Simple Ammonite-Scala script to shuffle a list of participants of "amigo secreto".

Shuffle.scala

#!/usr/bin/env amm

import $ivy.`com.sun.mail:javax.mail:1.6.2`
import javax.mail._
import javax.mail.internet._
import java.time.{ZoneId, ZonedDateTime}
import java.util.{Date, Properties}
import scala.jdk.CollectionConverters._

final case class Participant(name: String, email: String)
final case class Matched(participant: Participant, friend: String)

def randomMatch(participants: List[Participant]): List[Matched] = {
  val names = participants.map(_.name)
  
  @annotation.tailrec
  def loop(): List[Matched] = {
    val shuffled = scala.util.Random.shuffle(names)
    val zipped = (participants zip shuffled)
    
    val selfMatch = zipped.exists {
      case (participant, friend) =>
        participant.name == friend
    }
    
    if (selfMatch) loop()
    else zipped map {
      case (participant, friend) =>
        Matched(participant, friend)
    }
  }
  
  loop()
}

def sendEmails(user: String, password: String)(matches: List[Matched]): Unit = {
  val props = new Properties()
  props.putAll(
    Map(
      "mail.smtp.host" -> "outlook.office365.com",
      "mail.smtp.port" -> "587",
      "mail.smtp.auth" -> "true",
      "mail.smtp.starttls.enable" -> "true"
    ).asJava
  )
  
  val session = Session.getInstance(
    props,
    new Authenticator() {
      override protected def getPasswordAuthentication(): PasswordAuthentication =
        new PasswordAuthentication(user, password)
    }
  )
  
  val todaysDate = Date.from(
    ZonedDateTime.now().withZoneSameInstant(ZoneId.of("America/Bogota")).toInstant
  )
  
  matches.foreach {
    case Matched(Participant(participantName, participantEmail), friendName) =>
      val email = new MimeMessage(session)
      email.setFrom(new InternetAddress(user))
      email.setRecipient(Message.RecipientType.TO, new InternetAddress(participantEmail))
      email.setSubject("Amigo secreto")
      email.setSentDate(todaysDate)
      
      val multipart = new MimeMultipart()
      val msg = new MimeBodyPart()
      msg.setContent(
        s"Hola ${participantName}, tu amigo secreto es ${friendName}.",
        "text/html"
      )
      multipart.addBodyPart(msg)
      email.setContent(multipart)
      
      Transport.send(email)
  }
}

@main
def main(emailUser: String, emailPassword: String, arguments: Seq[String]): Unit = {
  val participants = arguments.toList.map { argument =>
    val Array(name, email) = argument.split(":")
    Participant(name, email)
  }
      
  val matches = randomMatch(participants)
  
  sendEmails(emailUser, emailPassword)(matches)
}