#region ================== Copyright (c) 2007 Pascal vd Heiden

/*
 * Copyright (c) 2007 Pascal vd Heiden, www.codeimp.com
 * This program is released under GNU General Public License
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 */

#endregion

#region ================== Namespaces

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using CodeImp.DoomBuilder.Data;
using CodeImp.DoomBuilder.Map;

#endregion

namespace CodeImp.DoomBuilder.Rendering
{
	internal class SurfaceManager : IRenderResource
	{
		#region ================== Constants
		
		// The true maximum lies at 65535 if I remember correctly, but that
		// is a scary big number for a vertexbuffer.
		private const int MAX_VERTICES_PER_BUFFER = 30000;
		
		// When a sector exceeds this number of vertices, it should split up it's triangles
		// This number must be a multiple of 3.
		public const int MAX_VERTICES_PER_SECTOR = 6000;
		
		#endregion
		
		#region ================== Variables
		
		// Set of buffers for a specific number of vertices per sector
		private Dictionary<int, SurfaceBufferSet> sets;
		
		// List of buffers that are locked
		// This is null when not in the process of updating
		private List<VertexBuffer> lockedbuffers;
		
		// Surface to be rendered.
		// Each BinaryHeap in the Dictionary contains all geometry that needs
		// to be rendered with the associated ImageData.
		// The BinaryHeap sorts the geometry by sector to minimize stream switchs.
		// This is null when not in the process of rendering
		private Dictionary<ImageData, List<SurfaceEntry>> surfaces;
		
		// This is 1 to add the number of vertices to the offset
		// (effectively rendering the ceiling vertices instead of floor vertices)
		private int surfacevertexoffsetmul;
		
		// This is set to true when the resources have been unloaded
		private bool resourcesunloaded;

		#endregion

		#region ================== Properties

		#endregion

		#region ================== Constructor / Disposer
		
		// Constructor
		public SurfaceManager()
		{
			sets = new Dictionary<int, SurfaceBufferSet>();
			lockedbuffers = new List<VertexBuffer>();

			General.Map.Graphics.RegisterResource(this);
		}
		
		// Disposer
		public void Dispose()
		{
			if(sets != null)
			{
				General.Map.Graphics.UnregisterResource(this);
				
				// Dispose all sets
				foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
				{
					// Dispose vertex buffers
					for(int i = 0; i < set.Value.buffers.Count; i++)
					{
						if(set.Value.buffers[i] != null)
						{
							set.Value.buffers[i].Dispose();
							set.Value.buffers[i] = null;
						}
					}
				}
				
				sets = null;
			}
		}
		
		#endregion

		#region ================== Management

		// Called when all resource must be unloaded
		public void UnloadResource()
		{
			resourcesunloaded = true;
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				// Dispose vertex buffers
				for(int i = 0; i < set.Value.buffers.Count; i++)
				{
					if(set.Value.buffers[i] != null)
					{
						set.Value.buffers[i].Dispose();
						set.Value.buffers[i] = null;
					}
				}
			}
			
			lockedbuffers.Clear();
		}

		// Called when all resource must be reloaded
		public void ReloadResource()
		{
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				// Rebuild vertex buffers
				for(int i = 0; i < set.Value.buffersizes.Count; i++)
				{
					// Make the new buffer!
					VertexBuffer b = new VertexBuffer();
                    General.Map.Graphics.SetBufferData(b, set.Value.buffersizes[i], VertexFormat.Flat);

                    // Start refilling the buffer with sector geometry
                    foreach (SurfaceEntry e in set.Value.entries)
					{
						if(e.bufferindex == i)
						{
                            General.Map.Graphics.SetBufferSubdata(b, e.vertexoffset, e.floorvertices);
                            General.Map.Graphics.SetBufferSubdata(b, e.vertexoffset + e.floorvertices.Length, e.ceilvertices);
						}
					}

