import { ref } from "vue";
import keyboardNameMap from "./keyBoardMaps/keyboardNameMap";
import keyboardCharMap from "./keyBoardMaps/keyboardCharMap";

interface KeyDownEvent {
    keyCode: number;
    shiftKey: boolean;
}

// This catches keys from a physical keyboard, a soft keyboard on a tablet, or a
// scanner attached via USB
export default function useKeyDownHandler(enterCallback: (input: string) => void | null) {

  const input = ref("");

  function keyDownHandler(e: KeyDownEvent) {
    // keyboardCharMap is an array of arrays, with each inner
    // array having 2 columns - un-shifted, and shifted values.
    // iCol = 0 is the un-shifted value, while iCol=1 is the shifted value.
    // See the "keyboardCharMap", below, for printable characters.
    // MODIFY keyboardCharMap to suit your needs if you want
    //    more/less/different characters to be considered "printable".
    let iCol = 0;
    if (e.shiftKey) {
      iCol = 1;
    }
    const ch = keyboardCharMap[e.keyCode][iCol];
    // Optionally do things with non-printables,
    // like CR, ESC, Backspace, LF, Tab, Arrows, F1-F24, etc.
    // See the arrary "keyboardNameMap", below, for possible keys.
    const cmd = keyboardNameMap[e.keyCode];
    switch (cmd) {
      case "ENTER":
        enterCallback(input.value);
        break;
      case "BACK_SPACE":
        input.value = input.value.slice(0, -1);
        break;
      case "ESCAPE":
        input.value = "";
        break;
      default:
        input.value += ch;
    }
  }

  return {
    keyDownHandler,
    input
  };
}