// src/main/java/com/productcatalog/model/Product.java
package com.productcatalog.model;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document(collection = "products")
public class Product {
    @Id
    private String id;
    private String sku;  // Format: ABC-1234
    private String name;
    private int inventory;
    
    // Constructors, Getters, Setters
}

// src/main/java/com/productcatalog/repository/ProductRepository.java
package com.productcatalog.repository;

import com.productcatalog.model.Product;
import org.springframework.data.mongodb.repository.MongoRepository;

public interface ProductRepository extends MongoRepository<Product, String> {
    Product findBySku(String sku);
}

// src/main/java/com/productcatalog/service/ProductService.java
package com.productcatalog.service;

import com.productcatalog.exception.InvalidSKUException;
import com.productcatalog.model.Product;
import com.productcatalog.repository.ProductRepository;
import org.springframework.stereotype.Service;

@Service
public class ProductService {
    private final ProductRepository repository;

    public ProductService(ProductRepository repository) {
        this.repository = repository;
    }

    public Product createProduct(Product product) throws InvalidSKUException {
        if (!product.getSku().matches("^[A-Z]{3}-\\d{4}$")) {
            throw new InvalidSKUException("SKU must match format ABC-1234");
        }
        return repository.save(product);
    }
}

// src/main/java/com/productcatalog/controller/ProductController.java
package com.productcatalog.controller;

import com.productcatalog.exception.InvalidSKUException;
import com.productcatalog.model.Product;
import com.productcatalog.service.ProductService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/products")
public class ProductController {
    private final ProductService productService;

    public ProductController(ProductService productService) {
        this.productService = productService;
    }

    @PostMapping
    public ResponseEntity<Product> createProduct(@RequestBody Product product) throws InvalidSKUException {
        return ResponseEntity.ok(productService.createProduct(product));
    }
}

// src/test/java/com/productcatalog/service/ProductServiceTest.java
package com.productcatalog.service;

import com.productcatalog.exception.InvalidSKUException;
import com.productcatalog.model.Product;
import com.productcatalog.repository.ProductRepository;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.when;

@SpringBootTest
class ProductServiceTest {
    @Mock
    private ProductRepository repository;
    
    @InjectMocks
    private ProductService productService;

    @Test
    void whenInvalidSKU_thenThrowsException() {
        Product product = new Product("INVALID", "Test Product", 10);
        assertThrows(InvalidSKUException.class, () -> productService.createProduct(product));
    }
}

// src/test/java/com/productcatalog/ProductIntegrationTest.java
package com.productcatalog;

import com.productcatalog.model.Product;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
import org.springframework.data.mongodb.core.MongoTemplate;

import static org.assertj.core.api.Assertions.assertThat;

@DataMongoTest
class ProductIntegrationTest {
    @Autowired
    private MongoTemplate mongoTemplate;

    @Test
    void whenSaveProduct_thenCanRetrieve() {
        Product product = new Product("ABC-1234", "Test Product", 10);
        mongoTemplate.save(product);
        
        Product found = mongoTemplate.findById(product.getId(), Product.class);
        assertThat(found.getSku()).isEqualTo(product.getSku());
    }
}

// src/test/java/com/productcatalog/controller/ProductControllerTest.java
package com.productcatalog.controller;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.productcatalog.model.Product;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@SpringBootTest
@AutoConfigureMockMvc
class ProductControllerTest {
    @Autowired
    private MockMvc mockMvc;

    @Test
    void whenValidInput_thenReturns200() throws Exception {
        Product product = new Product("ABC-1234", "Test Product", 10);
        
        mockMvc.perform(post("/api/products")
                .contentType(MediaType.APPLICATION_JSON)
                .content(new ObjectMapper().writeValueAsString(product)))
                .andExpect(status().isOk());
    }
}