Change websocket handling

With this commit, we stop waiting for the websocket connection to be
established before the game starts.
Now, the Connection type is responsible for waiting for the websocket
connection before writing.

.gitignore

@@ -0,0 +1 @@
+mchess_server

chess/game.go

@@ -2,9 +2,9 @@ package chess
 
 import (
 	"log"
+	"math/rand"
 	"mchess_server/api"
 	"mchess_server/types"
-	"time"
 
 	"github.com/google/uuid"
 )
@@ -18,7 +18,9 @@ type Game struct {
 }
 
 const (
-	PlayerToMove = iota
+	Init = iota
+	Prepare
+	PlayerToMove
 	CheckMove
 	CheckPlayerChange
 )
@@ -27,7 +29,7 @@ func NewGame() *Game {
 	var game = Game{
 		id:        uuid.New(),
 		board:     newBoard(),
-		gameState: PlayerToMove,
+		gameState: Init,
 	}
 	game.board.Init()
 
@@ -42,17 +44,18 @@ func (game Game) GetPlayer1() *Player {
 	return game.players[0]
 }
 
+func (game Game) GetRandomPlayer() *Player {
+	index := rand.Int() % 2
+	return game.players[index]
+}
+
 func (game Game) GetPlayer2() *Player {
 	return game.players[1]
 }
 
 func (game *Game) prepare() {
-	game.currentTurnPlayer = game.GetPlayer1()
-
-	ok := game.waitForWebsocketConnections()
-	if !ok {
-		return
-	}
+	game.players[0].color = types.White
+	game.players[1].color = types.Black
 
 	err := game.notifyPlayersAboutGameStart()
 	if err != nil {
@@ -60,18 +63,32 @@ func (game *Game) prepare() {
 	}
 }
 
+//CHANGES:
+/*
+Do not wait for the players websocket connection before the game.
+Let Connection do it.
+Then here in game handler, just read from Connection (aka messagebuffer) and when data arrives, we read it
+Question: how do we handle connection losses, should game handler observe state of connection and send a notification to the other player when one player is disconnected
+Question: How would reconnect work in this scenario?
+*/
 func (game *Game) Handle() {
 	defer game.killGame()
 
-	game.prepare()
-
 	var receivedMove types.Move
 	var err error
 
 	for {
 		switch game.gameState {
+		case Init:
+			game.currentTurnPlayer = game.GetPlayer1()
+			game.gameState = Prepare
+
+		case Prepare:
+			game.prepare()
+			game.gameState = PlayerToMove
+
 		case PlayerToMove:
-			log.Println("with player ", game.currentTurnPlayer, " to move")
+			log.Println("with ", game.currentTurnPlayer.GetPlayerColor(), " to move")
 			receivedMove, err = game.currentTurnPlayer.ReadMove()
 			if err != nil {
 				log.Println("Error while reading message:", err)
@@ -121,25 +138,6 @@ func (game *Game) killGame() {
 	log.Println("Game should be killed")
 }
 
-func (game *Game) waitForWebsocketConnections() bool {
-	timer := time.NewTimer(5 * time.Second)
-	numberOfConnections := 0
-	waitingForPlayers := make(chan bool)
-
-	go game.GetPlayer1().WaitForWebsocketConnection(waitingForPlayers)
-	go game.GetPlayer2().WaitForWebsocketConnection(waitingForPlayers)
-
-	for numberOfConnections < 2 {
-		select {
-		case <-waitingForPlayers:
-			numberOfConnections++
-		case <-timer.C:
-			return false
-		}
-	}
-	return true
-}
-
 func (game Game) notifyPlayersAboutGameStart() error {
 	colorDeterminedPlayer1, err := api.GetColorDeterminedMessage(types.White)
 	if err != nil {

chess/player.go

@@ -8,34 +8,32 @@ import (
 	"mchess_server/api"
 	conn "mchess_server/connection"
 	"mchess_server/types"
-	"time"
 
 	"github.com/google/uuid"
 	"nhooyr.io/websocket"
 )
 
 type Player struct {
-	Uuid              uuid.UUID
-	Conn              *conn.Connection
-	InGame            bool
-	wsConnEstablished chan bool
-	context           context.Context
+	Uuid   uuid.UUID
+	Conn   *conn.Connection
+	InGame bool
+	color  types.ChessColor
 }
 
 func NewPlayer(uuid uuid.UUID) *Player {
 	return &Player{
-		Uuid:              uuid,
-		Conn:              nil,
-		InGame:            false,
-		wsConnEstablished: make(chan bool),
-		context:           context.Background(),
+		Uuid:   uuid,
+		Conn:   conn.NewConnection(conn.WithContext(context.Background())),
+		InGame: false,
 	}
 }
 