					// Add to list
					set.Value.buffers[i] = b;
				}
			}
			
			resourcesunloaded = false;
		}
		
		// This resets all buffers and requires all sectors to get new entries
		public void Reset()
		{
			// Clear all items
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				foreach(SurfaceEntry entry in set.Value.entries)
				{
					entry.numvertices = -1;
					entry.bufferindex = -1;
				}
				
				foreach(SurfaceEntry entry in set.Value.holes)
				{
					entry.numvertices = -1;
					entry.bufferindex = -1;
				}

				foreach(VertexBuffer vb in set.Value.buffers)
					vb.Dispose();
			}

			// New dictionary
			sets = new Dictionary<int, SurfaceBufferSet>();
		}

		// Updating sector surface geometry should go in this order;
		// - Triangulate sectors
		// - Call FreeSurfaces to remove entries that have changed number of vertices
		// - Call AllocateBuffers
		// - Call UpdateSurfaces to add/update entries
		// - Call UnlockBuffers
		
		// This (re)allocates the buffers based on an analysis of the map
		// The map must be updated (triangulated) before calling this
		public void AllocateBuffers()
		{
			// Make analysis of sector geometry
			Dictionary<int, int> sectorverts = new Dictionary<int, int>();
			foreach(Sector s in General.Map.Map.Sectors)
			{
				if(s.Triangles != null)
				{
					int numvertices = s.Triangles.Vertices.Count;
					while(numvertices > 0)
					{
						// Determine for how many vertices in this entry
						int vertsinentry = (numvertices > MAX_VERTICES_PER_SECTOR) ? MAX_VERTICES_PER_SECTOR : numvertices;
						
						// We count the number of sectors that have specific number of vertices
						if(!sectorverts.ContainsKey(vertsinentry))
							sectorverts.Add(vertsinentry, 0);
						sectorverts[vertsinentry]++;

						numvertices -= vertsinentry;
					}
				}
			}
			
			// Now (re)allocate the needed buffers
			foreach(KeyValuePair<int, int> sv in sectorverts)
			{
				// Zero vertices can't be drawn
				if(sv.Key > 0)
				{
					SurfaceBufferSet set = GetSet(sv.Key);
					
					// Calculte how many free entries we need
					int neededentries = sv.Value;
					int freeentriesneeded = neededentries - set.entries.Count;

					// Allocate the space needed
					EnsureFreeBufferSpace(set, freeentriesneeded);
				}
			}
		}

		// This ensures there is enough space for a given number of free entries (also adds new bufers if needed)
		private void EnsureFreeBufferSpace(SurfaceBufferSet set, int freeentries)
		{
			VertexBuffer vb = null;
			
			// Check if we have to add entries
			int addentries = freeentries - set.holes.Count;

			// Begin resizing buffers starting with the last in this set
			int bufferindex = set.buffers.Count - 1;

			// Calculate the maximum number of entries we can put in a new buffer
			// Note that verticesperentry is the number of vertices multiplied by 2, because
			// we have to store both the floor and ceiling
			int verticesperentry = set.numvertices * 2;
			int maxentriesperbuffer = MAX_VERTICES_PER_BUFFER / verticesperentry;

			// Make a new bufer when the last one is full
			if((bufferindex > -1) && (set.buffersizes[bufferindex] >= (maxentriesperbuffer * verticesperentry)))
				bufferindex = -1;
			
			while(addentries > 0)
			{
				// Create a new buffer?
				if((bufferindex == -1) || (bufferindex > (set.buffers.Count - 1)))
				{
					// Determine the number of entries we will be making this buffer for
					int bufferentries = (addentries > maxentriesperbuffer) ? maxentriesperbuffer : addentries;

					// Calculate the number of vertices that will be
					int buffernumvertices = bufferentries * verticesperentry;

					if(!resourcesunloaded)
					{
						// Make the new buffer!
						vb = new VertexBuffer();
                        General.Map.Graphics.SetBufferData(vb, buffernumvertices, VertexFormat.Flat);

						// Add it.
						set.buffers.Add(vb);
					}
					else
					{
						// We can't make a vertexbuffer right now
						set.buffers.Add(null);
					}
					
