@@ -0,0 +1,147 @@
+package store.service;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import store.constant.ExceptionMessage;
+import store.domain.Product;
+import store.dto.TotalProductStock;
+import store.repository.ProductRepository;
+import store.view.InputView;
+
+public class ProductService {
+
+    private final ProductRepository productRepository;
+
+    public ProductService(ProductRepository productRepository) {
+        this.productRepository = productRepository;
+    }
+
+    public List<Product> getAllProducts() {
+        if(productRepository.getAllProducts().isEmpty()) {
+            parseProducts("src/main/resources/products.md");
+        }
+        return productRepository.getAllProducts();
+    }
+
+    public List<Product> parsePurchaseProductFromInput(String buyProductAmountsInput) {
+        String[] buyProductAmounts = buyProductAmountsInput.split(",");
+
+        replaceSquareBracketsToBlank(buyProductAmounts);
+
+        return setupBuyProducts(buyProductAmounts);
+    }
+
+    public Product getPromotionProductByName(String name) {
+        productRepository.getPromotionProducts();
+        return productRepository.getPromotionProductByName(name);
+    }
+
+    public Product getRegularProductByName(String name) {
+        productRepository.getRegularProducts();
+        return productRepository.getRegularProductByName(name);
+    }
+
+    public List<Product> cloneProductList(List<Product> purchaseProducts) {
+        return purchaseProducts.stream()
+                .map(Product::clone)
+                .collect(Collectors.toList());
+    }
+
+    public int getTotalProductPrice(List<Product> purchaseProducts, List<Product> stockProducts) {
+        int totalProductPrice = 0;
+        for (Product buyProduct : purchaseProducts) {
+            int price = getProductPrice(buyProduct.getName(), stockProducts) * buyProduct.getQuantity();
+            totalProductPrice += price;
+        }
+        return totalProductPrice;
+    }
+
+    public int getProductPrice(String name, List<Product> stockProducts) {
+        for(Product product : stockProducts) {
+            if(product.getName().equals(name)) {
+                return product.getPrice();
+            }
+        }
+        return 0;
+    }
+
+    public void increaseTotalPurchaseAmount(String name, List<Product> purchaseProductsForReceipt, int increaseAmount) {
+        for (Product product : purchaseProductsForReceipt) {
+            if(product.getName().equals(name)) {
+                product.increaseQuantity(increaseAmount);
+            }
+        }
+    }
+
+    public void decreaseTotalPurchaseAmount(String name, List<Product> purchaseProductsForReceipt, int decreaseAmount) {
+        for (Product product : purchaseProductsForReceipt) {
+            if(product.getName().equals(name)) {
+                product.decreaseQuantity(decreaseAmount);
+            }
+        }
+    }
+
+    private static List<Product> setupBuyProducts(String[] buyProductAmounts) {
+        List<Product> buyProducts = new ArrayList<>();
+        for (String buyProductAmount : buyProductAmounts) {
+            String[] splitProductAmount = buyProductAmount.split("-");
+            Product buyProduct = new Product(splitProductAmount[0].trim(), Integer.parseInt(splitProductAmount[1].trim()));
+            addBuyProduct(buyProducts, buyProduct);
+        }
+        return buyProducts;
+    }
+
+    private static void addBuyProduct(List<Product> buyProducts, Product buyProduct) {
+        boolean productExists = false;
+        productExists = addBuyProductAmountIfExist(buyProducts, buyProduct, productExists);
+        if (!productExists) {
+            buyProducts.add(buyProduct);
+        }
+    }
+
+    private static boolean addBuyProductAmountIfExist(List<Product> buyProducts, Product buyProduct, boolean productExists) {
+        for (Product product : buyProducts) {
+            if (product.getName().equals(buyProduct.getName())) {
+                product.increaseQuantity(buyProduct.getQuantity());
+                productExists = true;
+                break;
+            }
+        }
+        return productExists;
+    }
+
+    private static void replaceSquareBracketsToBlank(String[] buyProductAmounts) {
+        for (int i = 0; i < buyProductAmounts.length; i++) {
+            buyProductAmounts[i] = buyProductAmounts[i].replaceAll("[\\[\\]]", "").trim();
+        }
+    }
+
+    private void parseProducts(String filePath) {
+        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
+            reader.readLine();
+            parseProduct(reader);
+        } catch (IOException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    private void parseProduct(BufferedReader reader) throws IOException {
+        String line;
+        while((line = reader.readLine()) != null) {
+            String[] fields = line.split(",");
+            String name = fields[0];
+            int price = Integer.parseInt(fields[1]);
+            int quantity = Integer.parseInt(fields[2]);
+            String promotion = fields.length > 3 ? fields[3] : null; // 수정하기
+            productRepository.addProduct(new Product(name, price, quantity, promotion));
+        }
+    }
+
+
+}

리뷰: break말고 return true로 한다면 굳이 productExists를 파라미터로 안넘겨도 될 것 같아요