import 'package:flutter/material.dart';
import 'package:flutter_svg/svg.dart';
import 'package:provider/provider.dart';
import 'package:tm_app/core/theme/colors.dart';
import 'package:tm_app/core/utils/date_utils.dart';
import 'package:tm_app/core/utils/result.dart';
import 'package:tm_app/core/utils/size_config.dart';
import 'package:tm_app/data/services/board_service.dart';
import 'package:tm_app/data/services/model/board_response/board_response.dart';
import 'package:tm_app/views/shared/desktop_navigation_widget.dart';

import '../../../core/constants/assets.dart';
import '../../../core/utils/app_toast.dart';
import '../../../view_models/board_view_model.dart';
import '../strings/board_strings.dart';

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

  @override
  State<BoardScreen> createState() => _BoardScreenState();
}

class _BoardScreenState extends State<BoardScreen> {
  late BoardViewModel _boardViewModel;

  @override
  void initState() {
    super.initState();
    _boardViewModel = context.read<BoardViewModel>();
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      _boardViewModel.getBoard();
    });
  }

  Future<void> _onCardDropped(BoardCard card, BoardColumn target) async {
    final source = _boardViewModel.columnForCard(card.id ?? '');
    if (source == null || source.id == target.id) return;

    final result = await _boardViewModel.moveCard(
      card: card,
      targetColumn: target,
    );

    if (!mounted) return;
    if (result is Ok<MoveCardResponse>) {
      AppToast.success(
        context,
        BoardStrings.cardMovedMessage(
          source.name ?? '',
          target.name ?? '',
        ),
      );
    } else if (result is Error<MoveCardResponse>) {
      AppToast.error(context, BoardStrings.moveFailed);
    }
  }

  @override
  Widget build(BuildContext context) {
    SizeConfig.init(context);
    return Scaffold(
      backgroundColor: AppColors.backgroundColor,
      body: Column(
        children: [
          const DesktopNavigationWidget(currentIndex: 2),
          Consumer<BoardViewModel>(
            builder: (context, viewModel, child) {
              if (viewModel.isLoading) {
                return const Expanded(
                  child: Center(
                    child: CircularProgressIndicator(
                      color: AppColors.secondary50,
                    ),
                  ),
                );
              }
              if (viewModel.errorMessage != null) {
                return Expanded(
                  child: Center(child: Text(viewModel.errorMessage!)),
                );
              }
              if (!viewModel.hasData) {
                return const Expanded(
                  child: Center(child: Text(BoardStrings.emptyListText)),
                );
              }

              final columns = [...viewModel.columns]..sort(
                (a, b) => (a.order ?? 0).compareTo(b.order ?? 0),
              );

              return Expanded(
                child: SingleChildScrollView(
                  child: SizedBox(
                    width: 740,
                    height: 735,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        const SizedBox(height: 32),
                        Text(
                          viewModel.board?.name ?? BoardStrings.boardTitle,
                          style: TextStyle(
                            fontSize: 20.0.sp(),
                            fontWeight: FontWeight.w600,
                            color: AppColors.titleColor,
                          ),
                        ),
                        const SizedBox(height: 20),
                        Expanded(
                          child: Container(
                            padding: const EdgeInsets.all(16),
                            decoration: BoxDecoration(
                              borderRadius: BorderRadius.circular(12),
                              color: AppColors.primary20,
                            ),
                            child: Row(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                for (int i = 0; i < columns.length; i++) ...[
                                  if (i > 0) const SizedBox(width: 12),
                                  Expanded(
                                    child: _BoardColumnView(
                                      column: columns[i],
                                      onCardDropped: _onCardDropped,
                                    ),
                                  ),
                                ],
                              ],
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              );
            },
          ),
        ],
      ),
    );
  }
}

class _BoardColumnView extends StatelessWidget {
  final BoardColumn column;
  final Future<void> Function(BoardCard, BoardColumn) onCardDropped;

  const _BoardColumnView({required this.column, required this.onCardDropped});

  @override
  Widget build(BuildContext context) {
    final accent = _parseHexColor(column.color) ?? AppColors.textBlue;
    return DragTarget<BoardCard>(
      onWillAcceptWithDetails: (details) => details.data.columnId != column.id,
      onAcceptWithDetails: (details) => onCardDropped(details.data, column),
      builder: (context, candidateData, rejectedData) {
        final isHovering = candidateData.isNotEmpty;
        return Container(
          decoration: BoxDecoration(
            color:
                isHovering
                    ? accent.withValues(alpha: 0.15)
                    : AppColors.primary0,
            borderRadius: BorderRadius.circular(12),
            border: Border.all(
              color: isHovering ? accent : AppColors.borderBlue,
              width: isHovering ? 2 : 1,
            ),
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Container(
                width: double.infinity,
                height: 34,
                margin: const EdgeInsets.all(8),
                decoration: BoxDecoration(
                  color: accent.withValues(alpha: 0.15),
                  borderRadius: BorderRadius.circular(4),
                ),
                alignment: Alignment.center,
                child: Text(
                  _columnHeader(column),
                  style: TextStyle(
                    fontSize: 16,
                    fontWeight: FontWeight.w600,
                    color: accent,
                  ),
                ),
              ),
              Expanded(
                child: ListView.builder(
                  padding: const EdgeInsets.all(12),
                  itemCount: column.cards.length,
                  itemBuilder: (context, index) {
                    return _TaskCard(card: column.cards[index], accent: accent);
                  },
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  String _columnHeader(BoardColumn column) {
    final name = column.name ?? '';
    final limit = column.limit;
    if (limit == null || limit <= 0) return name;
    return '$name (${column.cards.length}/$limit)';
  }
}

class _TaskCard extends StatelessWidget {
  final BoardCard card;
  final Color accent;

  const _TaskCard({required this.card, required this.accent});

