environment_monitoring_app/lib/services/air_sampling_service.dart

import 'dart:async';
import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as path;
import 'package:image/image.dart' as img;
import 'package:intl/intl.dart';

import '../models/air_installation_data.dart';
import '../models/air_collection_data.dart';
import 'api_service.dart';
import 'local_storage_service.dart';

/// A dedicated service to handle all business logic for the Air Manual Sampling feature.
class AirSamplingService {
  final ApiService _apiService = ApiService();
  final LocalStorageService _localStorageService = LocalStorageService();

  /// Picks an image from the specified source, adds a timestamp watermark,
  /// and saves it to a temporary directory with a standardized name.
  Future<File?> pickAndProcessImage(
      ImageSource source, {
        required String stationCode,
        required String imageInfo,
      }) async {
    final picker = ImagePicker();
    final XFile? photo = await picker.pickImage(
        source: source, imageQuality: 85, maxWidth: 1024);
    if (photo == null) return null;

    final bytes = await photo.readAsBytes();
    img.Image? originalImage = img.decodeImage(bytes);
    if (originalImage == null) return null;

    final String watermarkTimestamp =
    DateFormat('yyyy-MM-dd HH:mm:ss').format(DateTime.now());
    final font = img.arial24;

    final textWidth = watermarkTimestamp.length * 12;
    img.fillRect(originalImage,
        x1: 5,
        y1: 5,
        x2: textWidth + 15,
        y2: 35,
        color: img.ColorRgb8(255, 255, 255));
    img.drawString(originalImage, watermarkTimestamp,
        font: font, x: 10, y: 10, color: img.ColorRgb8(0, 0, 0));

    final tempDir = await getTemporaryDirectory();
    final fileTimestamp = watermarkTimestamp.replaceAll(':', '-').replaceAll(' ', '_');
    final newFileName =
        "${stationCode}_${fileTimestamp}_INSTALL_${imageInfo.replaceAll(' ', '')}.jpg";
    final filePath = path.join(tempDir.path, newFileName);

    return File(filePath)..writeAsBytesSync(img.encodeJpg(originalImage));
  }

  /// Orchestrates a two-step submission process for air installation samples.
  Future<Map<String, dynamic>> submitInstallation(AirInstallationData data) async {
    // --- OFFLINE-FIRST HELPER ---
    Future<Map<String, dynamic>> saveLocally() async {
      debugPrint("Saving installation locally...");
      data.status = 'L1'; // Mark as Locally Saved, Pending Submission
      await _localStorageService.saveAirSamplingRecord(data.toMap(), data.refID!);
      return {
        'status': 'L1',
        'message': 'No connection or server error. Installation data saved locally.',
      };
    }

    // --- STEP 1: SUBMIT TEXT DATA ---
    debugPrint("Step 1: Submitting installation text data...");
    final textDataResult = await _apiService.post('air/manual/installation', data.toJsonForApi());

    if (textDataResult['success'] != true) {
      debugPrint("Failed to submit text data. Reason: ${textDataResult['message']}");
      return await saveLocally();
    }

    final recordId = textDataResult['data']?['air_man_id'];
    if (recordId == null) {
      debugPrint("Text data submitted, but did not receive a record ID.");
      return await saveLocally();
    }
    debugPrint("Text data submitted successfully. Received record ID: $recordId");

    // --- STEP 2: UPLOAD IMAGE FILES ---
    final filesToUpload = data.getImagesForUpload();
    if (filesToUpload.isEmpty) {
      debugPrint("No images to upload. Submission complete.");
      data.status = 'S1'; // Server Pending (no images needed)
      await _localStorageService.saveAirSamplingRecord(data.toMap(), data.refID!);
      return {'status': 'S1', 'message': 'Installation data submitted successfully.'};
    }

    debugPrint("Step 2: Uploading ${filesToUpload.length} images for record ID $recordId...");
    final imageUploadResult = await _apiService.air.uploadInstallationImages(
      airManId: recordId.toString(),
      files: filesToUpload,
    );

    if (imageUploadResult['success'] != true) {
      debugPrint("Image upload failed. Reason: ${imageUploadResult['message']}");
      return await saveLocally();
    }

    debugPrint("Images uploaded successfully.");
    data.status = 'S2'; // Server Pending (images uploaded)
    await _localStorageService.saveAirSamplingRecord(data.toMap(), data.refID!);
    return {
      'status': 'S2',
      'message': 'Installation data and images submitted successfully.',
    };
  }


  /// Submits only the collection data, linked to a previous installation.
  Future<Map<String, dynamic>> submitCollection(AirCollectionData data) async {
    try {
      final result = await _apiService.post(
          'air/manual/collection',
          data.toJson()
      );

      if (result['success'] == true) {
        data.status = 'S3'; // Server Completed
        // Also save the completed record locally
        await _localStorageService.saveAirSamplingRecord(data.toMap(), data.installationRefID!);
        return {'status': 'S3', 'message': 'Collection submitted successfully.'};
      } else {
        throw Exception(result['message'] ?? 'Unknown server error');
      }
    } catch (e) {
      debugPrint("API submission failed: $e. Saving collection locally.");
      data.status = 'L3'; // Mark as completed locally

      // CORRECTED: Use toMap() to ensure all data is saved locally on failure.
      await _localStorageService.saveAirSamplingRecord(data.toMap(), data.installationRefID!);

      return {
        'status': 'L3',
        'message': 'No connection. Collection data saved locally.',
      };
    }
  }

  /// Fetches installations that are pending collection from local storage.
  Future<List<AirInstallationData>> getPendingInstallations() async {
    debugPrint("Fetching pending installations from local storage...");

    final logs = await _localStorageService.getAllAirSamplingLogs();

    final pendingInstallations = logs
        .where((log) {
      final status = log['status'];
      // CORRECTED: Include 'S2' to show records that have successfully uploaded images
      // but are still pending collection.
      return status == 'L1' || status == 'S1' || status == 'S2';
    })
        .map((log) => AirInstallationData.fromJson(log))
        .toList();

    return pendingInstallations;
  }

  void dispose() {
    // Clean up any resources if necessary
  }
}