audio-ui/lib/history/commands/edit-command.ts

/**
 * Edit commands for audio buffer operations
 */

import { BaseCommand } from '../command';
import type { Selection } from '@/types/selection';
import {
  extractBufferSegment,
  deleteBufferSegment,
  insertBufferSegment,
  trimBuffer,
} from '@/lib/audio/buffer-utils';

export type EditCommandType = 'cut' | 'delete' | 'paste' | 'trim';

export interface EditCommandParams {
  type: EditCommandType;
  beforeBuffer: AudioBuffer;
  afterBuffer: AudioBuffer;
  selection?: Selection;
  clipboardData?: AudioBuffer;
  pastePosition?: number;
  onApply: (buffer: AudioBuffer) => void;
}

/**
 * Command for edit operations (cut, delete, paste, trim)
 */
export class EditCommand extends BaseCommand {
  private type: EditCommandType;
  private beforeBuffer: AudioBuffer;
  private afterBuffer: AudioBuffer;
  private selection?: Selection;
  private clipboardData?: AudioBuffer;
  private pastePosition?: number;
  private onApply: (buffer: AudioBuffer) => void;

  constructor(params: EditCommandParams) {
    super();
    this.type = params.type;
    this.beforeBuffer = params.beforeBuffer;
    this.afterBuffer = params.afterBuffer;
    this.selection = params.selection;
    this.clipboardData = params.clipboardData;
    this.pastePosition = params.pastePosition;
    this.onApply = params.onApply;
  }

  execute(): void {
    this.onApply(this.afterBuffer);
  }

  undo(): void {
    this.onApply(this.beforeBuffer);
  }

  getDescription(): string {
    switch (this.type) {
      case 'cut':
        return 'Cut';
      case 'delete':
        return 'Delete';
      case 'paste':
        return 'Paste';
      case 'trim':
        return 'Trim';
      default:
        return 'Edit';
    }
  }

  /**
   * Get the type of edit operation
   */
  getType(): EditCommandType {
    return this.type;
  }

  /**
   * Get the selection that was affected
   */
  getSelection(): Selection | undefined {
    return this.selection;
  }
}

/**
 * Factory functions to create edit commands
 */

export function createCutCommand(
  buffer: AudioBuffer,
  selection: Selection,
  onApply: (buffer: AudioBuffer) => void
): EditCommand {
  const afterBuffer = deleteBufferSegment(buffer, selection.start, selection.end);

  return new EditCommand({
    type: 'cut',
    beforeBuffer: buffer,
    afterBuffer,
    selection,
    onApply,
  });
}

export function createDeleteCommand(
  buffer: AudioBuffer,
  selection: Selection,
  onApply: (buffer: AudioBuffer) => void
): EditCommand {
  const afterBuffer = deleteBufferSegment(buffer, selection.start, selection.end);

  return new EditCommand({
    type: 'delete',
    beforeBuffer: buffer,
    afterBuffer,
    selection,
    onApply,
  });
}

export function createPasteCommand(
  buffer: AudioBuffer,
  clipboardData: AudioBuffer,
  pastePosition: number,
  onApply: (buffer: AudioBuffer) => void
): EditCommand {
  const afterBuffer = insertBufferSegment(buffer, clipboardData, pastePosition);

  return new EditCommand({
    type: 'paste',
    beforeBuffer: buffer,
    afterBuffer,
    clipboardData,
    pastePosition,
    onApply,
  });
}

export function createTrimCommand(
  buffer: AudioBuffer,
  selection: Selection,
  onApply: (buffer: AudioBuffer) => void
): EditCommand {
  const afterBuffer = trimBuffer(buffer, selection.start, selection.end);

  return new EditCommand({
    type: 'trim',
    beforeBuffer: buffer,
    afterBuffer,
    selection,
    onApply,
  });
}