import 'dart:async';

import 'package:flutter/material.dart';

import 'package:notas/data/note_body.dart';
import 'package:notas/data/note_repository.dart';
import 'package:notas/models/category.dart';
import 'package:notas/models/note.dart';
import 'package:notas/screens/note_editor_screen.dart';
import 'package:notas/theme/app_palette.dart';
import 'package:notas/widgets/category_editor_dialog.dart';
import 'package:notas/widgets/category_menu_button.dart';
import 'package:notas/widgets/category_style.dart';
import 'package:notas/widgets/note_list_view.dart';
import 'package:notas/widgets/search_app_bar.dart';
import 'package:notas/widgets/sync_status.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({
    super.key,
    required this.repository,
    required this.onOpenSettings,
    required this.onRequestSync,
    this.onVaultInvalid,
    this.syncStatus = SyncStatus.idle,
    this.syncProgress,
    this.syncDetailMessage,
    this.syncErrorMessage,
    this.refreshToken = 0,
  });

  final NoteRepository repository;
  final VoidCallback onOpenSettings;
  final Future<void> Function() onRequestSync;
  final Future<void> Function()? onVaultInvalid;
  final SyncStatus syncStatus;
  final double? syncProgress;
  final String? syncDetailMessage;
  final String? syncErrorMessage;
  final int refreshToken;

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  static const double _desktopBreakpoint = 900;

  final TextEditingController _searchController = TextEditingController();

  List<Note> _notes = <Note>[];
  List<Category> _categories = <Category>[];
  bool _isLoading = true;
  String _searchQuery = '';
  String? _selectedCategoryId;
  String? _selectedNoteId;
  DateTime? _lastSyncAt;

  AppPalette _paletteOf(BuildContext context) {
    return Theme.of(context).extension<AppPalette>() ??
        AppPalette.fromBrightness(Theme.of(context).brightness);
  }

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

  @override
  void dispose() {
    _searchController.dispose();
    super.dispose();
  }

  @override
  void didUpdateWidget(covariant HomeScreen oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.refreshToken != widget.refreshToken) {
      _loadData(keepSelection: true);
    }
  }

  Future<void> _loadData({bool keepSelection = false}) async {
    if (mounted) {
      setState(() {
        _isLoading = true;
      });
    }

    try {
      final List<Note> notes = await widget.repository.loadNotes();
      final List<Category> categories = await widget.repository.loadCategories();
      final DateTime? lastSyncAt = await widget.repository.getLastSyncAt();

      if (!mounted) {
        return;
      }

      setState(() {
        _notes = notes;
        _categories = categories;
        _lastSyncAt = lastSyncAt;
        _isLoading = false;

        if (!keepSelection) {
          _selectedNoteId = null;
        } else if (_selectedNoteId != null &&
            !_notes.any((Note note) => note.id == _selectedNoteId)) {
          _selectedNoteId = null;
        }
      });
    } catch (error, stackTrace) {
      debugPrint('Failed to load home data: $error\n$stackTrace');
      if (widget.onVaultInvalid != null) {
        await widget.onVaultInvalid!();
      }
    }
  }

  Future<void> _reloadNotes({bool keepSelection = true}) async {
    try {
      final List<Note> notes = await widget.repository.loadNotes();
      if (!mounted) {
        return;
      }

      setState(() {
        _notes = notes;
        if (!keepSelection ||
            (_selectedNoteId != null &&
                !_notes.any((Note note) => note.id == _selectedNoteId))) {
          _selectedNoteId = null;
        }
      });
    } catch (error) {
      debugPrint('Failed to reload notes: $error');
    }
  }

  void _setSearchQuery(String value) {
    if (!mounted) {
      return;
    }

    setState(() {
      _searchQuery = value.trim();
    });
  }

  List<Note> _visibleNotes() {
    Iterable<Note> notes = _notes;

    if (_selectedCategoryId != null) {
      notes = notes.where(
        (Note note) => note.categoryId == _selectedCategoryId,
      );
    }

    if (_searchQuery.isEmpty) {
      return notes.toList();
    }

    final String query = _searchQuery.toLowerCase();
    return notes
        .where(
          (Note note) =>
              note.title.toLowerCase().contains(query) ||
              noteBodyToPlainText(note.body).toLowerCase().contains(query),
        )
        .toList();
  }

