import crypto from 'crypto'

/**
 * At-rest encryption for WooCommerce consumer key/secret.
 *
 * AES-256-GCM with a dedicated env key, mirroring the Skatteverket token
 * store (extensions/general/skatteverket/lib/token-store.ts): 12-byte IV,
 * 16-byte auth tag, layout iv|tag|ciphertext, base64url encoded. The key is
 * deployment-wide (not per-tenant); what makes rows useless off-server is
 * that WOOCOMMERCE_CREDENTIALS_ENCRYPTION_KEY never leaves the environment.
 */

const ALGORITHM = 'aes-256-gcm'

/** Whether the integration is configured on this deployment. */
export function isWooCommerceConfigured(): boolean {
  return Boolean(process.env.WOOCOMMERCE_CREDENTIALS_ENCRYPTION_KEY)
}

function getEncryptionKey(): Buffer {
  const key = process.env.WOOCOMMERCE_CREDENTIALS_ENCRYPTION_KEY
  if (!key) throw new Error('WOOCOMMERCE_CREDENTIALS_ENCRYPTION_KEY is required')
  return crypto.createHash('sha256').update(key).digest()
}

export function encryptCredential(plaintext: string): string {
  const key = getEncryptionKey()
  const iv = crypto.randomBytes(12)
  const cipher = crypto.createCipheriv(ALGORITHM, key, iv)
  const encrypted = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()])
  const tag = cipher.getAuthTag()
  return Buffer.concat([iv, tag, encrypted]).toString('base64url')
}

export function decryptCredential(ciphertext: string): string {
  const key = getEncryptionKey()
  const combined = Buffer.from(ciphertext, 'base64url')
  const iv = combined.subarray(0, 12)
  const tag = combined.subarray(12, 28)
  const encrypted = combined.subarray(28)
  const decipher = crypto.createDecipheriv(ALGORITHM, key, iv)
  decipher.setAuthTag(tag)
  return Buffer.concat([decipher.update(encrypted), decipher.final()]).toString('utf8')
}