import { WebClient } from "https://deno.land/x/slack_web_api@1.0.3/mod.ts";

import { isEmail } from "https://deno.land/x/isemail@v1.0.1/mod.ts";

type Slack = {

  token: string;

};

export async function main(user_email: string, text: string, slack: Slack) {

  throwOnInvalidEmail(user_email);

  const client = new WebClient(slack.token);

  const userData = await getUserData(client, user_email);

  console.log(userData);

  const result = await sendDirectMessage(text, client, userData);

  return result;

}

interface UserData {

  id: string;

  email: string;

  real_name: string;

}

async function getUserData(

  client: WebClient,

  email: string,

): Promise<UserData> {

  try {

    const response = await client.users.lookupByEmail({ email: email });

    const { id, real_name } = response.user;

    return { id, email, real_name };

  } catch (err) {

    return handleApiResponse(email, err);

  }

}

async function sendDirectMessage(

  text: string,

  client: WebClient,

  userData: UserData,

) {

  const { ok, ts, channel } = await client.chat.postMessage({

    channel: userData.id,

    text,

  });

  return { ok, ts, channel, email: userData.email };

}

function throwOnInvalidEmail(email: string) {

  if (!isEmail(email)) {

    throw new Error("Expected user email");

  }

}

function handleApiResponse(email: string, error: Error) {

  return Promise.reject({ email, err_msg: error.message });

}