feat: added a hotkey for loop button

src/util/loopUtil.ts

@@ -0,0 +1,49 @@
+import { KGCore } from '../core/KGCore';
+import { ChangeLoopSettingsCommand } from '../core/commands';
+
+/**
+ * Toggle the loop mode on/off with proper validation.
+ * When enabling loop mode:
+ * - If loop range is [0, 0], sets it to the entire song [0, maxBars]
+ * - Validates that loop range is within [0, maxBars]
+ * Uses the command pattern for undo/redo support.
+ *
+ * @param currentIsLooping Current loop mode state
+ * @param currentLoopingRange Current loop range [startBar, endBar]
+ * @param maxBars Maximum number of bars in the project
+ */
+export const toggleLoop = (
+  currentIsLooping: boolean,
+  currentLoopingRange: [number, number],
+  maxBars: number
+): void => {
+  const newLoopingState = !currentIsLooping;
+  let newLoopingRange = currentLoopingRange;
+
+  // When enabling loop, validate and set the loop range
+  if (newLoopingState) {
+    const currentRange = currentLoopingRange;
+    const projectMaxBars = maxBars;
+
+    // If range is [0, 0], set it to the entire song
+    if (currentRange[0] === 0 && currentRange[1] === 0) {
+      newLoopingRange = [0, projectMaxBars] as [number, number];
+    } else {
+      // Validate range is within [0, maxBars]
+      const validatedStart = Math.max(0, Math.min(currentRange[0], projectMaxBars));
+      const validatedEnd = Math.max(0, Math.min(currentRange[1], projectMaxBars));
+
+      // If range changed, update it
+      if (validatedStart !== currentRange[0] || validatedEnd !== currentRange[1]) {
+        newLoopingRange = [validatedStart, validatedEnd] as [number, number];
+      }
+    }
+  }
+
+  // Execute command for undo/redo support
+  const command = new ChangeLoopSettingsCommand({
+    isLooping: newLoopingState,
+    loopingRange: newLoopingRange
+  });
+  KGCore.instance().executeCommand(command);
+};