feat(recommend): 추천 스냅샷 저장소를 추가한다

src/main/kotlin/kr/co/vividnext/sodalive/v2/recommend/adapter/out/persistence/RecommendationSnapshot.kt

@@ -0,0 +1,30 @@
+package kr.co.vividnext.sodalive.v2.recommend.adapter.out.persistence
+
+import kr.co.vividnext.sodalive.common.BaseEntity
+import kr.co.vividnext.sodalive.v2.recommend.domain.RecommendedSectionType
+import java.time.LocalDateTime
+import javax.persistence.Column
+import javax.persistence.Entity
+import javax.persistence.EnumType
+import javax.persistence.Enumerated
+import javax.persistence.Table
+
+@Entity
+@Table(name = "recommendation_snapshot")
+class RecommendationSnapshot(
+    @Enumerated(EnumType.STRING)
+    @Column(name = "section_type", nullable = false, updatable = false, length = 50)
+    val sectionType: RecommendedSectionType,
+
+    @Column(name = "target_id", nullable = false, updatable = false)
+    val targetId: Long,
+
+    @Column(name = "score", nullable = false, updatable = false)
+    val score: Double,
+
+    @Column(name = "snapshot_at", nullable = false, updatable = false)
+    val snapshotAt: LocalDateTime,
+
+    @Column(name = "random_tie_breaker", nullable = false, updatable = false)
+    val randomTieBreaker: Double
+) : BaseEntity()

src/main/kotlin/kr/co/vividnext/sodalive/v2/recommend/adapter/out/persistence/RecommendationSnapshotPersistenceAdapter.kt

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+package kr.co.vividnext.sodalive.v2.recommend.adapter.out.persistence
+
+import kr.co.vividnext.sodalive.v2.recommend.domain.RecommendedSectionType
+import kr.co.vividnext.sodalive.v2.recommend.port.out.RecommendationSnapshotPort
+import kr.co.vividnext.sodalive.v2.recommend.port.out.RecommendationSnapshotRecord
+import org.springframework.stereotype.Repository
+import java.time.LocalDateTime
+
+@Repository
+class RecommendationSnapshotPersistenceAdapter(
+    private val repository: RecommendationSnapshotRepository
+) : RecommendationSnapshotPort {
+    override fun findLatestSnapshots(sectionType: RecommendedSectionType): List<RecommendationSnapshotRecord> {
+        val snapshotAt = repository.findTopBySectionTypeOrderBySnapshotAtDesc(sectionType)?.snapshotAt ?: return emptyList()
+        return repository.findAllBySectionTypeAndSnapshotAtOrderByScoreDescRandomTieBreakerAsc(sectionType, snapshotAt)
+            .map { it.toRecord() }
+    }
+
+    override fun replaceSnapshots(
+        sectionType: RecommendedSectionType,
+        snapshotAt: LocalDateTime,
+        newSnapshots: List<RecommendationSnapshotRecord>
+    ) {
+        repository.deleteBySectionTypeAndSnapshotAt(sectionType, snapshotAt)
+        repository.saveAll(newSnapshots.map { it.toEntity() })
+    }
+
+    private fun RecommendationSnapshot.toRecord(): RecommendationSnapshotRecord {
+        return RecommendationSnapshotRecord(
+            sectionType = sectionType,
+            targetId = targetId,
+            score = score,
+            snapshotAt = snapshotAt,
+            randomTieBreaker = randomTieBreaker
+        )
+    }
+
+    private fun RecommendationSnapshotRecord.toEntity(): RecommendationSnapshot {
+        return RecommendationSnapshot(
+            sectionType = sectionType,
+            targetId = targetId,
+            score = score,
+            snapshotAt = snapshotAt,
+            randomTieBreaker = randomTieBreaker
+        )
+    }
+}

src/main/kotlin/kr/co/vividnext/sodalive/v2/recommend/adapter/out/persistence/RecommendationSnapshotRepository.kt

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+package kr.co.vividnext.sodalive.v2.recommend.adapter.out.persistence
+
+import kr.co.vividnext.sodalive.v2.recommend.domain.RecommendedSectionType
+import org.springframework.data.jpa.repository.JpaRepository
+import java.time.LocalDateTime
+
+interface RecommendationSnapshotRepository : JpaRepository<RecommendationSnapshot, Long> {
+    fun findTopBySectionTypeOrderBySnapshotAtDesc(sectionType: RecommendedSectionType): RecommendationSnapshot?
+
+    fun findAllBySectionTypeAndSnapshotAtOrderByScoreDescRandomTieBreakerAsc(
+        sectionType: RecommendedSectionType,
+        snapshotAt: LocalDateTime
+    ): List<RecommendationSnapshot>
+
+    fun deleteBySectionTypeAndSnapshotAt(sectionType: RecommendedSectionType, snapshotAt: LocalDateTime)
+}

src/main/kotlin/kr/co/vividnext/sodalive/v2/recommend/port/out/RecommendationSnapshotPort.kt

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+package kr.co.vividnext.sodalive.v2.recommend.port.out
+
+import kr.co.vividnext.sodalive.v2.recommend.domain.RecommendedSectionType
+import java.time.LocalDateTime
+
+interface RecommendationSnapshotPort {
+    fun findLatestSnapshots(sectionType: RecommendedSectionType): List<RecommendationSnapshotRecord>
+
+    fun replaceSnapshots(
+        sectionType: RecommendedSectionType,
+        snapshotAt: LocalDateTime,
+        newSnapshots: List<RecommendationSnapshotRecord>
+    )
+}
+
+data class RecommendationSnapshotRecord(
+    val sectionType: RecommendedSectionType,
+    val targetId: Long,
+    val score: Double,
+    val snapshotAt: LocalDateTime,
+    val randomTieBreaker: Double
+)