import crypto from 'crypto'
import { createClient } from '@supabase/supabase-js'

const KEY_PREFIX = 'gnubok_sk_'

/**
 * Create a Supabase service client that doesn't require cookies.
 * Used for API key validation (MCP, webhooks) where there's no browser session.
 */
export function createServiceClientNoCookies() {
  return createClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.SUPABASE_SERVICE_ROLE_KEY!
  )
}

export function generateApiKey(): { key: string; hash: string; prefix: string } {
  const random = crypto.randomBytes(32).toString('base64url')
  const key = `${KEY_PREFIX}${random}`
  const hash = hashApiKey(key)
  const prefix = key.slice(0, KEY_PREFIX.length + 8)
  return { key, hash, prefix }
}

export function hashApiKey(key: string): string {
  return crypto.createHash('sha256').update(key).digest('hex')
}

export function extractBearerToken(request: Request): string | null {
  const authHeader = request.headers.get('authorization')
  if (!authHeader?.startsWith('Bearer ')) return null
  return authHeader.slice(7)
}

/**
 * Validate an API key and enforce rate limiting.
 * Uses the DB RPC for atomic check + increment.
 * Returns the user_id on success, or an error with HTTP status.
 */
export async function validateApiKey(
  key: string
): Promise<{ userId: string } | { error: string; status: number }> {
  if (!key.startsWith(KEY_PREFIX)) {
    return { error: 'Invalid API key format', status: 401 }
  }

  const hash = hashApiKey(key)
  const supabase = createServiceClientNoCookies()

  const { data, error } = await supabase.rpc('validate_and_increment_api_key', {
    p_key_hash: hash,
  })

  if (error || !data || data.length === 0) {
    return { error: 'Invalid API key', status: 401 }
  }

  const row = data[0]

  if (row.rate_limited) {
    return { error: 'Rate limit exceeded', status: 429 }
  }

  return { userId: row.user_id }
}