feat: 랭킹 조회 API 컨트롤러 구현

- GET /api/v1/rankings?date=&page=&size=
- page 파라미터 1-based (API) → 0-based (내부) 변환

Author: sylee6529

apps/commerce-api/src/main/java/com/loopers/interfaces/api/ranking/RankingV1Controller.java

@@ -0,0 +1,35 @@
+package com.loopers.interfaces.api.ranking;
+
+import com.loopers.application.ranking.RankingFacade;
+import com.loopers.application.ranking.RankingInfo.RankingPageInfo;
+import com.loopers.interfaces.api.ApiResponse;
+import com.loopers.interfaces.api.ranking.RankingV1Dto.RankingPageResponse;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.*;
+
+@RequiredArgsConstructor
+@RestController
+@RequestMapping("/api/v1")
+public class RankingV1Controller {
+
+    private final RankingFacade rankingFacade;
+
+    /**
+     * 랭킹 페이지 조회
+     * GET /api/v1/rankings?date=yyyyMMdd&size=20&page=1
+     *
+     * @param page 페이지 번호 (1-based, 기본값 1)
+     */
+    @GetMapping("/rankings")
+    public ApiResponse<RankingPageResponse> getRankings(
+            @RequestParam(value = "date", required = false) String date,
+            @RequestParam(value = "page", defaultValue = "1") int page,
+            @RequestParam(value = "size", defaultValue = "20") int size
+    ) {
+        // API는 1-based, 내부는 0-based로 변환
+        int zeroBasedPage = Math.max(0, page - 1);
+        RankingPageInfo info = rankingFacade.getRankings(date, zeroBasedPage, size);
+        RankingPageResponse response = RankingPageResponse.from(info);
+        return ApiResponse.success(response);
+    }
+}

apps/commerce-api/src/main/java/com/loopers/interfaces/api/ranking/RankingV1Dto.java

@@ -0,0 +1,57 @@
+package com.loopers.interfaces.api.ranking;
+
+import com.loopers.application.ranking.RankingInfo.RankingItemInfo;
+import com.loopers.application.ranking.RankingInfo.RankingPageInfo;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+public class RankingV1Dto {
+
+    public record RankingPageResponse(
+            List<RankingItemResponse> rankings,
+            String date,
+            int page,  // 1-based page number for API response
+            int size,
+            long totalCount,
+            int totalPages,
+            boolean hasNext
+    ) {
+        public static RankingPageResponse from(RankingPageInfo info) {
+            List<RankingItemResponse> rankings = info.rankings().stream()
+                    .map(RankingItemResponse::from)
+                    .toList();
+            return new RankingPageResponse(
+                    rankings,
+                    info.date(),
+                    info.page() + 1,  // 0-based → 1-based 변환
+                    info.size(),
+                    info.totalCount(),
+                    info.totalPages(),
+                    info.hasNext()
+            );
+        }
+    }
+
+    public record RankingItemResponse(
+            int rank,
+            Long productId,
+            String productName,
+            String brandName,
+            BigDecimal price,
+            int likeCount,
+            Double score
+    ) {
+        public static RankingItemResponse from(RankingItemInfo info) {
+            return new RankingItemResponse(
+                    info.rank(),
+                    info.productId(),
+                    info.productName(),
+                    info.brandName(),
+                    info.price().getAmount(),
+                    info.likeCount(),
+                    info.score()
+            );
+        }
+    }
+}