export class RtlSdrDriver {
  private device: USBDevice | null = null;

  /**
   * Requests access to an RTL-SDR USB device from the user.
   * Must be called as a result of a user gesture (e.g., button click).
   */
  async requestDevice(): Promise<USBDevice> {
    if (!('usb' in navigator)) {
      throw new Error('WebUSB is not supported in this browser.');
    }

    // Standard Vendor IDs for RTL2832U based dongles
    this.device = await navigator.usb.requestDevice({
      filters: [
        { vendorId: 0x0bda, productId: 0x2838 }, // RTL2838 DVB-T
        { vendorId: 0x0bda, productId: 0x2832 }  // RTL2832U
      ]
    });

    return this.device;
  }

  /**
   * Opens the USB device and claims the necessary interfaces.
   */
  async open(): Promise<void> {
    if (!this.device) throw new Error('No device selected. Call requestDevice() first.');
    
    await this.device.open();
    
    if (this.device.configuration === null) {
      await this.device.selectConfiguration(1);
    }
    
    await this.device.claimInterface(0);
    
    // Send a basic reset command via control transfer
    await this.device.controlTransferOut({
      requestType: 'vendor',
      recipient: 'device',
      request: 0x01, // Example reset/init command
      value: 0,
      index: 0
    });
  }

  /**
   * Sets the center frequency of the SDR.
   * @param hz Frequency in Hertz
   */
  async setFrequency(hz: number): Promise<void> {
    if (!this.device) throw new Error('Device not connected');
    console.log(`[RTL-SDR] Setting PLL frequency to ${hz} Hz`);
    // In a full implementation, this involves calculating PLL multipliers 
    // and sending multiple controlTransferOut commands to the tuner IC (e.g., R820T2).
  }

  /**
   * Sets the sample rate.
   * @param rate Sample rate in Hz (e.g., 2048000 for 2.048 MSPS)
   */
  async setSampleRate(rate: number): Promise<void> {
    if (!this.device) throw new Error('Device not connected');
    console.log(`[RTL-SDR] Setting sample rate to ${rate} Hz`);
  }

  /**
   * Sets the tuner gain.
   * @param gain Gain in tenths of a dB
   */
  async setGain(gain: number): Promise<void> {
    if (!this.device) throw new Error('Device not connected');
    console.log(`[RTL-SDR] Setting gain to ${gain} dB`);
  }

  /**
   * Reads raw I/Q data from the bulk transfer endpoint.
   * @param length Number of bytes to read
   */
  async readIQ(length: number = 16384): Promise<Uint8Array> {
    if (!this.device) throw new Error('Device not connected');
    
    // Endpoint 1 is typically the bulk IN endpoint for RTL-SDR
    const result = await this.device.transferIn(1, length);
    return new Uint8Array(result.data?.buffer || new ArrayBuffer(0));
  }

  /**
   * Closes the connection and releases the interface.
   */
  async close(): Promise<void> {
    if (this.device) {
      try {
        await this.device.releaseInterface(0);
        await this.device.close();
      } catch (e) {
        console.error('Error closing RTL-SDR device:', e);
      } finally {
        this.device = null;
      }
    }
  }
}