Delimiter of every parameter is '|'.
Indicator of the end of the message is '\n'.
Prorocol message pattern is <userId>|<REQUEST_TYPE>|<parameter1>|<parameter2>|...>
Request does not end with a delimiter.
If the request is not according to the basics of the protocol - userId or request type or delimiters missing, too many or few parameters, response with 450 error code is returned.
Every user is represented by his userId assigned to him and chosen nickname.

Request to log user into the server with given nickname. Only users, who are not logged in may request to login. Nickname is limited to a-zA-Z0-9 characters and to maximum of 20 characters.

<userId>|CONNECT|<nickname>\n

• userId = 0 => new connection or reconnect, based on nickname
• userId <> 0 => invalid

200|<userId>\n - new connection ok
201|<userId>\n - reconnection ok
400\n - invalid nickname
401\n - invalid userId
402\n - cannot reconnect (not disconnected, nick already used)

Request to logout the player with given user ID. User will not be disconnected. Only existing users in lobby can logout.

<userId>|LOGOUT\n

202\n - logout ok
403\n - user non-existent
404\n - user cannot logout (in a game maybe, has to leave the game first)

Request to get all games waiting for second player to join. Only logged in players can request game list.

<userId>|GET_GAMES\n

203|<nickname>|<nickname>...\n - request ok, parameters are nicknames of the players waiting to be joined
405\n - user not logged in, cannot request games

Request to create a new game. Requesting player will be set as the first player, waiting for second to join. Only players in lobby may request creating new game.

<userId>|CREATE_GAME\n

204\n - ok, new game created and joined
406\n - cannot create new game, not in lobby
407\n - cannot create new game, not logged in

When new game is created, every client in lobby gets response from server:
250|<nickname>\n - nickname is the nick of player who is in the game, waiting to be joined

<userId>|EXIT_GAME\n

205\n - ok, left the game
408\n - cannot leave game, not logged in
409\n - cannot leave game, not in a game

When player, who created new game, exits the game during waiting for opponent to join, every client in lobby gets response from server:
260|<nickname>\n - nickname is the nick of player who left the game, waiting to be joined
When player leaves running game, opponent receives 280\n response, meaning that he won and will be removed from the game.
When client crashes unexpectedly or is disconnected due to too many invalid requests, the player's state is set to disconnected and if he is in the game, the game is paused and the opponent receives 290\n response, meaning that the opponent has lost connection.

<userId>|JOIN_GAME|<nickname>\n - nickname stands for nickname of opponent to be joined

206\n - ok, game joined and started Joining player is always player number two.
Player who was waiting to be joined, receives 270\n response and should request a game state
410\n - cannot join game, not logged in
411\n - cannot join game, invalid state (only players in lobby may join a game)
412\n - cannot join game, waiting game with player with given nick non existent

<userId>|GET_GAME_STATE\n - request to get the state of the game (token position) we are currently in

207|<playerOneNick>,<token1PosX>,<token1PosY>,<token2PosX>,<token2PosY>...|<playerTwoNick>,...|<playerOnTurnNick>\n - as a response, player s will receive nickname of player one, positions of all his tokens and the same respectively for player two.
Player one is considered to be the player at the bottom part of the table, player two as the top one. The player, who creates the game, is always player number one.
413\n - cannot get game state, not logged in
414\n - cannot get game state, not in a running game

<userId>|TURN|<fromX>,<fromY>|<toX><toY> - comma separated values are X,Y coordinates of source and destination position where player wants to move.

208|<playerOneNick>,<token1PosX>,<token1PosY>,<token2PosX>,<token2PosY>...|<playerTwoNick>,...\n - as a response, player receives current state of the game. This response is also sent to the opponent, signalling that he is on turn. If this turn was the winning turn, meaning that opponent's last token was removed, 210\n response is sent to both players instead, signalling the end of the game.