  Note? _selectedNote() {
    final String? selectedId = _selectedNoteId;
    if (selectedId == null) {
      return null;
    }

    for (final Note note in _notes) {
      if (note.id == selectedId) {
        return note;
      }
    }

    return null;
  }

  Category? _categoryById(String? categoryId) {
    if (categoryId == null) {
      return null;
    }

    for (final Category category in _categories) {
      if (category.id == categoryId) {
        return category;
      }
    }

    return null;
  }

  void _selectCategoryFilter(String? categoryId) {
    setState(() {
      _selectedCategoryId = categoryId;
      if (_selectedNoteId != null &&
          !_visibleNotes().any((Note note) => note.id == _selectedNoteId)) {
        _selectedNoteId = null;
      }
    });
  }

  Future<Category?> _saveCategory({Category? existingCategory}) async {
    final CategoryDraft? categoryDraft = await showCategoryEditorDialog(
      context: context,
      title: existingCategory == null ? 'Crear categoría' : 'Editar categoría',
      confirmLabel: existingCategory == null ? 'Crear' : 'Guardar',
      initialName: existingCategory?.name,
      initialColorValue:
          existingCategory?.colorValue ?? CategoryStyle.colorsOf(context).first.toARGB32(),
      initialIconCodePoint:
          existingCategory?.iconCodePoint ?? CategoryStyle.icons.first.codePoint,
    );

    if (categoryDraft == null) {
      return null;
    }

    final DateTime now = DateTime.now();
    final Category category = existingCategory == null
        ? Category(
            name: categoryDraft.name,
            updatedAt: now,
            colorValue: categoryDraft.colorValue,
            iconCodePoint: categoryDraft.iconCodePoint,
          )
        : existingCategory.copyWith(
            name: categoryDraft.name,
            updatedAt: now,
            isDirty: true,
            colorValue: categoryDraft.colorValue,
            iconCodePoint: categoryDraft.iconCodePoint,
          );

    await widget.repository.createCategory(category);

    if (!mounted) {
      return null;
    }

    setState(() {
      _categories = <Category>[
        for (final Category item in _categories)
          if (item.id == category.id) category else item,
      ];

      if (!_categories.any((Category item) => item.id == category.id)) {
        _categories = <Category>[..._categories, category];
      }
    });

    return category;
  }

  Future<void> _updateNoteCategory(Note note, String? categoryId) async {
    try {
      final Note updated = await widget.repository.updateNote(
        note.copyWith(
          categoryId: categoryId,
          updatedAt: DateTime.now(),
          isDirty: true,
        ),
      );

      if (!mounted) {
        return;
      }

      setState(() {
        _notes = <Note>[
          for (final Note item in _notes)
            if (item.id == updated.id) updated else item,
        ];
      });
    } catch (error) {
      if (!mounted) {
        return;
      }

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('No se pudo cambiar la categoría: $error')),
      );
    }
  }

  Future<void> _deleteNoteAfterConfirmation(Note note) async {
    final bool? confirmed = await showDialog<bool>(
      context: context,
      builder: (BuildContext dialogContext) {
        final AppPalette palette = _paletteOf(dialogContext);

        return AlertDialog(
          backgroundColor: palette.surfaceElevated,
          title: const Text('Eliminar nota'),
          content: const Text(
            'Esta acción eliminará la nota. ¿Quieres continuar?',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(dialogContext).pop(false),
              child: const Text('Cancelar'),
            ),
            FilledButton(
              onPressed: () => Navigator.of(dialogContext).pop(true),
              style: FilledButton.styleFrom(
                backgroundColor: Colors.red,
                foregroundColor: Colors.white,
              ),
              child: const Text('Confirmar'),
            ),
          ],
        );
      },
    );

    if (confirmed != true) {
      return;
    }

    try {
      await widget.repository.deleteNote(note);
      if (!mounted) {
        return;
      }

      setState(() {
        _notes = _notes.where((Note item) => item.id != note.id).toList();
        if (_selectedNoteId == note.id) {
          _selectedNoteId = null;
        }
      });
    } catch (error) {
      if (!mounted) {
        return;
      }

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('No se pudo eliminar la nota: $error')),
      );
    }
  }

  Future<void> _changeNoteCategory(BuildContext anchorContext, Note note) async {
    final String? selectedCategoryId = await showCategorySelectionMenu(
      anchorContext: anchorContext,
      categories: _categories,
      selectedCategoryId: note.categoryId,
      allowCreateCategory: true,
      emptyLabel: 'Sin categoría',
      createLabel: 'Crear categoría',
      onEditCategory: (Category category) {
        unawaited(_saveCategory(existingCategory: category));
      },
    );

    if (!mounted || selectedCategoryId == null) {
      return;
    }

    if (selectedCategoryId == kCreateCategoryMenuValue) {
      final Category? createdCategory = await _saveCategory();
      if (createdCategory == null || !mounted) {
        return;
      }

      await _updateNoteCategory(note, createdCategory.id);
      return;
    }

    final String? categoryId = selectedCategoryId.isEmpty
        ? null
        : selectedCategoryId;
    if (categoryId == note.categoryId) {
      return;
    }

