import {
  BarcodeScanner,
  BarcodeFormat,
  StartScanOptions,
  LensFacing,
} from "@capacitor-mlkit/barcode-scanning";
import { QRScannerService, ScanListener, QRScannerOptions } from "./types";
import { logger } from "@/utils/logger";

export class CapacitorQRScanner implements QRScannerService {
  private scanListener: ScanListener | null = null;
  private isScanning = false;
  private listenerHandles: Array<() => Promise<void>> = [];

  async checkPermissions(): Promise<boolean> {
    try {
      const { camera } = await BarcodeScanner.checkPermissions();
      return camera === "granted";
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error checking camera permissions:", wrappedError);
      return false;
    }
  }

  async requestPermissions(): Promise<boolean> {
    try {
      // First check if we already have permissions
      if (await this.checkPermissions()) {
        return true;
      }

      // Request permissions if we don't have them
      const { camera } = await BarcodeScanner.requestPermissions();
      return camera === "granted";
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error requesting camera permissions:", wrappedError);
      return false;
    }
  }

  async isSupported(): Promise<boolean> {
    try {
      const { supported } = await BarcodeScanner.isSupported();
      return supported;
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error checking scanner support:", wrappedError);
      return false;
    }
  }

  async startScan(options?: QRScannerOptions): Promise<void> {
    if (this.isScanning) {
      return;
    }

    try {
      // Ensure we have permissions before starting
      logger.log("Checking camera permissions...");
      if (!(await this.checkPermissions())) {
        logger.log("Requesting camera permissions...");
        const granted = await this.requestPermissions();
        if (!granted) {
          throw new Error("Camera permission denied");
        }
      }

      // Check if scanning is supported
      logger.log("Checking scanner support...");
      if (!(await this.isSupported())) {
        throw new Error("QR scanning not supported on this device");
      }

      logger.log("Starting MLKit scanner...");
      this.isScanning = true;

      const scanOptions: StartScanOptions = {
        formats: [BarcodeFormat.QrCode],
        lensFacing:
          options?.camera === "front" ? LensFacing.Front : LensFacing.Back,
      };

      logger.log("Scanner options:", scanOptions);
      
      // Add listener for barcode scans
      const handle = await BarcodeScanner.addListener('barcodeScanned', (result) => {
        if (this.scanListener) {
          this.scanListener.onScan(result.barcode.rawValue);
        }
      });
      this.listenerHandles.push(handle.remove);
      
      // Start continuous scanning
      await BarcodeScanner.startScan(scanOptions);
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error during QR scan:", wrappedError);
      this.scanListener?.onError?.(wrappedError);
      throw wrappedError;
    }
  }

  async stopScan(): Promise<void> {
    if (!this.isScanning) {
      return;
    }

    try {
      await BarcodeScanner.stopScan();
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error stopping QR scan:", wrappedError);
      this.scanListener?.onError?.(wrappedError);
      throw wrappedError;
    } finally {
      this.isScanning = false;
    }
  }

  addListener(listener: ScanListener): void {
    this.scanListener = listener;
  }

  async cleanup(): Promise<void> {
    try {
      await this.stopScan();
      for (const handle of this.listenerHandles) {
        await handle();
      }
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error during cleanup:", wrappedError);
      throw wrappedError;
    } finally {
      this.listenerHandles = [];
      this.scanListener = null;
    }
  }
}