/**
 * A loosely-typed shape covering the subset of `KeyboardEvent` properties
 * this helper reads across supported browsers, plus the legacy/vendor
 * properties (`keyIdentifier`, numeric `key`) exercised by the Safari/IE/Edge
 * fixtures in `key-mocks.ts`. `KeyboardEvent` itself only types `key`/`code`
 * as `string`, so callers passing those legacy shapes need this wider type.
 */
export interface KeyEventLike {
  code?: string;
  key?: string | number;
  which?: number;
  charCode?: number;
  keyCode?: number;
  keyIdentifier?: string;
}

type NumberKeyTest = (event: KeyEventLike) => number | undefined;

/**
 * Narrows an arbitrary event value to `KeyEventLike`, defaulting to an empty
 * object for anything that isn't a non-null object (matches this helper's
 * historical behavior of tolerating malformed/legacy event shapes rather
 * than throwing).
 */
function toKeyEventLike(event: unknown): KeyEventLike {
  if (typeof event === "object" && event !== null) {
    return event as KeyEventLike;
  }
  return {};
}

export class KeyHelper {
  private _allowedKeys: string[] = [];

  private _currentlySupported = [
    "enter",
    "up",
    "down",
    "left",
    "right",
    "tab",
    "esc",
    "space",
    "shift",
    "backspace",
    "1",
    "2",
    "3",
    "4",
    "5",
    "6",
    "7",
    "8",
    "9",
    "0",
    "delete",
  ];

  constructor(...keys: string[]) {
    this._setAllowedKeys(...keys);
  }

  public isAllowed(event: unknown): boolean {
    const val = this._allowedKeys.reduce((val, key) => {
      return KeyHelper.is(key, event) || val;
    }, false);
    return val;
  }

  private _setAllowedKeys(...keys: string[]) {
    keys.forEach((key) => {
      if (this._currentlySupported.indexOf(key) !== -1) {
        this._allowedKeys.push(key);
      } else {
        const ok = this._allowedToString();
        const msg = `Only supports ${ok} at this time`;
        throw new TypeError(msg);
      }
    });
  }

  private _allowedToString(): string {
    return this._allowedKeys.join(", ");
  }

  public static getKeyCode(event: unknown): string | number | undefined {
    const e = toKeyEventLike(event);
    if (e.key) {
      return e.key;
    } else if (e.code) {
      return e.code;
    } else if (e.keyIdentifier) {
      return e.keyIdentifier;
    } else {
      return undefined;
    }
  }

  public static getNumberFromKey(event: unknown): number | undefined {
    const e = toKeyEventLike(event);
    const tests: NumberKeyTest[] = [
      KeyHelper._zero,
      KeyHelper._one,
      KeyHelper._two,
      KeyHelper._three,
      KeyHelper._four,
      KeyHelper._five,
      KeyHelper._six,
      KeyHelper._seven,
      KeyHelper._eight,
      KeyHelper._nine,
    ];

    return tests.reduce((val: number | undefined, test: NumberKeyTest) => {
      return val !== undefined ? val : test(e);
    }, undefined);
  }

  public static is(validKeyParam: string, event: unknown): boolean {
    const e = toKeyEventLike(event);
    const lowercased = validKeyParam.toLowerCase();
    switch (lowercased) {
      case "enter":
        return this._isEnter(e);
      case "up":
        return this._isArrowUp(e);
      case "down":
        return this._isArrowDown(e);
      case "left":
        return this._isArrowLeft(e);
      case "right":
        return this._isArrowRight(e);
      case "tab":
        return this._isTab(e);
      case "esc":
        return this._isEscape(e);
      case "space":
        return this._isSpace(e);
      case "shift":
        return this._isShift(e);
      case "backspace":
        return this._isBackspace(e);
      case "delete":
        return this._isDelete(e);
      case "0":
        return this._isExpectedNumber(0, e);
      case "1":
        return this._isExpectedNumber(1, e);
      case "2":
        return this._isExpectedNumber(2, e);
      case "3":
        return this._isExpectedNumber(3, e);
      case "4":
        return this._isExpectedNumber(4, e);
      case "5":
        return this._isExpectedNumber(5, e);
      case "6":
        return this._isExpectedNumber(6, e);
      case "7":
        return this._isExpectedNumber(7, e);
      case "8":
        return this._isExpectedNumber(8, e);
      case "9":
        return this._isExpectedNumber(9, e);
      default:
        return false;
    }
  }

