import { fetch } from "undici"

export interface WeixinAccessTokenResult {
  accessToken: string
  expiresAt: number
  refreshToken: string
  openid: string
  scope: string
  unionid?: string | undefined
}

export interface WeixinUserInfoResult {
  openid: string
  nickname: string
  sex: number
  province: string
  city: string
  country: string
  headimgurl: string
  privilege: string[]
  unionid?: string | undefined
}

export interface WeixinOauth2Options {
  appId: string
  appSecret: string
}

export class WeixinOauth2 {
  protected options: WeixinOauth2Options

  constructor(options: WeixinOauth2Options) {
    this.options = options
  }

  /**
   * @description {@link https://developers.weixin.qq.com/doc/oplatform/Website_App/WeChat_Login/Wechat_Login.html | 关于微信快速登录功能的说明}
   */
  async getAccessToken(code: string): Promise<WeixinAccessTokenResult> {
    interface AccessTokenSuccessResponse {
      access_token: string
      expires_in: number
      refresh_token: string
      openid: string
      scope: string
      unionid?: string
    }
    interface AccessTokenErrorResponse {
      errcode: number
      errmsg: string
    }
    const { appId, appSecret } = this.options
    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,
        unionid: json.unionid,
      }
    } catch (exception) {
      console.error("Error getting access token:", exception)
      throw exception
    }
  }

  /**
   * @description {@link https://developers.weixin.qq.com/doc/oplatform/Website_App/WeChat_Login/Authorized_Interface_Calling_UnionID.html | 获取用户个人信息（UnionID机制）}
   */
  async getUserInfo(accessToken: string, openId: string): Promise<WeixinUserInfoResult> {
    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
    }
  }
}