import type {
  BoundInjectionToken,
  ClassType,
  FactoryInjectionToken,
  InjectionToken,
} from '../token/injection-token.mjs'

// Utility types for string manipulation and union handling
export type Join<TElements, TSeparator extends string> =
  TElements extends Readonly<[infer First, ...infer Rest]>
    ? Rest extends ReadonlyArray<string>
      ? First extends string
        ? `${First}${Rest extends [] ? '' : TSeparator}${Join<Rest, TSeparator>}`
        : never
      : never
    : ''

// credits goes to https://stackoverflow.com/a/50375286
export type UnionToIntersection<U> = (
  U extends any ? (k: U) => void : never
) extends (k: infer I) => void
  ? I
  : never

// Converts union to overloaded function
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 IsUnion<T> = [T] extends [UnionToIntersection<T>] ? false : true

export type UnionToArray<T, A extends unknown[] = []> =
  IsUnion<T> extends true
    ? UnionToArray<Exclude<T, PopUnion<T>>, [PopUnion<T>, ...A]>
    : [T, ...A]

export type InjectRequest = {
  token:
    | InjectionToken<any>
    | BoundInjectionToken<any, any>
    | FactoryInjectionToken<any, any>
    | ClassType
  promise: Promise<any>
  readonly result: any
  readonly error: Error | null
}

// InjectState interface for managing injection state
export interface InjectState {
  currentIndex: number
  isFrozen: boolean
  requests: InjectRequest[]
}