export enum TipState {
  Unknown,
  Unborn,
  Detached,
  Valid,
}

export interface IUnknownRepository {
  readonly kind: TipState.Unknown;
}

export interface IUnbornRepository {
  readonly kind: TipState.Unborn;

  /**
   * The symbolic reference that the unborn repository points to currently.
   *
   * Typically this will be "master" but a user can easily create orphaned
   * branches externally.
   */
  readonly ref: string;
}

export interface IDetachedHead {
  readonly kind: TipState.Detached;
  /**
   * The commit identifier of the current tip of the repository.
   */
  readonly currentSha: string;
}


export type Tip =
  | IUnknownRepository
  | IUnbornRepository
  | IDetachedHead
  ;