import {z} from 'zod'

export type CreateApiOauthParArgs = {authorization?: string | undefined, body: {client_id: string, client_secret?: string | undefined, redirect_uri: string, response_type: 'code', scope?: string | undefined, state?: string | undefined, code_challenge: string, code_challenge_method: 'S256', resource?: string | undefined} | {[key: string]: unknown}};

export type CreateApiOauthParOptions = {baseUrl: string, fetch?: typeof fetch | undefined};

export const pARResponse = z.object({request_uri: z.string(), expires_in: z.number().int()});

export const validateResponse = async <Output>(
  schema: {
    readonly '~standard': {
      readonly validate: (value: unknown) => ({ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }) | Promise<{ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }>
    }
  },
  value: unknown
): Promise<Output> => {
  const result = await schema['~standard'].validate(value)

  if (result.issues !== undefined) {
    const detail = result.issues
      .map(({ message, path }) =>
        path?.length
          ? `${path.map((segment) => String(typeof segment === 'object' ? segment.key : segment)).join('.')}: ${message}`
          : message
      )
      .join('; ')

    throw new Error(`Response does not match the schema: ${detail}`, { cause: { issues: result.issues } })
  }

  return result.value
};

/**
 * Pushed Authorization Request (RFC 9126)
 * 
 * POST /oauth/par
 */
export const createApiOauthPar = async (args: CreateApiOauthParArgs, options: CreateApiOauthParOptions) => {
const {baseUrl, fetch: fetchFn = fetch} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('content-type', "application/x-www-form-urlencoded")
headers.set('accept', "application/json")

if (args.authorization != null) headers.set("authorization", String(args.authorization))

const url = `${baseUrl.replace(/\/+$/, '')}/oauth/par${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "POST", headers, body: new URLSearchParams(Object.entries(args.body).flatMap(([key, value]) => (value == null ? [] : [[key, String(value)]])))})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(pARResponse, await res.json())
};