import { getResumeUrls } from "https://deno.land/x/windmill@v1.85.0/mod.ts";

import { encode as base64UrlEncode } from "https://deno.land/std@0.82.0/encoding/base64url.ts";

type Gmail = {

  token: string;

};

export async function main(

  gmail_auth: Gmail,

  approver_emails: string[],

  subject = "Resume Windmill flow",

) {

  throwOnInvalidApprovers(approver_emails);

  const token = gmail_auth["token"];

  const email_promises = approver_emails.map((to_email) =>

    sendEmail(token, to_email, subject),

  );

  const results = await Promise.all(email_promises);

  return results;

}

async function sendEmail(

  gmail_token: string,

  to_email: string,

  subject: string,

): Promise<object> {

  const email = await getEmailBody(to_email, subject);

  const SEND_EMAIL_URL = `https://gmail.googleapis.com/gmail/v1/users/me/messages/send`;

  const body = {

    raw: email,

  };

  const response = await fetch(SEND_EMAIL_URL, {

    method: "POST",

    body: JSON.stringify(body),

    headers: {

      Authorization: `Bearer ${gmail_token}`,

    },

  });

  const response_json = await response.json();

  return handleSendEmailResult(response_json, to_email);

}

async function getEmailBody(to_email: string, subject: string) {

  const { approvalPage } = await getResumeUrls(to_email);

  const message = `There is a Windmill flow at ${Deno.env.get(

    "WM_FLOW_PATH",

  )} run by ${Deno.env.get("WM_USERNAME")} waiting for your approval to resume.

In order to resume or cancel the flow go to ${approvalPage}`;

  const email_body = `From: <me>\nTo: <${to_email}>\nSubject: ${subject}\n\r ${message}`;

  return base64UrlEncode(email_body);

}

function throwOnInvalidApprovers(approvers: string[]) {

  if (!Array.isArray(approvers) || approvers.length === 0) {

    throw new Error("Expected at least one approver email");

  }

}

async function handleSendEmailResult(result: object, to_email: string) {

  if (Object.keys(result).includes("error")) {

    return Promise.reject({ wm_to_email: to_email, ...result });

  }

  return result;

}