import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:relationship_saver/core/config/app_theme.dart';
import 'package:relationship_saver/features/ideas/ideas_view.dart';
import 'package:relationship_saver/features/moments/moments_view.dart';
import 'package:relationship_saver/features/people/people_view.dart';
import 'package:relationship_saver/features/reminders/reminders_view.dart';
import 'package:relationship_saver/features/shared/frosted_card.dart';
import 'package:relationship_saver/features/sync/sync_coordinator.dart';
import 'package:relationship_saver/features/sync/sync_queue_repository.dart';
import 'package:relationship_saver/features/sync/sync_state.dart';
import 'package:relationship_saver/integrations/backend/models/backend_models.dart';

class SyncView extends ConsumerStatefulWidget {
  const SyncView({super.key});

  @override
  ConsumerState<SyncView> createState() => _SyncViewState();
}

class _SyncViewState extends ConsumerState<SyncView> {
  bool _busy = false;
  String _status = 'Ready. Local-first mode keeps app usable without sync.';
  final Set<String> _expandedRejections = <String>{};

  @override
  Widget build(BuildContext context) {
    final AsyncValue<SyncState> syncState = ref.watch(
      syncQueueRepositoryProvider,
    );

    return LayoutBuilder(
      builder: (BuildContext context, BoxConstraints constraints) {
        final bool compact = constraints.maxWidth < 760;
        return Padding(
          padding: EdgeInsets.fromLTRB(
            compact ? 16 : 28,
            compact ? 16 : 24,
            compact ? 16 : 28,
            compact ? 20 : 28,
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text('Sync', style: Theme.of(context).textTheme.headlineMedium),
              const SizedBox(height: 6),
              Text(
                'Queue local changes, then push and pull when network is available.',
                style: Theme.of(
                  context,
                ).textTheme.bodyLarge?.copyWith(color: AppTheme.textSecondary),
              ),
              const SizedBox(height: 16),
              Expanded(
                child: syncState.when(
                  data: (SyncState state) =>
                      _buildBody(context, state, compact),
                  loading: () =>
                      const Center(child: CircularProgressIndicator()),
                  error: (Object error, StackTrace stackTrace) {
                    return Center(
                      child: Text(
                        'Unable to load sync state. $error',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: AppTheme.textSecondary,
                        ),
                      ),
                    );
                  },
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  Widget _buildBody(BuildContext context, SyncState state, bool compact) {
    return ListView(
      children: <Widget>[
        FrostedCard(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Wrap(
                spacing: 10,
                runSpacing: 10,
                children: <Widget>[
                  FilledButton.icon(
                    onPressed: _busy ? null : _syncNow,
                    icon: const Icon(Icons.sync_rounded),
                    label: const Text('Sync Now'),
                  ),
                  OutlinedButton.icon(
                    onPressed: _busy ? null : _pushPending,
                    icon: const Icon(Icons.upload_rounded),
                    label: const Text('Push Pending'),
                  ),
                  OutlinedButton.icon(
                    onPressed: _busy ? null : _pullChanges,
                    icon: const Icon(Icons.download_rounded),
                    label: const Text('Pull Changes'),
                  ),
                  TextButton.icon(
                    onPressed: _busy ? null : _clearQueue,
                    icon: const Icon(Icons.clear_all_rounded),
                    label: const Text('Clear Queue'),
                  ),
                ],
              ),
              const SizedBox(height: 16),
              Text(
                _status,
                style: Theme.of(
                  context,
                ).textTheme.bodyLarge?.copyWith(color: AppTheme.textSecondary),
              ),
            ],
          ),
        ),
        const SizedBox(height: 16),
        FrostedCard(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text(
                'Queue Status',
                style: Theme.of(context).textTheme.titleMedium,
              ),
              const SizedBox(height: 10),
              _infoRow(
                label: 'Pending changes',
                value: '${state.pendingChanges.length}',
                compact: compact,
              ),
              _infoRow(
                label: 'Cursor',
                value: state.cursor ?? 'not set',
                compact: compact,
              ),
              _infoRow(
                label: 'Last sync',
                value: _formatDateTime(state.lastSyncAt),
                compact: compact,
              ),
              _infoRow(
                label: 'Last attempt',
                value: _formatDateTime(state.lastAttemptAt),
                compact: compact,
              ),
              _infoRow(
                label: 'Last rejected count',
                value: '${state.lastRejected.length}',
                compact: compact,
              ),
              _infoRow(
                label: 'Last error',
                value: state.lastError ?? 'none',
                compact: compact,
              ),
            ],
          ),
        ),
        const SizedBox(height: 16),
        if (state.lastRejected.isNotEmpty) ...<Widget>[
          FrostedCard(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Wrap(
                  spacing: 8,
                  runSpacing: 8,
                  crossAxisAlignment: WrapCrossAlignment.center,
                  children: <Widget>[
                    Text(
                      'Rejected Changes',
                      style: Theme.of(context).textTheme.titleMedium,
                    ),
                    TextButton.icon(
                      onPressed: _busy ? null : _requeueRejected,
                      icon: const Icon(Icons.replay_rounded),
                      label: const Text('Requeue'),
                    ),
                    TextButton.icon(
                      onPressed: _busy ? null : _dismissRejections,
                      icon: const Icon(Icons.done_all_rounded),
                      label: const Text('Dismiss'),
                    ),
                  ],
                ),
                const SizedBox(height: 8),
                ...state.lastRejected.map((MutationRejection rejection) {
                  final ChangeEnvelope? matched = _findRejectedChange(
                    state.lastRejectedChanges,
                    rejection.clientMutationId,
                  );
                  final bool expanded = _expandedRejections.contains(
                    rejection.clientMutationId,
                  );
                  return Padding(
                    padding: const EdgeInsets.only(bottom: 10),
                    child: _rejectionTile(
                      rejection,
                      matched: matched,
                      expanded: expanded,
                      onToggleExpanded: matched?.payload == null
                          ? null
                          : () => _toggleRejectionExpanded(
                              rejection.clientMutationId,
                            ),
                      onOpenEntity:
                          matched != null &&
                              _entityViewForType(matched.entityType) != null
                          ? () => _openEntityViewFor(matched)
                          : null,
                    ),
                  );
                }),
              ],
            ),
          ),
          const SizedBox(height: 16),
        ],
        FrostedCard(
          child: Text(
            'Sync policy\n• Core usage never blocks on backend\n• Local changes queue first and remain safe offline\n• Pull applies backend envelopes into local state',
            style: Theme.of(context).textTheme.bodyLarge,
          ),
        ),
      ],
    );
  }

