1 files changed, 195 insertions, 0 deletions
diff --git a/src/scalevalapokalypsi/Server/Server.scala b/src/scalevalapokalypsi/Server/Server.scala
new file mode 100644
index 0000000..13ca2f5
--- /dev/null
+++ b/src/scalevalapokalypsi/Server/Server.scala
@@ -0,0 +1,195 @@
+package scalevalapokalypsi.Server
+
+
+// TODO: TLS/SSL / import javax.net.ssl.SSLServerSocketFactory
+
+import java.lang.Thread.{currentThread, sleep}
+import java.io.IOException
+import java.net.{ServerSocket, Socket}
+import scalevalapokalypsi.constants.*
+import scalevalapokalypsi.Model.{Adventure,Entity,Player}
+import scalevalapokalypsi.utils.stringToByteArray
+
+import java.lang.System.currentTimeMillis
+import scala.util.Try
+
+
+/** `Server` exists to initialize a server for the game
+  *  and run it with its method `startServer`.
+  *
+  * @param port the TCP port the server should listen on
+  * @param maxClients the maximum number of clients that may be in the game
+  *                   simultaneously.
+  * @param timeLimit the time limit clients should have to execute their turns.
+  * @param joinAfterStart whether new clients are accepted after the game has
+  *                       been started
+  */
+class Server(
+	port: Int,
+	maxClients: Int,
+	val timeLimit: Int,
+	val joinAfterStart: Boolean
+):
+
+	private val socket = ServerSocket(port)
+	private val clientGetter = ConnectionGetter(socket)
+	private val clients: Clients = Clients(maxClients)
+	private val buffer: Array[Byte] = Array.ofDim(1024)
+	private var bufferIndex = 0
+	private var adventure: Option[Adventure] = None
+	private var previousTurn = 0.0
+
+	/** Starts the server. Won't terminate under normal circumstances. */
+	def startServer(): Unit =
+		while true do
+			this.serverStep()
+			sleep(POLL_INTERVAL)
+
+	private def serverStep(): Unit =
+		this.clients.removeNonCompliant()
+		if this.adventure.isEmpty || this.joinAfterStart then
+			this.receiveNewClient()
+		this.readFromAll()
+		this.clients.foreach(_.interpretData())
+		this.writeClientDataToClients()
+		this.writeObservations()
+		if this.canExecuteTurns then
+			this.clients.inRandomOrder(_.act())
+			this.writeClientDataToClients()
+			this.writeObservations()
+			this.clients.foreach(c =>
+				this.writeToClient(this.turnStartInfo(c), c)
+			)
+			this.previousTurn = currentTimeMillis() / 1000
+		if this.adventure.isDefined && this.joinAfterStart then
+			this.clients.foreach( c => if c.isReadyForGameStart then
+				this.adventure.foreach(a =>
+					c.getName.foreach(n => a.addPlayer(n))
+				)
+				startGameForClient(c)
+			)
+		else if this.adventure.isEmpty && !this.clients.isEmpty && this.clients.forall(_.isReadyForGameStart) then
+			this.adventure = Some(Adventure(this.clients.names))
+			this.clients.foreach(startGameForClient(_))
+			this.previousTurn = currentTimeMillis() / 1000
+
+	/** Helper function to start the game for the specified client c.
+	  * MAY ONLY BE USED IF `this.adventure` is Some!
+	  * Apparently guard clauses are bad because they use return or something,
+	  * but assertions should be fine, as long as they enforce the function
+	  * contract?
+	  */
+	private def startGameForClient(c: Client): Unit =
+		assert(this.adventure.isDefined)
+		c.gameStart()
+		val name = c.getName
+
+		val playerEntity: Option[Player] = name match
+			case Some(n) => this.adventure match
+				case Some(a) => a.getPlayer(n)
+				case None => None
+			case None => None
+		playerEntity.foreach(c.givePlayer(_))
+
+		this.writeToClient(
+			s"$timeLimit\r\n${this.turnStartInfo(c)}", c
+		)
+
+		this.clients.foreach(c =>
+			if c.player != playerEntity then
+				c.player.foreach(_.observe(s"${name.getOrElse("Unknown player")} joins the game."))
+		)
+
+	
+	private def writeObservations(): Unit =
+		this.clients.foreach(c =>
+			val observations = c.player.map(_.readAndClearObservations())
+			observations.foreach(_.foreach((s: String) =>
+				this.writeToClient(s"$ACTION_NONBLOCKING_INDICATOR$s\r\n", c))
+			)
+		)
+
+	/** Helper function to determine if the next turn can be taken */
+	private def canExecuteTurns: Boolean =
+		val requirement1 = this.adventure.isDefined
+		val requirement2 = !this.clients.isEmpty // nice! you can just return
+		                                         // to the game after everyone
+		                                         // left and everything is just
+		                                         // as before!
+		val allPlayersReady = this.clients.forall(_.isReadyToAct)
+		val requirement3 = (allPlayersReady
+			|| currentTimeMillis() / 1000 >= previousTurn + timeLimit)
+		requirement1 && requirement2 && requirement3
+
+
+	/** Receives a new client and stores it in `clients`.
+	  *
+	  * @return describes if a client was added
+	  */
+	private def receiveNewClient(): Boolean =
+		this.clientGetter.newClient() match
+			case Some(c) =>
+				clients.addClient(Client(c))
+				true
+			case None =>
+				false
+
+	private def turnStartInfo(client: Client): String =
+		val clientArea = client.player.map(_.location)
+		val areaDesc = clientArea
+			.map(_.description)
+			.getOrElse("You are floating in the middle of a soothing void.")
+		val directions = clientArea
+			.map(_.getNeighborNames.mkString(LIST_SEPARATOR))
+			.getOrElse("")
+		val items = clientArea
+			.map(_.getItemNames.mkString(LIST_SEPARATOR))
+			.getOrElse("")
+		val entities = client.player.map(c =>
+			c.location
+				.getEntityNames
+				.filter(c.name != _)
+				.mkString(LIST_SEPARATOR)
+		).getOrElse("")
+		s"$TURN_INDICATOR\r\n$areaDesc\r\n$directions\r\n$items\r\n$entities\r\n"
+
+	/** Sends `message` to all clients
+	  *
+	  * @param message the message to send
+	  */
+	private def writeToAll(message: String): Unit =
+		this.clients.mapAndRemove(c =>
+			val output = c.socket.getOutputStream
+			output.write(stringToByteArray(message))
+			output.flush()
+		)
+
+	private def writeToClient(message: String, client: Client): Unit =
+		try {
+			val output = client.socket.getOutputStream
+			output.write(stringToByteArray(message))
+			output.flush()
+		} catch {
+			case e: IOException => client.failedProtocol()
+		}
+
+	/** Sends every client's `dataToThisClient` to the client */
+	private def writeClientDataToClients(): Unit =
+		this.clients.mapAndRemove(c =>
+			val output = c.socket.getOutputStream
+			val data = c.dataToThisClient()
+			output.write(stringToByteArray(data))
+			output.flush()
+		)
+
+	/** Reads data sent by clients and stores it in the `Client`s of `clients` */
+	private def readFromAll(): Unit =
+		clients.mapAndRemove(c =>
+			val input = c.socket.getInputStream
+			while input.available() != 0 do
+				val bytesRead = input.read(buffer)
+				if bytesRead != -1 then
+					c.receiveData(buffer.take(bytesRead).toVector)
+		)
+
+end Server