import { fetch } from "undici"

export interface GetAuthAccessTokenOptions {
  appId: string
  appSecret: string
  code: string
}
export interface GetAuthAccessTokenResult {
  accessToken: string
  expiresAt: number
  refreshToken: string
  openid: string
  scope: string
  isSnapshotUser: boolean
  unionid?: string | undefined
}
export const getAuthAccessToken = async (
  options: GetAuthAccessTokenOptions,
): Promise<GetAuthAccessTokenResult> => {
  const { appId, appSecret, code } = options

  interface AccessTokenSuccessResponse {
    access_token: string
    expires_in: number
    refresh_token: string
    openid: string
    scope: string
    is_snapshotuser?: 1
    unionid?: string
  }
  interface AccessTokenErrorResponse {
    errcode: number
    errmsg: string
  }
  const url = `https://api.weixin.qq.com/sns/oauth2/access_token?appid=${appId}&secret=${appSecret}&code=${code}&grant_type=authorization_code`

  try {
    const now = Date.now()
    const result = await fetch(url, {
      method: "get",
    })

    const json = (await result.json()) as AccessTokenSuccessResponse | AccessTokenErrorResponse

    if ("errcode" in json) {
      throw new Error(`${json.errcode}: ${json.errmsg}`)
    }

    return {
      accessToken: json.access_token,
      expiresAt: now + json.expires_in * 1_000,
      refreshToken: json.refresh_token,
      openid: json.openid,
      scope: json.scope,
      isSnapshotUser: json.is_snapshotuser === 1,
      unionid: json.unionid,
    }
  } catch (exception) {
    console.error("Error getting access token:", exception)
    throw exception
  }
}

export interface GetUserInfoOptions {
  accessToken: string
  openId: string
}
export interface GetUserInfoResult {
  openid: string
  nickname: string
  sex: number
  province: string
  city: string
  country: string
  headimgurl: string
  privilege: string[]
  unionid: string
}
export const getUserInfo = async (options: GetUserInfoOptions): Promise<GetUserInfoResult> => {
  const { accessToken, openId } = options

  interface UserInfoSuccessResponse {
    openid: string
    nickname: string
    sex: number
    province: string
    city: string
    country: string
    headimgurl: string
    privilege: string[]
    unionid: string
  }
  interface UserInfoErrorResponse {
    errcode: number
    errmsg: string
  }
  const url = `https://api.weixin.qq.com/sns/userinfo?access_token=${accessToken}&openid=${openId}&lang=zh_CN`

  try {
    const result = await fetch(url, {
      method: "get",
    })

    const json = (await result.json()) as UserInfoSuccessResponse | UserInfoErrorResponse

    if ("errcode" in json) {
      throw new Error(`${json.errcode}: ${json.errmsg}`)
    }
    return json
  } catch (exception) {
    console.error("Error getting user info:", exception)
    throw exception
  }
}

export interface WeixinOfficialAccountOauth2Options {
  appId: string
  appSecret: string
}
/**
 * @see {@link https://developers.weixin.qq.com/doc/offiaccount/OA_Web_Apps/Wechat_webpage_authorization.html | 微信网页开发 / 网页授权}
 */
export class WeixinOfficialAccountOauth2 {
  private readonly appId: string
  private readonly appSecret: string

  constructor(options: WeixinOfficialAccountOauth2Options) {
    const { appId, appSecret } = options
    this.appId = appId
    this.appSecret = appSecret
  }

  async getAccessToken(code: string): Promise<GetAuthAccessTokenResult> {
    return await getAuthAccessToken({
      appId: this.appId,
      appSecret: this.appSecret,
      code,
    })
  }

  async getUserInfo(accessToken: string, openId: string): Promise<GetUserInfoResult> {
    return await getUserInfo({
      accessToken,
      openId,
    })
  }
}