import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:intl/intl.dart';
import 'package:lucide_icons/lucide_icons.dart';
import '../../../../app/di/injection.dart';
import '../../../../app/router/app_routes.dart';
import '../../../../core/l10n/l10n.dart';
import '../../../../shared/widgets/back_title_page_header.dart';
import '../../../../shared/widgets/detail_header_action_menu.dart';
import '../../../../shared/widgets/destructive_action_sheet.dart';
import '../../../../shared/widgets/error_retry_surface.dart';
import '../../../../shared/widgets/full_screen_loading.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';
import '../../data/apis/todo_api.dart';

enum _TodoHeaderAction { edit, delete }

class TodoDetailScreen extends StatefulWidget {
  final String todoId;

  const TodoDetailScreen({super.key, required this.todoId});

  @override
  State<TodoDetailScreen> createState() => _TodoDetailScreenState();
}

class _TodoDetailScreenState extends State<TodoDetailScreen> {
  final TodoApi _todoApi = sl<TodoApi>();

  TodoResponse? _todo;
  bool _isLoading = true;
  bool _didMutate = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    _loadTodo();
  }

  Future<void> _loadTodo() async {
    if (!mounted) {
      return;
    }
    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final todo = await _todoApi.getTodo(widget.todoId);
      if (!mounted) {
        return;
      }
      setState(() {
        _todo = todo;
        _isLoading = false;
      });
    } catch (e) {
      if (!mounted) {
        return;
      }
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  String _getPriorityLabel(int priority) {
    switch (priority) {
      case 1:
        return context.l10n.todoQuadrantImportantUrgent;
      case 2:
        return context.l10n.todoQuadrantImportantNotUrgent;
      case 3:
        return context.l10n.todoQuadrantUrgentNotImportant;
      case 4:
        return context.l10n.todoQuadrantNotUrgentNotImportant;
      default:
        return context.l10n.commonUnknown;
    }
  }

  Color _getPriorityColor(int priority, ColorScheme colorScheme) {
    switch (priority) {
      case 1:
        return colorScheme.error;
      case 2:
        return colorScheme.tertiary;
      case 3:
        return colorScheme.primary;
      default:
        return colorScheme.onSurfaceVariant;
    }
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    return Scaffold(
      backgroundColor: colorScheme.surface,
      body: SafeArea(
        child: Container(
          decoration: BoxDecoration(
            gradient: LinearGradient(
              begin: Alignment.topCenter,
              end: Alignment.bottomCenter,
              colors: [colorScheme.surfaceContainerHigh, colorScheme.surface],
            ),
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              _buildHeader(),
              Expanded(child: _buildContent()),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return BackTitlePageHeader(
      title: context.l10n.todoDetailTitle,
      onBack: () => context.pop(_didMutate),
      trailing: _buildHeaderMenu(),
    );
  }

  Widget? _buildHeaderMenu() {
    if (_todo == null) {
      return null;
    }
    return DetailHeaderActionMenu<_TodoHeaderAction>(
      items: [
        DetailHeaderActionItem<_TodoHeaderAction>(
          value: _TodoHeaderAction.edit,
          label: context.l10n.commonEdit,
          icon: LucideIcons.pencil,
        ),
        DetailHeaderActionItem<_TodoHeaderAction>(
          value: _TodoHeaderAction.delete,
          label: context.l10n.commonDelete,
          icon: LucideIcons.trash2,
          isDestructive: true,
        ),
      ],
      onSelected: _handleHeaderAction,
    );
  }

  void _handleHeaderAction(_TodoHeaderAction action) {
    switch (action) {
      case _TodoHeaderAction.edit:
        _editTodo();
        return;
      case _TodoHeaderAction.delete:
        _deleteTodo();
        return;
    }
  }

  Widget _buildContent() {
    final colorScheme = Theme.of(context).colorScheme;
    if (_isLoading) {
      return const FullScreenLoading();
    }

    if (_error != null) {
      return ErrorRetrySurface(
        message: context.l10n.commonLoadFailed(_error!),
        onRetry: _loadTodo,
      );
    }

    if (_todo == null) {
      return Center(child: Text(context.l10n.todoNotFound));
    }

    return Padding(
      padding: const EdgeInsets.only(left: 16, right: 16, top: 4, bottom: 20),
      child: ListView(
        children: [
          _buildMainCard(),
          const SizedBox(height: 12),
          if (_todo!.scheduleItems.isNotEmpty) ...[
            Text(
              context.l10n.todoCalendarEventCards,
              style: TextStyle(
                fontFamily: 'Inter',
                fontSize: 12,
                fontWeight: FontWeight.w500,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
            const SizedBox(height: 10),
            ..._todo!.scheduleItems.map(
              (item) => _buildEventCard(
                id: item.id,
                title: item.title,
                time: _formatEventTime(item.startAt, item.endAt),
                borderColor: colorScheme.outlineVariant,
                onTap: () =>
                    context.push(AppRoutes.calendarEventDetail(item.id)),
              ),
            ),
          ],
        ],
      ),
    );
  }

