import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:http/http.dart' as http;
import 'package:mileograph_flutter/services/accent_color_service.dart';
import 'package:mileograph_flutter/services/distance_unit_service.dart';
import 'package:mileograph_flutter/services/endpoint_service.dart';
import 'package:mileograph_flutter/services/theme_mode_service.dart';
import 'package:mileograph_flutter/services/data_service.dart';
import 'package:provider/provider.dart';

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

  @override
  State<SettingsPage> createState() => _SettingsPageState();
}

class _SettingsPageState extends State<SettingsPage> {
  late final TextEditingController _endpointController;
  bool _saving = false;
  static const List<Color> _accentPalette = [
    Colors.red,
    Colors.pink,
    Colors.orange,
    Colors.amber,
    Colors.green,
    Colors.teal,
    Colors.blue,
    Colors.indigo,
    Colors.purple,
    Colors.cyan,
  ];

  @override
  void initState() {
    super.initState();
    final endpoint = context.read<EndpointService>().baseUrl;
    _endpointController = TextEditingController(text: endpoint);
  }

  @override
  void dispose() {
    _endpointController.dispose();
    super.dispose();
  }

  Future<String?> _probeVersion(String url) async {
    try {
      var uri = Uri.parse(url.trim());
      if (uri.scheme.isEmpty) {
        uri = Uri.parse('https://$url');
      }
      // Probe the provided API endpoint as-is.
      final target = uri;
      final res = await http.get(target).timeout(const Duration(seconds: 10));
      debugPrint(
        'Endpoint probe ${target.toString()} -> ${res.statusCode} ${res.body}',
      );
      if (res.statusCode < 200 || res.statusCode >= 300) return null;
      final body = res.body.trim();
      debugPrint('Endpoint probe body: $body');
      // Try JSON first
      String? version;
      try {
        final parsed = jsonDecode(body);
        debugPrint('Endpoint probe parsed: $parsed');
        if (parsed is Map && parsed['version'] is String) {
          version = parsed['version'] as String;
        } else if (parsed is String) {
          final candidate = parsed.trim().replaceAll('"', '');
          if (RegExp(r'^\d+\.\d+\.\d+$').hasMatch(candidate)) {
            version = candidate;
          }
        }
      } catch (_) {
        // fall back to raw body parsing
      }
      version ??= body.split(RegExp(r'\s+')).firstWhere(
        (part) => RegExp(r'^\d+\.\d+\.\d+$').hasMatch(part),
        orElse: () => '',
      );
      if (version.isEmpty) return null;
      final isValid = RegExp(r'^\d+\.\d+\.\d+$').hasMatch(version);
      return isValid ? version : null;
    } catch (_) {
      return null;
    }
  }

  Future<void> _save() async {
    final endpointService = context.read<EndpointService>();
    final dataService = context.read<DataService>();
    final messenger = ScaffoldMessenger.of(context);
    final value = _endpointController.text.trim();
    if (value.isEmpty) {
      messenger.showSnackBar(
        const SnackBar(content: Text('Please enter an endpoint URL.')),
      );
      return;
    }
    setState(() => _saving = true);
    try {
      final version = await _probeVersion(value);
      if (version == null) {
        if (mounted) {
          messenger.showSnackBar(
            const SnackBar(
              content: Text('Endpoint test failed: no valid version returned.'),
            ),
          );
        }
        return;
      }
      await endpointService.setBaseUrl(value);
      if (mounted) {
        messenger.showSnackBar(
          SnackBar(content: Text('Endpoint set to "$value" ($version)')),
        );
        await Future.wait([
          dataService.fetchHomepageStats(),
          dataService.fetchOnThisDay(),
          dataService.fetchTrips(),
          dataService.fetchHadTraction(),
          dataService.fetchLatestLocoChanges(),
          dataService.fetchLegs(),
        ]);
      }
    } catch (e) {
      if (mounted) {
        messenger.showSnackBar(
          SnackBar(content: Text('Failed to save endpoint: $e')),
        );
      }
    } finally {
      if (mounted) {
        setState(() => _saving = false);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final endpointService = context.watch<EndpointService>();
    final distanceUnitService = context.watch<DistanceUnitService>();
    final accentService = context.watch<AccentColorService>();
    final themeModeService = context.watch<ThemeModeService>();
    if (!endpointService.isLoaded ||
        !distanceUnitService.isLoaded ||
        !accentService.isLoaded ||
        !themeModeService.isLoaded) {
      return const Scaffold(
        body: Center(child: CircularProgressIndicator()),
      );
    }

