keyboard_shortcuts.dart

library keyboard_shortcuts;

import 'package:collection/collection.dart' show IterableExtension;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:tuple/tuple.dart';
import 'package:visibility_detector/visibility_detector.dart';

Widget? _homeWidget;
List<_KeyBoardShortcuts> _keyBoardShortcuts = [];
Widget? _customGlobal;
String? _customTitle;
IconData? _customIcon;
bool _helperIsOpen = false;
List<Tuple3<Set<LogicalKeyboardKey>, Function(BuildContext context), String>> _newGlobal = [];

enum BasicShortCuts {
  creation,
  previousPage,
  nextPage,
  save,
}

void initShortCuts(
  Widget homePage, {
  Set<Set<LogicalKeyboardKey>>? keysToPress,
  Set<Function(BuildContext context)>? onKeysPressed,
  Set<String>? helpLabel,
  Widget? helpGlobal,
  String? helpTitle,
  IconData? helpIcon,
}) async {
  if (keysToPress != null &&
      onKeysPressed != null &&
      helpLabel != null &&
      keysToPress.length == onKeysPressed.length &&
      onKeysPressed.length == helpLabel.length) {
    _newGlobal = [];
    for (var i = 0; i < keysToPress.length; i++) {
      _newGlobal.add(Tuple3(keysToPress.elementAt(i), onKeysPressed.elementAt(i), helpLabel.elementAt(i)));
    }
  }
  _homeWidget = homePage;
  _customGlobal = helpGlobal;
  _customTitle = helpTitle;
  _customIcon = helpIcon;
}

bool _isPressed(Set<LogicalKeyboardKey> keysPressed, Set<LogicalKeyboardKey> keysToPress) {
  //when we type shift on chrome flutter's core return two pressed keys : Shift Left && Shift Right. So we need to delete one on the set to run the action
  var rights = keysPressed.where((element) => element.debugName!.contains("Right"));
  var lefts = keysPressed.where((element) => element.debugName!.contains("Left"));
  var toRemove = [];

  for (final rightElement in rights) {
    var leftElement =
        lefts.firstWhereOrNull((element) => element.debugName!.split(" ")[0] == rightElement.debugName!.split(" ")[0]);
    if (leftElement != null) {
      var actualKey = keysToPress.where((element) => element.debugName!.split(" ")[0] == rightElement.debugName!.split(" ")[0]);
      if (actualKey.length > 0 && actualKey.first.debugName!.isNotEmpty)
        actualKey.first.debugName!.contains("Right") ? toRemove.add(leftElement) : toRemove.add(rightElement);
    }
  }

  keysPressed.removeWhere((e) => toRemove.contains(e));

  return keysPressed.containsAll(keysToPress) && keysPressed.length == keysToPress.length;
}

class KeyBoardShortcuts extends StatefulWidget {
  final Widget child;

  /// You can use shortCut function with BasicShortCuts to avoid write data by yourself
  final Set<LogicalKeyboardKey>? keysToPress;

  /// Function when keys are pressed
  final VoidCallback? onKeysPressed;

  /// Label who will be displayed in helper
  final String? helpLabel;

  /// Activate when this widget is the first of the page
  final bool globalShortcuts;

  KeyBoardShortcuts({this.keysToPress, this.onKeysPressed, this.helpLabel, this.globalShortcuts = false, required this.child, Key? key})
      : super(key: key);

  @override
  _KeyBoardShortcuts createState() => _KeyBoardShortcuts();
}

class _KeyBoardShortcuts extends State<KeyBoardShortcuts> {
  FocusScopeNode? focusScopeNode;
  ScrollController _controller = ScrollController();
  bool controllerIsReady = false;
  bool listening = false;
  late Key key;
  @override
  void initState() {
    _controller.addListener(() {
      if (_controller.hasClients) setState(() => controllerIsReady = true);
    });
    _attachKeyboardIfDetached();
    key = widget.key ?? UniqueKey();
    super.initState();
  }

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
    _detachKeyboardIfAttached();
  }

  void _attachKeyboardIfDetached() {
    if (listening) return;
    _keyBoardShortcuts.add(this);
    RawKeyboard.instance.addListener(listener);
    listening = true;
  }

  void _detachKeyboardIfAttached() {
    if (!listening) return;
    _keyBoardShortcuts.remove(this);
    RawKeyboard.instance.removeListener(listener);
    listening = false;
  }

  void listener(RawKeyEvent v) async {
    if (!mounted || _helperIsOpen) return;

    Set<LogicalKeyboardKey> keysPressed = RawKeyboard.instance.keysPressed;
    if (v.runtimeType == RawKeyDownEvent) {
      // when user type keysToPress
      if (widget.keysToPress != null && widget.onKeysPressed != null && _isPressed(keysPressed, widget.keysToPress!)) {
        widget.onKeysPressed!();
      }

      // when user request help menu
      else if (_isPressed(keysPressed, {LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.keyH})) {
        List<Widget> activeHelp = [];

        //verify if element is visible or not
        List<_KeyBoardShortcuts> toRemove = [];
        _keyBoardShortcuts.forEach((element) {
          if (VisibilityDetectorController.instance.widgetBoundsFor(element.key) == null) {
            element.listening = false;
            toRemove.add(element);
          }
        });

