/// Settings tab: theme mode, API endpoint, bank link, and CSV import.
library;

import 'dart:convert';

import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../providers/bank_provider.dart';
import '../providers/preferences_provider.dart';
import '../providers/theme_provider.dart';
import '../utils/connect_bank.dart';
import '../utils/constants.dart';
import '../utils/helpers.dart';
import '../widgets/responsive_body.dart';
import 'labels_screen.dart';

class SettingsScreen extends StatelessWidget {
  const SettingsScreen({super.key});

  Future<void> _importCsv(BuildContext context, BankController bank) async {
    // Use FileType.any — Android often greys out real ING exports when
    // filtering to csv/txt (odd MIME types / no extension / Downloads).
    final picked = await FilePicker.platform.pickFiles(
      type: FileType.any,
      withData: true,
      allowMultiple: false,
    );
    if (picked == null || picked.files.isEmpty) return;

    final file = picked.files.single;
    var bytes = file.bytes;
    if ((bytes == null || bytes.isEmpty) && file.path != null) {
      bytes = await file.xFile.readAsBytes();
    }
    if (bytes == null || bytes.isEmpty) {
      if (!context.mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not read the selected file')),
      );
      return;
    }

    String raw;
    try {
      raw = utf8.decode(bytes);
    } catch (_) {
      raw = latin1.decode(bytes);
    }

    try {
      final result = await bank.importIngCsv(raw);
      if (!context.mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            result.added.isEmpty
                ? 'No new transactions '
                    '(${result.skippedDuplicates} already in the app)'
                : 'Imported ${result.added.length} new'
                    '${result.skippedDuplicates > 0 ? ' · skipped ${result.skippedDuplicates} duplicates' : ''}'
                    ' of ${result.parsed} CSV rows',
          ),
        ),
      );
    } on FormatException catch (error) {
      if (!context.mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(error.message)),
      );
    } catch (_) {
      if (!context.mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(bank.error ?? 'Import failed')),
      );
    }
  }

  Future<void> _clearImports(BuildContext context, BankController bank) async {
    final ok = await showDialog<bool>(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: const Text('Clear imported CSV?'),
          content: Text(
            'Removes ${bank.importedCount} locally imported transactions. '
            'Bank-linked data is kept.',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context, false),
              child: const Text('Cancel'),
            ),
            FilledButton(
              onPressed: () => Navigator.pop(context, true),
              child: const Text('Clear'),
            ),
          ],
        );
      },
    );
    if (ok != true || !context.mounted) return;
    await bank.clearImportedTransactions();
    if (!context.mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Imported transactions cleared')),
    );
  }

