//TODO
//we could flag textures as 'actually' render targets (keep a reference to the render target?) which could allow us to convert between them more quickly in some cases

using System;
using System.IO;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;

using BizHawk.Emulation.Common;
using BizHawk.Client.Common;
using BizHawk.Client.EmuHawk.FilterManager;
using BizHawk.Bizware.BizwareGL;

using OpenTK;

namespace BizHawk.Client.EmuHawk
{
	/// <summary>
	/// A DisplayManager is destined forevermore to drive the PresentationPanel it gets initialized with.
	/// Its job is to receive OSD and emulator outputs, and produce one single buffer (BitampBuffer? Texture2d?) for display by the PresentationPanel.
	/// Details TBD
	/// </summary>
	public class DisplayManager : IDisposable
	{
		class DisplayManagerRenderTargetProvider : IRenderTargetProvider
		{
			DisplayManagerRenderTargetProvider(Func<Size, RenderTarget> callback) { Callback = callback; }
			Func<Size, RenderTarget> Callback;
			RenderTarget IRenderTargetProvider.Get(Size size)
			{
				return Callback(size);
			}
		}

		public DisplayManager(PresentationPanel presentationPanel)
		{
			GL = GlobalWin.GL;
			this.presentationPanel = presentationPanel;
			GraphicsControl = this.presentationPanel.GraphicsControl;
			CR_GraphicsControl = GlobalWin.GLManager.GetContextForGraphicsControl(GraphicsControl);

			//it's sort of important for these to be initialized to something nonzero
			currEmuWidth = currEmuHeight = 1;

			Renderer = new GuiRenderer(GL);

			VideoTextureFrugalizer = new TextureFrugalizer(GL);

			ShaderChainFrugalizers = new RenderTargetFrugalizer[16]; //hacky hardcoded limit.. need some other way to manage these
			for (int i = 0; i < 16; i++)
			{
				ShaderChainFrugalizers[i] = new RenderTargetFrugalizer(GL);
			}

			using (var xml = typeof(Program).Assembly.GetManifestResourceStream("BizHawk.Client.EmuHawk.Resources.courier16px.fnt"))
			using (var tex = typeof(Program).Assembly.GetManifestResourceStream("BizHawk.Client.EmuHawk.Resources.courier16px_0.png"))
				TheOneFont = new StringRenderer(GL, xml, tex);

			var fiHq2x = new FileInfo(Path.Combine(PathManager.GetExeDirectoryAbsolute(),"Shaders/BizHawk/hq2x.cgp"));
			if(fiHq2x.Exists)
				using(var stream = fiHq2x.OpenRead())
					ShaderChain_hq2x = new Filters.RetroShaderChain(GL, new Filters.RetroShaderPreset(stream), Path.Combine(PathManager.GetExeDirectoryAbsolute(), "Shaders/BizHawk"));
			var fiScanlines = new FileInfo(Path.Combine(PathManager.GetExeDirectoryAbsolute(), "Shaders/BizHawk/BizScanlines.cgp"));
			if (fiScanlines.Exists)
				using (var stream = fiScanlines.OpenRead())
					ShaderChain_scanlines = new Filters.RetroShaderChain(GL, new Filters.RetroShaderPreset(stream), Path.Combine(PathManager.GetExeDirectoryAbsolute(), "Shaders/BizHawk"));
			var fiBicubic = new FileInfo(Path.Combine(PathManager.GetExeDirectoryAbsolute(), "Shaders/BizHawk/bicubic-fast.cgp"));
			if (fiBicubic.Exists)
				using (var stream = fiBicubic.OpenRead())
					ShaderChain_bicubic = new Filters.RetroShaderChain(GL, new Filters.RetroShaderPreset(stream), Path.Combine(PathManager.GetExeDirectoryAbsolute(), "Shaders/BizHawk"));

			LuaSurfaceSets["emu"] = new SwappableDisplaySurfaceSet();
			LuaSurfaceSets["native"] = new SwappableDisplaySurfaceSet();
			LuaSurfaceFrugalizers["emu"] = new TextureFrugalizer(GL);
			LuaSurfaceFrugalizers["native"] = new TextureFrugalizer(GL);