  @override
  Widget build(BuildContext context) {
    return Draggable<BoardCard>(
      data: card,
      feedback: Material(
        elevation: 8,
        borderRadius: BorderRadius.circular(12),
        child: Container(
          width: 280,
          padding: const EdgeInsets.all(16),
          decoration: BoxDecoration(
            color: AppColors.primary0,
            borderRadius: BorderRadius.circular(12),
            border: Border.all(color: AppColors.borderBlue, width: 2),
          ),
          child: _buildCardContent(context),
        ),
      ),
      childWhenDragging: Opacity(opacity: 0.3, child: _buildCard(context)),
      child: _buildCard(context),
    );
  }

  Widget _buildCard(BuildContext context) {
    return Container(
      margin: const EdgeInsets.only(bottom: 12),
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.primary0,
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: AppColors.grey30),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.05),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: _buildCardContent(context),
    );
  }

  Widget _buildCardContent(BuildContext context) {
    final due = card.dueDate;
    final labels = card.labels;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        if (due != null)
          Container(
            height: 24.0,
            padding: EdgeInsets.symmetric(horizontal: 10.0.w()),
            decoration: BoxDecoration(
              color: accent.withValues(alpha: 0.15),
              borderRadius: BorderRadius.circular(4),
            ),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  '${BoardStrings.deadlineLabel} :',
                  style: TextStyle(
                    fontSize: 14.0,
                    fontWeight: FontWeight.w500,
                    color: AppColors.textBlue,
                  ),
                ),
                Text(
                  timeConvertor(due),
                  style: TextStyle(
                    fontSize: 14.0,
                    fontWeight: FontWeight.w500,
                    color: AppColors.grey80,
                  ),
                ),
              ],
            ),
          ),
        if (due != null) const SizedBox(height: 12),
        SelectableText(
          card.title ?? '',
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w500,
            color: AppColors.grey70,
          ),
          maxLines: 3,
        ),
        const SizedBox(height: 12),
        if (card.priority != null) _PriorityChip(priority: card.priority!),
        if (labels.isNotEmpty) ...[
          const SizedBox(height: 8),
          Wrap(
            spacing: 6,
            runSpacing: 6,
            children: [for (final label in labels) _LabelChip(label: label)],
          ),
        ],
        const SizedBox(height: 12),
        Row(
          children: [
            SvgPicture.asset(AssetsManager.profile),
            const SizedBox(width: 4),
            Text(
              card.tenderId ?? '',
              style: TextStyle(fontSize: 12, color: AppColors.grey60),
              maxLines: 1,
              overflow: TextOverflow.ellipsis,
            ),
          ],
        ),
      ],
    );
  }
}

class _PriorityChip extends StatelessWidget {
  final String priority;
  const _PriorityChip({required this.priority});

  @override
  Widget build(BuildContext context) {
    final (bg, fg, dot) = _styleFor(priority);
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8.0, vertical: 4.0),
      decoration: BoxDecoration(
        color: bg,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Container(
            width: 8,
            height: 8,
            decoration: BoxDecoration(color: dot, shape: BoxShape.circle),
          ),
          const SizedBox(width: 6),
          Text(
            priority,
            style: TextStyle(
              fontSize: 12,
              color: fg,
              fontWeight: FontWeight.w400,
            ),
          ),
        ],
      ),
    );
  }

  (Color bg, Color fg, Color dot) _styleFor(String priority) {
    switch (priority.toLowerCase()) {
      case 'urgent':
      case 'high':
        return (AppColors.red0, AppColors.red20, AppColors.error);
      case 'low':
        return (AppColors.primary20, AppColors.textBlue, AppColors.textBlue);
      case 'medium':
      default:
        return (AppColors.orange10, AppColors.orange, AppColors.orange);
    }
  }
}

class _LabelChip extends StatelessWidget {
  final String label;
  const _LabelChip({required this.label});

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8.0, vertical: 2.0),
      decoration: BoxDecoration(
        color: AppColors.primary20,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Text(
        label,
        style: TextStyle(fontSize: 11, color: AppColors.textBlue),
      ),
    );
  }
}

Color? _parseHexColor(String? hex) {
  if (hex == null) return null;
  var value = hex.trim();
  if (value.startsWith('#')) value = value.substring(1);
  if (value.length == 6) value = 'FF$value';
  if (value.length != 8) return null;
  final parsed = int.tryParse(value, radix: 16);
  if (parsed == null) return null;
  return Color(parsed);
}