        _keyBoardShortcuts.removeWhere((element) => toRemove.contains(element));
        _keyBoardShortcuts.forEach((element) {
          Widget? elementWidget = _helpWidget(element);
          if (elementWidget != null) activeHelp.add(elementWidget);
        }); // get all custom shortcuts

        bool showGlobalShort = _keyBoardShortcuts.any((element) => element.widget.globalShortcuts);

        if (!_helperIsOpen && (activeHelp.isNotEmpty || showGlobalShort)) {
          _helperIsOpen = true;

          await showDialog<void>(
            context: context,
            builder: (BuildContext context) => AlertDialog(
              key: UniqueKey(),
              title: Text(_customTitle ?? 'Keyboard Shortcuts'),
              content: SingleChildScrollView(
                child: ListBody(
                  children: <Widget>[
                    if (activeHelp.isNotEmpty)
                      ListBody(
                        children: [
                          for (final i in activeHelp) i,
                          Divider(),
                        ],
                      ),
                    if (showGlobalShort)
                      _customGlobal != null
                          ? _customGlobal!
                          : ListBody(
                              children: [
                                for (final newElement in _newGlobal)
                                  ListTile(
                                    leading: Icon(_customIcon ?? Icons.settings),
                                    title: Text(newElement.item3),
                                    subtitle: Text(_getKeysToPress(newElement.item1)),
                                  ),
                                ListTile(
                                  leading: Icon(Icons.home),
                                  title: Text("Go on Home page"),
                                  subtitle: Text(LogicalKeyboardKey.home.debugName!),
                                ),
                                ListTile(
                                  leading: Icon(Icons.subdirectory_arrow_left),
                                  title: Text("Go on last page"),
                                  subtitle: Text(LogicalKeyboardKey.escape.debugName!),
                                ),
                                ListTile(
                                  leading: Icon(Icons.keyboard_arrow_up),
                                  title: Text("Scroll to top"),
                                  subtitle: Text(LogicalKeyboardKey.pageUp.debugName!),
                                ),
                                ListTile(
                                  leading: Icon(Icons.keyboard_arrow_down),
                                  title: Text("Scroll to bottom"),
                                  subtitle: Text(LogicalKeyboardKey.pageDown.debugName!),
                                ),
                              ],
                            ),
                  ],
                ),
              ),
            ),
          ).then((value) => _helperIsOpen = false);
        }
      } else if (widget.globalShortcuts) {
        if (_homeWidget != null && _isPressed(keysPressed, {LogicalKeyboardKey.home})) {
          Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (context) => _homeWidget!), (_) => false);
        } else if (_isPressed(keysPressed, {LogicalKeyboardKey.escape})) {
          Navigator.maybePop(context);
        } else if (controllerIsReady && keysPressed.containsAll({LogicalKeyboardKey.pageDown}) ||
            keysPressed.first.keyId == 0x10700000022) {
          _controller.animateTo(
            _controller.position.maxScrollExtent,
            duration: new Duration(milliseconds: 50),
            curve: Curves.easeOut,
          );
        } else if (controllerIsReady && keysPressed.containsAll({LogicalKeyboardKey.pageUp}) || keysPressed.first.keyId == 0x10700000021) {
          _controller.animateTo(
            _controller.position.minScrollExtent,
            duration: new Duration(milliseconds: 50),
            curve: Curves.easeOut,
          );
        }
        for (final newElement in _newGlobal) {
          if (_isPressed(keysPressed, newElement.item1)) {
            newElement.item2(context);
            return;
          }
        }
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return VisibilityDetector(
      key: key,
      child: PrimaryScrollController(controller: _controller, child: widget.child),
      onVisibilityChanged: (visibilityInfo) {
        if (visibilityInfo.visibleFraction == 1)
          _attachKeyboardIfDetached();
        else
          _detachKeyboardIfAttached();
      },
    );
  }
}

String _getKeysToPress(Set<LogicalKeyboardKey>? keysToPress) {
  String text = "";
  if (keysToPress != null) {
    for (final i in keysToPress) text += i.debugName! + " + ";
    text = text.substring(0, text.lastIndexOf(" + "));
  }
  return text;
}

Widget? _helpWidget(_KeyBoardShortcuts widget) {
  String text = _getKeysToPress(widget.widget.keysToPress);
  if (widget.widget.helpLabel != null && text != "")
    return ListTile(
      leading: Icon(_customIcon ?? Icons.settings),
      title: Text(widget.widget.helpLabel!),
      subtitle: Text(text),
    );
  return null;
}

Set<LogicalKeyboardKey> shortCut(BasicShortCuts basicShortCuts) {
  switch (basicShortCuts) {
    case BasicShortCuts.creation:
      return {LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.keyN};
    case BasicShortCuts.previousPage:
      return {LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.arrowLeft};
    case BasicShortCuts.nextPage:
      return {LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.arrowRight};
    case BasicShortCuts.save:
      return {LogicalKeyboardKey.controlLeft, LogicalKeyboardKey.keyS};
    default:
      return {};
  }
}