import type {HttpMethod} from 'openapi-typescript-helpers'

export const HTTP_METHODS = [
  'GET',
  'PUT',
  'POST',
  'DELETE',
  'OPTIONS',
  'HEAD',
  'PATCH',
  'TRACE',
] satisfies ReadonlyArray<Uppercase<HttpMethod>>

export type HTTPMethod = (typeof HTTP_METHODS)[number]

/**
 * The BetterRequest object is an extension of the native [Request](https://developer.mozilla.org/en-US/docs/Web/API/Request)
 * interface, with better typing and extended functionality such as mutable properties
 * though maybe we should allow for immutable requests?
 */
export type BetterRequest<TJson = unknown> = Omit<Request, 'method'> & {
  readonly method: HTTPMethod
  json: <T = TJson>() => Promise<T>
}

/**
 * The BetterResponse object is an extension of the native [Response](https://developer.mozilla.org/en-US/docs/Web/API/Response)
 * interface, with better typing and extended functionality.
 */
export type BetterResponse<TJson = unknown> = Omit<Response, 'json'> & {
  json: <T = TJson>() => Promise<T>
}

/** Heavily inspired by trpc and Apollo GraphQL */
export type Link = (
  req: BetterRequest,
  next: (req: BetterRequest | Request) => Promise<Response>,
) => Promise<BetterResponse>

export function applyLinks(
  req: BetterRequest | Request,
  links: Link[],
): Promise<BetterResponse> {
  const [link, ...rest] = links
  if (!link) {
    throw new Error('Terminating link missing in links chain')
  }
  // Every request is actually a BetterRequest :)
  return link(req as BetterRequest, (op) => applyLinks(op, rest))
}

/** Compose multiple links into a single link */
export function composeLinks(...links: Link[]): Link {
  return (req, next) => applyLinks(req, [...links, next])
}

/* Turn multiple links into a single request handler - a link with no "next" param */
export function composeLinksToHandler(
  ...links: Link[]
): (req: Request) => Promise<Response> {
  return (req) => applyLinks(req, links)
}