//-----------------------------------------------------------------------------
// PostScreenMenu.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using System;
using System.Collections;
using System.IO;
using System.Text;
using RacingGame.GameLogic;
using RacingGame.Graphics;
using RacingGame.Helpers;
using Texture = RacingGame.Graphics.Texture;

namespace RacingGame.Shaders
{
    /// <summary>
    /// Post screen glow shader based on PostScreenMenu.fx
    /// </summary>
    /// <returns>Shader effect</returns>
    public class PostScreenMenu : ShaderEffect
    {
        /// <summary>
        /// The shader effect filename for this shader.
        /// </summary>
        private const string Filename = "PostScreenMenu.fx";

        /// <summary>
        /// Effect handles for window size and scene map.
        /// </summary>
        protected EffectParameter windowSize,
            sceneMap,
            downsampleMap,
            blurMap1,
            blurMap2,
            noiseMap,
            timer;

        /// <summary>
        /// Links to the passTextures, easier to write code this way.
        /// This are just reference copies. Static to load them only once
        /// (used for both PostScreenMenu and PostScreenGlow).
        /// </summary>
        //dunno why, but RenderToTexture crashes if we do this:
        protected static RenderToTexture sceneMapTexture,
            // Instead load twice:
            //protected RenderToTexture sceneMapTexture = null,
            downsampleMapTexture,
            blurMap1Texture,
            blurMap2Texture;

        /// <summary>
        /// Helper texture for the noise and film effects.
        /// </summary>
        private Texture noiseMapTexture = null;

        /// <summary>
        /// Is this post screen shader started?
        /// Else don't execute Show if it is called.
        /// </summary>
        protected static bool started = false;

        /// <summary>
        /// Started
        /// </summary>
        /// <returns>Bool</returns>
        public static bool Started
        {
            get
            {
                return started;
            }
        }
        /// <summary>
        /// Create post screen menu. Also used for the constructor of
        /// PostScreenGlow (same RenderToTextures used there).
        /// </summary>
        protected PostScreenMenu(string shaderFilename)
            : base(shaderFilename)
        {
            // Scene map texture
            if (sceneMapTexture == null)
                sceneMapTexture = new RenderToTexture(
                    RenderToTexture.SizeType.FullScreen);
            // Downsample map texture (to 1/4 of the screen)
            if (downsampleMapTexture == null)
                downsampleMapTexture = new RenderToTexture(
                    RenderToTexture.SizeType.QuarterScreen);

            // Blur map texture
            if (blurMap1Texture == null)
                blurMap1Texture = new RenderToTexture(
                    RenderToTexture.SizeType.QuarterScreen);
            // Blur map texture
            if (blurMap2Texture == null)
                blurMap2Texture = new RenderToTexture(
                    RenderToTexture.SizeType.QuarterScreen);
        }

        /// <summary>
        /// Create post screen menu
        /// </summary>
        public PostScreenMenu()
            : this(Filename)
        {
        }
        /// <summary>
        /// Reload
        /// </summary>
        protected override void GetParameters()
        {
            // Can't get parameters if loading failed!
            if (effect == null)
                return;

            windowSize = effect.Parameters["windowSize"];
            sceneMap = effect.Parameters["sceneMap"];

            // We need both windowSize and sceneMap.
            if (windowSize == null ||
                sceneMap == null)
                throw new NotSupportedException("windowSize and sceneMap must be " +
                    "valid in PostScreenShader=" + Filename);

            // Init additional stuff
            downsampleMap = effect.Parameters["downsampleMap"];
            blurMap1 = effect.Parameters["blurMap1"];
            blurMap2 = effect.Parameters["blurMap2"];
            timer = effect.Parameters["Timer"];

            // Load noise texture for stripes effect
            noiseMap = effect.Parameters["noiseMap"];
            noiseMapTexture = new Texture("Noise128x128");
            // Set texture
            noiseMap.SetValue(noiseMapTexture.XnaTexture);
        }
        /// <summary>
        /// Start this post screen shader, will just call SetRenderTarget.
        /// All render calls will now be drawn on the sceneMapTexture.
        /// Make sure you don't reset the RenderTarget until you call Show()!
        /// </summary>
        public void Start()
        {
            // Only apply post screen shader if texture is valid and effect is valid 
            if (sceneMapTexture == null ||
                effect == null ||
                started == true ||
                // Also skip if we don't use post screen shaders at all!
                BaseGame.UsePostScreenShaders == false)
                return;

            BaseGame.SetRenderTarget(sceneMapTexture.RenderTarget, true);
            started = true;
        }
        /// <summary>
        /// Execute shaders and show result on screen, Start(..) must have been
        /// called before and the scene should be rendered to sceneMapTexture.
        /// </summary>
        public virtual void Show()
        {
            // Only apply post screen glow if texture is valid and effect is valid 
            if (sceneMapTexture == null ||
                Valid == false ||
                started == false)
                return;

            started = false;

            // Resolve sceneMapTexture render target for Xbox360 support
            sceneMapTexture.Resolve();

            // Don't use or write to the z buffer
            BaseGame.Device.DepthStencilState = DepthStencilState.None;

            // Also don't use any kind of blending.
            BaseGame.Device.BlendState = BlendState.Opaque;

            if (windowSize != null)
                windowSize.SetValue(
                    new Vector2(sceneMapTexture.Width, sceneMapTexture.Height));
            if (sceneMap != null)
                sceneMap.SetValue(sceneMapTexture.XnaTexture);

            if (timer != null)
                // Add a little offset to prevent first effect.
                timer.SetValue(BaseGame.TotalTime + 0.75f);

            effect.CurrentTechnique = effect.Techniques["ScreenGlow20"];

            // We must have exactly 4 passes!
            if (effect.CurrentTechnique.Passes.Count != 4)
                throw new InvalidOperationException(
                    "This shader should have exactly 4 passes!");

            try
            {
                for (int pass = 0; pass < effect.CurrentTechnique.Passes.Count; pass++)
                {
                    if (pass == 0)
                        downsampleMapTexture.SetRenderTarget();
                    else if (pass == 1)
                        blurMap1Texture.SetRenderTarget();
                    else if (pass == 2)
                        blurMap2Texture.SetRenderTarget();
                    else
                    {
                        BaseGame.ResetRenderTarget(true);
                    }

                    EffectPass effectPass = effect.CurrentTechnique.Passes[pass];
                    effectPass.Apply();
                    VBScreenHelper.Render();

                    if (pass == 0)
                    {
                        downsampleMapTexture.Resolve();
                        if (downsampleMap != null)
                            downsampleMap.SetValue(downsampleMapTexture.XnaTexture);
                        effectPass.Apply();
                    }
                    else if (pass == 1)
                    {
                        blurMap1Texture.Resolve();
                        if (blurMap1 != null)
                            blurMap1.SetValue(blurMap1Texture.XnaTexture);
                        effectPass.Apply();
                    }
                    else if (pass == 2)
                    {
                        blurMap2Texture.Resolve();
                        if (blurMap2 != null)
                            blurMap2.SetValue(blurMap2Texture.XnaTexture);
                        effectPass.Apply();
                    }
                }
            }
            finally
            {
                // Restore z buffer state
                BaseGame.Device.DepthStencilState = DepthStencilState.Default;
            }
        }
    }
}