Online Circular Chess in Silverlight, ASP.NET AJAX, WCF Web Services, and LINQ to SQL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using System.ServiceModel.Activation;
using System.Web;

namespace CChess
{
    [DataContract(Name = "CChessGameColors", Namespace = "")]
    public enum CChessGameColors : byte
    {
        [EnumMember()]
        White = 1,
        [EnumMember()]
        Black
    }

    [DataContract(Name = "CChessGameStates", Namespace = "")]
    public enum CChessGameStates : byte
    {
        [EnumMember()]
        NotStarted = 1,
        [EnumMember()]
        OnGoing,
        [EnumMember()]
        Finished
    }

    [AspNetCompatibilityRequirements(
        RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class CChessService : ICChessService
    {

        #region Authentication Region

        public void Login(CChessPlayer new_player)
        {
            CChessDataContext cdc = new CChessDataContext();

            new_player.last_activity = UnixDate.GetCurrentUnixTimestamp();
            //CChessPlayer new_player = new CChessPlayer() { player_nick = nickname, last_activity = UnixDate.GetCurrentUnixTimestamp() };
            cdc.CChessPlayers.InsertOnSubmit(new_player);
            cdc.SubmitChanges();
            // Store the player in his profile
            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            profile.CChessPlayer = new_player;
        }

        public void UpdateUserActivity()
        {
            CChessPlayer player = ((ProfileCommon)HttpContext.Current.Profile).CChessPlayer;
            if (player == null)
            {
                throw new Exception("You're not online.");
            }

            CChessDataContext cdc = new CChessDataContext();

            // Now, the reason I've used a stored procedure instead of standard Linq
            // is because in order to get player to be traced by the DataContext,
            // I'd need to select it again, and then update it. In this case, a 
            // standard stored procedure is a far better option (I'd even say
            // an easier solution).
            int affected_rows = cdc.UpdateUserActivity(player.player_id, UnixDate.GetCurrentUnixTimestamp());
            if (affected_rows < 1)
            {
                throw new Exception("Unable to update activity.");
            }
        }

        public List<CChessPlayer> GetOnlineUsers()
        {
            CChessDataContext cdc = new CChessDataContext();

            return cdc.GetOnlinePlayers(CChessPlayer.LEGAL_INACTIVITY_SECONDS, UnixDate.GetCurrentUnixTimestamp()).ToList<CChessPlayer>();
        }

        #endregion

        #region Chat Region

        public List<ChatMessage> GetLastNMessages(int n)
        {
            CChessDataContext cdc = new CChessDataContext();
            List<ChatMessage> messages = (from msgs in cdc.ChatMessages
                              orderby msgs.message_id descending
                              select msgs).Take(n).ToList();

            return messages;
        }

        public void SendMessage(String content)
        {
            CChessPlayer current_player = ((ProfileCommon)HttpContext.Current.Profile).CChessPlayer;
            if (current_player == null)
            {
                return;
            }

            ChatMessage msg = new ChatMessage
            {
                message_writer = current_player.player_id,
                message_content = content,
                sent_timestamp = UnixDate.GetCurrentUnixTimestamp()
            };
            CChessDataContext cdc = new CChessDataContext();
            cdc.ChatMessages.InsertOnSubmit(msg);
            cdc.SubmitChanges();
        }

        public List<ChatMessage> GetNewMessages(int last_msg_id)
        {
            CChessDataContext cdc = new CChessDataContext();

            var messages = (from msgs in cdc.ChatMessages
                            where msgs.message_id > last_msg_id
                            select msgs);

            return messages.ToList<ChatMessage>();
        }

        #endregion

        #region Circular Chess Region

        public void CreateNewGame(CChessGameColors starting_color)
        {
            CChessDataContext cdc = new CChessDataContext();
            CChessGame new_game = new CChessGame() { game_state = (byte)CChessGameStates.NotStarted };
            
            CChessPlayer current_player = ((ProfileCommon)HttpContext.Current.Profile).CChessPlayer;
            CChessGamesPlayers new_game_player = new CChessGamesPlayers() 
            { 
                game_id = new_game.game_id, 
                player_id = current_player.player_id, 
                color = (byte)starting_color
            };

            new_game.CChessGamesPlayers.Add(new_game_player);

            cdc.CChessGames.InsertOnSubmit(new_game);
            cdc.SubmitChanges();

