using System;

using Microsoft.Xna.Framework.Graphics;



namespace TTengine.Core

{

    /**

     * A Spritelet that supports drawing with a given shader effect applied (HLSL)

     */

    public class EffectSpritelet : Spritelet

    {

        /// <summary>

        /// whether the Effect is used when drawing (true), or not (false).

        /// </summary>

        public bool EffectEnabled = true;



        /// <summary>

        /// the Effect applied (if any)

        /// </summary>

        protected Effect eff = null;



        /// <summary>

        /// filename from which to load .fx Effect (if any)

        /// </summary>

        protected String effectFile = null;



        /// <summary>

        /// Link to certain default parameters in the shader effect

        /// </summary>

        protected EffectParameter timeParam, positionParam;



        /// <summary>

        /// construct with BasicEffect and given texture loaded from content file

        /// </summary>

        /// <param name="textureFile">texture content file</param>

        public EffectSpritelet(String textureFile)

            : base(textureFile)

        {

            this.effectFile = null;

            InitEffect();

        }



        /// <summary>

        /// construct with BasicEffect and given Texture2D

        /// </summary>

        /// <param name="texture">texture content file</param>

        public EffectSpritelet(Texture2D texture)

            : base(texture)

        {

            this.effectFile = null;

            InitEffect();

        }



        /// <summary>

        /// construct with given texture loaded from content file and given shader Effect

        /// </summary>

        /// <param name="textureFile">texture content file</param>

        /// <param name="effectFile">shader effect file</param>

        public EffectSpritelet(String textureFile, String effectFile)

            : base(textureFile)

        {

            this.effectFile = effectFile;

            InitEffect();

        }



        /// <summary>

        /// construct with given Texture2D and shader effect

        /// </summary>

        /// <param name="texture">texture to use</param>

        /// <param name="effectFile">shader effect file to load</param>

        public EffectSpritelet(Texture2D texture, String effectFile)

            : base(texture)

        {

            this.effectFile = effectFile;

            InitEffect();

        }



        /// <summary>

        /// Get reference to the Effect applied

        /// </summary>

        public Effect Eff

        {

            get { return eff; }

        }



        /// <summary>

        /// all Effect initialization goes here

        /// </summary>

        protected virtual void InitEffect()

        {

            if (effectFile != null)

                eff = TTengineMaster.ActiveGame.Content.Load<Effect>(effectFile);

            else

                eff = new BasicEffect(Screen.graphicsDevice);

            VertexShaderInit(eff);



            // find or create my effect-related spritebatch

            MySpriteBatch = Screen.CreateSharedSpriteBatch(eff);



            // try to find common parameters in the Effect (gets null if not found)

            timeParam = eff.Parameters["Time"];

            positionParam = eff.Parameters["Position"];

        }



        protected override void OnDraw(ref DrawParams p)

        {

            if (Texture != null)

            {

                // supply the shader parameters that may have been configured

                // TODO may not be useful with shared spritebatches: whole batch of drawn objects uses latest set shader params only.

                if (timeParam != null)

                    timeParam.SetValue(SimTime);

                if (positionParam != null)

                    positionParam.SetValue(Motion.Position);



                MySpriteBatch.Draw(Texture, DrawInfo.DrawPosition, null, DrawInfo.DrawColor,

                       Motion.RotateAbs, DrawInfo.DrawCenter, DrawInfo.DrawScale, SpriteEffects.None, DrawInfo.LayerDepth);

            }

        }



        public override SpriteBatch MySpriteBatch

        {

            get

            {

                if (EffectEnabled)

                {

                    Screen.UseSharedSpriteBatch(eff);

                    return mySpriteBatch;

                }

                else

                {

                    return Parent.MySpriteBatch;

                }

            }



            set

            {

                Screen.CreateSharedSpriteBatch(eff);

                mySpriteBatch = value;

            }

        }





    }

}