import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:printing/printing.dart';
import 'package:provider/provider.dart';

import '../services/app_state.dart';
import '../services/fuel_report.dart';
import '../services/fuel_report_pdf.dart';

class ReportScreen extends StatefulWidget {
  const ReportScreen({super.key});

  @override
  State<ReportScreen> createState() => _ReportScreenState();
}

class _ReportScreenState extends State<ReportScreen> {
  static final _dateFormat = DateFormat.yMMMd();

  DateTime? _startDate;
  DateTime? _endDate;
  bool _busy = false;

  Future<void> _pickDate({required bool isStart}) async {
    final now = DateTime.now();
    final picked = await showDatePicker(
      context: context,
      initialDate: (isStart ? _startDate : _endDate) ?? now,
      firstDate: DateTime(2000),
      lastDate: now,
    );
    if (picked == null) return;
    setState(() {
      if (isStart) {
        _startDate = picked;
      } else {
        _endDate = picked;
      }
    });
  }

  Future<void> _share(FuelReport report) async {
    setState(() => _busy = true);
    try {
      final bytes = await buildFuelReportPdf(report);
      await Printing.sharePdf(bytes: bytes, filename: fuelReportFileName(report));
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  Future<void> _print(FuelReport report) async {
    setState(() => _busy = true);
    try {
      final bytes = await buildFuelReportPdf(report);
      await Printing.layoutPdf(onLayout: (_) async => bytes, name: fuelReportFileName(report));
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final appState = context.watch<AppState>();

    String? rangeError;
    FuelReport? report;
    if (_startDate != null && _endDate != null) {
      if (_endDate!.isBefore(_startDate!)) {
        rangeError = 'End date must be on or after the start date.';
      } else {
        report = buildFuelReport(
          vehicles: appState.vehicles,
          fuelEntries: appState.fuelEntries,
          startDate: _startDate!,
          endDate: _endDate!,
        );
      }
    }

    return Scaffold(
      appBar: AppBar(title: const Text('Fuel Report')),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          Row(
            children: [
              Expanded(
                child: OutlinedButton(
                  onPressed: () => _pickDate(isStart: true),
                  child: Text(_startDate == null ? 'Start date' : _dateFormat.format(_startDate!)),
                ),
              ),
              const SizedBox(width: 12),
              Expanded(
                child: OutlinedButton(
                  onPressed: () => _pickDate(isStart: false),
                  child: Text(_endDate == null ? 'End date' : _dateFormat.format(_endDate!)),
                ),
              ),
            ],
          ),
          if (rangeError != null) ...[
            const SizedBox(height: 8),
            Text(rangeError, style: TextStyle(color: Theme.of(context).colorScheme.error)),
          ],
          const SizedBox(height: 16),
          if (report == null)
            const Padding(
              padding: EdgeInsets.symmetric(vertical: 24),
              child: Text('Choose a start and end date to generate a report.'),
            )
          else if (report.rows.isEmpty)
            const Padding(
              padding: EdgeInsets.symmetric(vertical: 24),
              child: Text('No vehicles had a receipted fuel entry in that date range.'),
            )
          else ...[
            for (final row in report.rows)
              Card(
                child: ListTile(
                  title: Text(row.vehicle.displayLabel),
                  subtitle: Text(
                    'VIN: ${row.vehicle.vin}\n${row.entryCount} receipted '
                    'entr${row.entryCount == 1 ? 'y' : 'ies'}',
                  ),
                  isThreeLine: true,
                  trailing: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.end,
                    children: [
                      Text('${row.totalGallons.toStringAsFixed(3)} gal'),
                      Text(NumberFormat.simpleCurrency().format(row.totalCost)),
                    ],
                  ),
                ),
              ),
            const Divider(height: 32),
            ListTile(
              title: const Text('Total', style: TextStyle(fontWeight: FontWeight.bold)),
              trailing: Text(
                '${report.totalGallons.toStringAsFixed(3)} gal · '
                '${NumberFormat.simpleCurrency().format(report.totalCost)}',
                style: const TextStyle(fontWeight: FontWeight.bold),
              ),
            ),
            const SizedBox(height: 16),
            Row(
              children: [
                Expanded(
                  child: FilledButton.icon(
                    onPressed: _busy ? null : () => _share(report!),
                    icon: const Icon(Icons.share_outlined),
                    label: const Text('Share'),
                  ),
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: OutlinedButton.icon(
                    onPressed: _busy ? null : () => _print(report!),
                    icon: const Icon(Icons.print_outlined),
                    label: const Text('Print'),
                  ),
                ),
              ],
            ),
          ],
        ],
      ),
    );
  }
}