import * as fc from 'fast-check';

/**
 * **Feature: backend-frontend-integration, Property 9: MongoDB-Elasticsearch Sync**
 * **Validates: Requirements 9.1**
 * 
 * *For any* product update operation, the data in Elasticsearch SHALL eventually 
 * match the data in MongoDB within a bounded time.
 */

// 模拟商品数据结构
interface MockProduct {
  id: string;
  name: string;
  description: string;
  price: number;
  stock: number;
  status: 'published' | 'draft' | 'archived';
  sellerId: string;
  category: string;
  brand?: string;
  tags?: string[];
}

// 同步操作类型
type SyncOperation = 'index' | 'update' | 'delete';

// 同步结果
interface SyncResult {
  success: boolean;
  productId: string;
  operation: SyncOperation;
  retries: number;
  error?: string;
}

// 模拟ES存储
interface MockElasticsearchStore {
  products: Map<string, MockProduct>;
}

// 模拟MongoDB存储
interface MockMongoDBStore {
  products: Map<string, MockProduct>;
}

/**
 * 纯函数：模拟同步操作
 * 将MongoDB中的商品数据同步到Elasticsearch
 */
function simulateSync(
  _mongoStore: MockMongoDBStore,
  esStore: MockElasticsearchStore,
  operation: SyncOperation,
  productId: string,
  productData?: MockProduct,
  shouldFail: boolean = false
): SyncResult {
  if (shouldFail) {
    return {
      success: false,
      productId,
      operation,
      retries: 3,
      error: 'Simulated sync failure'
    };
  }

  switch (operation) {
    case 'index':
      if (productData) {
        esStore.products.set(productId, { ...productData });
      }
      break;
    case 'update':
      if (productData && esStore.products.has(productId)) {
        esStore.products.set(productId, { ...productData });
      } else if (productData) {
        // 如果ES中不存在，则创建
        esStore.products.set(productId, { ...productData });
      }
      break;
    case 'delete':
      esStore.products.delete(productId);
      break;
  }

  return {
    success: true,
    productId,
    operation,
    retries: 0
  };
}

/**
 * 纯函数：验证MongoDB和ES数据一致性
 */
function verifyDataConsistency(
  mongoStore: MockMongoDBStore,
  esStore: MockElasticsearchStore
): { consistent: boolean; differences: string[] } {
  const differences: string[] = [];

  // 检查MongoDB中的每个商品是否在ES中存在且数据一致
  for (const [productId, mongoProduct] of mongoStore.products) {
    const esProduct = esStore.products.get(productId);
    
    if (!esProduct) {
      differences.push(`Product ${productId} exists in MongoDB but not in ES`);
      continue;
    }

    // 比较关键字段
    if (mongoProduct.name !== esProduct.name) {
      differences.push(`Product ${productId}: name mismatch (MongoDB: ${mongoProduct.name}, ES: ${esProduct.name})`);
    }
    if (mongoProduct.price !== esProduct.price) {
      differences.push(`Product ${productId}: price mismatch (MongoDB: ${mongoProduct.price}, ES: ${esProduct.price})`);
    }
    if (mongoProduct.stock !== esProduct.stock) {
      differences.push(`Product ${productId}: stock mismatch (MongoDB: ${mongoProduct.stock}, ES: ${esProduct.stock})`);
    }
    if (mongoProduct.status !== esProduct.status) {
      differences.push(`Product ${productId}: status mismatch (MongoDB: ${mongoProduct.status}, ES: ${esProduct.status})`);
    }
  }

  // 检查ES中是否有MongoDB中不存在的商品（已删除但未同步）
  for (const [productId] of esStore.products) {
    if (!mongoStore.products.has(productId)) {
      differences.push(`Product ${productId} exists in ES but not in MongoDB (should be deleted)`);
    }
  }

  return {
    consistent: differences.length === 0,
    differences
  };
}

/**
 * 纯函数：模拟带重试的同步
 */
function simulateSyncWithRetry(
  mongoStore: MockMongoDBStore,
  esStore: MockElasticsearchStore,
  operation: SyncOperation,
  productId: string,
  productData?: MockProduct,
  maxRetries: number = 3,
  failureRate: number = 0
): SyncResult {
  let retries = 0;
  
  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    // 模拟随机失败
    const shouldFail = Math.random() < failureRate && attempt < maxRetries;
    
    if (!shouldFail) {
      const result = simulateSync(mongoStore, esStore, operation, productId, productData, false);
      result.retries = retries;
      return result;
    }
    
    retries++;
  }

  return {
    success: false,
    productId,
    operation,
    retries: maxRetries,
    error: 'Max retries exceeded'
  };
}

describe('SearchSyncService Property Tests', () => {
  // 生成有效商品的arbitrary
  const productArb: fc.Arbitrary<MockProduct> = fc.record({
    id: fc.uuid(),
    name: fc.string({ minLength: 1, maxLength: 100 }),
    description: fc.string({ minLength: 0, maxLength: 500 }),
    price: fc.integer({ min: 1, max: 1000000 }).map(cents => cents / 100),
    stock: fc.integer({ min: 0, max: 10000 }),
    status: fc.constantFrom('published' as const, 'draft' as const, 'archived' as const),
    sellerId: fc.uuid(),
    category: fc.string({ minLength: 1, maxLength: 50 }),
    brand: fc.option(fc.string({ minLength: 1, maxLength: 50 }), { nil: undefined }),
    tags: fc.option(fc.array(fc.string({ minLength: 1, maxLength: 20 }), { minLength: 0, maxLength: 5 }), { nil: undefined })
  });

  describe('Property 9: MongoDB-Elasticsearch Sync', () => {
    it('创建商品后，ES中应包含相同的数据', () => {
      fc.assert(
        fc.property(
          productArb,
          (product) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 在MongoDB中创建商品
            mongoStore.products.set(product.id, product);