  Widget _infoRow({
    required String label,
    required String value,
    required bool compact,
  }) {
    if (compact) {
      return Padding(
        padding: const EdgeInsets.symmetric(vertical: 4),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text(
              label,
              style: Theme.of(
                context,
              ).textTheme.labelLarge?.copyWith(color: AppTheme.textSecondary),
            ),
            const SizedBox(height: 2),
            Text(value, style: Theme.of(context).textTheme.bodyMedium),
          ],
        ),
      );
    }

    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 2),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          SizedBox(width: 150, child: Text(label)),
          Expanded(
            child: Text(
              value,
              style: Theme.of(
                context,
              ).textTheme.bodyMedium?.copyWith(color: AppTheme.textSecondary),
            ),
          ),
        ],
      ),
    );
  }

  Widget _rejectionTile(
    MutationRejection rejection, {
    required ChangeEnvelope? matched,
    required bool expanded,
    required VoidCallback? onToggleExpanded,
    required VoidCallback? onOpenEntity,
  }) {
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: Colors.white.withValues(alpha: 0.72),
        borderRadius: BorderRadius.circular(12),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Wrap(
            spacing: 8,
            runSpacing: 8,
            crossAxisAlignment: WrapCrossAlignment.center,
            children: <Widget>[
              Container(
                padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 3),
                decoration: BoxDecoration(
                  color: const Color(0xFFEAF7FB),
                  borderRadius: BorderRadius.circular(999),
                ),
                child: Text(
                  rejection.code,
                  style: Theme.of(
                    context,
                  ).textTheme.labelMedium?.copyWith(color: AppTheme.primary),
                ),
              ),
              Text(
                'Mutation ${rejection.clientMutationId}',
                style: Theme.of(
                  context,
                ).textTheme.bodySmall?.copyWith(color: AppTheme.textSecondary),
              ),
              if (matched != null)
                Text(
                  '${matched.entityType}:${matched.entityId}',
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                    color: AppTheme.textSecondary,
                  ),
                ),
              if (onToggleExpanded != null)
                IconButton(
                  onPressed: onToggleExpanded,
                  tooltip: expanded ? 'Hide payload' : 'Show payload',
                  icon: Icon(
                    expanded
                        ? Icons.keyboard_arrow_up_rounded
                        : Icons.keyboard_arrow_down_rounded,
                    color: AppTheme.textSecondary,
                  ),
                ),
            ],
          ),
          const SizedBox(height: 6),
          Text(
            rejection.message,
            style: Theme.of(context).textTheme.bodyMedium,
          ),
          if (expanded && matched?.payload != null) ...<Widget>[
            const SizedBox(height: 10),
            Container(
              width: double.infinity,
              padding: const EdgeInsets.all(10),
              decoration: BoxDecoration(
                color: const Color(0xFFF3F8FB),
                borderRadius: BorderRadius.circular(10),
              ),
              child: SelectableText(
                const JsonEncoder.withIndent('  ').convert(matched!.payload),
                style: Theme.of(context).textTheme.bodySmall,
              ),
            ),
          ],
          if (onOpenEntity != null) ...<Widget>[
            const SizedBox(height: 8),
            Wrap(
              spacing: 8,
              children: <Widget>[
                TextButton.icon(
                  onPressed: onOpenEntity,
                  icon: const Icon(Icons.open_in_new_rounded),
                  label: const Text('Open Related Screen'),
                ),
              ],
            ),
          ],
        ],
      ),
    );
  }

