convert-ui/lib/wasm/wasmLoader.ts

import type { FFmpeg } from '@ffmpeg/ffmpeg';
import type { ConverterEngine, WASMModuleState } from '@/types/conversion';

/**
 * WASM module loading state
 */
const moduleState: WASMModuleState = {
  ffmpeg: false,
  imagemagick: false,
  pandoc: false,
};

/**
 * Cached WASM instances
 */
let ffmpegInstance: FFmpeg | null = null;
let imagemagickInstance: any = null;
let pandocInstance: any = null;

/**
 * Load FFmpeg WASM module
 */
export async function loadFFmpeg(): Promise<FFmpeg> {
  if (ffmpegInstance && moduleState.ffmpeg) {
    return ffmpegInstance;
  }

  try {
    const { FFmpeg } = await import('@ffmpeg/ffmpeg');
    const { toBlobURL } = await import('@ffmpeg/util');

    ffmpegInstance = new FFmpeg();

    // Load core and dependencies
    const baseURL = 'https://unpkg.com/@ffmpeg/core@0.12.6/dist/umd';

    ffmpegInstance.on('log', ({ message }) => {
      console.log('[FFmpeg]', message);
    });

    await ffmpegInstance.load({
      coreURL: await toBlobURL(`${baseURL}/ffmpeg-core.js`, 'text/javascript'),
      wasmURL: await toBlobURL(`${baseURL}/ffmpeg-core.wasm`, 'application/wasm'),
    });

    moduleState.ffmpeg = true;
    console.log('FFmpeg loaded successfully');

    return ffmpegInstance;
  } catch (error) {
    console.error('Failed to load FFmpeg:', error);
    throw new Error('Failed to load FFmpeg WASM module');
  }
}

/**
 * Load ImageMagick WASM module
 */
export async function loadImageMagick(): Promise<any> {
  if (imagemagickInstance && moduleState.imagemagick) {
    return imagemagickInstance;
  }

  try {
    const ImageMagick = await import('@imagemagick/magick-wasm');

    imagemagickInstance = ImageMagick;
    moduleState.imagemagick = true;
    console.log('ImageMagick loaded successfully');

    return imagemagickInstance;
  } catch (error) {
    console.error('Failed to load ImageMagick:', error);
    throw new Error('Failed to load ImageMagick WASM module');
  }
}

/**
 * Load Pandoc WASM module (placeholder for future implementation)
 */
export async function loadPandoc(): Promise<any> {
  if (pandocInstance && moduleState.pandoc) {
    return pandocInstance;
  }

  // TODO: Implement Pandoc WASM loading when available
  // For now, throw an error
  throw new Error('Pandoc WASM module is not yet implemented');
}

/**
 * Get loaded module state
 */
export function getModuleState(): WASMModuleState {
  return { ...moduleState };
}

/**
 * Check if a specific module is loaded
 */
export function isModuleLoaded(engine: ConverterEngine): boolean {
  return moduleState[engine];
}

/**
 * Load appropriate WASM module for converter engine
 */
export async function loadModule(engine: ConverterEngine): Promise<any> {
  switch (engine) {
    case 'ffmpeg':
      return loadFFmpeg();
    case 'imagemagick':
      return loadImageMagick();
    case 'pandoc':
      return loadPandoc();
    default:
      throw new Error(`Unknown converter engine: ${engine}`);
  }
}

/**
 * Unload all WASM modules and free memory
 */
export function unloadAll(): void {
  if (ffmpegInstance) {
    // FFmpeg doesn't have an explicit unload method
    // Just null the instance
    ffmpegInstance = null;
    moduleState.ffmpeg = false;
  }

  if (imagemagickInstance) {
    imagemagickInstance = null;
    moduleState.imagemagick = false;
  }

  if (pandocInstance) {
    pandocInstance = null;
    moduleState.pandoc = false;
  }

  console.log('All WASM modules unloaded');
}