import { hash } from "node:crypto"

import { fetch } from "undici"

export interface GetJsApiAccessTokenOptions {
  appId: string
  appSecret: string
}
export interface GetJsApiAccessTokenResult {
  accessToken: string
  /**
   * @description In milliseconds
   */
  accessTokenExpiresAt: number
}
/**
 * @see {@link https://developers.weixin.qq.com/doc/offiaccount/Basic_Information/getStableAccessToken.html}
 * @see {@link https://mp.weixin.qq.com/debug | 微信公众平台 - 接口调试工具}
 */
export const getJsApiAccessToken = async (
  options: GetJsApiAccessTokenOptions,
): Promise<GetJsApiAccessTokenResult | undefined> => {
  const { appId, appSecret } = options

  interface StableTokenResponse {
    access_token: string
    expires_in: number
  }
  try {
    const now = Date.now()
    const result = await fetch("https://api.weixin.qq.com/cgi-bin/stable_token", {
      method: "post",
      body: JSON.stringify({
        grant_type: "client_credential",
        appid: appId,
        secret: appSecret,
        force_refresh: false,
      }),
    })

    const json = (await result.json()) as StableTokenResponse

    return {
      accessToken: json.access_token,
      accessTokenExpiresAt: now + json.expires_in * 1_000,
    }
  } catch (exception) {
    console.error(exception)
    return undefined
  }
}

export interface GetJsApiTicketOptions {
  accessToken: string
}
export interface GetJsApiTicketResult {
  jsApiTicket: string
  /**
   * @description In milliseconds
   */
  expiresAt: number
}
/**
 * @see {@link https://developers.weixin.qq.com/doc/offiaccount/OA_Web_Apps/JS-SDK.html#62 | 附录 1 - JS-SDK 使用权限签名算法}
 */
export const getJsApiTicket = async (
  options: GetJsApiTicketOptions,
): Promise<GetJsApiTicketResult | undefined> => {
  const { accessToken } = options

  interface JsApiTicketResponse {
    errcode: number
    errmsg: string
    ticket: string
    expires_in: number
  }
  try {
    const now = Date.now()
    const result = await fetch(
      `https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=${accessToken}&type=jsapi`,
      {
        method: "get",
      },
    )

    const json = (await result.json()) as JsApiTicketResponse

    return {
      jsApiTicket: json.ticket,
      expiresAt: now + json.expires_in * 1_000,
    }
  } catch (exception) {
    console.error(exception)
    return undefined
  }
}

export interface SignJsSdkConfigOptions {
  url: string
  jsApiTicket: string
}
export interface SignJsSdkConfigResult {
  timestamp: number
  nonceStr: string
  signature: string
}
/**
 * @see {@link https://developers.weixin.qq.com/doc/offiaccount/OA_Web_Apps/JS-SDK.html#62 | 签名算法}
 * @see {@link https://mp.weixin.qq.com/debug/cgi-bin/sandbox?t=jsapisign | 微信公众平台 - 微信 JS 接口签名校验工具}
 */
export const signJsSdkConfig = (options: SignJsSdkConfigOptions): SignJsSdkConfigResult => {
  const { url, jsApiTicket } = options

  const nonceStr = Math.random().toString(36).slice(2, 17)
  const timestamp = Math.floor(Date.now() / 1_000)

  const rawString = `jsapi_ticket=${jsApiTicket}&noncestr=${nonceStr}&timestamp=${timestamp}&url=${url}`
  const signature = hash("sha1", rawString)

  return {
    timestamp,
    nonceStr,
    signature,
  }
}