  ChangeEnvelope? _findRejectedChange(
    List<ChangeEnvelope> changes,
    String clientMutationId,
  ) {
    for (final ChangeEnvelope change in changes) {
      if (change.clientMutationId == clientMutationId) {
        return change;
      }
    }
    return null;
  }

  String _formatDateTime(DateTime? value) {
    if (value == null) {
      return 'never';
    }

    final DateTime local = value.toLocal();
    final String month = local.month.toString().padLeft(2, '0');
    final String day = local.day.toString().padLeft(2, '0');
    final String hour = local.hour.toString().padLeft(2, '0');
    final String minute = local.minute.toString().padLeft(2, '0');
    return '${local.year}-$month-$day $hour:$minute';
  }

  Future<void> _syncNow() async {
    await _run((SyncCoordinator coordinator) => coordinator.syncNow());
  }

  Future<void> _pushPending() async {
    await _run((SyncCoordinator coordinator) => coordinator.pushPending());
  }

  Future<void> _pullChanges() async {
    await _run((SyncCoordinator coordinator) => coordinator.pullRemote());
  }

  Future<void> _clearQueue() async {
    setState(() {
      _busy = true;
    });

    try {
      await ref.read(syncQueueRepositoryProvider.notifier).clearQueue();
      setState(() {
        _status = 'Cleared pending sync queue.';
      });
    } finally {
      if (mounted) {
        setState(() {
          _busy = false;
        });
      }
    }
  }

  Future<void> _dismissRejections() async {
    setState(() {
      _busy = true;
    });

    try {
      await ref.read(syncQueueRepositoryProvider.notifier).clearRejections();
      setState(() {
        _status = 'Dismissed latest rejected-mutation details.';
      });
    } finally {
      if (mounted) {
        setState(() {
          _busy = false;
        });
      }
    }
  }

  Future<void> _requeueRejected() async {
    setState(() {
      _busy = true;
    });

    try {
      await ref
          .read(syncQueueRepositoryProvider.notifier)
          .requeueRejectedChanges();
      setState(() {
        _status = 'Requeued rejected changes. Sync again after local fixes.';
      });
    } finally {
      if (mounted) {
        setState(() {
          _busy = false;
        });
      }
    }
  }

  Future<void> _run(
    Future<SyncRunResult> Function(SyncCoordinator coordinator) action,
  ) async {
    setState(() {
      _busy = true;
      _status = 'Running sync operation...';
    });

    try {
      final SyncRunResult result = await action(
        ref.read(syncCoordinatorProvider),
      );
      setState(() {
        _status = result.message;
      });
    } catch (error) {
      setState(() {
        _status = 'Sync operation failed unexpectedly. ($error)';
      });
    } finally {
      if (mounted) {
        setState(() {
          _busy = false;
        });
      }
    }
  }

  void _toggleRejectionExpanded(String clientMutationId) {
    setState(() {
      if (_expandedRejections.contains(clientMutationId)) {
        _expandedRejections.remove(clientMutationId);
      } else {
        _expandedRejections.add(clientMutationId);
      }
    });
  }

  Future<void> _openEntityViewFor(ChangeEnvelope matched) async {
    final Widget? view = _entityViewForType(matched.entityType);
    if (view == null) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text('No editor available for ${matched.entityType}.'),
        ),
      );
      return;
    }

    await Navigator.of(context).push<void>(
      MaterialPageRoute<void>(
        builder: (BuildContext context) => _EntityResolveScreen(
          title: _titleForEntityType(matched.entityType),
          child: view,
        ),
      ),
    );
  }

  Widget? _entityViewForType(String entityType) {
    switch (entityType) {
      case 'person':
        return const PeopleView();
      case 'capture':
        return const MomentsView();
      case 'giftIdea':
      case 'eventIdea':
        return const IdeasView();
      case 'reminderRule':
        return const RemindersView();
      default:
        return null;
    }
  }

  String _titleForEntityType(String entityType) {
    switch (entityType) {
      case 'person':
        return 'Resolve Person';
      case 'capture':
        return 'Resolve Moment';
      case 'giftIdea':
      case 'eventIdea':
        return 'Resolve Idea';
      case 'reminderRule':
        return 'Resolve Reminder';
      default:
        return 'Resolve Item';
    }
  }
}

class _EntityResolveScreen extends StatelessWidget {
  const _EntityResolveScreen({required this.title, required this.child});

  final String title;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(title)),
      body: child,
    );
  }
}