feat: 상품 도메인 API 구현

- 상품 생성
- 상품 상세 정보 조회
- 상품 목록 조회

Author: Kimjipang

apps/commerce-api/src/main/java/com/loopers/application/product/ProductFacade.java

@@ -0,0 +1,54 @@
+package com.loopers.application.product;
+
+import com.loopers.domain.like.LikeRepository;
+import com.loopers.domain.product.Product;
+import com.loopers.domain.product.ProductRepository;
+import com.loopers.domain.user.UserRepository;
+import com.loopers.interfaces.api.product.ProductV1Dto;
+import com.loopers.support.error.CoreException;
+import com.loopers.support.error.ErrorType;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+
+@Component
+@RequiredArgsConstructor
+public class ProductFacade {
+    private final ProductRepository productRepository;
+    private final LikeRepository likeRepository;
+
+
+    @Transactional
+    public ProductInfo registerProduct(ProductV1Dto.ProductRequest request) {
+        Product product = request.toEntity();
+        productRepository.save(product);
+
+        return ProductInfo.from(product, 0);
+    }
+
+    @Transactional
+    public List<ProductInfo> findAllProducts() {
+        List<Product> products = productRepository.findAll();
+
+        return products.stream()
+                .map(product -> {
+                    int likeCount = likeRepository.countByProductId(product.getId());
+                    return ProductInfo.from(product, likeCount);
+                })
+                .toList();
+    }
+
+    @Transactional(readOnly = true)
+    public ProductInfo findProductById(Long id) {
+        Product product = productRepository.findById(id).orElseThrow(
+                () -> new CoreException(ErrorType.NOT_FOUND, "찾고자 하는 상품이 존재하지 않습니다.")
+        );
+
+        int likeCount = likeRepository.countByProductId(id);
+
+        return ProductInfo.from(product, likeCount);
+    }
+
+}

apps/commerce-api/src/main/java/com/loopers/application/product/ProductInfo.java

@@ -0,0 +1,18 @@
+package com.loopers.application.product;
+
+import com.loopers.domain.product.Product;
+
+import java.math.BigDecimal;
+
+public record ProductInfo(Long id, Long brandId, String name, BigDecimal price, int stock, int likeCount) {
+    public static ProductInfo from(Product product, int likeCount) {
+        return new ProductInfo(
+            product.getId(),
+            product.getBrandId(),
+            product.getName(),
+            product.getPrice(),
+            product.getStock(),
+            likeCount
+        );
+    }
+}

apps/commerce-api/src/main/java/com/loopers/domain/product/Product.java

@@ -0,0 +1,61 @@
+package com.loopers.domain.product;
+
+import com.loopers.domain.BaseEntity;
+import com.loopers.support.error.CoreException;
+import com.loopers.support.error.ErrorType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.Table;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.math.BigDecimal;
+
+@Getter
+@Entity
+@Table(name = "product")
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class Product extends BaseEntity {
+    @Column(name = "ref_brand_id", nullable = false)
+    private Long brandId;
+
+    @Column(name = "name", nullable = false)
+    private String name;
+
+    @Column(name = "price", nullable = false)
+    private BigDecimal price;
+
+    @Column(name = "stock", nullable = false)
+    private int stock;
+
+
+    public Product(Long brandId, String name, BigDecimal price, int stock) {
+        this.brandId = brandId;
+        this.name = name;
+        this.price = price;
+        this.stock = stock;
+    }
+
+    public Product changePrice(BigDecimal newPrice) {
+        this.price = newPrice;
+        return this;
+    }
+
+    public Product decreaseStock(int amount) {
+        if (amount <= 0) {
+            throw new CoreException(ErrorType.BAD_REQUEST, "재고 감소량은 0보다 커야 합니다.");
+        }
+        if (this.stock < amount) {
+            throw new CoreException(ErrorType.BAD_REQUEST, "재고가 부족합니다.");
+        }
+        this.stock -= amount;
+
+        return this;
+    }
+
+    public boolean isInStock(int quantity) {
+        return this.stock >= quantity;
+    }
+
+}

apps/commerce-api/src/main/java/com/loopers/domain/product/ProductRepository.java

@@ -0,0 +1,16 @@
+package com.loopers.domain.product;
+
+import com.loopers.interfaces.api.product.ProductV1Dto;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface ProductRepository {
+    Optional<Product> findById(Long id);
+
+    Product save(Product product);
+
+    List<Product> findAll();
+
+    List<Product> searchProductsByCondition(ProductV1Dto.SearchProductRequest request);
+}

apps/commerce-api/src/main/java/com/loopers/infrastructure/product/ProductJpaRepository.java

@@ -0,0 +1,7 @@
+package com.loopers.infrastructure.product;
+
+import com.loopers.domain.product.Product;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface ProductJpaRepository extends JpaRepository<Product, Long> {
+}

apps/commerce-api/src/main/java/com/loopers/infrastructure/product/ProductRepositoryImpl.java

