import { createApp, App } from "vue";
import { QRScannerService, ScanListener, QRScannerOptions } from "./types";
import QRScannerDialog from "@/components/QRScanner/QRScannerDialog.vue";
import { logger } from "@/utils/logger";

export class WebDialogQRScanner implements QRScannerService {
  private dialogInstance: App | null = null;
  private dialogComponent: InstanceType<typeof QRScannerDialog> | null = null;
  private scanListener: ScanListener | null = null;
  private isScanning = false;
  private container: HTMLElement | null = null;
  private sessionId: number | null = null;
  private failsafeTimeout: any = null;

  constructor(private options?: QRScannerOptions) {}

  async checkPermissions(): Promise<boolean> {
    try {
      console.log("[QRScanner] Checking camera permissions...");
      const permissions = await navigator.permissions.query({
        name: "camera" as PermissionName,
      });
      console.log("[QRScanner] Permission state:", permissions.state);
      return permissions.state === "granted";
    } catch (error) {
      console.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;
      this.sessionId = Date.now();
      console.log(`[WebDialogQRScanner] Opening dialog, session: ${this.sessionId}`);

      // Create and mount dialog component
      this.container = document.createElement("div");
      document.body.appendChild(this.container);

      this.dialogInstance = createApp(QRScannerDialog, {
        onScan: (result: string) => {
          if (this.scanListener) {
            this.scanListener.onScan(result);
          }
        },
        onError: (error: Error) => {
          if (this.scanListener?.onError) {
            this.scanListener.onError(error);
          }
        },
        onClose: () => {
          console.log(`[WebDialogQRScanner] onClose received from dialog, session: ${this.sessionId}`);
          this.stopScan('dialog onClose');
        },
        options: this.options,
        sessionId: this.sessionId,
      });

      this.dialogComponent = this.dialogInstance.mount(this.container) as InstanceType<typeof QRScannerDialog>;

      // Failsafe: force cleanup after 60s if dialog is still open
      this.failsafeTimeout = setTimeout(() => {
        if (this.isScanning) {
          console.warn(`[WebDialogQRScanner] Failsafe triggered, forcing cleanup for session: ${this.sessionId}`);
          this.stopScan('failsafe timeout');
        }
      }, 60000);
      console.log(`[WebDialogQRScanner] Failsafe timeout set for session: ${this.sessionId}`);
    } 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);
      this.cleanupContainer();
      throw wrappedError;
    }
  }

  async stopScan(reason: string = 'manual') : Promise<void> {
    if (!this.isScanning) {
      return;
    }

    try {
      console.log(`[WebDialogQRScanner] stopScan called, reason: ${reason}, session: ${this.sessionId}`);
      if (this.dialogComponent) {
        await this.dialogComponent.close();
        console.log(`[WebDialogQRScanner] dialogComponent.close() called, session: ${this.sessionId}`);
      }
      if (this.dialogInstance) {
        this.dialogInstance.unmount();
        console.log(`[WebDialogQRScanner] dialogInstance.unmount() called, session: ${this.sessionId}`);
      }
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error stopping scan:", wrappedError);
      throw wrappedError;
    } finally {
      this.isScanning = false;
      if (this.failsafeTimeout) {
        clearTimeout(this.failsafeTimeout);
        this.failsafeTimeout = null;
        console.log(`[WebDialogQRScanner] Failsafe timeout cleared, session: ${this.sessionId}`);
      }
      this.cleanupContainer();
    }
  }

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

  private cleanupContainer(): void {
    if (this.container && this.container.parentNode) {
      this.container.parentNode.removeChild(this.container);
      console.log(`[WebDialogQRScanner] Dialog container removed from DOM, session: ${this.sessionId}`);
    } else {
      console.log(`[WebDialogQRScanner] Dialog container NOT removed from DOM, session: ${this.sessionId}`);
    }
    this.container = null;
  }

  async cleanup(): Promise<void> {
    try {
      await this.stopScan('cleanup');
    } catch (error) {
      const wrappedError =
        error instanceof Error ? error : new Error(String(error));
      logger.error("Error during cleanup:", wrappedError);
      throw wrappedError;
    } finally {
      this.dialogComponent = null;
      this.dialogInstance = null;
      this.scanListener = null;
      this.cleanupContainer();
      this.sessionId = null;
    }
  }
}