import { createCipheriv, createDecipheriv, randomBytes } from 'crypto'
import { createLogger } from '@sim/logger'
import { env } from '@/lib/core/config/env'

const logger = createLogger('ApiKeyCrypto')

/**
 * Get the API encryption key from the environment
 * @returns The API encryption key
 */
function getApiEncryptionKey(): Buffer | null {
  const key = env.API_ENCRYPTION_KEY
  if (!key) {
    logger.warn(
      'API_ENCRYPTION_KEY not set - API keys will be stored in plain text. Consider setting this for better security.'
    )
    return null
  }
  if (key.length !== 64) {
    throw new Error('API_ENCRYPTION_KEY must be a 64-character hex string (32 bytes)')
  }
  return Buffer.from(key, 'hex')
}

/**
 * Encrypts an API key using the dedicated API encryption key
 * @param apiKey - The API key to encrypt
 * @returns A promise that resolves to an object containing the encrypted API key and IV
 */
export async function encryptApiKey(apiKey: string): Promise<{ encrypted: string; iv: string }> {
  const key = getApiEncryptionKey()

  // If no API encryption key is set, return the key as-is for backward compatibility
  if (!key) {
    return { encrypted: apiKey, iv: '' }
  }

  const iv = randomBytes(16)
  const cipher = createCipheriv('aes-256-gcm', key, iv)
  let encrypted = cipher.update(apiKey, 'utf8', 'hex')
  encrypted += cipher.final('hex')

  const authTag = cipher.getAuthTag()

  // Format: iv:encrypted:authTag
  return {
    encrypted: `${iv.toString('hex')}:${encrypted}:${authTag.toString('hex')}`,
    iv: iv.toString('hex'),
  }
}

/**
 * Decrypts an API key using the dedicated API encryption key
 * @param encryptedValue - The encrypted value in format "iv:encrypted:authTag" or plain text
 * @returns A promise that resolves to an object containing the decrypted API key
 */
export async function decryptApiKey(encryptedValue: string): Promise<{ decrypted: string }> {
  // Check if this is actually encrypted (contains colons)
  if (!encryptedValue.includes(':') || encryptedValue.split(':').length !== 3) {
    // This is a plain text key, return as-is
    return { decrypted: encryptedValue }
  }

  const key = getApiEncryptionKey()

  // If no API encryption key is set, assume it's plain text
  if (!key) {
    return { decrypted: encryptedValue }
  }

  const parts = encryptedValue.split(':')
  const ivHex = parts[0]
  const authTagHex = parts[parts.length - 1]
  const encrypted = parts.slice(1, -1).join(':')

  if (!ivHex || !encrypted || !authTagHex) {
    throw new Error('Invalid encrypted API key format. Expected "iv:encrypted:authTag"')
  }

  const iv = Buffer.from(ivHex, 'hex')
  const authTag = Buffer.from(authTagHex, 'hex')

  try {
    const decipher = createDecipheriv('aes-256-gcm', key, iv)
    decipher.setAuthTag(authTag)

    let decrypted = decipher.update(encrypted, 'hex', 'utf8')
    decrypted += decipher.final('utf8')

    return { decrypted }
  } catch (error: unknown) {
    logger.error('API key decryption error:', {
      error: error instanceof Error ? error.message : 'Unknown error',
    })
    throw error
  }
}

/**
 * Generates a standardized API key with the 'sim_' prefix (legacy format)
 * @returns A new API key string
 */
export function generateApiKey(): string {
  return `sim_${randomBytes(24).toString('base64url')}`
}

/**
 * Generates a new encrypted API key with the 'sk-sim-' prefix
 * @returns A new encrypted API key string
 */
export function generateEncryptedApiKey(): string {
  return `sk-sim-${randomBytes(24).toString('base64url')}`
}

/**
 * Determines if an API key uses the new encrypted format based on prefix
 * @param apiKey - The API key to check
 * @returns true if the key uses the new encrypted format (sk-sim- prefix)
 */
export function isEncryptedApiKeyFormat(apiKey: string): boolean {
  return apiKey.startsWith('sk-sim-')
}

/**
 * Determines if an API key uses the legacy format based on prefix
 * @param apiKey - The API key to check
 * @returns true if the key uses the legacy format (sim_ prefix)
 */
export function isLegacyApiKeyFormat(apiKey: string): boolean {
  return apiKey.startsWith('sim_') && !apiKey.startsWith('sk-sim-')
}