					// Also add available entries as holes, because they are not used yet.
					set.buffersizes.Add(buffernumvertices);
					for(int i = 0; i < bufferentries; i++)
						set.holes.Add(new SurfaceEntry(set.numvertices, set.buffers.Count - 1, i * verticesperentry));

					// Done
					addentries -= bufferentries;
				}
				// Reallocate a buffer
				else
				{
					if((set.buffers[bufferindex] != null) && !resourcesunloaded)
						set.buffers[bufferindex].Dispose();

					// Get the entries that are in this buffer only
					List<SurfaceEntry> theseentries = new List<SurfaceEntry>();
					foreach(SurfaceEntry e in set.entries)
					{
						if(e.bufferindex == bufferindex)
							theseentries.Add(e);
					}

					// Determine the number of entries we will be making this buffer for
					int bufferentries = ((theseentries.Count + addentries) > maxentriesperbuffer) ? maxentriesperbuffer : (theseentries.Count + addentries);

					// Calculate the number of vertices that will be
					int buffernumvertices = bufferentries * verticesperentry;

					if(!resourcesunloaded)
					{
						// Make the new buffer and lock it
						vb = new VertexBuffer();
                        General.Map.Graphics.SetBufferData(vb, buffernumvertices, VertexFormat.Flat);
                    }

                    // Start refilling the buffer with sector geometry
                    int vertexoffset = 0;
					foreach(SurfaceEntry e in theseentries)
					{
						if(!resourcesunloaded)
						{
							// Fill buffer
							General.Map.Graphics.SetBufferSubdata(vb, vertexoffset, e.floorvertices);
							General.Map.Graphics.SetBufferSubdata(vb, vertexoffset + e.floorvertices.Length, e.ceilvertices);
						}

						// Set the new location in the buffer
						e.vertexoffset = vertexoffset;

						// Move on
						vertexoffset += verticesperentry;
					}

					if(!resourcesunloaded)
					{
						set.buffers[bufferindex] = vb;
					}
					else
					{
						// No vertex buffer at this time, sorry
						set.buffers[bufferindex] = null;
					}

					// Set the new buffer and add available entries as holes, because they are not used yet.
					set.buffersizes[bufferindex] = buffernumvertices;
					set.holes.Clear();
					for(int i = 0; i < bufferentries - theseentries.Count; i++)
						set.holes.Add(new SurfaceEntry(set.numvertices, bufferindex, i * verticesperentry + vertexoffset));

					// Done
					addentries -= bufferentries;
				}

				// Always continue in next (new) buffer
				bufferindex = set.buffers.Count;
			}
		}
		
		// This adds or updates sector geometry into a buffer.
		// Modiies the list of SurfaceEntries with the new surface entry for the stored geometry.
		public void UpdateSurfaces(SurfaceEntryCollection entries, SurfaceUpdate update)
		{
			// Free entries when number of vertices has changed
			if((entries.Count > 0) && (entries.totalvertices != update.numvertices))
			{
				FreeSurfaces(entries);
				entries.Clear();
			}
			
			if((entries.Count == 0) && (update.numvertices > 0))
			{
				#if DEBUG
				if((update.floorvertices == null) || (update.ceilvertices == null))
					General.Fail("We need both floor and ceiling vertices when the number of vertices changes!");
				#endif
				
				// If we have no entries yet, we have to make them now
				int vertsremaining = update.numvertices;
				while(vertsremaining > 0)
				{
					// Determine for how many vertices in this entry
					int vertsinentry = (vertsremaining > MAX_VERTICES_PER_SECTOR) ? MAX_VERTICES_PER_SECTOR : vertsremaining;

					// Lookup the set that holds entries for this number of vertices
					SurfaceBufferSet set = GetSet(vertsinentry);

					// Make sure we can get a new entry in this set
					EnsureFreeBufferSpace(set, 1);