  private static _isEnter(e: KeyEventLike): boolean {
    if (
      e.code === "Enter" ||
      e.key === "Enter" ||
      e.keyIdentifier === "Enter" ||
      e.which === 13 ||
      e.charCode === 13 ||
      e.keyCode === 13
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isArrowUp(e: KeyEventLike): boolean {
    if (
      e.code === "ArrowUp" ||
      e.key === "ArrowUp" ||
      e.key === "Up" ||
      e.keyIdentifier === "Up" ||
      e.which === 38 ||
      e.keyCode === 38
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isArrowDown(e: KeyEventLike): boolean {
    if (
      e.code === "ArrowDown" ||
      e.key === "ArrowDown" ||
      e.key === "Down" ||
      e.keyIdentifier === "Down" ||
      e.which === 40 ||
      e.keyCode === 40
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isArrowLeft(e: KeyEventLike): boolean {
    if (
      e.code === "ArrowLeft" ||
      e.key === "ArrowLeft" ||
      e.key === "Left" ||
      e.keyIdentifier === "Left" ||
      e.which === 37 ||
      e.keyCode === 37
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isArrowRight(e: KeyEventLike): boolean {
    if (
      e.code === "ArrowRight" ||
      e.key === "ArrowRight" ||
      e.key === "Right" ||
      e.keyIdentifier === "Right" ||
      e.which === 39 ||
      e.keyCode === 39
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isTab(e: KeyEventLike): boolean {
    if (
      e.code === "Tab" ||
      e.key === "Tab" ||
      e.keyIdentifier === "U+0009" ||
      e.which === 9 ||
      e.keyCode === 9
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isEscape(e: KeyEventLike): boolean {
    if (
      e.code === "Escape" ||
      e.key === "Escape" ||
      e.key === "Esc" ||
      e.keyIdentifier === "U+001B" ||
      e.which === 27 ||
      e.keyCode === 27
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isSpace(e: KeyEventLike): boolean {
    if (
      e.code === "Space" ||
      e.key === " " ||
      e.key === "Spacebar" ||
      e.keyIdentifier === "U+0020" ||
      e.which === 32 ||
      e.keyCode === 32
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isShift(e: KeyEventLike): boolean {
    if (
      e.code === "ShiftLeft" ||
      e.code === "ShiftRight" ||
      e.key === "Shift" ||
      e.keyIdentifier === "Shift" ||
      e.which === 16 ||
      e.keyCode === 16
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isBackspace(e: KeyEventLike): boolean {
    if (
      e.code === "Backspace" ||
      e.key === "Backspace" ||
      e.keyIdentifier === "U+0008" ||
      e.which === 8 ||
      e.keyCode === 8
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _isDelete(e: KeyEventLike): boolean {
    if (
      e.code === "Delete" ||
      e.key === "Delete" ||
      e.keyIdentifier === "U+007F" ||
      e.which === 46 ||
      e.keyCode === 46
    ) {
      return true;
    } else {
      return false;
    }
  }

  private static _zero(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit0" ||
      e.code === "Numpad0" ||
      e.key === 0 ||
      e.keyCode === 48 ||
      e.keyCode === 96 ||
      e.keyIdentifier === "U+0030" ||
      e.which === 48
    ) {
      return 0;
    } else {
      return undefined;
    }
  }

  private static _one(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit1" ||
      e.code === "Numpad1" ||
      e.key === 1 ||
      e.keyCode === 49 ||
      e.keyCode === 97 ||
      e.keyIdentifier === "U+0031" ||
      e.which === 49
    ) {
      return 1;
    } else {
      return undefined;
    }
  }

  private static _two(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit2" ||
      e.code === "Numpad2" ||
      e.key === 2 ||
      e.keyCode === 50 ||
      e.keyCode === 98 ||
      e.keyIdentifier === "U+0032" ||
      e.which === 50
    ) {
      return 2;
    } else {
      return undefined;
    }
  }

  private static _three(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit3" ||
      e.code === "Numpad3" ||
      e.key === 3 ||
      e.keyCode === 51 ||
      e.keyCode === 99 ||
      e.keyIdentifier === "U+0033" ||
      e.which === 51
    ) {
      return 3;
    } else {
      return undefined;
    }
  }

  private static _four(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit4" ||
      e.code === "Numpad4" ||
      e.key === 4 ||
      e.keyCode === 52 ||
      e.keyCode === 100 ||
      e.keyIdentifier === "U+0034" ||
      e.which === 52
    ) {
      return 4;
    } else {
      return undefined;
    }
  }
  private static _five(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit5" ||
      e.code === "Numpad5" ||
      e.key === 5 ||
      e.keyCode === 53 ||
      e.keyCode === 101 ||
      e.keyIdentifier === "U+0035" ||
      e.which === 53
    ) {
      return 5;
    } else {
      return undefined;
    }
  }

  private static _six(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit6" ||
      e.code === "Numpad6" ||
      e.key === 6 ||
      e.keyCode === 54 ||
      e.keyCode === 102 ||
      e.keyIdentifier === "U+0036" ||
      e.which === 54
    ) {
      return 6;
    } else {
      return undefined;
    }
  }

  private static _seven(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit7" ||
      e.code === "Numpad7" ||
      e.key === 7 ||
      e.keyCode === 55 ||
      e.keyCode === 103 ||
      e.keyIdentifier === "U+0037" ||
      e.which === 55
    ) {
      return 7;
    } else {
      return undefined;
    }
  }

  private static _eight(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit8" ||
      e.code === "Numpad8" ||
      e.key === 8 ||
      e.keyCode === 56 ||
      e.keyCode === 104 ||
      e.keyIdentifier === "U+0038" ||
      e.which === 56
    ) {
      return 8;
    } else {
      return undefined;
    }
  }

  private static _nine(e: KeyEventLike): number | undefined {
    if (
      e.code === "Digit9" ||
      e.code === "Numpad9" ||
      e.key === 9 ||
      e.keyCode === 57 ||
      e.keyCode === 105 ||
      e.keyIdentifier === "U+0039" ||
      e.which === 57
    ) {
      return 9;
    } else {
      return undefined;
    }
  }

  private static _isExpectedNumber(
    expected: number,
    event: KeyEventLike
  ): boolean {
    return expected === KeyHelper.getNumberFromKey(event);
  }
}

export enum KEYS {
  ENTER = "enter",
  UP = "up",
  DOWN = "down",
  LEFT = "left",
  RIGHT = "right",
  TAB = "tab",
  ESC = "esc",
  SPACE = "space",
  SHIFT = "shift",
  BACKSPACE = "backspace",
  ONE = "1",
  TWO = "2",
  THREE = "3",
  FOUR = "4",
  FIVE = "5",
  SIX = "6",
  SEVEN = "7",
  EIGHT = "8",
  NINE = "9",
  ZERO = "0",
  DELETE = "delete",
}