  String _formatEventTime(DateTime start, DateTime? end) {
    final startStr = DateFormat.yMd(
      context.l10n.localeName,
    ).add_Hm().format(start);
    if (end != null) {
      final endStr =
          '${end.hour.toString().padLeft(2, '0')}:${end.minute.toString().padLeft(2, '0')}';
      return '$startStr - $endStr';
    }
    return startStr;
  }

  Widget _buildMainCard() {
    final colorScheme = Theme.of(context).colorScheme;
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: colorScheme.surface,
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: colorScheme.outlineVariant, width: 1),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            _todo!.title,
            style: TextStyle(
              fontFamily: 'Inter',
              fontSize: 18,
              fontWeight: FontWeight.w700,
              color: colorScheme.onSurface,
            ),
          ),
          const SizedBox(height: 4),
          Text(
            _buildSubtitle(),
            style: TextStyle(
              fontFamily: 'Inter',
              fontSize: 12,
              fontWeight: FontWeight.w500,
              color: colorScheme.onSurfaceVariant,
            ),
          ),
          if (_todo!.description != null && _todo!.description!.isNotEmpty) ...[
            const SizedBox(height: 8),
            Text(
              _todo!.description!,
              style: TextStyle(
                fontFamily: 'Inter',
                fontSize: 13,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
          ],
          const SizedBox(height: 8),
          Container(height: 1, color: colorScheme.outlineVariant),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: context.l10n.todoPriorityQuadrant,
            value: _getPriorityLabel(_todo!.priority),
            valueColor: _getPriorityColor(_todo!.priority, colorScheme),
          ),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: context.l10n.todoLinkedCalendarEvents,
            value: context.l10n.todoItemCount(_todo!.scheduleItems.length),
            valueColor: colorScheme.tertiary,
          ),
          const SizedBox(height: 8),
          _buildInfoRow(
            label: context.l10n.todoStatus,
            value: _todo!.status == 'done'
                ? context.l10n.todoStatusDone
                : context.l10n.todoStatusInProgress,
            valueColor: _todo!.status == 'done'
                ? colorScheme.tertiary
                : colorScheme.primary,
          ),
        ],
      ),
    );
  }

  String _buildSubtitle() {
    final parts = <String>[];
    parts.add(context.l10n.todoQuadrantOrder(_todo!.order + 1));
    if (_todo!.scheduleItems.isNotEmpty) {
      parts.add(context.l10n.todoSplitToEvents(_todo!.scheduleItems.length));
    } else {
      parts.add(context.l10n.todoNoLinkedEvents);
    }
    return parts.join(' · ');
  }

  Widget _buildInfoRow({
    required String label,
    required String value,
    required Color valueColor,
  }) {
    final colorScheme = Theme.of(context).colorScheme;
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: [
        Text(
          label,
          style: TextStyle(
            fontFamily: 'Inter',
            fontSize: 12,
            fontWeight: FontWeight.w600,
            color: colorScheme.outline,
          ),
        ),
        Text(
          value,
          style: TextStyle(
            fontFamily: 'Inter',
            fontSize: 12,
            fontWeight: FontWeight.w700,
            color: valueColor,
          ),
        ),
      ],
    );
  }

  Widget _buildEventCard({
    required String id,
    required String title,
    required String time,
    required Color borderColor,
    VoidCallback? onTap,
  }) {
    final colorScheme = Theme.of(context).colorScheme;
    return GestureDetector(
      onTap: onTap,
      child: Container(
        width: double.infinity,
        padding: const EdgeInsets.all(10),
        margin: const EdgeInsets.only(bottom: 10),
        decoration: BoxDecoration(
          color: colorScheme.surface,
          borderRadius: BorderRadius.circular(14),
          border: Border.all(color: borderColor, width: 1),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: TextStyle(
                fontFamily: 'Inter',
                fontSize: 13,
                fontWeight: FontWeight.w600,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
            const SizedBox(height: 8),
            Text(
              time,
              style: TextStyle(
                fontFamily: 'Inter',
                fontSize: 12,
                fontWeight: FontWeight.w500,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _editTodo() async {
    if (_todo == null) {
      return;
    }
    final changed = await context.push<bool>(AppRoutes.todoEdit(_todo!.id));
    if (changed == true) {
      _didMutate = true;
      if (!mounted) {
        return;
      }
      context.pop(true);
    }
  }

  void _deleteTodo() async {
    final confirm = await showDestructiveActionSheet(
      context,
      title: context.l10n.todoDeleteTitle,
      message: context.l10n.todoDeleteMessage,
      confirmText: context.l10n.todoDeleteConfirm,
    );

    if (confirm == true) {
      try {
        await _todoApi.deleteTodo(_todo!.id);
        if (mounted) {
          context.pop(true);
        }
      } catch (e) {
        if (mounted) {
          Toast.show(
            context,
            context.l10n.todoDeleteFailed(e.toString()),
            type: ToastType.error,
          );
        }
      }
    }
  }
}