import { and, lt, isNull } from 'drizzle-orm'
import { carts } from '../database/schema'

/**
 * Cart Cleanup Utilities
 *
 * These functions prepare the structure for automatic cart cleanup.
 * The actual cleanup job will be implemented in a later phase using BullMQ.
 *
 * Cleanup Strategy:
 * - User carts: Keep until updated_at > CART_EXPIRY_DAYS
 * - Guest carts: Keep until updated_at > CART_EXPIRY_DAYS
 * - Rationale: Inactive carts consume database space and should be pruned
 *
 * Future Implementation:
 * - BullMQ scheduled job runs daily at night (e.g., 3 AM)
 * - Calls getExpiredCarts() to find carts to delete
 * - Deletes expired carts (cascade deletes cart_items automatically)
 * - Logs cleanup statistics for monitoring
 */

/**
 * Get carts that are older than the configured expiry period
 *
 * @returns Array of expired cart IDs
 */
export async function getExpiredCarts(): Promise<string[]> {
  const db = useDatabase()
  const config = useRuntimeConfig()

  // Calculate expiry date
  const expiryDays = config.cart.expiryDays
  const expiryDate = new Date()
  expiryDate.setDate(expiryDate.getDate() - expiryDays)

  // Find carts not updated since expiry date
  const expiredCarts = await db
    .select({ id: carts.id })
    .from(carts)
    .where(lt(carts.updatedAt, expiryDate))

  return expiredCarts.map((cart) => cart.id)
}

/**
 * Delete expired carts
 *
 * Note: cart_items are automatically deleted via CASCADE foreign key constraint
 *
 * @param cartIds - Array of cart UUIDs to delete
 * @returns Number of carts deleted
 */
export async function deleteExpiredCarts(cartIds: string[]): Promise<number> {
  if (cartIds.length === 0) {
    return 0
  }

  const db = useDatabase()

  // Delete carts (cart_items cascade automatically)
  const result = await db
    .delete(carts)
    .where(
      and(
        ...cartIds.map((id) => eq(carts.id, id))
      )
    )

  return cartIds.length
}

/**
 * Get cleanup statistics
 *
 * @returns Statistics about carts in the database
 */
export async function getCartStatistics() {
  const db = useDatabase()
  const config = useRuntimeConfig()

  // Calculate expiry date
  const expiryDays = config.cart.expiryDays
  const expiryDate = new Date()
  expiryDate.setDate(expiryDate.getDate() - expiryDays)

  // Count carts by type
  const [totalCarts] = await db.select({ count: count() }).from(carts)

  const [userCarts] = await db
    .select({ count: count() })
    .from(carts)
    .where(isNull(carts.userId).not())

  const [guestCarts] = await db
    .select({ count: count() })
    .from(carts)
    .where(isNull(carts.userId))

  const [expiredCarts] = await db
    .select({ count: count() })
    .from(carts)
    .where(lt(carts.updatedAt, expiryDate))

  return {
    totalCarts: totalCarts?.count || 0,
    userCarts: userCarts?.count || 0,
    guestCarts: guestCarts?.count || 0,
    expiredCarts: expiredCarts?.count || 0,
    expiryDays,
    expiryDate: expiryDate.toISOString(),
  }
}

// Note: Import count function
import { count } from 'drizzle-orm'
import { eq } from 'drizzle-orm'