using System;
using System.Diagnostics;

namespace SpaceInvaders
{
    public class GameContext
    {
        //-------------------------------------------------------------------
        //  FIELDS
        //-------------------------------------------------------------------

        static GameContext poInstance = null;
        readonly State pStateAttract;
        State pCurrState;

        bool isTwoPlayer;
        int highscore;


        //-------------------------------------------------------------------
        //  PRIVATE CONSTRUCTION
        //-------------------------------------------------------------------

        private GameContext()
        {            
            this.pStateAttract = new State_Attract();
            Debug.Assert(this.pStateAttract != null);
            this.pStateAttract.SetContext(this);

            this.pCurrState = this.pStateAttract;

            this.isTwoPlayer = false;
            this.highscore = 0;
        }


        //-------------------------------------------------------------------
        //  PUBLIC METHODS
        //-------------------------------------------------------------------

        public bool GetPlayMode()
        {
            return this.isTwoPlayer;
        }

        public void ChangeState(State newState)
        {
            Debug.Assert(this.pCurrState != null);
            Debug.Assert(newState != null);

            this.pCurrState.OnExit();

            this.pCurrState = newState;
            this.pCurrState.OnEnter();
        }

        public void Restart()
        {
            Debug.Assert(this.pStateAttract != null);
            ((State_Attract)this.pStateAttract).Reset();

            this.ChangeState(this.pStateAttract);
        }

        public void UpdateHighScore(int newScore)
        {
            if(this.highscore < newScore)
            {
                // save new score
                this.highscore = newScore;

                Font pFont = FontMan.FindFont(Font.FontName.HighScore);
                pFont.UpdateMessage(this.highscore.ToString("D4"));
            }
        }

        public int GetHighScore()
        {
            return this.highscore;
        }


        //-------------------------------------------------------------------
        //  PUBLIC STATIC METHODS
        //-------------------------------------------------------------------

        public static void Create()
        {
            if(GameContext.poInstance == null)
            {
                GameContext.poInstance = new GameContext();
                Debug.Assert(GameContext.poInstance != null);
            }

            GameContext.poInstance.pStateAttract.Init();
            GameContext.poInstance.pStateAttract.OnEnter();
        }

        public static void SetPlayMode(bool isTwoPlayer)
        {
            GameContext context = GameContext.GetInstance();
            Debug.Assert(context != null);

            //do we have two players?
            context.isTwoPlayer = isTwoPlayer;
        }

        public static State GetCurrState()
        {
            GameContext context = GameContext.GetInstance();
            Debug.Assert(context != null);

            return context.pCurrState;
        }

        public static void ResetLevel()
        {
            GameContext context = GameContext.GetInstance();
            Debug.Assert(context != null);

            Debug.Assert(context.pCurrState != null);
            ((State_Play)context.pCurrState).ResetLevel();
        }

        public static void Update(float sysTime)
        {
            GameContext context = GameContext.GetInstance();
            Debug.Assert(context != null);

            context.pCurrState.Update(sysTime);
        }

        public static void Draw()
        {
            GameContext context = GameContext.GetInstance();
            Debug.Assert(context != null);

            context.pCurrState.Draw();
        }


        //-------------------------------------------------------------------
        //  PRIVATE METHODS
        //-------------------------------------------------------------------

        private static GameContext GetInstance()
        {
            if(GameContext.poInstance == null)
            {
                GameContext.Create();
                Debug.Assert(GameContext.poInstance != null);
            }

            return GameContext.poInstance;
        }


    } // end class

} // end namespace