@@ -0,0 +1,145 @@
+package store.domain;
+
+import static store.enums.ErrorMessage.EXCEED_PURCHASE;
+import static store.enums.ErrorMessage.INVALID_FILE_FORMAT;
+import static store.utils.Constants.ENTER;
+import static store.utils.Constants.SPACE_BAR;
+
+import java.util.Objects;
+import java.util.StringJoiner;
+import store.domain.vo.ProductName;
+import store.exception.InvalidFileFormatException;
+import store.utils.StringUtils;
+
+public class Product {
+
+    private static final String CURRENCY_UNIT = "원";
+    private static final String DIVIDER = "-";
+
+    private final ProductName name;
+    private final long price;
+    private final Stock stock;
+    private Promotion promotion;
+
+    public Product(ProductName name, long price, Promotion promotion) {
+        this.name = name;
+        this.price = price;
+        this.stock = new Stock();
+        updatePromotion(promotion);
+    }
+
+    public Product(ProductName name, long price, Stock stock, Promotion promotion) {
+        this.name = name;
+        this.price = price;
+        this.stock = stock;
+        this.promotion = promotion;
+    }
+
+    public void validStock(long requestCount) {
+        if (stock.total() < requestCount) {
+            throw new IllegalArgumentException(EXCEED_PURCHASE.getMessage());
+        }
+    }
+
+    public void updatePromotion(Promotion promotion) {
+        if (this.promotion != null && !this.promotion.equals(promotion)) {
+            throw new InvalidFileFormatException(INVALID_FILE_FORMAT.getMessage());
+        }
+
+        this.promotion = promotion;
+    }
+
+    public void validPrice(long dtoPrice) {
+        if (price != dtoPrice) {
+            throw new InvalidFileFormatException(INVALID_FILE_FORMAT.getMessage());
+        }
+    }
+
+    public void addNormalQuantity(long quantity) {
+        stock.addNormalProduct(quantity);
+    }
+
+    public void addPromotionQuantity(long quantity) {
+        stock.addPromotionProduct(quantity);
+    }
+
+    public long calculateRequiredQuantity(long requestQuantity) {
+        return stock.problemQuantity(requestQuantity, promotion);
+    }
+
+    public long sumOriginalPrice(long requestQuantity) {
+        long originalQuantity = stock.calculateOriginalPriceQuantity(requestQuantity, promotion);
+
+        return -originalQuantity * price;
+    }
+
+    public long calculateGiftQuantity(long requestQuantity) {
+        return stock.calculateGiftQuantity(requestQuantity, promotion);
+    }
+
+    public long calculateSumPrice(long quantity) {
+        return quantity * price;
+    }
+
+    public void applyStock(long requestQuantity) {
+        stock.applyQuantity(requestQuantity);
+    }
+
+    @Override
+    public String toString() {
+        StringJoiner enterJoiner = new StringJoiner(ENTER);
+
+        if (promotion != null) {
+            enterJoiner.add(promotionStatus());
+        }
+
+        return enterJoiner.add(normalStatus())
+                .toString();
+    }
+
+    private String promotionStatus() {
+        StringJoiner spaceBarJoiner = new StringJoiner(SPACE_BAR);
+        return spaceBarJoiner.add(DIVIDER)
+                .add(name.value())
+                .add(toFormatPrice())
+                .add(stock.toPromotionCountString())
+                .add(promotion.toString())
+                .toString();
+    }
+
+    private String normalStatus() {
+        StringJoiner spaceBarJoiner = new StringJoiner(SPACE_BAR);
+        return spaceBarJoiner.add(DIVIDER)
+                .add(name.value())
+                .add(toFormatPrice())
+                .add(stock.toNormalCountString())
+                .toString();
+    }
+
+    private String toFormatPrice() {
+        return StringUtils.numberFormat(price) + CURRENCY_UNIT;
+    }
+
+    protected String toProductName() {
+        return name.value();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        Product product = (Product) o;
+        return price == product.price && Objects.equals(name, product.name) && Objects.equals(stock,
+                product.stock) && Objects.equals(promotion, product.promotion);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, price, stock, promotion);
+    }
+
+}

리뷰: 해당 update은 상태가 null일때만 새로운 업데이트가 가능하도록 하였습니다. 만약 제품이 두개가 이름과 가격이 중복인데 참조하는 프로모션이 다르다면 파일의 문제이므로 예외처리 하였습니다.