implement game turn logic

game-server/internal/protocol/protocol.go

@@ -12,8 +12,10 @@
 //	3  S->C  STATE       [3, <seq>, <state_code>]
 //	4  C<->S ACK         [4, <seq>]
 //	5  C->S  PLACE_SHIPS [5, ship0_orientation, ship0_x, ship0_y, ...]
+//	6  C->S  FIRE        [6, <x>, <y>]
+//	7  S->C  FIRE_RESULT [7, <seq>, <result_code>]
 //
-// Every state-changing server->client message (END, STATE) carries a
+// Every state-changing server->client message (END, STATE, FIRE_RESULT) carries a
 // per-player monotonically increasing sequence number. The client confirms
 // delivery with an ACK message containing the sequence number of the last
 // received message (ACK is cumulative). Unacknowledged messages are kept in
@@ -36,6 +38,8 @@ const (
 	OpState      = 3 // S->C: game state transition
 	OpAck        = 4 // C<->S: delivery acknowledgement
 	OpPlaceShips = 5 // C->S: ship placement
+	OpFire       = 6 // C->S: fire shot
+	OpFireResult = 7 // S->C: shot result
 )
 
 // Board and ship configuration constants.
@@ -89,9 +93,19 @@ const (
 	StateWaitOpponentTurn  = 5 // wait for the opponent's move
 )
 
+// Shot result codes for FIRE_RESULT (OpFireResult).
+const (
+	FireResultMiss            = 1 // miss (промах)
+	FireResultHit             = 2 // hit (простое попадание)
+	FireResultSunk            = 3 // ship sunk (корабль потоплен)
+	FireResultInvalidPosition = 4 // invalid position (неверная позиция)
+)
+
 // Match end codes.
 const (
 	EndCodeJoinTimeout = -1 // the second player never joined
+	EndCodeVictory     = 1  // you won (all opponent ships sunk)
+	EndCodeDefeat      = 2  // you lost (all your ships sunk)
 )
 
 // WebSocket close codes used by the server (application range 4000+ and RFC 6455 codes).
@@ -275,3 +289,42 @@ func BuildPlaceShips(ships []Ship) []byte {
 	}
 	return build(v)
 }
+
+// ParseFire extracts the x and y coordinates from FIRE arguments.
+func ParseFire(args []json.RawMessage) (x, y int, err error) {
+	if len(args) != 2 {
+		return 0, 0, fmt.Errorf("FIRE expects 2 arguments, got %d", len(args))
+	}
+	if err := json.Unmarshal(args[0], &x); err != nil {
+		return 0, 0, fmt.Errorf("x coordinate is not an integer: %w", err)
+	}
+	if err := json.Unmarshal(args[1], &y); err != nil {
+		return 0, 0, fmt.Errorf("y coordinate is not an integer: %w", err)
+	}
+	return x, y, nil
+}
+
+// BuildFire builds a FIRE message: [6, x, y].
+func BuildFire(x, y int) []byte {
+	return build([]any{OpFire, x, y})
+}
+
+// ParseFireResult extracts seq and result code from FIRE_RESULT arguments.
+func ParseFireResult(args []json.RawMessage) (seq int64, result int, err error) {
+	if len(args) != 2 {
+		return 0, 0, fmt.Errorf("FIRE_RESULT expects 2 arguments, got %d", len(args))
+	}
+	if err := json.Unmarshal(args[0], &seq); err != nil {
+		return 0, 0, fmt.Errorf("seq is not a number: %w", err)
+	}
+	if err := json.Unmarshal(args[1], &result); err != nil {
+		return 0, 0, fmt.Errorf("result is not a number: %w", err)
+	}
+	return seq, result, nil
+}
+
+// BuildFireResult builds a FIRE_RESULT message: [7, seq, result].
+func BuildFireResult(seq int64, result int) []byte {
+	return build([]any{OpFireResult, seq, result})
+}
+