/** Get the Params type for a given Shape */
export type EndpointParam<E> =
  E extends (first: infer A, ...rest: any) => any ? A
  : E extends { key: (first: infer A, ...rest: any) => any } ? A
  : never;

/** What the function's promise resolves to */
export type ResolveType<E extends (...args: any) => any> =
  ReturnType<E> extends Promise<infer R> ? R : never;

export type PartialArray<A> =
  A extends [] ? []
  : A extends [infer F] ? [F] | []
  : A extends [infer F, ...infer Rest] ? [F] | [F, ...PartialArray<Rest>]
  : A extends (infer T)[] ? T[]
  : never;

// workaround for https://github.com/microsoft/TypeScript/issues/29919
export type PartialParameters<T extends (...args: any[]) => any> =
  T extends (...args: infer P) => any ? Partial<P> : never;

export type EndpointToFunction<E extends (...args: any) => Promise<any>> = (
  this: E,
  ...args: Parameters<E>
) => ReturnType<E>;