import 'dart:async';
import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

import 'package:notas/models/category.dart';
import 'package:notas/models/note.dart';
import 'package:notas/platform/app_platform.dart';
import 'package:notas/widgets/category_style.dart';

// NoteEditorScreen: unified UI for creating and editing notes.
// - Use `NoteEditorScreen.showDialog(context, note: existing)` to edit.
// - Use `NoteEditorScreen.showDialog(context)` to create a new note.
// The screen returns either a `Note` (saved) or the string `'delete'` when
// the user confirmed deletion. `null` indicates the user closed without saving.

class NoteEditorScreen extends StatefulWidget {
  const NoteEditorScreen({
    super.key,
    required this.note,
    this.categoryId,
    this.categories = const <Category>[],
    this.onComplete,
  });

  final Note? note;
  final String? categoryId;
  final List<Category> categories;
  final ValueChanged<dynamic>? onComplete;

  @override
  State<NoteEditorScreen> createState() => _NoteEditorScreenState();

  static Future<dynamic> _showGeneralEditorDialog(
    BuildContext context, {
    Note? note,
    String? categoryId,
    List<Category> categories = const <Category>[],
  }) {
    return showGeneralDialog<dynamic>(
      context: context,
      barrierDismissible: false,
      barrierColor: Colors.transparent,
      transitionDuration: const Duration(milliseconds: 200),
      pageBuilder: (context, animation, secondaryAnimation) {
        return NoteEditorScreen(
          note: note,
          categoryId: categoryId,
          categories: categories,
        );
      },
      transitionBuilder: (context, animation, secondaryAnimation, child) {
        return ScaleTransition(scale: animation, child: child);
      },
    );
  }

  static Future<dynamic> showDialog(
    BuildContext context, {
    Note? note,
    String? categoryId,
    List<Category> categories = const <Category>[],
  }) {
    if (isAndroid || isIOS) {
      return _showGeneralEditorDialog(
        context,
        note: note,
        categoryId: categoryId,
        categories: categories,
      );
    }

    final OverlayState? overlayState = Overlay.of(context, rootOverlay: true);
    if (overlayState == null) {
      return _showGeneralEditorDialog(
        context,
        note: note,
        categoryId: categoryId,
        categories: categories,
      );
    }

    final Completer<dynamic> completer = Completer<dynamic>();
    late final OverlayEntry entry;

    entry = OverlayEntry(
      builder: (BuildContext overlayContext) {
        return NoteEditorScreen(
          note: note,
          categoryId: categoryId,
          categories: categories,
          onComplete: (dynamic result) {
            if (!completer.isCompleted) {
              completer.complete(result);
            }
            if (entry.mounted) {
              entry.remove();
            }
          },
        );
      },
    );

    overlayState.insert(entry);
    return completer.future;
  }
}

class _NoteEditorScreenState extends State<NoteEditorScreen> {
  late TextEditingController _titleController;
  late TextEditingController _bodyController;
  late Note _currentNote;
  late bool _isNewNote;
  String? _selectedCategoryId;
  final GlobalKey _categorySelectorKey = GlobalKey();
  OverlayEntry? _categoryMenuEntry;
  bool _didComplete = false;

  bool get _isMobileLayout => isAndroid || isIOS;

  @override
  void initState() {
    super.initState();
    _isNewNote = widget.note == null;

    if (_isNewNote) {
      final DateTime now = DateTime.now();
      _currentNote = Note(
        title: '',
        body: '',
        createdAt: now,
        updatedAt: now,
        position: 0,
        categoryId: widget.categoryId,
      );
    } else {
      _currentNote = widget.note!;
    }

    _selectedCategoryId = _currentNote.categoryId ?? widget.categoryId;

    _titleController = TextEditingController(text: _currentNote.title);
    _bodyController = TextEditingController(text: _currentNote.body);
  }

  @override
  void dispose() {
    _closeCategoryMenu();
    _titleController.dispose();
    _bodyController.dispose();
    super.dispose();
  }

  void _complete(dynamic result) {
    if (_didComplete) {
      return;
    }

    _didComplete = true;
    _closeCategoryMenu();

    final ValueChanged<dynamic>? callback = widget.onComplete;

    if (callback != null) {
      callback(result);
      return;
    }

    Navigator.of(context).pop(result);
  }

  void _closeWithoutSaving() {
    _complete(null);
  }

  void _saveNote() {
    final String title = _titleController.text.trim();
    final String body = _bodyController.text.trim();
    final bool categoryChanged = _selectedCategoryId != _currentNote.categoryId;

    if (title.isEmpty && body.isEmpty && !categoryChanged) {
      _complete(null);
      return;
    }

    final Note updatedNote = _currentNote.copyWith(
      title: title.isEmpty ? 'Sin título' : title,
      body: body,
      categoryId: _selectedCategoryId,
      updatedAt: DateTime.now(),
      isDirty: true,
    );

