// ================================
// Helper types for making custom typescript errors
// ================================

const _errorSymbol = Symbol()

export type TypeError<TMessage extends string> = TMessage & {
  _: typeof _errorSymbol
}

// Helper type to remove TypeErrors from unions
/**
 * Remove TypeErrors from a union to allow the actual type to be used.
 */
export type ExcludeTE<T> = Exclude<T, TypeError<string>>

/**
 * Type assertion helper that removes TypeErrors from a union type.
 * This is a no-op function that only exists to help TypeScript's type system.
 * Use this when ExcludeTE type helper alone isn't sufficient to narrow the type.
 */
export function ASSERT_NO_TYPE_ERROR<T>(_: T): asserts _ is ExcludeTE<T> {}

/**
 * Type assertion helper that removes TypeErrors from a union type.
 * This is a unit function that returns it's input and only exists to help TypeScript's type system.
 */
export function EXCLUDE_TYPE_ERROR<T>(_: T): ExcludeTE<T> {
  return _ as ExcludeTE<T>
}

// ================================
// String type manipulation
// ================================

export declare type UnionToIntersection<U> = (
  U extends any
    ? (k: U) => void
    : never
) extends (k: infer I) => void
  ? I
  : never

export type UnionToOvlds<U> = UnionToIntersection<
  U extends any ? (f: U) => void : never
>
export type PopUnion<U> = UnionToOvlds<U> extends (a: infer A) => void
  ? A
  : never

export type StringConcatenationOrder<
  S extends string,
  SEPARATOR extends string,
> = PopUnion<S> extends infer SELF
  ? //
    SELF extends string
    ? Exclude<S, SELF> extends never
      ? `${SELF}`
      : // This works because the values of S are always interpreted in ascending lexiographical order
        `${StringConcatenationOrder<Exclude<S, SELF>, SEPARATOR>}${SEPARATOR}${SELF}`
    : never
  : never