    await _updateNoteCategory(note, categoryId);
  }

  Future<void> _createNote({required bool openEditor}) async {
    final DateTime now = DateTime.now();
    final Note draft = Note(
      title: 'Sin título',
      body: '',
      createdAt: now,
      updatedAt: now,
      position: 0,
      categoryId: _selectedCategoryId,
    );

    try {
      if (_searchQuery.isNotEmpty) {
        _searchController.clear();
        _searchQuery = '';
      }

      final Note created = await widget.repository.createNote(draft);
      if (!mounted) {
        return;
      }

      await _reloadNotes(keepSelection: false);

      if (!mounted) {
        return;
      }

      setState(() {
        _selectedNoteId = created.id;
      });

      if (openEditor) {
        await _openEditor(created, embedded: false);
      }
    } catch (error) {
      if (!mounted) {
        return;
      }

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('No se pudo crear la nota: $error')),
      );
    }
  }

  Future<void> _openExistingNote(Note note, {required bool embedded}) async {
    setState(() {
      _selectedNoteId = note.id;
    });

    if (embedded) {
      return;
    }

    await _openEditor(note, embedded: false);
  }

  Future<void> _openEditor(Note note, {required bool embedded}) async {
    final Widget editor = NoteEditorScreen(
      key: ValueKey<String>(note.id),
      repository: widget.repository,
      note: note,
      embedded: embedded,
      onSaved: (Note saved) {
        if (!mounted) {
          return;
        }

        setState(() {
          _notes = <Note>[
            for (final Note item in _notes)
              if (item.id == saved.id) saved else item,
          ];
        });
      },
    );

    if (embedded) {
      return;
    }

    await Navigator.of(context).push(
      MaterialPageRoute<void>(builder: (_) => editor),
    );
  }

  Future<void> _handleNoteTap(Note note, bool isDesktop) async {
    if (isDesktop) {
      await _openExistingNote(note, embedded: true);
      return;
    }

    await _openEditor(note, embedded: false);
  }

  Future<void> _handleReorder(int oldIndex, int newIndex) async {
    final List<Note> visibleNotes = _visibleNotes();
    if (oldIndex < 0 || oldIndex >= visibleNotes.length) {
      return;
    }

    final Note movedNote = visibleNotes[oldIndex];
    final List<Note> remainingVisible = <Note>[...visibleNotes]..removeAt(oldIndex);
    final int clampedNewIndex = newIndex.clamp(0, remainingVisible.length);

    int targetFullIndex;
    if (remainingVisible.isEmpty) {
      targetFullIndex = 0;
    } else if (clampedNewIndex == 0) {
      targetFullIndex = 0;
    } else if (clampedNewIndex >= remainingVisible.length) {
      targetFullIndex = _notes.length - 1;
    } else {
      final Note afterNote = remainingVisible[clampedNewIndex];
      targetFullIndex = _notes.indexWhere(
        (Note note) => note.id == afterNote.id,
      );
      if (targetFullIndex < 0) {
        targetFullIndex = 0;
      }
    }

    try {
      await widget.repository.moveNote(movedNote, targetFullIndex);
      await _reloadNotes(keepSelection: true);
    } catch (error) {
      if (!mounted) {
        return;
      }

      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('No se pudo reordenar la nota: $error')),
      );
    }
  }

  Widget _buildEmptyDetailPane(BuildContext context) {
    final AppPalette palette = _paletteOf(context);

    return Center(
      child: Text(
        'Selecciona una nota o\ncrea una nueva para empezar.',
        textAlign: TextAlign.center,
        style: TextStyle(
          color: palette.textSecondary,
          fontSize: 18,
          fontWeight: FontWeight.w500,
        ),
      ),
    );
  }

  Widget _buildDesktopLayout(BuildContext context, BoxConstraints constraints) {
    final AppPalette palette = _paletteOf(context);
    final double leftWidth = (constraints.maxWidth * 0.34).clamp(320, 440);
    final Note? selectedNote = _selectedNote();
    final bool selectedIsVisible =
        selectedNote != null &&
        _visibleNotes().any((Note note) => note.id == selectedNote.id);