			RefreshUserShader();
		}

		public bool Disposed { get; private set; }

		public void Dispose()
		{
			if (Disposed) return;
			Disposed = true;
			VideoTextureFrugalizer.Dispose();
			foreach (var f in LuaSurfaceFrugalizers.Values)
				f.Dispose();
			foreach (var f in ShaderChainFrugalizers)
				if (f != null)
					f.Dispose();
		}

		//dont know what to do about this yet
		public bool NeedsToPaint { get; set; }

		//rendering resources:
		public IGL GL;
		StringRenderer TheOneFont;
		GuiRenderer Renderer;

		//layer resources
		PresentationPanel presentationPanel; //well, its the final layer's target, at least
		GraphicsControl GraphicsControl; //well, its the final layer's target, at least
		GLManager.ContextRef CR_GraphicsControl;
		FilterProgram CurrentFilterProgram;

		/// <summary>
		/// these variables will track the dimensions of the last frame's (or the next frame? this is confusing) emulator native output size
		/// </summary>
		int currEmuWidth, currEmuHeight;

		TextureFrugalizer VideoTextureFrugalizer;
		Dictionary<string, TextureFrugalizer> LuaSurfaceFrugalizers = new Dictionary<string, TextureFrugalizer>();
		RenderTargetFrugalizer[] ShaderChainFrugalizers;
		Filters.RetroShaderChain ShaderChain_hq2x, ShaderChain_scanlines, ShaderChain_bicubic;
		Filters.RetroShaderChain ShaderChain_user;

		public void RefreshUserShader()
		{
			if (ShaderChain_user != null)
				ShaderChain_user.Dispose();
			if (File.Exists(Global.Config.DispUserFilterPath))
			{
				var fi = new FileInfo(Global.Config.DispUserFilterPath);
				using (var stream = fi.OpenRead())
					ShaderChain_user = new Filters.RetroShaderChain(GL, new Filters.RetroShaderPreset(stream), Path.GetDirectoryName(Global.Config.DispUserFilterPath));
			}
		}

		FilterProgram BuildDefaultChain(Size chain_insize, Size chain_outsize)
		{
			//select user special FX shader chain
			Dictionary<string, object> selectedChainProperties = new Dictionary<string, object>();
			Filters.RetroShaderChain selectedChain = null;
			if (Global.Config.TargetDisplayFilter == 1 && ShaderChain_hq2x != null && ShaderChain_hq2x.Available)
				selectedChain = ShaderChain_hq2x;
			if (Global.Config.TargetDisplayFilter == 2 && ShaderChain_scanlines != null && ShaderChain_scanlines.Available)
			{
				//shader.Pipeline["uIntensity"].Set(1.0f - Global.Config.TargetScanlineFilterIntensity / 256.0f);
				selectedChain = ShaderChain_scanlines;
				selectedChainProperties["uIntensity"] = 1.0f - Global.Config.TargetScanlineFilterIntensity / 256.0f;
			}
			if (Global.Config.TargetDisplayFilter == 3 && ShaderChain_user != null && ShaderChain_user.Available)
				selectedChain = ShaderChain_user;

			Filters.FinalPresentation fPresent = new Filters.FinalPresentation(chain_outsize);
			Filters.SourceImage fInput = new Filters.SourceImage(chain_insize);
			Filters.OSD fOSD = new Filters.OSD();
			fOSD.RenderCallback = () =>
			{
				var size = fOSD.FindInput().SurfaceFormat.Size;
				Renderer.Begin(size.Width, size.Height);
				MyBlitter myBlitter = new MyBlitter(this);
				myBlitter.ClipBounds = new Rectangle(0, 0, size.Width, size.Height);
				Renderer.SetBlendState(GL.BlendNormal);
				GlobalWin.OSD.Begin(myBlitter);
				GlobalWin.OSD.DrawScreenInfo(myBlitter);
				GlobalWin.OSD.DrawMessages(myBlitter);
				Renderer.End();
			};

			var chain = new FilterProgram();

			//add the first filter, encompassing output from the emulator core
			chain.AddFilter(fInput, "input");

			//add lua layer 'emu'
			AppendLuaLayer(chain, "emu");