            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            profile.CChessGameID = new_game.game_id;
        }

        public List<CChessGamesPlayers> GetCurrentGamePlayers()
        {
            CChessDataContext cdc = new CChessDataContext();

            List<CChessGamesPlayers> current_game_players = (from games_players in cdc.CChessGamesPlayers
                                                             where UnixDate.GetCurrentUnixTimestamp() - games_players.CChessPlayer.last_activity < CChessPlayer.LEGAL_INACTIVITY_SECONDS
                                                             orderby games_players.game_id
                                                             select games_players).ToList();

            return current_game_players;
        }

        public void AddToGame(long game_id, CChessGameColors color)
        {
            CChessDataContext cdc = new CChessDataContext();

            CChessGamesPlayers new_player = new CChessGamesPlayers()
            {
                game_id = game_id,
                player_id = ((ProfileCommon)HttpContext.Current.Profile).CChessPlayer.player_id,
                color = (byte)color
            };

            cdc.CChessGamesPlayers.InsertOnSubmit(new_player);
            cdc.SubmitChanges();

            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            profile.CChessGameID = game_id;
        }

        public CChessGamesPlayers GetYou()
        {
            CChessDataContext cdc = new CChessDataContext();
            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            CChessGamesPlayers you = cdc.CChessGamesPlayers.Single(p => p.player_id == profile.CChessPlayer.player_id && p.game_id == profile.CChessGameID);
            return you;
        }

        public CChessGamesPlayers GetOpponent()
        {
            CChessDataContext cdc = new CChessDataContext();
            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            CChessGamesPlayers players = cdc.CChessGamesPlayers.FirstOrDefault(p =>
                (p.player_id != profile.CChessPlayer.player_id) &&
                (p.game_id == profile.CChessGameID) &&
                (UnixDate.GetCurrentUnixTimestamp() - p.CChessPlayer.last_activity < CChessPlayer.LEGAL_INACTIVITY_SECONDS));
            return players;
        }

        /// <summary>
        /// Submits a move to the database after checking it's valid
        /// </summary>
        /// <returns>The id of the move (mostly because I get an error in Silverlight if I return null)</returns>
        public long MovePiece(CChessMove move)
        {
            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;
            CChessDataContext cdc = new CChessDataContext();

            if (move.player_id == profile.CChessPlayer.player_id &&
                cdc.CChessGamesPlayers.Contains(new CChessGamesPlayers()
                {
                    player_id = move.player_id,
                    game_id = move.game_id
                }))
            {
                CChessBoard board = new CChessBoard();
                List<CChessMove> moves = GetAllMoves(move.game_id);
                foreach (CChessMove curr_move in moves)
                {
                    board.MovePiece(curr_move.piece_id, curr_move.destination_ring, curr_move.destination_square);
                }
                board.MovePiece(move.piece_id, move.destination_ring, move.destination_square);

                cdc.CChessMoves.InsertOnSubmit(move);
                cdc.SubmitChanges();

                return move.move_id;
            }
            else
            {
                throw new Exception("You're not allowed to move in this game.");
            }
        }

        public CChessMove GetLastMove(long last_move_id)
        {
            CChessDataContext cdc = new CChessDataContext();
            ProfileCommon profile = (ProfileCommon)HttpContext.Current.Profile;

            // Get the last move of the current game, where the id is greater 
            // than the last move gotten
            CChessMove last_move = cdc.CChessMoves.Where(m => m.game_id == profile.CChessGameID && m.move_id > last_move_id).OrderByDescending(m => m.move_id).FirstOrDefault();

            return last_move;
        }

        public List<CChessMove> GetAllMoves(long game_id)
        {
            CChessDataContext cdc = new CChessDataContext();

            List<CChessMove> game_moves = (from m in cdc.CChessMoves
                                           where m.game_id == game_id
                                           orderby m.move_id ascending
                                           select m).ToList();

            return game_moves;
        }

        #endregion
    }
}