    _complete(updatedNote);
  }

  Widget _buildDeleteConfirmationDialog({
    required ValueChanged<bool> onConfirmed,
  }) {
    final bool isDeletedNote = _currentNote.isDeleted;

    return AlertDialog(
      backgroundColor: const Color(0xFF303134),
      title: Text(
        isDeletedNote ? 'Eliminar permanentemente' : 'Eliminar nota',
        style: const TextStyle(color: Colors.white),
      ),
      content: Text(
        isDeletedNote
            ? 'Esta nota ya está borrada. Si la eliminas ahora, se borrará permanentemente.'
            : '¿Estás seguro de que deseas eliminar esta nota?',
        style: const TextStyle(color: Colors.white70),
      ),
      actions: [
        TextButton(
          onPressed: () => onConfirmed(false),
          child: const Text(
            'Cancelar',
            style: TextStyle(color: Colors.white70),
          ),
        ),
        TextButton(
          onPressed: () => onConfirmed(true),
          child: Text(
            isDeletedNote ? 'Eliminar permanentemente' : 'Eliminar',
            style: const TextStyle(color: Colors.red),
          ),
        ),
      ],
    );
  }

  Future<bool> _showDeleteConfirmation() async {
    if (_isMobileLayout) {
      final bool? confirmed = await showDialog<bool>(
        context: context,
        barrierDismissible: false,
        barrierColor: Colors.transparent,
        builder: (BuildContext dialogContext) {
          return _buildDeleteConfirmationDialog(
            onConfirmed: (bool confirmed) =>
                Navigator.of(dialogContext).pop(confirmed),
          );
        },
      );

      return confirmed ?? false;
    }

    final OverlayState? overlayState = Overlay.of(context, rootOverlay: true);
    if (overlayState == null) {
      final bool? confirmed = await showDialog<bool>(
        context: context,
        barrierDismissible: false,
        barrierColor: Colors.transparent,
        builder: (BuildContext dialogContext) {
          return _buildDeleteConfirmationDialog(
            onConfirmed: (bool confirmed) =>
                Navigator.of(dialogContext).pop(confirmed),
          );
        },
      );

      return confirmed ?? false;
    }

    final Completer<bool> completer = Completer<bool>();
    late final OverlayEntry entry;
    bool didRemove = false;

    entry = OverlayEntry(
      builder: (BuildContext overlayContext) {
        final ValueChanged<bool> close = (bool confirmed) {
          if (!completer.isCompleted) {
            completer.complete(confirmed);
          }
          if (!didRemove && entry.mounted) {
            didRemove = true;
            entry.remove();
          }
        };

        return Material(
          color: Colors.transparent,
          child: Stack(
            children: [
              const Positioned.fill(
                child: ModalBarrier(
                  dismissible: false,
                  color: Color.fromARGB(140, 0, 0, 0),
                ),
              ),
              Center(
                child: ConstrainedBox(
                  constraints: const BoxConstraints(maxWidth: 420),
                  child: _buildDeleteConfirmationDialog(onConfirmed: close),
                ),
              ),
            ],
          ),
        );
      },
    );

    overlayState.insert(entry);
    return completer.future;
  }

  Category? _categoryById(String? id) {
    for (final Category category in widget.categories) {
      if (category.id == id) {
        return category;
      }
    }

    return null;
  }

  Color _categoryBackgroundColor(Category? category) {
    if (category?.colorValue == null) {
      return Colors.white.withValues(alpha: 0.08);
    }

    return Color(category!.colorValue!);
  }

  Color _categoryForegroundColor(Category? category) {
    if (category == null || category.colorValue == null) {
      return Colors.white;
    }

    final Color background = Color(category.colorValue!);
    return background.computeLuminance() > 0.55 ? Colors.black87 : Colors.white;
  }