			//add user-selected retro shader
			if (selectedChain != null)
				AppendRetroShaderChain(chain, "retroShader", selectedChain, selectedChainProperties);

			//choose final filter
			Filters.FinalPresentation.eFilterOption finalFilter = Filters.FinalPresentation.eFilterOption.None;
			if (Global.Config.DispFinalFilter == 1) finalFilter = Filters.FinalPresentation.eFilterOption.Bilinear;
			if (Global.Config.DispFinalFilter == 2) finalFilter = Filters.FinalPresentation.eFilterOption.Bicubic;
			//if bicubic is selected and unavailable, dont use it
			if (!ShaderChain_bicubic.Available && fPresent.FilterOption == Filters.FinalPresentation.eFilterOption.Bicubic)
			{
				finalFilter = Filters.FinalPresentation.eFilterOption.None;
			}
			fPresent.FilterOption = finalFilter;

			//now if bicubic is chosen, insert it
			if (finalFilter == Filters.FinalPresentation.eFilterOption.Bicubic)
				AppendRetroShaderChain(chain, "bicubic", ShaderChain_bicubic, null);

			//add final presentation 
			chain.AddFilter(fPresent, "presentation");

			//add lua layer 'native'
			AppendLuaLayer(chain, "native");

			//and OSD goes on top of that
			chain.AddFilter(fOSD, "osd");

			return chain;
		}

		void AppendRetroShaderChain(FilterProgram program, string name, Filters.RetroShaderChain retroChain, Dictionary<string, object> properties)
		{
			for (int i = 0; i < retroChain.Passes.Length; i++)
			{
				var pass = retroChain.Passes[i];
				var rsp = new Filters.RetroShaderPass(retroChain, i);
				string fname = string.Format("{0}[{1}]", name, i);
				program.AddFilter(rsp, fname);
				rsp.Parameters = properties;
			}
		}

		Filters.LuaLayer AppendLuaLayer(FilterProgram chain, string name)
		{
			Texture2d luaNativeTexture = null;
			var luaNativeSurface = LuaSurfaceSets[name].GetCurrent();
			if (luaNativeSurface == null)
				return null;
			luaNativeTexture = LuaSurfaceFrugalizers[name].Get(luaNativeSurface);
			var fLuaLayer = new Filters.LuaLayer();
			fLuaLayer.SetTexture(luaNativeTexture);
			chain.AddFilter(fLuaLayer, name);
			return fLuaLayer;
		}

		/// <summary>
		/// Using the current filter program, turn a mouse coordinate from window space to the original emulator screen space.
		/// </summary>
		public Point UntransformPoint(Point p)
		{
			//first, turn it into a window coordinate
			p = presentationPanel.Control.PointToClient(p);
			
			//now, if theres no filter program active, just give up
			if (CurrentFilterProgram == null) return p;
			
			//otherwise, have the filter program untransform it
			Vector2 v = new Vector2(p.X, p.Y);
			v = CurrentFilterProgram.UntransformPoint("default",v);
			return new Point((int)v.X, (int)v.Y);
		}


		/// <summary>
		/// This will receive an emulated output frame from an IVideoProvider and run it through the complete frame processing pipeline
		/// Then it will stuff it into the bound PresentationPanel.
		/// ---
		/// If the int[] is size=1, then it contains an openGL texture ID (and the size should be as specified from videoProvider)
		/// Don't worry about the case where the frontend isnt using opengl; it isnt supported yet, and it will be my responsibility to deal with anyway
		/// </summary>
		public void UpdateSource(IVideoProvider videoProvider)
		{
			var job = new JobInfo
			{
				videoProvider = videoProvider,
				simulate = false,
				chain_outsize = GraphicsControl.Size
			};
			UpdateSourceInternal(job);
		}

		public BitmapBuffer RenderOffscreen(IVideoProvider videoProvider)
		{
			var job = new JobInfo
			{
				videoProvider = videoProvider,
				simulate = false,
				chain_outsize = GraphicsControl.Size,
				offscreen = true
			};
			UpdateSourceInternal(job);
			return job.offscreenBB;
		}		

		class FakeVideoProvider : IVideoProvider
		{
			public int[] GetVideoBuffer() { return new int[] {}; }

			public int VirtualWidth { get; set; }
			public int VirtualHeight { get; set; }

			public int BufferWidth { get; set; }
			public int BufferHeight { get; set; }
			public int BackgroundColor { get; set; }
		}

