import { QRScannerService, ScanListener, QRScannerOptions } from "./types";
import { logger } from "@/utils/logger";
import { EventEmitter } from "events";

export class WebInlineQRScanner implements QRScannerService {
  private scanListener: ScanListener | null = null;
  private isScanning = false;
  private stream: MediaStream | null = null;
  private events = new EventEmitter();

  constructor(private options?: QRScannerOptions) {}

  async checkPermissions(): Promise<boolean> {
    try {
      logger.log("[QRScanner] Checking camera permissions...");
      const permissions = await navigator.permissions.query({
        name: "camera" as PermissionName,
      });
      logger.log("[QRScanner] Permission state:", permissions.state);
      return permissions.state === "granted";
    } catch (error) {
      logger.error("[QRScanner] Error checking camera permissions:", error);
      return false;
    }
  }

  async requestPermissions(): Promise<boolean> {
    try {
      // First check if we have any video devices
      const devices = await navigator.mediaDevices.enumerateDevices();
      const videoDevices = devices.filter(
        (device) => device.kind === "videoinput",
      );

      if (videoDevices.length === 0) {
        logger.error("No video devices found");
        throw new Error("No camera found on this device");
      }

      // Try to get a stream with specific constraints
      const stream = await navigator.mediaDevices.getUserMedia({
        video: {
          facingMode: "environment",
          width: { ideal: 1280 },
          height: { ideal: 720 },
        },
      });

      // Stop the test stream immediately
      stream.getTracks().forEach((track) => track.stop());
      return true;
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error requesting camera permissions:", {
        error: wrappedError.message,
        stack: wrappedError.stack,
        name: wrappedError.name,
      });

      // Provide more specific error messages
      if (
        wrappedError.name === "NotFoundError" ||
        wrappedError.name === "DevicesNotFoundError"
      ) {
        throw new Error("No camera found on this device");
      } else if (
        wrappedError.name === "NotAllowedError" ||
        wrappedError.name === "PermissionDeniedError"
      ) {
        throw new Error(
          "Camera access denied. Please grant camera permission and try again",
        );
      } else if (
        wrappedError.name === "NotReadableError" ||
        wrappedError.name === "TrackStartError"
      ) {
        throw new Error("Camera is in use by another application");
      } else {
        throw new Error(`Camera error: ${wrappedError.message}`);
      }
    }
  }

  async isSupported(): Promise<boolean> {
    try {
      // Check for secure context first
      if (!window.isSecureContext) {
        logger.warn("Camera access requires HTTPS (secure context)");
        return false;
      }

      // Check for camera API support
      if (!navigator.mediaDevices || !navigator.mediaDevices.getUserMedia) {
        logger.warn("Camera API not supported in this browser");
        return false;
      }

      // Check if we have any video devices
      const devices = await navigator.mediaDevices.enumerateDevices();
      const hasVideoDevices = devices.some(
        (device) => device.kind === "videoinput",
      );

      if (!hasVideoDevices) {
        logger.warn("No video devices found");
        return false;
      }

      return true;
    } catch (error) {
      logger.error("Error checking camera support:", {
        error: error instanceof Error ? error.message : String(error),
        stack: error instanceof Error ? error.stack : undefined,
      });
      return false;
    }
  }

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

    try {
      this.isScanning = true;
      logger.log("[WebInlineQRScanner] Starting scan");

      // Get camera stream
      this.stream = await navigator.mediaDevices.getUserMedia({
        video: {
          facingMode: "environment",
          width: { ideal: 1280 },
          height: { ideal: 720 },
        },
      });

      // Emit stream to component
      this.events.emit("stream", this.stream);
    } catch (error) {
      this.isScanning = false;
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      if (this.scanListener?.onError) {
        this.scanListener.onError(wrappedError);
      }
      logger.error("Error starting scan:", wrappedError);
      throw wrappedError;
    }
  }

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

    try {
      logger.log("[WebInlineQRScanner] Stopping scan");

      // Stop all tracks in the stream
      if (this.stream) {
        this.stream.getTracks().forEach((track) => track.stop());
        this.stream = null;
      }

      // Emit stream stopped event
      this.events.emit("stream", null);
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error stopping scan:", wrappedError);
      throw wrappedError;
    } finally {
      this.isScanning = false;
    }
  }

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

  // Add method to get stream events
  onStream(callback: (stream: MediaStream | null) => void): void {
    this.events.on("stream", callback);
  }

  async cleanup(): Promise<void> {
    try {
      await this.stopScan();
      this.events.removeAllListeners();
    } catch (error) {
      logger.error("Error during cleanup:", error);
    }
  }
}