  Widget _buildCategorySelectorBox({Category? category}) {
    final String label = category?.name ?? 'Sin categoría';
    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);
    final Color backgroundColor = _categoryBackgroundColor(category);
    final Color foregroundColor = _categoryForegroundColor(category);

    return Container(
      key: _categorySelectorKey,
      padding: const EdgeInsets.symmetric(horizontal: 9, vertical: 6),
      decoration: BoxDecoration(
        color: backgroundColor,
        borderRadius: BorderRadius.circular(10),
        border: Border.all(
          color: category?.colorValue != null
              ? backgroundColor.withValues(alpha: 0.85)
              : Colors.white24,
        ),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(icon, color: foregroundColor, size: 15),
          const SizedBox(width: 6),
          Expanded(
            child: Text(
              label,
              overflow: TextOverflow.ellipsis,
              style: TextStyle(
                color: foregroundColor,
                fontSize: 12,
                fontWeight: FontWeight.w600,
              ),
            ),
          ),
          const SizedBox(width: 6),
          Icon(
            Icons.arrow_drop_down,
            color: foregroundColor.withValues(alpha: 0.9),
            size: 16,
          ),
        ],
      ),
    );
  }

  void _closeCategoryMenu() {
    final OverlayEntry? entry = _categoryMenuEntry;
    if (entry != null && entry.mounted) {
      entry.remove();
    }
    _categoryMenuEntry = null;
  }

  void _toggleCategoryMenu() {
    if (_categoryMenuEntry != null) {
      _closeCategoryMenu();
      return;
    }

    final OverlayState? overlayState = Overlay.of(context, rootOverlay: true);
    if (overlayState == null) {
      return;
    }

    _categoryMenuEntry = OverlayEntry(
      builder: (BuildContext overlayContext) {
        final Size screenSize = MediaQuery.of(overlayContext).size;
        final double menuWidth = math.min(screenSize.width - 32, 320);
        final double menuHeight = math.min(screenSize.height - 32, 360);

        return Material(
          color: Colors.transparent,
          child: Stack(
            children: [
              Positioned.fill(
                child: GestureDetector(
                  behavior: HitTestBehavior.translucent,
                  onTap: _closeCategoryMenu,
                  child: const SizedBox.expand(),
                ),
              ),
              Center(
                child: ConstrainedBox(
                  constraints: BoxConstraints(
                    maxWidth: menuWidth,
                    maxHeight: menuHeight,
                  ),
                  child: Material(
                    elevation: 10,
                    color: const Color(0xFF303134),
                    borderRadius: BorderRadius.circular(12),
                    clipBehavior: Clip.antiAlias,
                    child: ListView(
                      padding: const EdgeInsets.symmetric(vertical: 8),
                      shrinkWrap: true,
                      children: [
                        _buildCategoryMenuItem(
                          category: null,
                          label: 'Sin categoría',
                          isSelected: _selectedCategoryId == null,
                          onTap: () {
                            setState(() {
                              _selectedCategoryId = null;
                            });
                            _closeCategoryMenu();
                          },
                        ),
                        for (final Category category in widget.categories)
                          _buildCategoryMenuItem(
                            category: category,
                            label: category.name,
                            isSelected: _selectedCategoryId == category.id,
                            onTap: () {
                              setState(() {
                                _selectedCategoryId = category.id;
                              });
                              _closeCategoryMenu();
                            },
                          ),
                      ],
                    ),
                  ),
                ),
              ),
            ],
          ),
        );
      },
    );

    overlayState.insert(_categoryMenuEntry!);
  }

  Widget _buildCategoryMenuItem({
    required Category? category,
    required String label,
    required bool isSelected,
    required VoidCallback onTap,
  }) {
    final Color backgroundColor = _categoryBackgroundColor(category);
    final Color foregroundColor = _categoryForegroundColor(category);
    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);

    return InkWell(
      onTap: onTap,
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
        color: isSelected ? Colors.white.withValues(alpha: 0.08) : null,
        child: Row(
          children: [
            Container(
              width: 28,
              height: 28,
              decoration: BoxDecoration(
                color: backgroundColor,
                borderRadius: BorderRadius.circular(8),
                border: Border.all(
                  color: category?.colorValue != null
                      ? backgroundColor.withValues(alpha: 0.85)
                      : Colors.white24,
                ),
              ),
              child: Icon(icon, size: 16, color: foregroundColor),
            ),
            const SizedBox(width: 12),
            Expanded(
              child: Text(
                label,
                overflow: TextOverflow.ellipsis,
                style: TextStyle(
                  color: foregroundColor,
                  fontSize: 13,
                  fontWeight: FontWeight.w600,
                ),
              ),
            ),
            if (isSelected)
              Icon(Icons.check, color: foregroundColor, size: 18),
          ],
        ),
      ),
    );
  }

  Future<void> _deleteNote() async {
    final bool confirmed = await _showDeleteConfirmation();
    if (!mounted || !confirmed) {
      return;
    }