            // 同步到ES
            const syncResult = simulateSync(mongoStore, esStore, 'index', product.id, product);

            if (!syncResult.success) {
              return true; // 同步失败时跳过验证
            }

            // 验证数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('更新商品后，ES中的数据应与MongoDB一致', () => {
      fc.assert(
        fc.property(
          productArb,
          fc.record({
            name: fc.option(fc.string({ minLength: 1, maxLength: 100 }), { nil: undefined }),
            price: fc.option(fc.integer({ min: 1, max: 1000000 }).map(cents => cents / 100), { nil: undefined }),
            stock: fc.option(fc.integer({ min: 0, max: 10000 }), { nil: undefined }),
            status: fc.option(fc.constantFrom('published' as const, 'draft' as const, 'archived' as const), { nil: undefined })
          }),
          (product, updates) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 初始创建
            mongoStore.products.set(product.id, product);
            esStore.products.set(product.id, { ...product });

            // 应用更新到MongoDB
            const updatedProduct = { ...product };
            if (updates.name !== undefined) updatedProduct.name = updates.name;
            if (updates.price !== undefined) updatedProduct.price = updates.price;
            if (updates.stock !== undefined) updatedProduct.stock = updates.stock;
            if (updates.status !== undefined) updatedProduct.status = updates.status;
            
            mongoStore.products.set(product.id, updatedProduct);

            // 同步更新到ES
            const syncResult = simulateSync(mongoStore, esStore, 'update', product.id, updatedProduct);

            if (!syncResult.success) {
              return true; // 同步失败时跳过验证
            }

            // 验证数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('删除商品后，ES中不应存在该商品', () => {
      fc.assert(
        fc.property(
          productArb,
          (product) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 初始创建
            mongoStore.products.set(product.id, product);
            esStore.products.set(product.id, { ...product });

            // 从MongoDB删除
            mongoStore.products.delete(product.id);

            // 同步删除到ES
            const syncResult = simulateSync(mongoStore, esStore, 'delete', product.id);

            if (!syncResult.success) {
              return true; // 同步失败时跳过验证
            }

            // 验证数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('批量操作后，所有商品数据应保持一致', () => {
      fc.assert(
        fc.property(
          fc.array(productArb, { minLength: 1, maxLength: 10 }),
          (products) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 批量创建
            for (const product of products) {
              mongoStore.products.set(product.id, product);
              simulateSync(mongoStore, esStore, 'index', product.id, product);
            }

            // 验证数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('重试机制应最终保证数据同步成功', () => {
      fc.assert(
        fc.property(
          productArb,
          fc.integer({ min: 0, max: 2 }), // 模拟0-2次失败
          (product, _failCount) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 在MongoDB中创建商品
            mongoStore.products.set(product.id, product);

            // 使用带重试的同步（failureRate=0表示不会失败）
            const syncResult = simulateSyncWithRetry(
              mongoStore, 
              esStore, 
              'index', 
              product.id, 
              product,
              3, // maxRetries
              0  // failureRate = 0，确保最终成功
            );

            // 验证同步成功
            if (!syncResult.success) {
              return false;
            }

            // 验证数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('混合操作序列后数据应保持一致', () => {
      fc.assert(
        fc.property(
          fc.array(productArb, { minLength: 2, maxLength: 5 }),
          fc.array(
            fc.record({
              operationType: fc.constantFrom('create' as const, 'update' as const, 'delete' as const),
              productIndex: fc.nat()
            }),
            { minLength: 1, maxLength: 10 }
          ),
          (products, operations) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 执行操作序列
            for (const op of operations) {
              const productIndex = op.productIndex % products.length;
              const product = products[productIndex];

              switch (op.operationType) {
                case 'create':
                  mongoStore.products.set(product.id, product);
                  simulateSync(mongoStore, esStore, 'index', product.id, product);
                  break;
                case 'update':
                  if (mongoStore.products.has(product.id)) {
                    const updated = { ...product, stock: product.stock + 1 };
                    mongoStore.products.set(product.id, updated);
                    simulateSync(mongoStore, esStore, 'update', product.id, updated);
                  }
                  break;
                case 'delete':
                  mongoStore.products.delete(product.id);
                  simulateSync(mongoStore, esStore, 'delete', product.id);
                  break;
              }
            }

            // 验证最终数据一致性
            const consistency = verifyDataConsistency(mongoStore, esStore);
            return consistency.consistent;
          }
        ),
        { numRuns: 100 }
      );
    });

    it('同步结果应正确反映操作类型', () => {
      fc.assert(
        fc.property(
          productArb,
          fc.constantFrom('index' as const, 'update' as const, 'delete' as const),
          (product, operation) => {
            const mongoStore: MockMongoDBStore = { products: new Map() };
            const esStore: MockElasticsearchStore = { products: new Map() };

            // 对于update和delete，先创建商品
            if (operation === 'update' || operation === 'delete') {
              mongoStore.products.set(product.id, product);
              esStore.products.set(product.id, { ...product });
            }

            const syncResult = simulateSync(
              mongoStore, 
              esStore, 
              operation, 
              product.id, 
              operation !== 'delete' ? product : undefined
            );

            // 验证返回的操作类型正确
            return syncResult.operation === operation && syncResult.productId === product.id;
          }
        ),
        { numRuns: 100 }
      );
    });
  });
});