
  ]).toString('utf8');
}

// Generate a key (store in KMS, never hardcode)
export function generateKey(): Buffer {
  return randomBytes(KEY_LENGTH);
}

import { SignJWT, jwtVerify, generateKeyPair } from 'jose';

// Generate a key pair once (store private key in secrets manager)
export async function generateJwtKeys() {
  return generateKeyPair('ES256'); // prefer ES256 over RS256 - smaller, faster
}

// Sign a JWT
export async function signToken(
  payload: Record<string, unknown>,
  privateKey: CryptoKey
): Promise<string> {
  return new SignJWT(payload)
    .setProtectedHeader({ alg: 'ES256' })
    .setIssuedAt()
    .setExpirationTime('15m')      // short-lived access tokens
    .setIssuer('https://your-api.example.com')
    .setAudience('https://your-api.example.com')
    .sign(privateKey);
}

// Verify a JWT
export async function verifyToken(
  token: string,
  publicKey: CryptoKey
): Promise<Record<string, unknown>> {
  const { payload } = await jwtVerify(token, publicKey, {
    issuer: 'https://your-api.example.com',
    audience: 'https://your-api.example.com',
    algorithms: ['ES256'], // explicit allowlist - never omit this
  });
  return payload as Record<string, unknown>;
}

import https from 'https';
import fs from 'fs';

const server = https.createServer(
  {
    key: fs.readFileSync('/etc/ssl/private/server.key'),
    cert: fs.readFileSync('/etc/ssl/certs/server.crt'),
    ca: fs.readFileSync('/etc/ssl/certs/ca.crt'), // optional: chain file

    minVersion: 'TLSv1.3',
    // If TLSv1.2 is required for legacy clients:
    // minVersion: 'TLSv1.2',
    // ciphers: [
    //   'TLS_AES_256_GCM_SHA384',
    //   'TLS_CHACHA20_POLY1305_SHA256',
    //   'ECDHE-RSA-AES256-GCM-SHA384',
    // ].join(':'),

    honorCipherOrder: true,
  },
  app
);

import { createHmac, timingSafeEqual } from 'crypto';

const WEBHOOK_SECRET = process.env.WEBHOOK_SECRET!;
const TIMESTAMP_TOLERANCE_SECONDS = 300; // 5 minutes - prevent replay attacks

export function signWebhookPayload(payload: string, timestamp: number): string {
  const message = `${timestamp}.${payload}`;
  return createHmac('sha256', WEBHOOK_SECRET).update(message).digest('hex');
}

export function verifyWebhookSignature(
  payload: string,
  signature: string,
  timestamp: number
): boolean {
  // Reject stale requests
  const now = Math.floor(Date.now() / 1000);
  if (Math.abs(now - timestamp) > TIMESTAMP_TOLERANCE_SECONDS) {
    return false;
  }

  const expected = signWebhookPayload(payload, timestamp);
  const expectedBuf = Buffer.from(expected, 'hex');
  const receivedBuf = Buffer.from(signature, 'hex');

  // Buffers must be equal length for timingSafeEqual
  if (expectedBuf.length !== receivedBuf.length) {
    return false;
  }

  return timingSafeEqual(expectedBuf, receivedBuf);
}

// Pseudo-implementation showing the envelope encryption + rotation pattern
interface EncryptedRecord {
  ciphertext: string;
  iv: string;
  tag: string;
  encryptedDek: string;  // DEK wrapped by KEK from KMS
  keyVersion: string;    // which KEK version was used
}

// Encryption: generate a fresh DEK per record (or per session)
async function encryptWithEnvelope(plaintext: string, kmsClient: KMSClient): Promise<EncryptedRecord> {
  const dek = generateKey(); // random 256-bit DEK
  const { ciphertext, iv, tag } = encrypt(plaintext, dek);

  // KMS wraps (encrypts) the DEK - the DEK never leaves your process in plaintext
  const { encryptedDek, keyVersion } = await kmsClient.encryptKey(dek);
  dek.fill(0); // zero out DEK from memory immediately after use

  return { ciphertext, iv, tag, encryptedDek, keyVersion };
}

// Key rotation: re-wrap the DEK with the new KEK version, no data re-encryption needed
async function rotateKey(record: EncryptedRecord, kmsClient: KMSClient): Promise<EncryptedRecord> {
  const dek = await kmsClient.decryptKey(record.encryptedDek, record.keyVersion);
  const { encryptedDek, keyVersion } = await kmsClient.encryptKey(dek, 'latest');
  dek.fill(0);
  return { ...record, encryptedDek, keyVersion };
}

import { randomBytes } from 'crypto';

// URL-safe base64 token (default 32 bytes = 256 bits)
export function generateToken(bytes = 32): string {
  return randomBytes(bytes).toString('base64url');
}

// Hex token (for systems that require hex)
export function generateHexToken(bytes = 32): string {
  return randomBytes(bytes).toString('hex');
}

// Numeric OTP (e.g., 6-digit)
export function generateOtp(digits = 6): string {
  const max = 10 ** digits;
  const value = Number(randomBytes(4).readUInt32BE(0)) % max;
  return value.toString().padStart(digits, '0');
}