add undo option

src/lib/utils/UndoManager.ts

@@ -0,0 +1,64 @@
+export interface AudioState {
+  leftChannel: Float32Array;
+  rightChannel: Float32Array;
+  params: any;
+  isProcessed: boolean;
+  waveformColor: string;
+  engineIndex: number;
+}
+
+export class UndoManager {
+  private undoStack: AudioState[] = [];
+  private readonly maxHistorySize: number;
+
+  constructor(maxHistorySize: number = 20) {
+    this.maxHistorySize = maxHistorySize;
+  }
+
+  pushState(state: AudioState): void {
+    this.undoStack.push({
+      leftChannel: state.leftChannel.slice(),
+      rightChannel: state.rightChannel.slice(),
+      params: state.params,
+      isProcessed: state.isProcessed,
+      waveformColor: state.waveformColor,
+      engineIndex: state.engineIndex,
+    });
+
+    if (this.undoStack.length > this.maxHistorySize) {
+      this.undoStack.shift();
+    }
+  }
+
+  undo(): AudioState | null {
+    const previousState = this.undoStack.pop();
+    return previousState || null;
+  }
+
+  canUndo(): boolean {
+    return this.undoStack.length > 0;
+  }
+
+  clear(): void {
+    this.undoStack = [];
+  }
+
+  static captureState(
+    buffer: AudioBuffer | null,
+    params: any,
+    isProcessed: boolean,
+    waveformColor: string,
+    engineIndex: number
+  ): AudioState | null {
+    if (!buffer) return null;
+
+    return {
+      leftChannel: buffer.getChannelData(0).slice(),
+      rightChannel: buffer.getChannelData(1).slice(),
+      params,
+      isProcessed,
+      waveformColor,
+      engineIndex,
+    };
+  }
+}

src/lib/utils/keyboard.ts

@@ -8,6 +8,7 @@ export interface KeyboardActions {
   onVolumeDecrease?: (large: boolean) => void;
   onVolumeIncrease?: (large: boolean) => void;
   onEscape?: () => void;
+  onUndo?: () => void;
 }
 
 export function createKeyboardHandler(actions: KeyboardActions) {
@@ -18,6 +19,9 @@ export function createKeyboardHandler(actions: KeyboardActions) {
     const isLargeAdjustment = event.shiftKey;
 
     switch (key) {
+      case 'z':
+        actions.onUndo?.();
+        break;
       case 'm':
         actions.onMutate?.();
         break;