export const KEYBOARD_CONTRACT_SCHEMA_VERSION = 1 as const;

export interface KeyboardObservation {
  schemaVersion: typeof KEYBOARD_CONTRACT_SCHEMA_VERSION;
  key: string;
  code: string;
  location: 0 | 1 | 2 | 3;
  shiftKey: boolean;
  ctrlKey: boolean;
  altKey: boolean;
  metaKey: boolean;
  repeat: boolean;
  isComposing: boolean;
  deadKey: boolean;
}

export function observeKeyboardEvent(event: { key?: string; code?: string; location?: number; shiftKey?: boolean; ctrlKey?: boolean; altKey?: boolean; metaKey?: boolean; repeat?: boolean; isComposing?: boolean }): KeyboardObservation {
  if (typeof event.key !== "string" || event.key.length === 0 || event.key.length > 128) throw new Error("KEY_IDENTITY_INVALID");
  if (typeof event.code !== "string" || event.code.length === 0 || event.code.length > 64) throw new Error("KEY_CODE_INVALID");
  if (!Number.isInteger(event.location) || event.location! < 0 || event.location! > 3) throw new Error("KEY_LOCATION_INVALID");
  return {
    schemaVersion: KEYBOARD_CONTRACT_SCHEMA_VERSION,
    key: event.key,
    code: event.code,
    location: event.location as 0 | 1 | 2 | 3,
    shiftKey: Boolean(event.shiftKey),
    ctrlKey: Boolean(event.ctrlKey),
    altKey: Boolean(event.altKey),
    metaKey: Boolean(event.metaKey),
    repeat: Boolean(event.repeat),
    isComposing: Boolean(event.isComposing),
    deadKey: event.key === "Dead",
  };
}