feat: 구역별 잔여석 조회

Author: yj0111

src/main/java/TiCatch/backend/domain/ticketing/controller/TicketingController.java

@@ -88,6 +88,13 @@ public Mono<ResponseEntity<SingleResponseResult<Map<String, Boolean>>>> getSecti
                 .map(seats -> ResponseEntity.ok(new SingleResponseResult<>(seats)));
     }
 
+    // 구역별 잔여석 조회
+    @GetMapping("/seats/{ticketingId}/unreserved")
+    public Mono<ResponseEntity<SingleResponseResult<Map<String, Long>>>> checkUnreservedSeat(@PathVariable("ticketingId") Long ticketingId) {
+        return ticketingService.getSeatCountBySection(ticketingId)
+                .map(sectionCounts -> ResponseEntity.ok(new SingleResponseResult<>(sectionCounts)));
+    }
+
     // 좌석 예약 가능 여부 확인
     @GetMapping("/seats/{ticketingId}/check/{seatKey}")
     public ResponseEntity<SingleResponseResult<String>> checkSeatAvailability(@PathVariable("ticketingId") Long ticketingId, @PathVariable("seatKey") String seatKey) {

src/main/java/TiCatch/backend/domain/ticketing/service/TicketingService.java

@@ -32,10 +32,10 @@
 import java.io.InputStream;
 import java.time.Instant;
 import java.time.ZoneOffset;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.time.LocalDateTime;
-import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import static TiCatch.backend.domain.ticketing.entity.TicketingLevel.*;
 import static TiCatch.backend.global.constant.TicketingConstants.*;
@@ -192,6 +192,30 @@ public Mono<Map<String, Boolean>> getSectionSeats(Long ticketingId, String secti
                 );
     }
 
+    public Mono<Map<String, Long>> getSeatCountBySection(Long ticketingId) {
+        String redisKey = TICKETING_SEAT_PREFIX + ticketingId;
+
+        return reactiveRedisTemplate.<String, String>opsForHash().entries(redisKey)
+                .collectList()
+                .flatMap(entries -> {
+                    Set<String> allSections = entries.stream()
+                            .map(entry -> entry.getKey().split(":")[0])
+                            .collect(Collectors.toSet());
+
+                    Map<String, Long> availableCounts = entries.stream()
+                            .filter(entry -> "0".equals(entry.getValue()))
+                            .map(entry -> entry.getKey().split(":")[0])
+                            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
+
+                    Map<String, Long> result = new HashMap<>();
+                    for (String section : allSections) {
+                        result.put(section, availableCounts.getOrDefault(section, 0L));
+                    }
+
+                    return Mono.just(result);
+                });
+    }
+
     public void isAvailable(Long ticketingId, String seatKey) {
         String redisKey = TICKETING_SEAT_PREFIX + ticketingId;
         HashOperations<String, String, String> hashOperations = redisTemplate.opsForHash();