import { Converter, MaybeAsyncFunction } from "../types.js";

export interface EqualityComparer<T> {
  equals(a: T, b: T): boolean;
  equalityComparison(): EqualityComparison<T>;
  opposite(): EqualityComparer<T>;
  then(equalityComparer: EqualityComparer<T>): EqualityComparer<T>;
  thenEquals(equalityComparison: EqualityComparison<T>): EqualityComparer<T>;
  thenEqualsUsing<U>(projection: Converter<T, U>, equalityComparison?: EqualityComparisonOrComparer<U>): EqualityComparer<T>;
}

export type EqualityComparison<T> = (first: T, second: T) => boolean;
export type EqualityComparisonOrComparer<T> = EqualityComparison<T> | EqualityComparer<T>;

export type MaybeAsyncEqualityComparison<T> = MaybeAsyncFunction<EqualityComparison<T>>;