/*
 * Common types and interfaces
 */

import type { Types } from 'mongoose';

import { isValidObjectId } from '../utils/objectid-utils';

type ObjectId = Types.ObjectId;

// Foreign key field
export type Ref<T> = string | ObjectId | T & { _id: string | ObjectId };

export type Populated<T, K extends keyof T> = {
  [P in keyof T]: P extends K
    ? T[P] extends null
      ? null
      : T[P] extends Ref<infer R>
        ? R
        : T[P]
    : T[P];
};

export type Nullable<T> = T | null | undefined;

export const isRef = <T>(obj: unknown): obj is Ref<T> => {
  return obj != null
    && (
      (typeof obj === 'string' && isValidObjectId(obj))
        || (typeof obj === 'object' && '_bsontype' in obj && obj._bsontype === 'ObjectID')
        || (typeof obj === 'object' && '_id' in obj)
    );
};

export const isPopulated = <T>(ref: Ref<T>): ref is T & { _id: string | ObjectId } => {
  return ref != null
    && typeof ref !== 'string'
    && !('_bsontype' in ref && ref._bsontype === 'ObjectID');
};

export const getIdForRef = <T>(ref: Ref<T>): string | ObjectId => {
  return isPopulated(ref)
    ? ref._id
    : ref;
};

export const getIdStringForRef = <T>(ref: Ref<T>): string => {
  return getIdForRef(ref).toString();
};