Session.scala

import org.scalajs.dom.document

object Session {
  val CookieName = "SessionId"
  val key: String = CookieName

  var username: Option[String] = Option(JsGlobals.username)

  def get: Option[String] =
    document.cookie.split(";").toList.flatMap { part =>
      part.split("=").toList match {
        case `key` :: value :: Nil if value.nonEmpty => List(value)
        case _ => Nil
      }
    }.headOption

  def set(key: String, value: String, expires: String, path: String = "/"): Unit =
    document.cookie = s"$key=$value; expires=$expires; path=$path"

  def set: Option[String] => Unit = {
    case None       => set(key, "",   "Thu, 01-Jan-1970 00:00:01 GMT")
    case Some(sess) => set(key, sess, "Fri, 31 Dec 9999 23:59:59 GMT")
  }

  def reset(): Unit = {
    username = None
    set(None)
  }

  def set(username: String, hash: String): Unit = {
    this.username = Some(username)
    set(Some(hash))
  }
}

object LogInPage {
  def manage(): Unit = {
    TagRef[tag.Button]("login").click := {
      val username = TagRef[tag.Input]("username").dom.value
      val password = TagRef[tag.Input]("password").dom.value

      API.request(protocol.LogIn(username, password)).foreach {
        case None =>
          Session.reset()
          window.alert("Log-in failed")

        case Some(hash) =>
          Session.set(username, hash)
          val host = window.location.origin
          window.location.href = s"$host/"
      }
    }
  }
}