build.sbt

import Dependencies._

ThisBuild / scalaVersion     := "2.13.1"
ThisBuild / version          := "0.1.0-SNAPSHOT"
ThisBuild / organization     := "com.example"
ThisBuild / organizationName := "example"

lazy val root = (project in file("."))
  .settings(
    name := "email"
  )

libraryDependencies ++= Seq("com.lihaoyi" %% "requests" % "0.5.1",
"com.typesafe.play" %% "play-json" % "2.8.1",
"net.debasishg" %% "redisclient" % "3.20")

Email.scala

import play.api.libs.json._
import scala.collection.mutable.ArrayBuffer
import scala.concurrent.Future
import scala.util.Success
import scala.util.Failure
import java.io.BufferedWriter
import java.io.FileWriter
import requests.auth
import com.redis._

object Main extends App {

  val outf = new BufferedWriter(new FileWriter("out.csv"))
  val redis = new RedisClient("localhost", 6379)
  val login = ("github user", "pass")

  Main.args(0) match {
    case "scrape" => {
      import scala.concurrent.ExecutionContext.Implicits.global

      val url = "https://api.github.com/users?since="
      val simpleEmailRegex = "mailto:.*.(\"|')>".r
      val range = Main.args(1).toInt

      def getUrls(n: Int, counter: Int = 0, from_id: Int = 0): List[String] = {
        if (counter == n) List()
        else {
          val data = Json.parse(requests.get(url + from_id, auth = login).text)
          val last = (data \\ "id").last.as[Int]
          (data \\ "login").toList
            .map(_.as[String]) ::: getUrls(n, (counter + 1), last)
        }
      }

      println(s"fetching ${range * 29} records...")

      getUrls(range)
        .map("https://" + _ + ".github.io")
        .toList
        .zipWithIndex
        .foreach({
          case (el, index) => {
            val mail: Future[List[String]] = Future {
              val site = requests.get(el)
              if (site.statusCode == 200) {
                index.toString :: el :: simpleEmailRegex
                  .findAllIn(site.text)
                  .toList
                  .filter(_.length < 200)
                  .map(el => el.take(el.length - 2))
                  .map(_.replace("mailto:", ""))
              } else List()
            }

            mail.onComplete({
              case Success(value) => {
                if (value.length > 2) {
                  println(s"${value.head}: ${value.length}")
                  try {
                    value.tail.foreach(redis.rpush(value.head, _))
                  } catch {
                    case t: Throwable => ()
                  }
                }
              }
              case Failure(exception) => ()
            })
          }
        })
    }

    case "csv" => {
      println(s"found ${redis.keys("*").get.length} keys")
      redis
        .keys("*")
        .foreach(el =>
          el.foreach(identifier => redis.lrange(identifier.get, 0, -1).get.zipWithIndex
            .foreach{case (el, index) => {
                outf.write(el.get)
                outf.write(if(index == redis.lrange(identifier.get, 0, -1).get.length - 1) "\n" else ",")
              }
            }
          )
        )
        outf.close()
    }

    case _ => println("Usage: run [scrape n | csv]")

  }

}