feat: implement global chord track

src/core/commands/global-region/InsertChordRegionAtBeatCommand.ts

@@ -0,0 +1,86 @@
+import { KGCommand } from '../KGCommand';
+import { KGCore } from '../../KGCore';
+import { GlobalTrackType } from '../../global-track';
+import { KGChordRegion } from '../../region/KGChordRegion';
+import { generateUniqueId } from '../../../util/miscUtil';
+import { findChordRegionAtBeat, findGlobalTrackByType } from '../../../util/globalTrackUtil';
+
+export class InsertChordRegionAtBeatCommand extends KGCommand {
+  private readonly insertBeat: number;
+  private readonly symbol: string;
+  private readonly regionId: string;
+  private createdRegion: KGChordRegion | null = null;
+  private targetRegionId: string | null = null;
+  private originalTargetLength = 0;
+
+  constructor(insertBeat: number, symbol: string = 'C', regionId?: string) {
+    super();
+    this.insertBeat = insertBeat;
+    this.symbol = symbol;
+    this.regionId = regionId ?? generateUniqueId('KGChordRegion');
+  }
+
+  execute(): void {
+    const project = KGCore.instance().getCurrentProject();
+    const chordTrack = findGlobalTrackByType(project, GlobalTrackType.Chord);
+    if (!chordTrack) {
+      throw new Error('Chord global track not found');
+    }
+
+    const occupiedRegion = findChordRegionAtBeat(project, this.insertBeat);
+    if (!occupiedRegion) {
+      throw new Error(`No chord region found at beat ${this.insertBeat}`);
+    }
+
+    const regionStart = occupiedRegion.getStartFromBeat();
+    const regionEnd = regionStart + occupiedRegion.getLength();
+    if (this.insertBeat <= regionStart || this.insertBeat >= regionEnd) {
+      throw new Error(`Cannot insert chord at beat ${this.insertBeat} without shrinking region below minimum length`);
+    }
+
+    this.targetRegionId = occupiedRegion.getId();
+    this.originalTargetLength = occupiedRegion.getLength();
+    occupiedRegion.setLength(this.insertBeat - regionStart);
+
+    this.createdRegion = new KGChordRegion(
+      this.regionId,
+      chordTrack.getId(),
+      chordTrack.getTrackIndex(),
+      this.symbol,
+      this.insertBeat,
+      regionEnd - this.insertBeat
+    );
+
+    chordTrack.setRegions(
+      [...chordTrack.getRegions(), this.createdRegion]
+        .sort((left, right) => left.getStartFromBeat() - right.getStartFromBeat())
+    );
+  }
+
+  undo(): void {
+    const project = KGCore.instance().getCurrentProject();
+    const chordTrack = findGlobalTrackByType(project, GlobalTrackType.Chord);
+    if (!chordTrack || !this.targetRegionId || !this.createdRegion) {
+      throw new Error('Cannot undo inserted chord region');
+    }
+
+    chordTrack.removeRegion(this.createdRegion.getId());
+    const targetRegion = chordTrack.getRegions().find((region): region is KGChordRegion => (
+      region instanceof KGChordRegion && region.getId() === this.targetRegionId
+    ));
+    if (!targetRegion) {
+      throw new Error(`Chord region ${this.targetRegionId} not found during undo`);
+    }
+
+    targetRegion.setLength(this.originalTargetLength);
+    chordTrack.setRegions([...chordTrack.getRegions()].sort((left, right) => left.getStartFromBeat() - right.getStartFromBeat()));
+  }
+
+  getDescription(): string {
+    return `Insert chord "${this.symbol}"`;
+  }
+
+  public getCreatedRegion(): KGChordRegion | null {
+    return this.createdRegion;
+  }
+}