feat: add waitlist entity and repository

src/main/java/com/slotline/reservation/WaitlistEntry.java

@@ -0,0 +1,101 @@
+package com.slotline.reservation;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+import java.time.Instant;
+
+@Entity
+@Table(name = "waitlist_entry")
+public class WaitlistEntry {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "resource_id", nullable = false)
+    private Long resourceId;
+
+    @Column(name = "organization_id", nullable = false)
+    private Long organizationId;
+
+    @Column(name = "user_id", nullable = false)
+    private Long userId;
+
+    @Column(name = "start_time", nullable = false)
+    private Instant startTime;
+
+    @Column(name = "end_time", nullable = false)
+    private Instant endTime;
+
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false, length = 16)
+    private WaitlistStatus status;
+
+    @Column(name = "created_at", nullable = false)
+    private Instant createdAt;
+
+    @Column(name = "promoted_reservation_id")
+    private Long promotedReservationId;
+
+    protected WaitlistEntry() {
+    }
+
+    public WaitlistEntry(Long resourceId, Long organizationId, Long userId, Instant startTime, Instant endTime,
+                         Instant createdAt) {
+        this.resourceId = resourceId;
+        this.organizationId = organizationId;
+        this.userId = userId;
+        this.startTime = startTime;
+        this.endTime = endTime;
+        this.status = WaitlistStatus.WAITING;
+        this.createdAt = createdAt;
+    }
+
+    public void promote(Long reservationId) {
+        this.status = WaitlistStatus.PROMOTED;
+        this.promotedReservationId = reservationId;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public Long getResourceId() {
+        return resourceId;
+    }
+
+    public Long getOrganizationId() {
+        return organizationId;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public Instant getStartTime() {
+        return startTime;
+    }
+
+    public Instant getEndTime() {
+        return endTime;
+    }
+
+    public WaitlistStatus getStatus() {
+        return status;
+    }
+
+    public Instant getCreatedAt() {
+        return createdAt;
+    }
+
+    public Long getPromotedReservationId() {
+        return promotedReservationId;
+    }
+}

src/main/java/com/slotline/reservation/WaitlistRepository.java

@@ -0,0 +1,25 @@
+package com.slotline.reservation;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import java.time.Instant;
+import java.util.List;
+
+public interface WaitlistRepository extends JpaRepository<WaitlistEntry, Long> {
+
+    List<WaitlistEntry> findByUserIdOrderByCreatedAtDesc(Long userId);
+
+    @Query("""
+            select w from WaitlistEntry w
+            where w.resourceId = :resourceId
+              and w.status = com.slotline.reservation.WaitlistStatus.WAITING
+              and w.startTime < :end
+              and w.endTime > :start
+            order by w.createdAt asc
+            """)
+    List<WaitlistEntry> findWaitingOverlaps(@Param("resourceId") Long resourceId,
+                                            @Param("start") Instant start,
+                                            @Param("end") Instant end);
+}

src/main/java/com/slotline/reservation/WaitlistStatus.java

@@ -0,0 +1,7 @@
+package com.slotline.reservation;
+
+public enum WaitlistStatus {
+    WAITING,
+    PROMOTED,
+    CANCELLED
+}