/**
 * Property-based tests for order delete functionality
 * **Feature: order-delete, Property 2: Deleted orders are excluded from list queries**
 * **Validates: Requirements 1.3**
 */

import { describe, it, expect } from 'vitest'
import * as fc from 'fast-check'

/**
 * Order status constants
 * 1: 待支付 (pending)
 * 2: 已支付 (paid)
 * 3: 已取消 (cancelled)
 * 4: 已退款 (refunded)
 */
const ORDER_STATUS = {
  PENDING: 1,
  PAID: 2,
  CANCELLED: 3,
  REFUNDED: 4
} as const

/**
 * Simulates the canDeleteOrder function from the frontend
 * Orders with status 2 (paid) cannot be deleted
 */
function canDeleteOrder(status: number): boolean {
  return status !== ORDER_STATUS.PAID
}

/**
 * Simulates filtering orders that are not deleted
 * This represents the backend behavior that the frontend relies on
 */
function filterNonDeletedOrders<T extends { isDeleted: boolean }>(orders: T[]): T[] {
  return orders.filter(order => !order.isDeleted)
}

/**
 * Generates a mock order for testing
 */
const orderArbitrary = fc.record({
  orderId: fc.integer({ min: 1, max: 1000000 }),
  orderNo: fc.string({ minLength: 10, maxLength: 20 }),
  status: fc.constantFrom(ORDER_STATUS.PENDING, ORDER_STATUS.PAID, ORDER_STATUS.CANCELLED, ORDER_STATUS.REFUNDED),
  isDeleted: fc.boolean(),
  amount: fc.float({ min: Math.fround(0.01), max: Math.fround(10000), noNaN: true }),
})

describe('Order Delete Property Tests', () => {
  /**
   * Property 2: Deleted orders are excluded from list queries
   * *For any* order query, the result SHALL NOT include orders where IsDeleted is true.
   * **Validates: Requirements 1.3**
   */
  describe('Property 2: Deleted orders are excluded from list queries', () => {
    it('should never include deleted orders in filtered results', () => {
      fc.assert(
        fc.property(
          fc.array(orderArbitrary, { minLength: 0, maxLength: 50 }),
          (orders) => {
            const filteredOrders = filterNonDeletedOrders(orders)
            
            // Property: No order in the result should have isDeleted = true
            return filteredOrders.every(order => order.isDeleted === false)
          }
        ),
        { numRuns: 100 }
      )
    })

    it('should include all non-deleted orders in filtered results', () => {
      fc.assert(
        fc.property(
          fc.array(orderArbitrary, { minLength: 0, maxLength: 50 }),
          (orders) => {
            const filteredOrders = filterNonDeletedOrders(orders)
            const nonDeletedOrders = orders.filter(o => !o.isDeleted)
            
            // Property: The count of filtered orders should equal the count of non-deleted orders
            return filteredOrders.length === nonDeletedOrders.length
          }
        ),
        { numRuns: 100 }
      )
    })

    it('should preserve order data integrity after filtering', () => {
      fc.assert(
        fc.property(
          fc.array(orderArbitrary, { minLength: 1, maxLength: 50 }),
          (orders) => {
            const filteredOrders = filterNonDeletedOrders(orders)
            
            // Property: Each filtered order should exist in the original list with same data
            return filteredOrders.every(filtered => 
              orders.some(original => 
                original.orderId === filtered.orderId &&
                original.orderNo === filtered.orderNo &&
                original.status === filtered.status &&
                original.amount === filtered.amount
              )
            )
          }
        ),
        { numRuns: 100 }
      )
    })

    it('should return empty array when all orders are deleted', () => {
      fc.assert(
        fc.property(
          fc.array(
            fc.record({
              orderId: fc.integer({ min: 1, max: 1000000 }),
              orderNo: fc.string({ minLength: 10, maxLength: 20 }),
              status: fc.constantFrom(ORDER_STATUS.PENDING, ORDER_STATUS.PAID, ORDER_STATUS.CANCELLED, ORDER_STATUS.REFUNDED),
              isDeleted: fc.constant(true), // All orders are deleted
              amount: fc.float({ min: Math.fround(0.01), max: Math.fround(10000), noNaN: true }),
            }),
            { minLength: 1, maxLength: 20 }
          ),
          (allDeletedOrders) => {
            const filteredOrders = filterNonDeletedOrders(allDeletedOrders)
            
            // Property: When all orders are deleted, result should be empty
            return filteredOrders.length === 0
          }
        ),
        { numRuns: 100 }
      )
    })
  })

  /**
   * Additional property: Order deletion eligibility based on status
   * This validates the frontend's canDeleteOrder function
   * **Validates: Requirements 2.1, 2.2**
   */
  describe('Order deletion eligibility', () => {
    it('should only allow deletion of non-paid orders', () => {
      fc.assert(
        fc.property(
          fc.constantFrom(ORDER_STATUS.PENDING, ORDER_STATUS.PAID, ORDER_STATUS.CANCELLED, ORDER_STATUS.REFUNDED),
          (status) => {
            const canDelete = canDeleteOrder(status)
            
            // Property: canDelete should be true if and only if status is not PAID
            return canDelete === (status !== ORDER_STATUS.PAID)
          }
        ),
        { numRuns: 100 }
      )
    })

    it('should never allow deletion of paid orders', () => {
      fc.assert(
        fc.property(
          fc.constant(ORDER_STATUS.PAID),
          (status) => {
            return canDeleteOrder(status) === false
          }
        ),
        { numRuns: 100 }
      )
    })

    it('should always allow deletion of pending, cancelled, and refunded orders', () => {
      fc.assert(
        fc.property(
          fc.constantFrom(ORDER_STATUS.PENDING, ORDER_STATUS.CANCELLED, ORDER_STATUS.REFUNDED),
          (status) => {
            return canDeleteOrder(status) === true
          }
        ),
        { numRuns: 100 }
      )
    })
  })
})