  @override
  Widget build(BuildContext context) {
    final themeController = context.watch<ThemeController>();
    final prefs = context.watch<PreferencesController>();
    final bank = context.watch<BankController>();
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(title: const Text('Settings')),
      body: ResponsiveBody(
        child: ListView(
          children: [
            const SizedBox(height: 8),
            Text('Appearance', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Text(
              'Theme is saved with shared_preferences and restored on launch.',
              style: theme.textTheme.bodyMedium,
            ),
            const SizedBox(height: 16),
            SegmentedButton<ThemeMode>(
              segments: const [
                ButtonSegment(
                  value: ThemeMode.system,
                  label: Text('System'),
                  icon: Icon(Icons.brightness_auto),
                ),
                ButtonSegment(
                  value: ThemeMode.light,
                  label: Text('Light'),
                  icon: Icon(Icons.light_mode_outlined),
                ),
                ButtonSegment(
                  value: ThemeMode.dark,
                  label: Text('Dark'),
                  icon: Icon(Icons.dark_mode_outlined),
                ),
              ],
              selected: {themeController.themeMode},
              onSelectionChanged: (selection) {
                themeController.setThemeMode(selection.first);
              },
            ),
            const SizedBox(height: 28),
            Text('Look ahead', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Card(
              child: ListTile(
                leading: const Icon(Icons.event_repeat_outlined),
                title: const Text('Projection horizon'),
                subtitle: Text(
                  'Navigate up to ${prefs.lookAheadMaxYears} year'
                  '${prefs.lookAheadMaxYears == 1 ? '' : 's'} ahead',
                ),
                trailing: DropdownButton<int>(
                  value: prefs.lookAheadMaxYears,
                  underline: const SizedBox.shrink(),
                  items: [
                    for (final y in const [1, 2, 3, 5, 7, 10, 15, 20, 30])
                      DropdownMenuItem(value: y, child: Text('$y')),
                  ],
                  onChanged: (value) {
                    if (value == null) return;
                    prefs.setLookAheadMaxYears(value);
                  },
                ),
              ),
            ),
            const SizedBox(height: 28),
            Text('Backend', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Card(
              child: Column(
                children: [
                  ListTile(
                    leading: const Icon(Icons.dns_outlined),
                    title: const Text('API base URL'),
                    subtitle: Text(bank.apiBaseUrl),
                  ),
                  const Divider(height: 1),
                  ListTile(
                    leading: Icon(
                      bank.isLinked
                          ? Icons.link
                          : Icons.link_off_outlined,
                    ),
                    title: const Text('Bank link'),
                    subtitle: Text(
                      bank.isLinked
                          ? 'Linked · ${bank.status.status}'
                          : 'Not linked',
                    ),
                    trailing: bank.isLinked
                        ? null
                        : TextButton(
                            onPressed: bank.isConnecting
                                ? null
                                : () => runConnectBank(context, bank),
                            child: Text(
                              bank.isConnecting ? 'Opening…' : 'Connect',
                            ),
                          ),
                  ),
                  const Divider(height: 1),
                  ListTile(
                    leading: const Icon(Icons.open_in_browser_outlined),
                    title: const Text('Enable Banking redirect'),
                    subtitle: Text(kEnableBankingRedirectUri),
                  ),
                ],
              ),
            ),
            const SizedBox(height: 12),
            Text(
              'Enable Banking only allows http(s) redirects. Keep '
              '$kEnableBankingRedirectUri in the Control Panel and backend '
              'REDIRECT_URI. The app captures that callback path in a WebView. '
              'Override with `--dart-define=API_BASE_URL=https://…`.',
              style: theme.textTheme.bodyMedium,
            ),
            const SizedBox(height: 28),
            Text('Labels', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Card(
              child: ListTile(
                leading: const Icon(Icons.label_outline),
                title: const Text('Manage labels'),
                subtitle: const Text('Create, nest, move, or delete'),
                trailing: const Icon(Icons.chevron_right),
                onTap: () {
                  Navigator.of(context).push(
                    MaterialPageRoute<void>(
                      builder: (_) => const LabelsScreen(),
                    ),
                  );
                },
              ),
            ),
            const SizedBox(height: 28),
            Text('CSV import', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Card(
              child: Column(
                children: [
                  ListTile(
                    leading: const Icon(Icons.upload_file_outlined),
                    title: const Text('Import ING CSV'),
                    subtitle: Text(
                      bank.isImporting
                          ? 'Importing…'
                          : bank.importedCount == 0
                              ? 'Adds older history without duplicating bank feed'
                              : '${bank.importedCount} imported rows kept locally',
                    ),
                    trailing: TextButton(
                      onPressed: bank.isImporting
                          ? null
                          : () => _importCsv(context, bank),
                      child: Text(bank.isImporting ? '…' : 'Import'),
                    ),
                  ),
                  if (bank.importedCount > 0) ...[
                    const Divider(height: 1),
                    ListTile(
                      leading: const Icon(Icons.delete_outline),
                      title: const Text('Clear imported CSV'),
                      onTap: () => _clearImports(context, bank),
                    ),
                  ],
                ],
              ),
            ),
            const SizedBox(height: 8),
            Text(
              'Supports ING Netherlands exports (Dutch or English headers, '
              'comma or semicolon). Matching uses date + amount + merchant, '
              'so overlaps with the live feed are skipped.',
              style: theme.textTheme.bodyMedium,
            ),
            const SizedBox(height: 28),
            Text('About', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            Card(
              child: Column(
                children: [
                  const ListTile(
                    leading: Icon(Icons.apps),
                    title: Text(kAppName),
                    subtitle: Text('Personal bank data via Enable Banking'),
                  ),
                  const Divider(height: 1),
                  const ListTile(
                    leading: Icon(Icons.fingerprint),
                    title: Text('Package'),
                    subtitle: Text(kPackageName),
                  ),
                  const Divider(height: 1),
                  ListTile(
                    leading: const Icon(Icons.contrast),
                    title: const Text('Active theme'),
                    subtitle: Text(labelForThemeMode(themeController.themeMode)),
                  ),
                ],
              ),
            ),
            const SizedBox(height: 24),
          ],
        ),
      ),
    );
  }
}