import { isApiError, type ApiError } from "@/lib/errors"

type JsonRequestInit = Omit<RequestInit, "body" | "headers"> & {
  headers?: HeadersInit
  body?: BodyInit | null
  json?: unknown
}

async function readJsonBody(res: Response): Promise<unknown | null> {
  const text = await res.text()
  if (!text) return null

  try {
    return JSON.parse(text) as unknown
  } catch {
    return null
  }
}

export async function httpJson<T>(path: string, init?: JsonRequestInit): Promise<T> {
  if (/^https?:\/\//.test(path)) {
    throw new Error("Absolute URLs are not allowed")
  }

  const { json, headers: headersInit, body: bodyInit, ...rest } = init ?? {}

  const headers = new Headers(headersInit)
  headers.set("Accept", "application/json")

  const body = json === undefined ? bodyInit : JSON.stringify(json)

  if (json !== undefined && !headers.has("Content-Type")) {
    headers.set("Content-Type", "application/json")
  }

  const res = await fetch(path, {
    ...rest,
    headers,
    body,
  })

  const data = await readJsonBody(res)

  if (res.ok) {
    return data as T
  }

  const apiError = isApiError(data) ? data : null
  if (res.status === 401 || apiError?.code === 401) {
    throw new Error("UNAUTHORIZED")
  }

  if (apiError) {
    throw apiError
  }

  throw { code: res.status, msg: res.statusText || "Request failed" } satisfies ApiError
}