		/// <summary>
		/// Attempts to calculate a good client size with the given zoom factor, considering the user's DisplayManager preferences
		/// </summary>
		public Size CalculateClientSize(IVideoProvider videoProvider, int zoom)
		{
			var fvp = new FakeVideoProvider ();
			fvp.BufferWidth = videoProvider.BufferWidth;
			fvp.BufferHeight = videoProvider.BufferHeight;
			fvp.VirtualWidth = videoProvider.VirtualWidth;
			fvp.VirtualHeight = videoProvider.VirtualHeight;

			Size chain_outsize = new Size(fvp.BufferWidth * zoom, fvp.BufferHeight * zoom);

			//zero 27-may-2014 - this code is now slightly suspicious.. but no proof we need to get rid of it
			//zero 02-jun-2014 - now, I suspect it is more important
			if (Global.Config.DispObeyAR && Global.Config.DispFixAspectRatio)
			  chain_outsize = new Size(fvp.VirtualWidth * zoom, fvp.VirtualHeight * zoom);

			var job = new JobInfo
			{
				videoProvider = fvp,
				simulate = true,
				chain_outsize = chain_outsize
			};
			var filterProgram = UpdateSourceInternal(job);

			var size = filterProgram.Filters[filterProgram.Filters.Count - 1].FindOutput().SurfaceFormat.Size;
			
			//zero 22-may-2014 - added this to combat problem where nes would default to having sidebars
			//this would use the actual chain output size. this is undesireable, in the following scenario:
			//load a nes game at 2x with system-preferred and integer AR enabled, and there will be sidebars.
			//the sidebars were created by this, so we can peek into it and remove the sidebars.
			//Only do this if integer fixing is enabled, since only in that case do we have discardable sidebars.
			//Otherwise discarding the 'sidebars' would result in cropping image. 
			//This is getting complicated..
			if (Global.Config.DispFixScaleInteger)
			{
				var fp = filterProgram["presentation"] as Filters.FinalPresentation;
				size = fp.GetContentSize();
			}

			return size;
		}

		class JobInfo
		{
			public IVideoProvider videoProvider;
			public bool simulate;
			public Size chain_outsize;
			public bool offscreen;
			public BitmapBuffer offscreenBB;
		}

		FilterProgram UpdateSourceInternal(JobInfo job)
		{
			GlobalWin.GLManager.Activate(CR_GraphicsControl);

			IVideoProvider videoProvider = job.videoProvider;
			bool simulate = job.simulate;
			Size chain_outsize = job.chain_outsize;
			
			int vw = videoProvider.BufferWidth;
			int vh = videoProvider.BufferHeight;

			if (Global.Config.DispObeyAR && Global.Config.DispFixAspectRatio)
			{
			  vw = videoProvider.VirtualWidth;
			  vh = videoProvider.VirtualHeight;
			}

			int[] videoBuffer = videoProvider.GetVideoBuffer();
			
TESTEROO:
			int bufferWidth = videoProvider.BufferWidth;
			int bufferHeight = videoProvider.BufferHeight;
			bool isGlTextureId = videoBuffer.Length == 1;


			BitmapBuffer bb = null;
			Texture2d videoTexture = null;
			if (!simulate)
			{
				if (isGlTextureId)
				{
					videoTexture = GL.WrapGLTexture2d(new IntPtr(videoBuffer[0]), bufferWidth, bufferHeight);
				}
				else
				{
					//wrap the videoprovider data in a BitmapBuffer (no point to refactoring that many IVideoProviders)
					bb = new BitmapBuffer(bufferWidth, bufferHeight, videoBuffer);

					//now, acquire the data sent from the videoProvider into a texture
					videoTexture = VideoTextureFrugalizer.Get(bb);
					GL.SetTextureWrapMode(videoTexture, true);
				}

				//TEST (to be removed once we have an actual example of bring in a texture ID from opengl emu core):
				if (!isGlTextureId)
				{
					videoBuffer = new int[1] { videoTexture.Id.ToInt32() };
					goto TESTEROO;
				}
			}

