import { Source } from "./source";

export type KeyName = "up" | "down" | "left" | "right" | "a" | "b" | "menu";

const KEY_NAMES: Record<string, KeyName> = {
  // compact keys (WASD+ZXC)
  KeyZ: "a",
  KeyX: "b",
  KeyC: "menu",
  KeyW: "up",
  KeyS: "down",
  KeyA: "left",
  KeyD: "right",
  // full-board keys (arrows+space/shift/enter)
  Space: "a",
  ShiftLeft: "b",
  ShiftRight: "b",
  Enter: "menu",
  ArrowUp: "up",
  ArrowDown: "down",
  ArrowLeft: "left",
  ArrowRight: "right",
};

/** A keypress/release event for an abstract button, or else ["focus", "release"] if for some reason future release events might not be registered. */
export type KeyEvent = [KeyName | "focus", "press" | "release"];

export function keyControl(source: HTMLElement): Source<KeyEvent> {
  const tabIndex = source.getAttribute("tabIndex");
  source.setAttribute(
    "tabindex",
    tabIndex == "" || tabIndex == null ? "-1" : tabIndex
  );

  return ((callback?: (keyEvent: KeyEvent) => void) => {
    if (callback) {
      const handle = (evt: KeyboardEvent, action: "press" | "release") => {
        const keyName = KEY_NAMES[evt.code];
        if (keyName != undefined) {
          evt.preventDefault();
          evt.stopPropagation();

          callback([keyName, action]);
        }
      };
      const keyUp = (evt: KeyboardEvent) => handle(evt, "release");
      const keyDown = (evt: KeyboardEvent) => handle(evt, "press");
      const focus = () => callback(["focus", "press"]);
      const blur = () => callback(["focus", "release"]);

      source.addEventListener("keyup", keyUp, false);
      source.addEventListener("keydown", keyDown, false);
      source.addEventListener("focus", focus, false);
      source.addEventListener("blur", blur, false);
      source.focus({ focusVisible: true } as FocusOptions);

      return () => {
        source.removeEventListener("keyup", keyUp, false);
        source.removeEventListener("keydown", keyDown, false);
        source.removeEventListener("focus", focus, false);
        source.removeEventListener("blur", blur, false);
      };
    } else {
      return ["blur", "release"];
    }
  }) as Source<KeyEvent>;
}