    _complete('delete');
  }

  String _formatDate(DateTime date) {
    final DateTime now = DateTime.now();
    final DateTime today = DateTime(now.year, now.month, now.day);
    final DateTime yesterday = today.subtract(const Duration(days: 1));
    final DateTime noteDate = DateTime(date.year, date.month, date.day);

    if (noteDate == today) {
      return 'Hoy ${DateFormat('HH:mm').format(date)}';
    } else if (noteDate == yesterday) {
      return 'Ayer ${DateFormat('HH:mm').format(date)}';
    } else {
      return DateFormat('dd/MM/yyyy HH:mm').format(date);
    }
  }

  Widget _buildEditorContent({required bool isMobile}) {
    final double titleSpacing = isMobile ? 16.0 : 8.0;

    return Column(
      children: [
        Container(
          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
          decoration: BoxDecoration(
            border: Border(bottom: BorderSide(color: Colors.white12, width: 1)),
          ),
          child: Row(
            children: [
              IconButton(
                onPressed: _closeWithoutSaving,
                icon: const Icon(Icons.close, color: Colors.white70),
                tooltip: 'Cerrar sin guardar',
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      'Creado: ${_formatDate(_currentNote.createdAt)}',
                      style: const TextStyle(
                        color: Colors.white54,
                        fontSize: 12,
                      ),
                    ),
                    if (_currentNote.updatedAt != _currentNote.createdAt)
                      Text(
                        'Modificado: ${_formatDate(_currentNote.updatedAt)}',
                        style: const TextStyle(
                          color: Colors.white54,
                          fontSize: 12,
                        ),
                      ),
                  ],
                ),
              ),
              ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 150),
                child: SizedBox(
                  width: 150,
                  child: KeyedSubtree(
                    key: const ValueKey<String>('category_selector'),
                    child: InkWell(
                      onTap: _toggleCategoryMenu,
                      borderRadius: BorderRadius.circular(12),
                      child: _buildCategorySelectorBox(
                        category: _categoryById(_selectedCategoryId),
                      ),
                    ),
                  ),
                ),
              ),
            ],
          ),
        ),
        Expanded(
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                TextField(
                  controller: _titleController,
                  style: const TextStyle(
                    color: Colors.white,
                    fontSize: 28,
                    fontWeight: FontWeight.bold,
                  ),
                  decoration: const InputDecoration(
                    hintText: 'Título',
                    hintStyle: TextStyle(color: Colors.white30),
                    border: InputBorder.none,
                    contentPadding: EdgeInsets.zero,
                  ),
                ),
                SizedBox(height: titleSpacing),
                Expanded(
                  child: TextField(
                    controller: _bodyController,
                    keyboardType: TextInputType.multiline,
                    maxLines: null,
                    expands: true,
                    style: const TextStyle(
                      color: Colors.white,
                      fontSize: 16,
                      height: 1.6,
                    ),
                    decoration: const InputDecoration(
                      hintText: 'Escribe tu nota...',
                      hintStyle: TextStyle(color: Colors.white30),
                      border: InputBorder.none,
                      contentPadding: EdgeInsets.zero,
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
        Container(
          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
          decoration: BoxDecoration(
            border: Border(top: BorderSide(color: Colors.white12, width: 1)),
          ),
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              if (!_isNewNote)
                IconButton(
                  onPressed: _deleteNote,
                  icon: const Icon(Icons.delete_outline, color: Colors.red),
                  tooltip: 'Eliminar nota',
                )
              else
                const SizedBox(width: 48),
              FilledButton(onPressed: _saveNote, child: const Text('Guardar')),
            ],
          ),
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    if (_isMobileLayout) {
      return Material(
        color: Colors.transparent,
        child: SafeArea(
          child: Container(
            color: const Color.fromARGB(255, 24, 25, 26),
            child: _buildEditorContent(isMobile: true),
          ),
        ),
      );
    }

    return LayoutBuilder(
      builder: (BuildContext context, BoxConstraints constraints) {
        final double maxWidth = math.min(constraints.maxWidth - 32, 600);
        final double maxHeight = math.min(constraints.maxHeight - 32, 720);

        return Stack(
          children: [
            Positioned.fill(
              child: ModalBarrier(
                dismissible: false,
                color: const Color.fromARGB(54, 0, 0, 0).withValues(alpha: 0.5),
              ),
            ),
            Positioned.fill(
              child: Center(
                child: SizedBox(
                  width: maxWidth,
                  height: maxHeight,
                  child: Material(
                    color: const Color.fromRGBO(24, 25, 26, 1),
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(16),
                      side: BorderSide(color: Colors.white24, width: 1),
                    ),
                    clipBehavior: Clip.antiAlias,
                    child: _buildEditorContent(isMobile: false),
                  ),
                ),
              ),
            ),
          ],
        );
      },
    );
  }
}