-func (p *Player) SetConnection(ctx context.Context, ws *websocket.Conn) {
-	p.Conn = conn.NewConnection(conn.WithWebsocket(ws), conn.WithContext(p.context))
-	p.context = ctx
-	p.wsConnEstablished <- true
+func (p Player) HasWebsocketConnection() bool {
+	return p.Conn.HasWebsocketConnection()
+}
+
+func (p *Player) SetWebsocketConnection(ctx context.Context, ws *websocket.Conn) {
+	p.Conn.SetWebsocketConnection(ws)
 }
 
 func (p *Player) SendMoveAndPosition(move types.Move, boardPosition string) error {
@@ -58,9 +56,7 @@ func (p *Player) SendMoveAndPosition(move types.Move, boardPosition string) erro
 }
 
 func (p *Player) writeMessage(msg []byte) error {
-	log.Printf("Writing message: %s to player %s", string(msg), p.Uuid.String())
-
-	return p.Conn.Write(p.context, msg)
+	return p.Conn.Write(msg)
 }
 
 func (p *Player) ReadMove() (types.Move, error) {
@@ -83,19 +79,12 @@ func (p *Player) ReadMove() (types.Move, error) {
 }
 
 func (p *Player) readMessage() ([]byte, error) {
-	msg, err := p.Conn.Read(p.context)
+	msg, err := p.Conn.Read()
 	log.Printf("Reading message: %s from player %s", string(msg), p.Uuid.String())
 
 	return msg, err
 }
 
-func (p *Player) WaitForWebsocketConnection(c chan bool) {
-	timer := time.NewTimer(5 * time.Second)
-
-	select {
-	case <-p.wsConnEstablished:
-		c <- true
-	case <-timer.C:
-		return
-	}
+func (p Player) GetPlayerColor() string {
+	return string(p.color)
 }

connection/message_buffer.go

@@ -18,8 +18,7 @@ type message struct {
 }
 
 func newMessageBuffer(size int) *MessageBuffer {
-	mutex := &sync.Mutex{}
-	cond := sync.NewCond(mutex)
+	cond := sync.NewCond(&sync.Mutex{})
 
 	return &MessageBuffer{
 		messages:           make([]message, size),

connection/type.go

@@ -2,34 +2,30 @@ package connection
 
 import (
 	"context"
+	"log"
 
 	"nhooyr.io/websocket"
 )
 
 type Connection struct {
-	ws     *websocket.Conn
-	ctx    context.Context
-	buffer MessageBuffer
+	ws                      *websocket.Conn
+	wsConnectionEstablished chan bool
+	ctx                     context.Context
+	buffer                  MessageBuffer
 }
 
+var dbg_index int
+
 func NewConnection(options ...func(*Connection)) *Connection {
 	connection := Connection{
-		buffer: *newMessageBuffer(100),
+		buffer:                  *newMessageBuffer(100),
+		wsConnectionEstablished: make(chan bool),
 	}
 
 	for _, option := range options {
 		option(&connection)
 	}
 
-	if connection.ws != nil {
-		go func() {
-			for {
-				_, msg, _ := connection.ws.Read(connection.ctx)
-				connection.buffer.Insert(string(msg))
-			}
-		}()
-	}
-
 	return &connection
 }
 
@@ -45,13 +41,43 @@ func WithContext(ctx context.Context) func(*Connection) {
 	}
 }
 
-func (conn *Connection) Write(ctx context.Context, msg []byte) error {
-	return conn.ws.Write(ctx, websocket.MessageText, msg)
+func (conn *Connection) HasWebsocketConnection() bool {
+	return conn.ws != nil
 }
 
-func (conn *Connection) Read(ctx context.Context) ([]byte, error) {
+func (conn *Connection) SetWebsocketConnection(ws *websocket.Conn) {
+	if ws == nil {
+		return
+	}
+
+	conn.ws = ws
+
+	select {
+	case conn.wsConnectionEstablished <- true:
+	default:
+	}
+
+	go func() {
+		for {
+			_, msg, _ := conn.ws.Read(conn.ctx)
+			conn.buffer.Insert(string(msg))
+		}
+	}()
+}
+
+func (conn *Connection) Write(msg []byte) error {
+	if conn.ws == nil { //if ws is not yet set, we wait for it
+		<-conn.wsConnectionEstablished
+	}
+
+	log.Printf("Writing message: %s", string(msg))
+	return conn.ws.Write(conn.ctx, websocket.MessageText, msg)
+}
+
+func (conn *Connection) Read() ([]byte, error) {
 	msg, err := conn.buffer.Get()
 	if err != nil {
+		conn.ws = nil
 		return nil, err // Tell game-handler that connection was lost
 	}
 
@@ -60,4 +86,5 @@ func (conn *Connection) Read(ctx context.Context) ([]byte, error) {
 
 func (conn *Connection) Close(msg string) {
 	conn.ws.Close(websocket.StatusCode(400), msg)
+	conn.ws = nil
 }

main.go

@@ -137,7 +137,7 @@ func waitForAndHandlePlayerID(ctx context.Context, conn *websocket.Conn) {
 		return
 	}
 
-	log.Println("read from websocket: ", msgType, string(msg), err)
+	log.Println("read from websocket endpoint: ", msgType, string(msg), err)
 
 	var info api.PlayerInfo
 	err = json.Unmarshal(msg, &info)
@@ -149,14 +149,18 @@ func waitForAndHandlePlayerID(ctx context.Context, conn *websocket.Conn) {
 	}
 
 	lobby := lobbies.GetLobbyRegistry().GetLobbyByUUID(*info.LobbyID)
+	if lobby == nil {
+		conn.Close(websocket.StatusCode(400), "lobby not found")
+	}
+
 	player, found := lobby.GetPlayerByUUID(*info.PlayerID)
 	if !found {
 		conn.Close(websocket.StatusCode(400), "player not found")
 		return
 	}
-	if player.Conn != nil {
+	if player.Conn.HasWebsocketConnection() {
 		player.Conn.Close("closing existing connection")
 	}
-	player.SetConnection(ctx, conn)
+	player.SetWebsocketConnection(ctx, conn)
 	log.Println("player after setting connection: ", player)
 }