import 'package:auto_route/auto_route.dart';
import 'package:collection/collection.dart';
import 'package:easy_localization/easy_localization.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:selfprivacy/logic/bloc/server_logs/server_logs_bloc.dart';
import 'package:selfprivacy/logic/models/server_logs.dart';
import 'package:selfprivacy/ui/helpers/empty_page_placeholder.dart';
import 'package:selfprivacy/utils/platform_adapter.dart';

@RoutePage()
class ServerLogsScreen extends StatefulWidget {
  const ServerLogsScreen({this.serviceId, super.key});

  final String? serviceId;

  @override
  State<ServerLogsScreen> createState() => _ServerLogsScreenState();
}

class _ServerLogsScreenState extends State<ServerLogsScreen> {
  final ScrollController _scrollController = ScrollController();
  late ServerLogsBloc _serverLogsBloc;

  String? _selectedSystemdUnit;

  @override
  void initState() {
    super.initState();
    _serverLogsBloc = BlocProvider.of<ServerLogsBloc>(context);
    _scrollController.addListener(_onScroll);
    _serverLogsBloc.add(ServerLogsFetch(serviceId: widget.serviceId));
  }

  @override
  void dispose() {
    _scrollController.dispose();
    _serverLogsBloc.add(ServerLogsDisconnect());
    super.dispose();
  }

  void _onScroll() {
    if (_scrollController.position.pixels >=
        _scrollController.position.maxScrollExtent) {
      _serverLogsBloc.add(ServerLogsFetchMore());
    }
  }

  Widget _buildDrawer(final List<String> systemdUnits) => Drawer(
        child: ListView(
          padding: EdgeInsets.zero,
          children: [
            DrawerHeader(
              child: Text('server.filter_by_systemd_unit'.tr()),
            ),
            // a tile to reset filter
            RadioListTile(
              title: Text('server.all_units'.tr()),
              value: null,
              groupValue: _selectedSystemdUnit,
              onChanged: (final value) {
                setState(() {
                  _selectedSystemdUnit = value;
                });
              },
            ),
            for (final unit in systemdUnits.sorted())
              RadioListTile(
                title: Text(unit),
                value: unit,
                groupValue: _selectedSystemdUnit,
                onChanged: (final value) {
                  setState(() {
                    _selectedSystemdUnit = value;
                  });
                },
              ),
          ],
        ),
      );

  @override
  Widget build(final BuildContext context) {
    const Key centerKey = ValueKey<String>('server-logs-center-key');
    return Scaffold(
      appBar: AppBar(
        title: Text(
          widget.serviceId == null
              ? 'server.logs'.tr()
              : 'service_page.logs'.tr(),
        ),
      ),
      endDrawer: BlocBuilder<ServerLogsBloc, ServerLogsState>(
        builder: (final context, final state) {
          if (state is ServerLogsLoaded) {
            return _buildDrawer(state.systemdUnits);
          }
          // Return an empty drawer if the state is not loaded
          return const Drawer(child: SizedBox());
        },
      ),
      body: BlocBuilder<ServerLogsBloc, ServerLogsState>(
        builder: (final context, final state) {
          final isLoadingMore = state is ServerLogsLoaded && state.loadingMore;
          if (state is ServerLogsLoading) {
            return const Center(child: CircularProgressIndicator());
          } else if (state is ServerLogsLoaded) {
            final List<ServerLogEntry> filteredNewLogs =
                _selectedSystemdUnit == null
                    ? state.newEntries
                    : state.newEntriesForUnit(_selectedSystemdUnit!);
            final List<ServerLogEntry> filteredOldLogs =
                _selectedSystemdUnit == null
                    ? state.oldEntries
                    : state.oldEntriesForUnit(_selectedSystemdUnit!);
            if (filteredOldLogs.isEmpty && filteredNewLogs.isEmpty) {
              return Center(
                child: EmptyPagePlaceholder(
                  title: 'server.logs_empty'.tr(),
                  iconData: Icons.info_outline,
                ),
              );
            }
            return CustomScrollView(
              center: centerKey,
              controller: _scrollController,
              slivers: [
                SliverList(
                  delegate: SliverChildBuilderDelegate(
                    (final context, final index) {
                      final logEntry =
                          filteredNewLogs[(filteredNewLogs.length - 1) - index];
                      return LogEntryWidget(
                        logEntry: logEntry,
                        key: ValueKey(logEntry.cursor),
                      );
                    },
                    childCount: filteredNewLogs.length,
                  ),
                ),
                SliverList(
                  key: centerKey,
                  delegate: SliverChildBuilderDelegate(
                    (final context, final index) {
                      if (isLoadingMore && index == filteredOldLogs.length) {
                        return const Center(
                          child: CircularProgressIndicator(),
                        );
                      }
                      final logEntry = filteredOldLogs[index];
                      return LogEntryWidget(
                        logEntry: logEntry,
                        key: ValueKey(logEntry.cursor),
                      );
                    },
                    childCount:
                        filteredOldLogs.length + (isLoadingMore ? 1 : 0),
                  ),
                ),
                if (isLoadingMore)
                  const SliverFillRemaining(
                    child: Center(child: CircularProgressIndicator()),
                  ),
              ],
            );
          } else if (state is ServerLogsError) {
            return Center(
              child: EmptyPagePlaceholder(
                title: 'basis.error'.tr(),
                iconData: Icons.error_outline,
                description: state.error.toString(),
              ),
            );
          }
          return Center(child: Text('server.logs_empty'.tr()));
        },
      ),
    );
  }
}

class LogEntryWidget extends StatelessWidget {
  const LogEntryWidget({
    required this.logEntry,
    super.key,
  });

  final ServerLogEntry logEntry;

