Refactor some of the game handler code

api/move.go

@@ -1,11 +1,33 @@
 package api
 
-type Coordinate struct {
-	Col int `json:"col"`
-	Row int `json:"row"`
+import "local/m/mchess_server/types"
+
+type WebsocketMessage struct {
+	Type  MessageType `json:"messageType"`
+	Move  *types.Move `json:"move,omitempty"`
+	Color *Color      `json:"color,omitempty"`
 }
 
-type Move struct {
-	StartSquare Coordinate `json:"startSquare"`
-	EndSquare   Coordinate `json:"endSquare"`
+type MessageType string
+
+const (
+	MoveMessage     MessageType = "move"
+	ColorDetermined MessageType = "colorDetermined"
+)
+
+type Color string
+
+const (
+	Black Color = "black"
+	White Color = "white"
+)
+
+func (m WebsocketMessage) IsValidMove() bool {
+	if m.Type != MoveMessage {
+		return false
+	}
+	if m.Move == nil {
+		return false
+	}
+	return true
 }

chess/game.go

@@ -3,6 +3,7 @@ package chess
 import (
 	"encoding/json"
 	"local/m/mchess_server/api"
+	"local/m/mchess_server/types"
 	"log"
 	"time"
 
@@ -48,30 +49,26 @@ func (game *Game) Handle() {
 		return
 	}
 
+	err := game.notifyPlayersAboutGameStart()
+	if err != nil {
+		return
+	}
+
 	gameState := PlayerToMove
 	game.currentTurnPlayer = game.GetPlayer1()
-	var move api.Move
-	var receivedMessage []byte
-	var err error
+	var receivedMove types.Move
 
 	for {
 
 		switch gameState {
 		case PlayerToMove:
-			_, receivedMessage, err = game.currentTurnPlayer.ReadMessageFromPlayer()
+			receivedMove, err = game.currentTurnPlayer.ReadMove()
 			if err != nil {
 				log.Println("Error while reading message:", err)
-				// At the moment, we return when there is an error while reading a message.
-				// This means, the game just ends uncontrolled
 				return
 			}
-			err = json.Unmarshal(receivedMessage, &move)
-			log.Println("Player ", game.currentTurnPlayer, " moved:\n", move)
+			log.Println("Player ", game.currentTurnPlayer, " moved:\n", receivedMove)
 
-			if err != nil {
-				log.Println("Game: ", game.id, err)
-				continue
-			}
 			gameState = CheckPlayerChange
 
 		case CheckPlayerChange:
@@ -81,18 +78,13 @@ func (game *Game) Handle() {
 				game.currentTurnPlayer = game.players[0]
 			}
 
-			err := game.GetPlayer1().WriteMessageToPlayer(receivedMessage)
+			err = game.broadcastMove(receivedMove)
 			if err != nil {
-				log.Println("Error during message writing:", err)
-				continue
+				log.Println("Error broadcasting move ", err)
+				return
 			}
-			err = game.GetPlayer2().WriteMessageToPlayer(receivedMessage)
-			if err != nil {
-				log.Println("Error during message writing:", err)
-				continue
-			}
-			gameState = PlayerToMove
 
+			gameState = PlayerToMove
 		}
 
 		log.Println("GameState = ", gameState)
@@ -128,3 +120,35 @@ func (game *Game) waitForWebsocketConnections() bool {
 	}
 	return true
 }
+
+func (game Game) notifyPlayersAboutGameStart() error {
+	white := api.White
+	black := api.Black
+	colorDeterminedPlayer1, err := json.Marshal(api.WebsocketMessage{Type: api.ColorDetermined, Color: &white})
+	if err != nil {
+		log.Println("Error marshalling 'colorDetermined' message for player 1", err)
+		return err
+	}
+	colorDeterminedPlayer2, err := json.Marshal(api.WebsocketMessage{Type: api.ColorDetermined, Color: &black})
+	if err != nil {
+		log.Println("Error marshalling 'colorDetermined' message for player 2", err)
+		return err
+	}
+
+	game.GetPlayer1().writeMessage(colorDeterminedPlayer1)
+	game.GetPlayer2().writeMessage(colorDeterminedPlayer2)
+	return nil
+}
+
+func (game Game) broadcastMove(move types.Move) error {
+	err := game.GetPlayer1().SendMove(move)
+	if err != nil {
+		return err
+	}
+
+	err = game.GetPlayer2().SendMove(move)
+	if err != nil {
+		return err
+	}
+	return nil
+}

chess/player.go

@@ -2,6 +2,10 @@ package chess
 
 import (
 	"context"
+	"encoding/json"
+	"errors"
+	"local/m/mchess_server/api"
+	"local/m/mchess_server/types"
 	"log"
 	"time"
 
@@ -32,15 +36,52 @@ func (p *Player) SetConnection(ctx context.Context, conn *websocket.Conn) {
 	p.wsConnEstablished <- true
 }
 
-func (p *Player) WriteMessageToPlayer(msg []byte) error {
-	log.Printf("Writing message: %s to player %d", string(msg), p.Uuid)
+func (p *Player) SendMove(move types.Move) error {
+	messageToSend, err := json.Marshal(api.WebsocketMessage{
+		Type: api.MoveMessage,
+		Move: &move,
+	})
+	if err != nil {
+		log.Println("Error while marshalling: ", err)
+		return err
+	}
+
+	err = p.writeMessage(messageToSend)
+	if err != nil {
+		log.Println("Error during message writing:", err)
+		return err
+	}
+	return nil
+}
+
+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, websocket.MessageText, msg)
 }
 
-func (p *Player) ReadMessageFromPlayer() (websocket.MessageType, []byte, error) {
+func (p *Player) ReadMove() (types.Move, error) {
+	_, receivedMessage, err := p.readMessage()
+	if err != nil {
+		return types.Move{}, err
+	}
+
+	var msg api.WebsocketMessage
+	err = json.Unmarshal(receivedMessage, &msg)
+	if err != nil {
+		return types.Move{}, err
+	}
+
+	if !msg.IsValidMove() {
+		return types.Move{}, errors.New("not a valid move")
+	}
+
+	return *msg.Move, nil
+}
+
+func (p *Player) readMessage() (websocket.MessageType, []byte, error) {
 	msgType, msg, err := p.Conn.Read(p.context)
-	log.Printf("Reading message: %s (with messagetype %d) from player %d", string(msg), msgType, p.Uuid)
+	log.Printf("Reading message: %s from player %s", string(msg), p.Uuid.String())
 
 	return msgType, msg, err
 }

main.go

@@ -66,7 +66,7 @@ func registerForRandomGame(c *gin.Context) {
 }
 
 func registerWebSocketConnection(c *gin.Context) {
-	webSocketConn, err := websocket.Accept(c.Writer, c.Request, &websocket.AcceptOptions{OriginPatterns: []string{"chess.sw-gross.de"}})
+	webSocketConn, err := websocket.Accept(c.Writer, c.Request, &websocket.AcceptOptions{OriginPatterns: []string{"chess.sw-gross.de", "localhost:*"}})
 	if err != nil {
 		log.Println(err)
 		return

types/chess_types.go

@@ -0,0 +1,11 @@
+package types
+
+type Coordinate struct {
+	Col int `json:"col"`
+	Row int `json:"row"`
+}
+
+type Move struct {
+	StartSquare Coordinate `json:"startSquare"`
+	EndSquare   Coordinate `json:"endSquare"`
+}