feat: add ex3

add parametrized type, union, enum, alias

src/main/scala/TopSongs/TopSongs.scala

@@ -1,15 +1,38 @@
 package TopSongs
-import scala.io.Source
 import java.io.File
 import com.github.tototoshi.csv._
 
-trait Person:
+trait Person {
   val name: String
+}
+
+case class Singer(name: String) extends Person
 
-case class Artist(name: String) extends Person
 case class Writer(name: String) extends Person
+
 case class Producer(name: String) extends Person
-class Album(title: String, label: String)
+
+// The parametrized type Artist can be a Singer, a Writer or a Producer
+// They do a different creation action
+class Artist[A <: Person](val person: A) {
+  def create(): String = {
+    person match {
+      case s: Singer => s"${s.name} sing"
+      case w: Writer => s"${w.name} write"
+      case p: Producer => s"${p.name} produce"
+      case _ => s"${person.name} create"
+    }
+  }
+}
+
+
+// Defined a MusicGender as en enum
+enum MusicGenre:
+  case Rock, Soul, Blues, Folk, Funk, Reggae, HipHop, NewWave, Electro, Metal
+
+// Define an Album with a union between a String and a MusicGenre
+class Album(title: String, label: String, genre: String|MusicGenre)
+
 class Streak(val s: String) {
   val streak: Option[Int] = {
     val regex = "\\d+".r
@@ -23,8 +46,9 @@ class Streak(val s: String) {
     }
   }
 }
+
 class Position(val p: String) {
-  val position: Option[Int] = {
+  val pos: Option[Int] = {
     val regex = "\\d+".r
     regex.findFirstIn(p) match {
       case Some(value) => Some(Integer.parseInt(value))
@@ -33,55 +57,87 @@ class Position(val p: String) {
   }
 }
 
+// Defined a type alias Rank which is a tuple of Streak and Position
+// Streak and Position are linked together, it's why there are regrouped in the Rank type alias
+type Rank = (Streak, Position)
+
+// Defined an intersection type of Artist & Writer & Producer
+// Defined with an alias : God
+// It's a way to define a type that is a combination of other types
+// If an Artist is also a Writer and a Producer, it's basically a God of the music
+type God = Singer & Writer & Producer
+
 class Song(
   val title: String,
   val description: Option[String],
-  val artist: List[Artist],
-  val writer: List[Writer],
-  val producer: List[Producer],
+  val singer: List[Artist[Singer]],
+  val writer: List[Artist[Writer]],
+  val producer: List[Artist[Producer]],
   val album: Option[Album],
-  val streak: Streak,
-  val position: Position
+  val rank: Rank
 )
 
 
-object TopSongs {
-  var songs: List[Song] = List()
-  def addSong(song: Song): Unit = {
-    songs = song :: songs
+case class TopSongs(songs: List[Song] = List()) {
+  def addSong(song: Song): TopSongs = {
+    TopSongs(song :: songs)
   }
   def printSongs(): Unit = {
-    songs.foreach(song => println(
-      s"${song.title} by ${song.artist.map(_.name).mkString(", ")} " +
-        s"produced by ${song.producer.map(_.name).mkString(", ")} " +
-        s"spent ${song.streak.streak.getOrElse("no")} weeks " +
-        s"on the charts on Pos. ${song.position.position.getOrElse("NA")}"
-    ))
+    songs.foreach(song => {
+      val title = song.title
+      val singer = song.singer
+      val producers = song.producer.map(_.create()).mkString(", ")
+      val streak = song.rank._1.streak.getOrElse("no")
+      val pos = song.rank._2.pos.getOrElse("NA")
+
+      if (singer.exists(a => {
+        a.isInstanceOf[God]
+      })) {
+        println(s"$title by God ${singer.map(_.person.name).mkString(", ")} spent $streak weeks on the charts on Pos. $pos")
+      } else {
+        println(
+          s"$title by ${singer.map(_.person.name).mkString(", ")}. " +
+            s"$producers this song that " +
+            s"spent $streak weeks " +
+            s"on the charts on Pos. $pos"
+        )
+      }
+
+    })
   }
 }
 
 @main def main(): Unit =
   // create a new TopSongs object
-  val topSongs = TopSongs
+  var topSongs = TopSongs()
 
   val reader = CSVReader.open(new File("src/main/resources/songs.csv"))
   val allRows = reader.allWithHeaders()
   for (row <- allRows) {
+    val title = row("title")
+    val description = row("description")
+    val singer = List(Artist[Singer](Singer(row("artist"))))
+    val writers = List(Artist[Writer](Writer(row("writers"))))
+    val producers = List(Artist[Producer](Producer(row("producer"))))
+    val album = Some(Album(row("appears on"), "NA", null))
+    val rank = (Streak(row("streak")), Position(row("position")))
+
     val s = Song(
-      title = row("title"),
-      description = Some(row("description")),
-      artist = List(Artist(row("artist"))),
-      writer = List(Writer(row("writers"))),
-      producer = List(Producer(row("producer"))),
-      album = Some(Album(row("appears on"), "NA")),
-      streak = Streak(row("streak")),
-      position = Position(row("position"))
+      title = title,
+      description = Some(description),
+      singer = singer,
+      writer = writers,
+      producer = producers,
+      album = album,
+      rank = rank
     )
 
     // add the song to the TopSongs object
-    topSongs.addSong(s)
+    topSongs = topSongs.addSong(s)
   }
   reader.close()
 
+  val foo: Boolean = topSongs.songs.exists(s => s.rank._1.streak.contains(1))
+
   // print the songs
   topSongs.printSongs()