import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../core/constants.dart';
import '../../providers/auth_provider.dart';
import '../../providers/settings_provider.dart';
import '../../providers/update_provider.dart';

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

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final serverUrl = ref.watch(serverUrlProvider);
    final themeMode = ref.watch(themeModeProvider);
    final repoUrl = ref.watch(forgejoRepoUrlProvider);
    final update = ref.watch(updateProvider);

    return Scaffold(
      appBar: AppBar(title: const Text('Settings')),
      body: ListView(
        children: [
          ListTile(
            title: const Text('Server URL'),
            subtitle: Text(serverUrl ?? 'Not configured'),
            leading: const Icon(Icons.dns),
            onTap: () => context.go(Routes.setup),
          ),
          const Divider(),
          ListTile(
            title: const Text('Appearance'),
            leading: const Icon(Icons.brightness_6),
            trailing: SegmentedButton<ThemeMode>(
              segments: const [
                ButtonSegment(
                  value: ThemeMode.system,
                  icon: Icon(Icons.brightness_auto),
                  tooltip: 'System',
                ),
                ButtonSegment(
                  value: ThemeMode.light,
                  icon: Icon(Icons.light_mode),
                  tooltip: 'Light',
                ),
                ButtonSegment(
                  value: ThemeMode.dark,
                  icon: Icon(Icons.dark_mode),
                  tooltip: 'Dark',
                ),
              ],
              selected: {themeMode},
              onSelectionChanged: (modes) =>
                  ref.read(themeModeProvider.notifier).setMode(modes.first),
            ),
          ),
          const Divider(),

          // ── Updates ──────────────────────────────────────────────────────
          ListTile(
            leading: const Icon(Icons.update),
            title: const Text('Update repository'),
            subtitle: Text(repoUrl?.isNotEmpty == true
                ? repoUrl!
                : 'Not configured — tap to set'),
            onTap: () => _editRepoUrl(context, ref, repoUrl),
          ),
          ListTile(
            leading: const Icon(Icons.info_outline),
            title: const Text('App version'),
            subtitle: _versionSubtitle(update),
            trailing: update.status == UpdateStatus.checking
                ? const SizedBox(
                    width: 20,
                    height: 20,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  )
                : TextButton(
                    onPressed: () {
                      final url = ref.read(forgejoRepoUrlProvider);
                      if (url == null || url.isEmpty) {
                        ScaffoldMessenger.of(context).showSnackBar(
                          const SnackBar(
                            content: Text(
                                'Set a repository URL first.'),
                          ),
                        );
                        return;
                      }
                      ref.read(updateProvider.notifier).check(url);
                    },
                    child: const Text('Check'),
                  ),
          ),
          if (update.status == UpdateStatus.available ||
              update.status == UpdateStatus.downloading)
            _UpdateTile(update: update),
          if (update.status == UpdateStatus.error)
            ListTile(
              leading:
                  const Icon(Icons.error_outline, color: Colors.red),
              title: const Text('Update check failed'),
              subtitle: Text(
                update.errorMessage ?? 'Unknown error',
                maxLines: 2,
                overflow: TextOverflow.ellipsis,
              ),
            ),

          const Divider(),
          ListTile(
            title: const Text('Sign Out'),
            leading: const Icon(Icons.logout),
            onTap: () async {
              await ref.read(authProvider.notifier).logout();
              if (context.mounted) context.go(Routes.login);
            },
          ),
        ],
      ),
    );
  }

  Widget _versionSubtitle(UpdateState update) {
    final current = update.currentVersion;
    final latest = update.latestVersion;

    if (current == null && latest == null) {
      return const Text('Tap "Check" to look for updates');
    }
    if (update.status == UpdateStatus.upToDate) {
      return Text('v$current — up to date');
    }
    if (update.status == UpdateStatus.available ||
        update.status == UpdateStatus.downloading) {
      return Text('v$current installed');
    }
    return Text(current != null ? 'v$current' : '');
  }

  Future<void> _editRepoUrl(
      BuildContext context, WidgetRef ref, String? current) async {
    String draft = current ?? '';
    await showDialog<void>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: const Text('Update repository URL'),
        content: TextFormField(
          initialValue: draft,
          onChanged: (v) => draft = v,
          decoration: const InputDecoration(
            hintText: 'https://git.example.com/user/fabled_app',
            border: OutlineInputBorder(),
          ),
          autocorrect: false,
          keyboardType: TextInputType.url,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(dialogContext),
            child: const Text('Cancel'),
          ),
          FilledButton(
            onPressed: () {
              ref
                  .read(forgejoRepoUrlProvider.notifier)
                  .setUrl(draft.trim());
              Navigator.pop(dialogContext);
            },
            child: const Text('Save'),
          ),
        ],
      ),
    );
  }
}

class _UpdateTile extends ConsumerWidget {
  final UpdateState update;
  const _UpdateTile({required this.update});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final isDownloading = update.status == UpdateStatus.downloading;

    return ListTile(
      leading: const Icon(Icons.system_update, color: Colors.green),
      title: Text('v${update.latestVersion} available'),
      subtitle: isDownloading
          ? Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                const SizedBox(height: 4),
                LinearProgressIndicator(
                  value: update.downloadProgress > 0
                      ? update.downloadProgress
                      : null,
                ),
                const SizedBox(height: 2),
                Text(
                    '${(update.downloadProgress * 100).toStringAsFixed(0)}%'),
              ],
            )
          : const Text('Tap to download and install'),
      trailing: isDownloading
          ? null
          : FilledButton(
              onPressed: () =>
                  ref.read(updateProvider.notifier).downloadAndInstall(),
              child: const Text('Install'),
            ),
    );
  }
}