    return Scaffold(
      appBar: AppBar(
        title: const Text('Settings'),
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () {
            final navigator = Navigator.of(context);
            if (navigator.canPop()) {
              navigator.pop();
            } else {
              context.go('/more');
            }
          },
        ),
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'Distance units',
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w700,
                  ),
            ),
            const SizedBox(height: 8),
            Text(
              'Choose how distances are displayed across the app.',
              style: Theme.of(context).textTheme.bodySmall,
            ),
            const SizedBox(height: 12),
            SegmentedButton<DistanceUnit>(
              segments: DistanceUnit.values
                  .map(
                    (unit) => ButtonSegment<DistanceUnit>(
                      value: unit,
                      label: Text(unit.label),
                    ),
                  )
                  .toList(),
              selected: {distanceUnitService.unit},
              onSelectionChanged: (selection) {
                final next = selection.first;
                distanceUnitService.setUnit(next);
              },
            ),
            const SizedBox(height: 24),
            Text(
              'Accent colour',
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w700,
                  ),
            ),
            const SizedBox(height: 8),
            Text(
              'Choose your preferred accent colour or use system colours.',
              style: Theme.of(context).textTheme.bodySmall,
            ),
            const SizedBox(height: 12),
            Wrap(
              spacing: 12,
              runSpacing: 8,
              crossAxisAlignment: WrapCrossAlignment.center,
              children: [
                OutlinedButton.icon(
                  onPressed:
                      accentService.useSystem ? null : () => accentService.setUseSystem(true),
                  icon: const Icon(Icons.phone_android),
                  label: const Text('Use system colours'),
                ),
                ..._accentPalette.map(
                  (color) => _AccentSwatchButton(
                    color: color,
                    selected:
                        !accentService.useSystem &&
                            accentService.seedColor.toARGB32() == color.toARGB32(),
                    onTap: () => accentService.setSeedColor(color),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 24),
            Text(
              'Theme mode',
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w700,
                  ),
            ),
            const SizedBox(height: 8),
            SegmentedButton<ThemeMode>(
              segments: const [
                ButtonSegment(
                  value: ThemeMode.system,
                  icon: Icon(Icons.settings_suggest),
                  label: Text('System'),
                ),
                ButtonSegment(
                  value: ThemeMode.light,
                  icon: Icon(Icons.light_mode),
                  label: Text('Light'),
                ),
                ButtonSegment(
                  value: ThemeMode.dark,
                  icon: Icon(Icons.dark_mode),
                  label: Text('Dark'),
                ),
              ],
              selected: {themeModeService.mode},
              onSelectionChanged: (selection) {
                final mode = selection.first;
                themeModeService.setMode(mode);
              },
            ),
            const SizedBox(height: 24),
            Text(
              'API endpoint',
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    fontWeight: FontWeight.w700,
                  ),
            ),
            const SizedBox(height: 8),
            Text(
              'Set the base URL for the Mileograph API. Leave blank to use the default.',
              style: Theme.of(context).textTheme.bodySmall,
            ),
            const SizedBox(height: 16),
            TextField(
              controller: _endpointController,
              decoration: const InputDecoration(
                labelText: 'Endpoint URL',
                hintText: 'https://mileograph.co.uk/api/v1',
                border: OutlineInputBorder(),
              ),
            ),
            const SizedBox(height: 16),
            Row(
              children: [
                FilledButton.icon(
                  onPressed: _saving ? null : _save,
                  icon: _saving
                      ? const SizedBox(
                          width: 18,
                          height: 18,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        )
                      : const Icon(Icons.save),
                  label: const Text('Save endpoint'),
                ),
                const SizedBox(width: 12),
                TextButton(
                  onPressed: _saving
                      ? null
                      : () {
                          _endpointController.text =
                              EndpointService.defaultBaseUrl;
                        },
                  child: const Text('Reset to default'),
                ),
              ],
            ),
            const SizedBox(height: 12),
            Text(
              'Current: ${endpointService.baseUrl}',
              style: Theme.of(context).textTheme.labelSmall,
            ),
          ],
        ),
      ),
    );
  }
}

class _AccentSwatchButton extends StatelessWidget {
  const _AccentSwatchButton({
    required this.color,
    required this.selected,
    required this.onTap,
  });

  final Color color;
  final bool selected;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final borderColor = selected
        ? Theme.of(context).colorScheme.onSurface
        : Colors.black26;
    return InkWell(
      onTap: onTap,
      customBorder: const CircleBorder(),
      child: Container(
        width: 40,
        height: 40,
        decoration: BoxDecoration(
          color: color,
          shape: BoxShape.circle,
          border: Border.all(
            color: borderColor,
            width: selected ? 3 : 1,
          ),
          boxShadow: [
            BoxShadow(
              color: Colors.black.withValues(alpha: 0.15),
              blurRadius: 4,
              offset: const Offset(0, 2),
            ),
          ],
        ),
        child: selected
            ? const Center(
                child: Icon(
                  Icons.check,
                  size: 18,
                  color: Colors.white,
                ),
              )
            : null,
      ),
    );
  }
}