using System;
using System.Linq;
using NJDOTNET.Trivia.Exceptions;

namespace NJDOTNET.Trivia
{
    /// <summary>
    /// <c ref="GameController">GameController</c> is a base implementation of an IGameController
    /// which takes care of most of the basic/typical behaviors.
    /// </summary>
    public abstract class GameController : IGameController
    {
        protected readonly Game game;

        private GameStatus _Status = GameStatus.PlayerRegistration;
        /// <summary>
        /// Gets or sets the current game status.
        /// </summary>
        /// <value>The current game status.</value>
        public virtual GameStatus Status
        {
            get { return _Status; }
            internal set { _Status = value; }
        }

        protected virtual bool CanStart
        {
            get 
            { 
                // Make sure the game is not already in progress
                // and that we've got some players registered.
                // (there's nothing more boring than a game without players...)
                return 
                       Status != GameStatus.InProgress
                    && game.Players.Count() > 0; 
            }
        }
        protected virtual bool CanEnd
        {
            get { return Status == GameStatus.InProgress; }
        }


        public event EventHandler<EventArgs<Question>> OnNextQuestion;
        public event EventHandler<EventArgs<Game>> OnGameStarted;
        public event EventHandler<EventArgs<GameSummary>> OnGameEnded;

        protected GameController(Game game)
        {
            this.game = game;
        }

        public GameSummary GenerateGameSummary()
        {
            return new GameSummary(game);
        }

        public void AddPlayer(Player player)
        {
            if (Status == GameStatus.PlayerRegistration)
                game.AddPlayer(player);
            else
                throw new PlayerRegistrationClosedException();
        }

        public virtual void Start()
        {
            // If we're not in the right state to start right now,
            // boot 'em out (and not very nicely)
            if (!CanStart)
                throw new InvalidStateException();

            Status = GameStatus.InProgress;

            if (OnGameStarted != null)
                OnGameStarted(this, new EventArgs<Game>(game));
        }

        public virtual void End()
        {
            // If we're not in the right state to end right now,
            // boot 'em out (and not very nicely)
            if (!CanEnd)
                throw new InvalidStateException();

            Status = GameStatus.Ended;

            if (OnGameEnded != null)
                OnGameEnded(this, new EventArgs<GameSummary>(GenerateGameSummary()));
        }

        protected virtual void TriggerNextQuestion(Question question)
        {
            if (OnNextQuestion != null)
                OnNextQuestion(this, new EventArgs<Question>(question));
        }

    }

}