import 'package:camera/camera.dart';
import 'package:flutter/foundation.dart';
import '../../core/utils/file_helper.dart';

abstract class CameraDataSource {
  Future<CameraController> getCameraController();
  Future<String> captureImage(CameraController controller);
  Future<void> disposeCamera(CameraController controller);
  Future<void> startImageStream(CameraController controller, Function(CameraImage) onImage);
  Future<void> stopImageStream(CameraController controller);
}

class CameraDataSourceImpl implements CameraDataSource {
  @override
  Future<CameraController> getCameraController() async {
    List<CameraDescription> cameras = [];
    try {
      cameras = await availableCameras();
    } catch (e) {
      debugPrint("availableCameras() failed: $e");
    }
    
    if (cameras.isEmpty) {
      if (kIsWeb) {
        debugPrint("No cameras found. Attempting Web Fallback with default configuration.");
        // Fallback for Web: Create a generic camera description.
        // This attempts to bypass enumeration issues caused by browser privacy blocks.
        cameras = [
          const CameraDescription(
            name: 'Default Web Camera',
            lensDirection: CameraLensDirection.external, // Use external/front as default safe bet
            sensorOrientation: 0,
          ),
        ];
      } else {
        throw Exception('No cameras available. Please ensure camera permission is granted.');
      }
    }
    
    // Web-safe image format selection
    ImageFormatGroup? formatGroup;
    if (!kIsWeb) {
      formatGroup = defaultTargetPlatform == TargetPlatform.android 
          ? ImageFormatGroup.yuv420 
          : ImageFormatGroup.bgra8888;
    }

    // Use medium resolution for better Web compatibility
    // 'low' might be even safer for initial connection
    final controller = CameraController(
      cameras.first, 
      kIsWeb ? ResolutionPreset.medium : ResolutionPreset.high,
      enableAudio: false,
      imageFormatGroup: formatGroup,
    );
    
    try {
      await controller.initialize();
      return controller;
    } catch (e) {
      debugPrint("Controller initialization failed: $e");
      throw Exception("Failed to start camera: $e");
    }
  }

  @override
  Future<String> captureImage(CameraController controller) async {
    final image = await controller.takePicture();
    return await FileHelper.saveCapturedImage(image);
  }

  @override
  Future<void> disposeCamera(CameraController controller) async {
    await controller.dispose();
  }

  @override
  Future<void> startImageStream(CameraController controller, Function(CameraImage) onImage) async {
    // Web: check if streaming is supported to avoid assertion error
    if (kIsWeb) {
        try {
           if (!controller.value.isStreamingImages) {
             await controller.startImageStream(onImage);
           }
        } catch (e) {
           debugPrint("Web Image Stream failed (expected on some browsers): $e");
        }
        return;
    }

    // Native logic
    if (!controller.value.isStreamingImages) {
      await controller.startImageStream(onImage);
    }
  }

  @override
  Future<void> stopImageStream(CameraController controller) async {
    try {
      if (controller.value.isStreamingImages) {
        await controller.stopImageStream();
      }
    } catch (e) {
      // ignore
    }
  }
}