import * as plugins from './smartstream.plugins.js';
import { Duplex, type DuplexOptions } from 'stream';

export class SmartStream extends Duplex {
  private observableSubscription?: plugins.smartrx.rxjs.Subscription;

  constructor(options?: DuplexOptions) {
    super(options);
  }

  _read(size: number) {
    // Implement if you need custom behavior, otherwise leave it empty
  }

  _write(chunk: any, encoding: string, callback: (error?: Error | null) => void) {
    // Implement if you need custom behavior
    callback();
  }

  static fromBuffer(buffer: Buffer, options?: DuplexOptions): SmartStream {
    const smartStream = new SmartStream(options);
    process.nextTick(() => {
      smartStream.push(buffer);
      smartStream.push(null); // Signal the end of the data
    });
    return smartStream;
  }

  static fromObservable(observable: plugins.smartrx.rxjs.Observable<any>, options?: DuplexOptions): SmartStream {
    const smartStream = new SmartStream(options);
    smartStream.observableSubscription = observable.subscribe({
      next: (data) => {
        if (!smartStream.push(data)) {
          // Pause the observable if the stream buffer is full
          smartStream.observableSubscription?.unsubscribe();
          smartStream.once('drain', () => {
            // Resume the observable when the stream buffer is drained
            smartStream.observableSubscription?.unsubscribe();
            smartStream.observableSubscription = observable.subscribe(data => {
              smartStream.push(data);
            });
          });
        }
      },
      error: (err) => {
        smartStream.emit('error', err);
      },
      complete: () => {
        smartStream.push(null); // Signal the end of the data
      }
    });

    return smartStream;
  }
}