  @override
  Widget build(final BuildContext context) {
    final Color color = logEntry.priority == 4
        ? Theme.of(context).colorScheme.primary
        : logEntry.priority != null && logEntry.priority! <= 3
            ? Theme.of(context).colorScheme.error
            : Theme.of(context).colorScheme.onSurface;
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 12),
      child: ListTile(
        dense: true,
        title: Text.rich(
          TextSpan(
            style: DefaultTextStyle.of(context).style,
            children: <TextSpan>[
              TextSpan(
                text: '${logEntry.localTimeString}: ',
                style: TextStyle(
                  fontFeatures: const [FontFeature.tabularFigures()],
                  color: color,
                ),
              ),
              TextSpan(
                text: logEntry.systemdUnit,
                style: TextStyle(
                  fontWeight: FontWeight.bold,
                  color: color,
                ),
              ),
            ],
          ),
        ),
        subtitle: Text(
          logEntry.message,
          overflow: TextOverflow.ellipsis,
          maxLines: 6,
        ),
        onTap: () => showDialog(
          context: context,
          builder: (final BuildContext context) =>
              ServerLogEntryDialog(log: logEntry),
        ),
      ),
    );
  }
}

/// dialog with detailed log content
class ServerLogEntryDialog extends StatelessWidget {
  const ServerLogEntryDialog({
    required this.log,
    super.key,
  });

  final ServerLogEntry log;

  @override
  Widget build(final BuildContext context) => AlertDialog(
        scrollable: true,
        title: Text(log.localTimeString),
        contentPadding: const EdgeInsets.symmetric(
          vertical: 16,
          horizontal: 12,
        ),
        content: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            const Divider(),
            _KeyValueRow(
              'console_page.logged_at'.tr(),
              '${log.localTimeString} (${log.localDateString(context.locale.languageCode)})',
            ),
            _KeyValueRow('UTC', log.fullUTCString),
            const Divider(),
            _SectionRow('server.log_dialog.metadata'.tr()),
            _KeyValueRow('server.log_dialog.cursor'.tr(), log.cursor),
            if (log.priority != null)
              _KeyValueRow(
                'server.log_dialog.priority'.tr(),
                log.priority?.toString(),
              ),
            if (log.systemdSlice != null)
              _KeyValueRow(
                'server.log_dialog.systemd_slice'.tr(),
                log.systemdSlice,
              ),
            if (log.systemdUnit != null)
              _KeyValueRow(
                'server.log_dialog.systemd_unit'.tr(),
                log.systemdUnit,
              ),
            const Divider(),
            _SectionRow('server.log_dialog.message'.tr()),
            _DataRow(log.message),
          ],
        ),
        actions: [
          // A button to copy the request to the clipboard
          if (log.message.isNotEmpty)
            TextButton(
              onPressed: () => PlatformAdapter.setClipboard(log.message),
              child: Text('console_page.copy'.tr()),
            ),
          // close dialog
          TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: Text('basis.close'.tr()),
          ),
        ],
      );
}

class _SectionRow extends StatelessWidget {
  const _SectionRow(this.title);

  final String title;

  @override
  Widget build(final BuildContext context) => Padding(
        padding: const EdgeInsets.symmetric(vertical: 8),
        child: DecoratedBox(
          decoration: BoxDecoration(
            border: Border(
              bottom: BorderSide(
                color: Theme.of(context).colorScheme.outlineVariant,
                width: 2.4,
              ),
            ),
          ),
          child: SelectableText(
            title.tr(),
            style: const TextStyle(
              fontWeight: FontWeight.w800,
              fontSize: 20,
            ),
          ),
        ),
      );
}

class _KeyValueRow extends StatelessWidget {
  const _KeyValueRow(this.title, this.value);

  final String title;
  final String? value;

  @override
  Widget build(final BuildContext context) => Padding(
        padding: const EdgeInsets.symmetric(horizontal: 12),
        child: SelectableText.rich(
          TextSpan(
            style: DefaultTextStyle.of(context).style,
            children: <TextSpan>[
              TextSpan(
                text: '$title: ',
                style: const TextStyle(fontWeight: FontWeight.bold),
              ),
              TextSpan(text: value ?? ''),
            ],
          ),
        ),
      );
}

class _DataRow extends StatelessWidget {
  const _DataRow(this.data);

  final String? data;

  @override
  Widget build(final BuildContext context) => Padding(
        padding: const EdgeInsets.symmetric(horizontal: 12),
        child: SelectableText(
          data ?? 'null',
          style: const TextStyle(fontWeight: FontWeight.w400),
        ),
      );
}