import { createUseFetch } from '#imports'
import type { AsyncData, UseFetchOptions } from '#app'
import type { KeysOf, PickFrom } from '#app/composables/asyncData'
import type { NitroFetchRequest, TypedInternalResponse, AvailableRouterMethod } from 'nitropack/types'
import type { FetchError } from 'ofetch'
import type { Ref } from 'vue'

/** 与 `R.success` / `R.error` 返回结构对齐 */
export type ApiResponse<T = unknown> = {
  code: number
  message: string
  data: T
}

/** 从 Nitro 推断的响应体上剥离一层 `ApiResponse`，得到 `data` 字段类型 */
export type UnwrapApiResponse<T> = T extends ApiResponse<infer D> ? D : T

export function unwrapApiBody<T>(payload: ApiResponse<T>): T {
  if (payload.code !== 0) {
    throw new Error(payload.message)
  }
  return payload.data
}

export const request = $fetch.create({})

const httpFetchDefaults = {
  retry: 0,
  $fetch: request,
  transform: unwrapApiBody,
}

const _useHttpFetch = createUseFetch(httpFetchDefaults)
const _useLazyHttpFetch = createUseFetch({
  ...httpFetchDefaults,
  lazy: true,
})

type DefaultMethod<ReqT extends NitroFetchRequest> = 'get' extends AvailableRouterMethod<ReqT>
  ? 'get'
  : AvailableRouterMethod<ReqT>

type HttpFetchOptions<
  _ResT,
  DataT,
  PickKeys extends KeysOf<DataT>,
  DefaultT,
  ReqT extends NitroFetchRequest,
  Method extends AvailableRouterMethod<ReqT>,
> = Omit<UseFetchOptions<_ResT, DataT, PickKeys, DefaultT, ReqT, Method>, 'transform'>

/**
 * 带项目默认选项的 `useFetch`，并在类型上将 `data` 视为接口 `{ code, data, message }` 中的内层 `data`。
 *
 * 说明：Nuxt的 `createUseFetch` 在类型上不会把工厂里的 `transform` 的出参当作 `AsyncData['data']`，
 * 因此这里用薄包装修正 `DataT`（见 `UnwrapApiResponse`）。
 */
export function useHttpFetch<
  ResT = void,
  ErrorT = FetchError,
  ReqT extends NitroFetchRequest = NitroFetchRequest,
  Method extends AvailableRouterMethod<ReqT> = ResT extends void
    ? DefaultMethod<ReqT>
    : AvailableRouterMethod<ReqT>,
  _ResT = ResT extends void ? TypedInternalResponse<ReqT, unknown, Lowercase<Method>> : ResT,
  DataT = UnwrapApiResponse<_ResT>,
  PickKeys extends KeysOf<DataT> = KeysOf<DataT>,
  DefaultT = undefined,
>(
  url: ReqT | Ref<ReqT, ReqT> | (() => ReqT),
  opts?: HttpFetchOptions<_ResT, DataT, PickKeys, DefaultT, ReqT, Method>,
): AsyncData<DefaultT | PickFrom<DataT, PickKeys>, ErrorT | undefined> {
  return _useHttpFetch(url, opts) as AsyncData<DefaultT | PickFrom<DataT, PickKeys>, ErrorT | undefined>
}

export function useLazyHttpFetch<
  ResT = void,
  ErrorT = FetchError,
  ReqT extends NitroFetchRequest = NitroFetchRequest,
  Method extends AvailableRouterMethod<ReqT> = ResT extends void
    ? DefaultMethod<ReqT>
    : AvailableRouterMethod<ReqT>,
  _ResT = ResT extends void ? TypedInternalResponse<ReqT, unknown, Lowercase<Method>> : ResT,
  DataT = UnwrapApiResponse<_ResT>,
  PickKeys extends KeysOf<DataT> = KeysOf<DataT>,
  DefaultT = undefined,
>(
  url: ReqT | Ref<ReqT, ReqT> | (() => ReqT),
  opts?: HttpFetchOptions<_ResT, DataT, PickKeys, DefaultT, ReqT, Method>,
): AsyncData<DefaultT | PickFrom<DataT, PickKeys>, ErrorT | undefined> {
  return _useLazyHttpFetch(url, opts) as AsyncData<
    DefaultT | PickFrom<DataT, PickKeys>,
    ErrorT | undefined
  >
}