import type { Transport, OpenOptions } from "./interface";

export class WebSerial implements Transport {
  constructor(private port: SerialPort) {}
  private reader?: ReadableStreamDefaultReader<Uint8Array>;
  private writer?: WritableStreamDefaultWriter<Uint8Array>;

  async open(options: OpenOptions): Promise<void> {
    await this.port.open({
      baudRate: options.baudRate,
    });
    
    if (this.port.readable) {
      this.reader = this.port.readable.getReader();
    }
    if (this.port.writable) {
      this.writer = this.port.writable.getWriter();
    }
  }

  async close(): Promise<void> {
    if (this.port.readable && this.reader) {
      await this.reader.cancel();
      this.reader.releaseLock();
    }
    if (this.port.writable && this.writer) {
      await this.writer.close();
      this.writer.releaseLock();
    }
    await this.port.close();
  }

  async read(): Promise<Buffer> {
    if (!this.reader) throw new Error("reader not initialized");

    while (this.port.readable && this.port.readable.locked) {
      const { value, done } = await this.reader.read();

      if (done) {
        break;
      }

      if (value) {
        return Buffer.from(value);
      }
    }

    throw new Error("read failed");
  }

  async write(data: Buffer): Promise<void> {
    if (!this.writer) throw new Error("writer not initialized");
    await this.writer.write(data);
  }
}