			//record the size of what we received, since lua and stuff is gonna want to draw onto it
			currEmuWidth = bufferWidth;
			currEmuHeight = bufferHeight;

			//build the default filter chain and set it up with services filters will need
			Size chain_insize = new Size(bufferWidth, bufferHeight);

			var filterProgram = BuildDefaultChain(chain_insize, chain_outsize);
			filterProgram.GuiRenderer = Renderer;
			filterProgram.GL = GL;

			//setup the source image filter
			Filters.SourceImage fInput = filterProgram["input"] as Filters.SourceImage;
			fInput.Texture = videoTexture;
			
			//setup the final presentation filter
			Filters.FinalPresentation fPresent = filterProgram["presentation"] as Filters.FinalPresentation;
			fPresent.VirtualTextureSize = new Size(vw, vh);
			fPresent.TextureSize = new Size(bufferWidth, bufferHeight);
			fPresent.BackgroundColor = videoProvider.BackgroundColor;
			fPresent.GuiRenderer = Renderer;
			fPresent.GL = GL;

			filterProgram.Compile("default", chain_insize, chain_outsize, !job.offscreen);

			if (simulate)
			{
			}
			else
			{
				CurrentFilterProgram = filterProgram;
				UpdateSourceDrawingWork(job);
			}

			//cleanup:
			if (bb != null) bb.Dispose();

			return filterProgram;
		}

		void UpdateSourceDrawingWork(JobInfo job)
		{
			//begin rendering on this context
			//should this have been done earlier?
			//do i need to check this on an intel video card to see if running excessively is a problem? (it used to be in the FinalTarget command below, shouldnt be a problem)
			//GraphicsControl.Begin();

			//run filter chain
			Texture2d texCurr = null;
			RenderTarget rtCurr = null;
			int rtCounter = 0;
			bool inFinalTarget = false;
			foreach (var step in CurrentFilterProgram.Program)
			{
				switch (step.Type)
				{
					case FilterProgram.ProgramStepType.Run:
						{
							int fi = (int)step.Args;
							var f = CurrentFilterProgram.Filters[fi];
							f.SetInput(texCurr);
							f.Run();
							var orec = f.FindOutput();
							if (orec != null)
							{
								if (orec.SurfaceDisposition == SurfaceDisposition.Texture)
								{
									texCurr = f.GetOutput();
									rtCurr = null;
								}
							}
							break;
						}
					case FilterProgram.ProgramStepType.NewTarget:
						{
							var size = (Size)step.Args;
							rtCurr = ShaderChainFrugalizers[rtCounter++].Get(size);
							rtCurr.Bind();
							CurrentFilterProgram.CurrRenderTarget = rtCurr;
							break;
						}
					case FilterProgram.ProgramStepType.FinalTarget:
						{
							var size = (Size)step.Args;
							inFinalTarget = true;
							rtCurr = null;
							CurrentFilterProgram.CurrRenderTarget = null;
							GL.BindRenderTarget(null);
							break;
						}
				}
			}

			if (job.offscreen)
			{
				job.offscreenBB = rtCurr.Texture2d.Resolve();
			}
			else
			{
				Debug.Assert(inFinalTarget);
				//apply the vsync setting (should probably try to avoid repeating this)
				bool vsync = Global.Config.VSyncThrottle || Global.Config.VSync;
				if (LastVsyncSetting != vsync || LastVsyncSettingGraphicsControl != presentationPanel.GraphicsControl)
				{
					presentationPanel.GraphicsControl.SetVsync(vsync);
					LastVsyncSettingGraphicsControl = presentationPanel.GraphicsControl;
					LastVsyncSetting = vsync;
				}

				//present and conclude drawing
				presentationPanel.GraphicsControl.SwapBuffers();

				//nope. dont do this. workaround for slow context switching on intel GPUs. just switch to another context when necessary before doing anything
				//presentationPanel.GraphicsControl.End();

				NeedsToPaint = false; //??
			}
		}

		bool? LastVsyncSetting;
		GraphicsControl LastVsyncSettingGraphicsControl;

