feat: implemented global marker track

src/util/globalTrackUtil.ts

@@ -0,0 +1,85 @@
+import { KGProject } from '../core/KGProject';
+import {
+  GlobalTrackType,
+  KGGlobalTrack,
+  createDefaultGlobalTracks,
+} from '../core/global-track';
+import { KGGlobalRegion } from '../core/region/KGGlobalRegion';
+
+export const DEFAULT_MARKER_REGION_NAME = 'Marker';
+
+export function ensureDefaultGlobalTracks(project: KGProject): KGGlobalTrack[] {
+  const existingTracks = project.getGlobalTracks?.() ?? [];
+  const nextTracks = createDefaultGlobalTracks();
+
+  for (const existingTrack of existingTracks) {
+    const matchedTrack = nextTracks.find(track => track.getType() === existingTrack.getType());
+    if (matchedTrack) {
+      matchedTrack.setRegions(existingTrack.getRegions());
+    }
+  }
+
+  nextTracks.forEach((track, index) => {
+    track.setTrackIndex(index);
+  });
+
+  project.setGlobalTracks(nextTracks);
+  return nextTracks;
+}
+
+export function getSongEndBeat(project: KGProject): number {
+  return project.getMaxBars() * project.getTimeSignature().numerator;
+}
+
+export function findGlobalTrackByType(project: KGProject, type: GlobalTrackType): KGGlobalTrack | null {
+  return project.getGlobalTracks().find(track => track.getType() === type) ?? null;
+}
+
+export function findGlobalTrackContainingRegion(
+  project: KGProject,
+  regionId: string
+): { track: KGGlobalTrack; region: KGGlobalRegion; regionIndex: number } | null {
+  for (const track of project.getGlobalTracks()) {
+    const regionIndex = track.getRegions().findIndex(region => region.getId() === regionId);
+    if (regionIndex !== -1) {
+      const region = track.getRegions()[regionIndex];
+      return { track, region, regionIndex };
+    }
+  }
+
+  return null;
+}
+
+export function findMarkerNeighborBounds(
+  project: KGProject,
+  regionId: string | null,
+  proposedStartBeat: number
+): { minStartBeat: number; maxEndBeat: number; nextStartBeat: number | null } {
+  const markerTrack = findGlobalTrackByType(project, GlobalTrackType.Marker);
+  const songEndBeat = getSongEndBeat(project);
+
+  if (!markerTrack) {
+    return { minStartBeat: 0, maxEndBeat: songEndBeat, nextStartBeat: null };
+  }
+
+  const otherRegions = markerTrack.getRegions()
+    .filter(region => region.getId() !== regionId)
+    .sort((left, right) => left.getStartFromBeat() - right.getStartFromBeat());
+
+  let minStartBeat = 0;
+  let maxEndBeat = songEndBeat;
+  let nextStartBeat: number | null = null;
+
+  for (const region of otherRegions) {
+    if (region.getStartFromBeat() < proposedStartBeat) {
+      minStartBeat = Math.max(minStartBeat, region.getStartFromBeat() + region.getLength());
+      continue;
+    }
+
+    maxEndBeat = Math.min(maxEndBeat, region.getStartFromBeat());
+    nextStartBeat = region.getStartFromBeat();
+    break;
+  }
+
+  return { minStartBeat, maxEndBeat, nextStartBeat };
+}