dees-domtools/ts/domtools.classes.keyboard.ts

import * as plugins from './domtools.plugins.js';

export enum Key {
  Backspace = 8,
  Tab = 9,
  Enter = 13,
  Shift = 16,
  Ctrl = 17,
  Alt = 18,
  PauseBreak = 19,
  CapsLock = 20,
  Escape = 27,
  Space = 32,
  PageUp = 33,
  PageDown = 34,
  End = 35,
  Home = 36,

  LeftArrow = 37,
  UpArrow = 38,
  RightArrow = 39,
  DownArrow = 40,

  Insert = 45,
  Delete = 46,

  Zero = 48,
  ClosedParen = Zero,
  One = 49,
  ExclamationMark = One,
  Two = 50,
  AtSign = Two,
  Three = 51,
  PoundSign = Three,
  Hash = PoundSign,
  Four = 52,
  DollarSign = Four,
  Five = 53,
  PercentSign = Five,
  Six = 54,
  Caret = Six,
  Hat = Caret,
  Seven = 55,
  Ampersand = Seven,
  Eight = 56,
  Star = Eight,
  Asterik = Star,
  Nine = 57,
  OpenParen = Nine,

  A = 65,
  B = 66,
  C = 67,
  D = 68,
  E = 69,
  F = 70,
  G = 71,
  H = 72,
  I = 73,
  J = 74,
  K = 75,
  L = 76,
  M = 77,
  N = 78,
  O = 79,
  P = 80,
  Q = 81,
  R = 82,
  S = 83,
  T = 84,
  U = 85,
  V = 86,
  W = 87,
  X = 88,
  Y = 89,
  Z = 90,

  LeftWindowKey = 91,
  RightWindowKey = 92,
  SelectKey = 93,

  Numpad0 = 96,
  Numpad1 = 97,
  Numpad2 = 98,
  Numpad3 = 99,
  Numpad4 = 100,
  Numpad5 = 101,
  Numpad6 = 102,
  Numpad7 = 103,
  Numpad8 = 104,
  Numpad9 = 105,

  Multiply = 106,
  Add = 107,
  Subtract = 109,
  DecimalPoint = 110,
  Divide = 111,

  F1 = 112,
  F2 = 113,
  F3 = 114,
  F4 = 115,
  F5 = 116,
  F6 = 117,
  F7 = 118,
  F8 = 119,
  F9 = 120,
  F10 = 121,
  F11 = 122,
  F12 = 123,

  NumLock = 144,
  ScrollLock = 145,

  SemiColon = 186,
  Equals = 187,
  Comma = 188,
  Dash = 189,
  Period = 190,
  UnderScore = Dash,
  PlusSign = Equals,
  ForwardSlash = 191,
  Tilde = 192,
  GraveAccent = Tilde,

  OpenBracket = 219,
  ClosedBracket = 221,
  Quote = 222,
}

type KeyCombo = Array<Key>;

export class Keyboard {
  private mapCombosToHandlers = new Map<number[], plugins.smartrx.rxjs.Subject<KeyboardEvent>>();
  private pressedKeys = new Set<Key>();

  constructor(private domNode: Element | Document) {
    this.startListening();
  }

  public keyEnum = Key;

  public on(keys: Key[] | KeyCombo[]) {
    const combos = this.toCombos(keys);
    const subject = new plugins.smartrx.rxjs.Subject<KeyboardEvent>();
    combos.forEach((combo) => {
      this.registerComboCallback(combo, subject);
    });
    return subject;
  }

  public startListening() {
    this.domNode.addEventListener('keydown', this.handleKeyDown);
    this.domNode.addEventListener('keyup', this.handleKeyUp);
  }

  public stopListening() {
    this.domNode.removeEventListener('keydown', this.handleKeyDown);
    this.domNode.removeEventListener('keyup', this.handleKeyUp);
  }

  public clear() {
    this.stopListening();
    this.mapCombosToHandlers.clear();
    this.pressedKeys.clear();
  }

  private handleKeyDown = (event: KeyboardEvent) => {
    this.pressedKeys.add(event.keyCode);

    this.mapCombosToHandlers.forEach((subjectArg, comboArg) => {
      if (this.isComboPressed(comboArg)) {
        subjectArg.next(event);
      }
    });
  };

  private handleKeyUp = (event: KeyboardEvent) => {
    this.pressedKeys.delete(event.keyCode);
  };

  private isComboPressed(combo: number[]) {
    let result = true;

    combo.forEach((key) => {
      if (!this.pressedKeys.has(key)) {
        result = false;
      }
    });

    return result;
  }

  private registerComboCallback(
    comboArg: Array<Key>,
    subjectArg: plugins.smartrx.rxjs.Subject<KeyboardEvent>
  ) {
    if (!this.mapCombosToHandlers.has(comboArg)) {
      this.mapCombosToHandlers.set(comboArg, subjectArg);
    } else {
      const subject = this.mapCombosToHandlers.get(comboArg);
      return subject;
    }
  }

  private toCombos(keys: KeyCombo[] | Key[]) {
    if (keys.length === 0) {
      return [];
    }

    const isKeys = !Array.isArray(keys[0]);
    let combos: KeyCombo[] = [];

    if (isKeys) {
      combos = (keys as Key[]).map((key) => [key]);
    } else {
      combos = keys as KeyCombo[];
      combos = combos.filter((combo) => combo.length > 0);
    }

    return combos;
  }
}