    return Row(
      children: [
        SizedBox(
          width: leftWidth,
          child: Container(
            decoration: BoxDecoration(
              color: palette.transparent,
              border: Border(right: BorderSide(color: palette.border)),
            ),
            child: Stack(
              children: [
                Column(
                  children: [
                    SearchAppBar(
                      controller: _searchController,
                      leadingWidget: CategoryMenuButton(
                        categories: _categories,
                        selectedCategoryId: _selectedCategoryId,
                        onCategorySelected: _selectCategoryFilter,
                        onEditCategory: (Category category) {
                          unawaited(_saveCategory(existingCategory: category));
                        },
                        icon: Icons.filter_alt_outlined,
                        tooltip: 'Filtrar por categorías',
                        isActive: _selectedCategoryId != null,
                      ),
                      showLeadingButton: false,
                      trailingWidget: IconButton(
                        onPressed: widget.onOpenSettings,
                        icon: Icon(
                          Icons.settings_outlined,
                          color: palette.textSecondary,
                        ),
                        tooltip: 'Ajustes',
                      ),
                      onSearchChanged: _setSearchQuery,
                      searchMaxWidth: 640,
                      padding: const EdgeInsets.symmetric(
                        horizontal: 12,
                        vertical: 10,
                      ),
                    ),
                    Expanded(
                      child: NoteListView(
                        notes: _visibleNotes(),
                        isLoading: _isLoading,
                        selectedNoteId: _selectedNoteId,
                        showSelectionBorder: true,
                        categoryForNote: _categoryById,
                        lastSyncAt: _lastSyncAt,
                        onRefresh: () async {
                          await widget.onRequestSync();
                          await _loadData(keepSelection: true);
                        },
                        onReorder: _handleReorder,
                        onNoteTap: (Note note) => _handleNoteTap(note, true),
                        onDeleteNote: _deleteNoteAfterConfirmation,
                        onChangeCategory: _changeNoteCategory,
                      ),
                    ),
                  ],
                ),
                Positioned(
                  right: 20,
                  bottom: 20,
                  child: FloatingActionButton(
                    onPressed: () => _createNote(openEditor: false),
                    child: const Icon(Icons.add),
                  ),
                ),
              ],
            ),
          ),
        ),
        Expanded(
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: AnimatedSwitcher(
              duration: const Duration(milliseconds: 220),
              child: selectedIsVisible
                  ? NoteEditorScreen(
                      key: ValueKey<String>(selectedNote.id),
                      repository: widget.repository,
                      note: selectedNote,
                      embedded: true,
                      onSaved: (Note saved) {
                        if (!mounted) {
                          return;
                        }

                        setState(() {
                          _notes = <Note>[
                            for (final Note item in _notes)
                              if (item.id == saved.id) saved else item,
                          ];
                        });
                      },
                    )
                  : _buildEmptyDetailPane(context),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildMobileLayout(BuildContext context) {
    final AppPalette palette = _paletteOf(context);

    return Stack(
      children: [
        Column(
          children: [
            SearchAppBar(
              controller: _searchController,
              leadingWidget: CategoryMenuButton(
                categories: _categories,
                selectedCategoryId: _selectedCategoryId,
                onCategorySelected: _selectCategoryFilter,
                onEditCategory: (Category category) {
                  unawaited(_saveCategory(existingCategory: category));
                },
                icon: Icons.filter_alt_outlined,
                tooltip: 'Filtrar por categorías',
                isActive: _selectedCategoryId != null,
              ),
              showLeadingButton: false,
              trailingWidget: IconButton(
                onPressed: widget.onOpenSettings,
                icon: Icon(Icons.settings_outlined, color: palette.textSecondary),
                tooltip: 'Ajustes',
              ),
              onSearchChanged: _setSearchQuery,
              searchMaxWidth: 640,
              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
            ),
            Expanded(
              child: NoteListView(
                notes: _visibleNotes(),
                isLoading: _isLoading,
                selectedNoteId: _selectedNoteId,
                showSelectionBorder: false,
                categoryForNote: _categoryById,
                lastSyncAt: _lastSyncAt,
                onRefresh: () async {
                  await widget.onRequestSync();
                  await _loadData(keepSelection: true);
                },
                onReorder: _handleReorder,
                onNoteTap: (Note note) => _handleNoteTap(note, false),
                onDeleteNote: _deleteNoteAfterConfirmation,
                onChangeCategory: _changeNoteCategory,
              ),
            ),
          ],
        ),
        Positioned(
          right: 20,
          bottom: 20,
          child: FloatingActionButton(
            onPressed: () => _createNote(openEditor: true),
            child: const Icon(Icons.add),
          ),
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    final AppPalette palette = _paletteOf(context);

    return Scaffold(
      body: Container(
        decoration: BoxDecoration(gradient: palette.backdropGradient),
        child: LayoutBuilder(
          builder: (BuildContext context, BoxConstraints constraints) {
            final bool isDesktop = constraints.maxWidth >= _desktopBreakpoint;
            return isDesktop
                ? _buildDesktopLayout(context, constraints)
                : _buildMobileLayout(context);
          },
        ),
      ),
    );
  }
}