import Service from '@ember/service';
// We use the special Vite query parameter to load this as a web worker
import Worker from '../workers/image-processor?worker';

export default class ImageProcessorService extends Service {
  _worker = null;
  _callbacks = new Map();
  _msgId = 0;

  constructor() {
    super(...arguments);
    this._initWorker();
  }

  _initWorker() {
    if (!this._worker && typeof Worker !== 'undefined') {
      try {
        this._worker = new Worker();
        this._worker.onmessage = this._handleMessage.bind(this);
        this._worker.onerror = this._handleError.bind(this);
      } catch (e) {
        console.warn('Failed to initialize image-processor worker:', e);
      }
    }
  }

  _handleMessage(e) {
    const { id, success, blob, dim, blurhash, error } = e.data;
    const resolver = this._callbacks.get(id);

    if (resolver) {
      this._callbacks.delete(id);
      if (success) {
        resolver.resolve({ blob, dim, blurhash });
      } else {
        resolver.reject(new Error(error));
      }
    }
  }

  _handleError(error) {
    console.error('Image Processor Worker Error:', error);
    // Reject all pending jobs
    for (const [, resolver] of this._callbacks.entries()) {
      resolver.reject(new Error('Worker crashed'));
    }
    this._callbacks.clear();
    // Restart the worker for future jobs
    this._worker.terminate();
    this._worker = null;
    this._initWorker();
  }

  async process(file, maxDimension, quality, computeBlurhash = false) {
    if (!this._worker) {
      // Fallback if worker initialization failed (e.g. incredibly old browsers)
      throw new Error('Image processor worker is not available.');
    }

    return new Promise((resolve, reject) => {
      const id = ++this._msgId;
      this._callbacks.set(id, { resolve, reject });

      this._worker.postMessage({
        id,
        file,
        maxDimension,
        quality,
        computeBlurhash,
      });
    });
  }

  willDestroy() {
    super.willDestroy(...arguments);
    if (this._worker) {
      this._worker.terminate();
      this._worker = null;
    }
    this._callbacks.clear();
  }
}