		Dictionary<string, DisplaySurface> MapNameToLuaSurface = new Dictionary<string,DisplaySurface>();
		Dictionary<DisplaySurface, string> MapLuaSurfaceToName = new Dictionary<DisplaySurface, string>();
		Dictionary<string, SwappableDisplaySurfaceSet> LuaSurfaceSets = new Dictionary<string, SwappableDisplaySurfaceSet>();
		SwappableDisplaySurfaceSet luaNativeSurfaceSet = new SwappableDisplaySurfaceSet();
		public void SetLuaSurfaceNativePreOSD(DisplaySurface surface) { luaNativeSurfaceSet.SetPending(surface); }

		/// <summary>
		/// Peeks a locked lua surface, or returns null if it isnt locked
		/// </summary>
		public DisplaySurface PeekLockedLuaSurface(string name)
		{
			if (MapNameToLuaSurface.ContainsKey(name))
				return MapNameToLuaSurface[name];
			return null;
		}

		/// <summary>
		/// Locks the requested lua surface name
		/// </summary>
		public DisplaySurface LockLuaSurface(string name)
		{
			if (MapNameToLuaSurface.ContainsKey(name))
				throw new InvalidOperationException("Lua surface is already locked: " + name);

			SwappableDisplaySurfaceSet sdss;
			if (!LuaSurfaceSets.TryGetValue(name, out sdss))
			{
				sdss = new SwappableDisplaySurfaceSet();
				LuaSurfaceSets.Add(name, sdss);
			}

			//placeholder logic for more abstracted surface definitions from filter chain
			int currNativeWidth = presentationPanel.NativeSize.Width;
			int currNativeHeight = presentationPanel.NativeSize.Height;

			int width,height;
			if(name == "emu") { width = currEmuWidth; height = currEmuHeight; }
			else if(name == "native") { width = currNativeWidth; height = currNativeHeight; }
			else throw new InvalidOperationException("Unknown lua surface name: " +name);

			DisplaySurface ret = sdss.AllocateSurface(width, height);
			MapNameToLuaSurface[name] = ret;
			MapLuaSurfaceToName[ret] = name;
			return ret;
		}

		public void ClearLuaSurfaces()
		{
			foreach (var kvp in LuaSurfaceSets)
			{
				var surf = PeekLockedLuaSurface(kvp.Key);
				DisplaySurface surfLocked = null;
				if (surf == null)
					surf = surfLocked = LockLuaSurface(kvp.Key);
				surf.Clear();
				if(surfLocked != null)
					UnlockLuaSurface(surfLocked);
				LuaSurfaceSets[kvp.Key].SetPending(null);
			}
		}

		/// <summary>
		/// Unlocks this DisplaySurface which had better have been locked as a lua surface
		/// </summary>
		public void UnlockLuaSurface(DisplaySurface surface)
		{
			if (!MapLuaSurfaceToName.ContainsKey(surface))
				throw new InvalidOperationException("Surface was not locked as a lua surface");
			string name = MapLuaSurfaceToName[surface];
			MapLuaSurfaceToName.Remove(surface);
			MapNameToLuaSurface.Remove(name);
			LuaSurfaceSets[name].SetPending(surface);
		}

		//helper classes:

		class MyBlitter : IBlitter
		{
			DisplayManager Owner;
			public MyBlitter(DisplayManager dispManager)
			{
				Owner = dispManager;
			}

			class FontWrapper : IBlitterFont
			{
				public FontWrapper(StringRenderer font)
				{
					this.font = font;
				}

				public readonly StringRenderer font;
			}

	
			IBlitterFont IBlitter.GetFontType(string fontType) { return new FontWrapper(Owner.TheOneFont); }
			void IBlitter.DrawString(string s, IBlitterFont font, Color color, float x, float y)
			{
				var stringRenderer = ((FontWrapper)font).font;
				Owner.Renderer.SetModulateColor(color);
				stringRenderer.RenderString(Owner.Renderer, x, y, s);
				Owner.Renderer.SetModulateColorWhite();
			}
			SizeF IBlitter.MeasureString(string s, IBlitterFont font)
			{
				var stringRenderer = ((FontWrapper)font).font;
				return stringRenderer.Measure(s);
			}
			public Rectangle ClipBounds { get; set; }
		}

		
	}

}