#!/usr/bin/env node

const fs = require("fs");
const readline = require("readline");
const nodemailer = require("nodemailer");

const mailer = nodemailer.createTransport({
  sendmail: true,
  newline: "unix",
  path: "/usr/sbin/sendmail"
});

function mail(email, name, pick) {
  mailer.sendMail(
    {
      from: "Wichtelbot <tomru@uber.space>",
      to: email,
      subject: `Dein Wichtel...`,
      text: `Hey ${name},

ich hab diese Jahr für Dich >> ${pick} << gezogen! 

Viel Spaß beim Wichteln!
Dein Weihnachtswichtel™
`
    },
    (err, info) => {
      console.log(info.envelope);
      console.log(info.messageId);
    }
  );
}

function read() {
  return new Promise((resolve, reject) => {
    const people = [];
    const rl = readline.createInterface({
      input: process.stdin
    });

    rl.on("line", line => {
      const [name, email, group] = line.split(/\s+/);
      people.push({ name, email, group });
    });

    rl.on("error", reject);

    rl.on("close", () => {
      resolve(people);
    });
  });
}

const run = async () => {
  const people = await read();
  const send = process.argv[2] === "--send";

  if (!people || !people.length) {
    throw new Error("input file empty");
  }

  people.forEach((drawer, index) => {
    let picked;

    let pickable = people.filter(
      p =>
        !p.picked &&
        drawer.name !== p.name &&
        (!drawer.group || drawer.group !== p.group)
    );

    if (pickable.length === 0) {
      throw new Error(`ohhh shoot. None left for ${drawer.name}. Just try to roll again...`);
    }

    let pickIndex = Math.floor(Math.random() * pickable.length);
    drawer.pick = pickable[pickIndex].name;
    pickable[pickIndex].picked = true;
  });

  console.log('Yay, I could draw someone for everybody! Writing ./picks.txt');

  fs.writeFileSync(
    `./picks.txt`,
    people.map(({ name, pick }) => `${name} picked ${pick}`).join("\n")
  );

  if (!send) {
    console.log("DRY RUN: did not send emails! To send pass --send option");
    return;
  }
  people.forEach(p => mail(p.email, p.name, p.pick));
};

run().catch((e) => console.error(`Error: ${e.message}`));