import 'dart:convert';
import 'dart:io';

import 'package:csv/csv.dart';
import 'package:path_provider/path_provider.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'package:share_plus/share_plus.dart';

import 'package:timetrack/features/entries/data/drift_entries_repository.dart';
import 'package:timetrack/features/entries/data/entries_repository.dart';
import 'package:timetrack/features/entries/domain/time_entry.dart';
import 'package:timetrack/features/projects/data/drift_projects_repository.dart';
import 'package:timetrack/features/projects/data/projects_repository.dart';
import 'package:timetrack/features/projects/domain/project.dart';

part 'export_service.g.dart';

enum ExportFormat { csv, pdf, json }

@riverpod
ExportService exportService(ExportServiceRef ref) {
  return ExportService(
    entriesRepo: ref.watch(timeEntriesRepositoryProvider),
    projectsRepo: ref.watch(projectsRepositoryProvider),
  );
}

class ExportService {
  ExportService({
    required this.entriesRepo,
    required this.projectsRepo,
  });

  final TimeEntriesRepository entriesRepo;
  final ProjectsRepository projectsRepo;

  Future<void> export({
    required ExportFormat format,
    required DateTime from,
    required DateTime to,
    int? projectId,
  }) async {
    final entries = await entriesRepo.watchByDateRange(from, to).first;
    final allProjects = await projectsRepo.watchAll().first;
    final projectMap = {for (final p in allProjects) p.id: p};

    final filtered = projectId != null
        ? entries.where((e) => e.projectId == projectId).toList()
        : entries;

    switch (format) {
      case ExportFormat.csv:
        await _exportCsv(filtered, projectMap);
        break;
      case ExportFormat.pdf:
        await _exportPdf(filtered, projectMap, from, to);
        break;
      case ExportFormat.json:
        await _exportJson(filtered, allProjects);
        break;
    }
  }

  Future<void> _exportCsv(
    List<TimeEntry> entries,
    Map<int, Project> projectMap,
  ) async {
    final rows = <List<dynamic>>[
      ['id', 'project', 'start_time', 'end_time', 'duration_seconds', 'note', 'tags'],
      ...entries.map((e) => [
            e.id,
            projectMap[e.projectId]?.name ?? '',
            e.startTime.toIso8601String(),
            e.endTime?.toIso8601String() ?? '',
            e.durationSeconds ?? '',
            e.note ?? '',
            e.tags.join('|'),
          ]),
    ];

    final csvStr = const ListToCsvConverter().convert(rows);
    // UTF-8 BOM for Excel compatibility
    final bom = '\uFEFF';
    final content = bom + csvStr;

    final file = await _tempFile('timetrack_export', 'csv');
    await file.writeAsString(content, encoding: utf8);
    await Share.shareXFiles([XFile(file.path)],
        subject: 'Timetrack Export');
  }

  Future<void> _exportPdf(
    List<TimeEntry> entries,
    Map<int, Project> projectMap,
    DateTime from,
    DateTime to,
  ) async {
    final doc = pw.Document();

    doc.addPage(pw.Page(
      build: (ctx) => pw.Column(
        crossAxisAlignment: pw.CrossAxisAlignment.start,
        children: [
          pw.Text('Timetrack Export',
              style: pw.TextStyle(fontSize: 20, fontWeight: pw.FontWeight.bold)),
          pw.SizedBox(height: 4),
          pw.Text(
              '${from.toIso8601String().substring(0, 10)} – ${to.toIso8601String().substring(0, 10)}'),
          pw.SizedBox(height: 16),
          pw.TableHelper.fromTextArray(
            headers: ['Project', 'Start', 'End', 'Duration', 'Note'],
            data: entries.map((e) {
              final dur = Duration(seconds: e.durationSeconds ?? 0);
              return [
                projectMap[e.projectId]?.name ?? '—',
                e.startTime.toIso8601String().substring(0, 16),
                e.endTime?.toIso8601String().substring(0, 16) ?? '—',
                '${dur.inHours}h ${dur.inMinutes % 60}m',
                e.note ?? '',
              ];
            }).toList(),
          ),
        ],
      ),
    ));

    final file = await _tempFile('timetrack_report', 'pdf');
    await file.writeAsBytes(await doc.save());
    await Share.shareXFiles([XFile(file.path)],
        subject: 'Timetrack Report');
  }

  Future<void> _exportJson(
    List<TimeEntry> entries,
    List<Project> projects,
  ) async {
    final data = {
      'exportedAt': DateTime.now().toIso8601String(),
      'version': 1,
      'projects': projects
          .map((p) => {
                'id': p.id,
                'name': p.name,
                'color': p.colorValue,
                'description': p.description,
              })
          .toList(),
      'entries': entries
          .map((e) => {
                'id': e.id,
                'projectId': e.projectId,
                'startTime': e.startTime.toIso8601String(),
                'endTime': e.endTime?.toIso8601String(),
                'durationSeconds': e.durationSeconds,
                'note': e.note,
                'tags': e.tags,
              })
          .toList(),
    };

    final file = await _tempFile('timetrack_backup', 'json');
    await file.writeAsString(const JsonEncoder.withIndent('  ').convert(data));
    await Share.shareXFiles([XFile(file.path)],
        subject: 'Timetrack Backup');
  }

  Future<File> _tempFile(String name, String ext) async {
    final dir = await getTemporaryDirectory();
    final date = DateTime.now().toIso8601String().substring(0, 10);
    return File('${dir.path}/${name}_$date.$ext');
  }
}