Feat: 대시보드 스케줄 중복 시간 체커 구현

src/main/java/org/guzzing/studayserver/domain/dashboard/service/overlap/DashboardScheduleOverlapChecker.java

@@ -0,0 +1,39 @@
+package org.guzzing.studayserver.domain.dashboard.service.overlap;
+
+import java.util.List;
+import org.guzzing.studayserver.domain.dashboard.model.DashboardSchedule;
+import org.guzzing.studayserver.global.time.TimeConverter;
+import org.springframework.stereotype.Component;
+
+@Component
+public class DashboardScheduleOverlapChecker {
+
+    public void checkScheduleOverlap(
+            List<DashboardSchedule> dashboardSchedules,
+            List<DashboardSchedule> childDashboardSchedules
+    ) {
+        final long overlapCount = childDashboardSchedules.stream()
+                .filter(childDashboardSchedule -> dashboardSchedules.stream()
+                        .anyMatch(dashboardSchedule -> isScheduleOverlap(dashboardSchedule, childDashboardSchedule)))
+                .count();
+
+        if (overlapCount > 0) {
+            throw new IllegalStateException("시간이 겹치는 대시보드 스케줄이 있습니다.");
+        }
+    }
+
+    private boolean isScheduleOverlap(DashboardSchedule dashboardSchedule, DashboardSchedule childDashboardSchedule) {
+        final boolean isSameDayOfWeek = dashboardSchedule.getDayOfWeek() == childDashboardSchedule.getDayOfWeek();
+        final boolean isAfterSchedule = TimeConverter.getLocalTime(dashboardSchedule.getStartTime()).isAfter(
+                TimeConverter.getLocalTime(childDashboardSchedule.getEndTime()));
+        final boolean isBeforeSchedules = TimeConverter.getLocalTime(dashboardSchedule.getEndTime()).isBefore(
+                TimeConverter.getLocalTime(childDashboardSchedule.getStartTime()));
+        final boolean isSameStartTime = TimeConverter.getLocalTime(dashboardSchedule.getStartTime()).equals(
+                TimeConverter.getLocalTime(childDashboardSchedule.getStartTime()));
+        final boolean isSameEndTime = TimeConverter.getLocalTime(dashboardSchedule.getEndTime()).equals(
+                TimeConverter.getLocalTime(childDashboardSchedule.getEndTime()));
+
+        return isSameDayOfWeek && (isAfterSchedule || isBeforeSchedules || isSameStartTime || isSameEndTime);
+    }
+
+}