@@ -0,0 +1,38 @@
+package com.loopers.infrastructure.product;
+
+import com.loopers.domain.product.Product;
+import com.loopers.domain.product.ProductRepository;
+import com.loopers.interfaces.api.product.ProductV1Dto;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import jakarta.persistence.EntityManager;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+import java.util.Optional;
+
+@Component
+public class ProductRepositoryImpl implements ProductRepository {
+    private final ProductJpaRepository productJpaRepository;
+    private final JPAQueryFactory queryFactory;
+
+    public ProductRepositoryImpl(ProductJpaRepository productJpaRepository, EntityManager entityManager) {
+        this.productJpaRepository = productJpaRepository;
+        this.queryFactory = new JPAQueryFactory(entityManager);
+    }
+
+    @Override
+    public Optional<Product> findById(Long id) {
+        return productJpaRepository.findById(id);
+    }
+
+    @Override
+    public Product save(Product product) {
+        return productJpaRepository.save(product);
+    }
+
+    @Override
+    public List<Product> findAll() {
+        return productJpaRepository.findAll();
+    }
+
+}

apps/commerce-api/src/main/java/com/loopers/interfaces/api/product/ProductV1ApiSpec.java

@@ -0,0 +1,20 @@
+package com.loopers.interfaces.api.product;
+
+import com.loopers.interfaces.api.ApiResponse;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+
+import java.util.List;
+
+@Tag(name = "Product V1 API", description = "Product API 입니다.")
+public interface ProductV1ApiSpec {
+    @Operation(summary = "상품 등록")
+    ApiResponse<ProductV1Dto.ProductResponse> registerProduct (ProductV1Dto.ProductRequest request);
+
+    @Operation(summary = "상품 목록 조회")
+    ApiResponse<List<ProductV1Dto.ProductResponse>> findAllProducts ();
+
+    @Operation(summary = "상품 상세 조회")
+    ApiResponse<ProductV1Dto.ProductResponse> findProductById (Long id);
+
+}

apps/commerce-api/src/main/java/com/loopers/interfaces/api/product/ProductV1Controller.java

@@ -0,0 +1,52 @@
+package com.loopers.interfaces.api.product;
+
+import com.loopers.application.product.ProductFacade;
+import com.loopers.application.product.ProductInfo;
+import com.loopers.interfaces.api.ApiResponse;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/v1/products")
+@RequiredArgsConstructor
+public class ProductV1Controller implements ProductV1ApiSpec {
+    private final ProductFacade productFacade;
+
+    @PostMapping
+    @Override
+    public ApiResponse<ProductV1Dto.ProductResponse> registerProduct(@RequestBody ProductV1Dto.ProductRequest request) {
+        ProductInfo info = productFacade.registerProduct(request);
+        ProductV1Dto.ProductResponse response = ProductV1Dto.ProductResponse.from(info);
+
+        return ApiResponse.success(response);
+    }
+
+    @GetMapping
+    @Override
+    public ApiResponse<List<ProductV1Dto.ProductResponse>> findAllProducts() {
+        List<ProductInfo> infos = productFacade.findAllProducts();
+
+        List<ProductV1Dto.ProductResponse> responses = infos.stream()
+                .map(ProductV1Dto.ProductResponse::from)
+                .toList();
+
+        return ApiResponse.success(responses);
+    }
+
+    @GetMapping("/{id}")
+    @Override
+    public ApiResponse<ProductV1Dto.ProductResponse> findProductById(@PathVariable Long id) {
+        ProductInfo info = productFacade.findProductById(id);
+        ProductV1Dto.ProductResponse response = ProductV1Dto.ProductResponse.from(info);
+
+        return ApiResponse.success(response);
+    }
+
+}

apps/commerce-api/src/main/java/com/loopers/interfaces/api/product/ProductV1Dto.java

@@ -0,0 +1,36 @@
+package com.loopers.interfaces.api.product;
+
+import com.loopers.application.product.ProductInfo;
+import com.loopers.domain.product.Product;
+
+import java.math.BigDecimal;
+
+public class ProductV1Dto {
+    public record ProductResponse(Long id, Long brandId, String name, BigDecimal price, int stock, int likeCount) {
+        public static ProductResponse from(ProductInfo info) {
+            return new ProductResponse(
+                    info.id(),
+                    info.brandId(),
+                    info.name(),
+                    info.price(),
+                    info.stock(),
+                    info.likeCount()
+            );
+        }
+    }
+
+    public record ProductRequest(Long brandId, String name, BigDecimal price, int stock) {
+        public Product toEntity() {
+            return new Product(
+                    brandId,
+                    name,
+                    price,
+                    stock
+            );
+        }
+    }
+
+    public record SearchProductRequest(String sortBy, String order) {
+
+    }
+}