					// Get a new entry in this set
					SurfaceEntry e = set.holes[set.holes.Count - 1];
					set.holes.RemoveAt(set.holes.Count - 1);
					set.entries.Add(e);
					
					// Fill the entry data
					e.floorvertices = new FlatVertex[vertsinentry];
					e.ceilvertices = new FlatVertex[vertsinentry];
					Array.Copy(update.floorvertices, update.numvertices - vertsremaining, e.floorvertices, 0, vertsinentry);
					Array.Copy(update.ceilvertices, update.numvertices - vertsremaining, e.ceilvertices, 0, vertsinentry);
					e.floortexture = update.floortexture;
					e.ceiltexture = update.ceiltexture;
					e.hidden = update.hidden;
                    e.desaturation = update.desaturation;
					
					entries.Add(e);
					vertsremaining -= vertsinentry;
				}
			}
			else
			{
				// We re-use the same entries, just copy over the updated data
				int vertsremaining = update.numvertices;
				foreach(SurfaceEntry e in entries)
				{
					if(update.floorvertices != null)
					{
						Array.Copy(update.floorvertices, update.numvertices - vertsremaining, e.floorvertices, 0, e.numvertices);
						e.floortexture = update.floortexture;
					}

					if(update.ceilvertices != null)
					{
						Array.Copy(update.ceilvertices, update.numvertices - vertsremaining, e.ceilvertices, 0, e.numvertices);
						e.ceiltexture = update.ceiltexture;
					}

					e.hidden = update.hidden;
                    e.desaturation = update.desaturation;

                    vertsremaining -= e.numvertices;
				}
			}

			entries.totalvertices = update.numvertices;
			
			// Time to update or create the buffers
			foreach(SurfaceEntry e in entries)
			{
				SurfaceBufferSet set = GetSet(e.numvertices);

				// Update bounding box
				e.UpdateBBox();
				
				if(!resourcesunloaded)
				{
					VertexBuffer vb = set.buffers[e.bufferindex];
                    General.Map.Graphics.SetBufferSubdata(vb, e.vertexoffset, e.floorvertices);
                    General.Map.Graphics.SetBufferSubdata(vb, e.vertexoffset + e.floorvertices.Length, e.ceilvertices);
				}
			}
		}

		// This frees the given surface entry
		public void FreeSurfaces(SurfaceEntryCollection entries)
		{
			foreach(SurfaceEntry e in entries)
			{
				if((e.numvertices > 0) && (e.bufferindex > -1))
				{
					SurfaceBufferSet set = sets[e.numvertices];
					set.entries.Remove(e);
					SurfaceEntry newentry = new SurfaceEntry(e);
					set.holes.Add(newentry);
				}
				e.numvertices = -1;
				e.bufferindex = -1;
			}
		}
		
		// This unlocks the locked buffers
		public void UnlockBuffers()
		{
			if(!resourcesunloaded)
			{
				// Clear list
				lockedbuffers = new List<VertexBuffer>();
			}
		}
		
		// This gets or creates a set for a specific number of vertices
		private SurfaceBufferSet GetSet(int numvertices)
		{
			SurfaceBufferSet set;
			
			// Get or create the set
			if(!sets.ContainsKey(numvertices))
			{
				set = new SurfaceBufferSet();
				set.numvertices = numvertices;
				set.buffers = new List<VertexBuffer>();
				set.buffersizes = new List<int>();
				set.entries = new List<SurfaceEntry>();
				set.holes = new List<SurfaceEntry>();
				sets.Add(numvertices, set);
			}
			else
			{
				set = sets[numvertices];
			}

			return set;
		}
		
		#endregion
		
		#region ================== Rendering
		
		// This renders all sector floors
		internal void RenderSectorFloors(RectangleF viewport, bool skipHidden)
		{
			surfaces = new Dictionary<ImageData, List<SurfaceEntry>>();
			surfacevertexoffsetmul = 0;
			
			// Go for all surfaces as they are sorted in the buffers, so that
			// they are automatically already sorted by vertexbuffer
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				foreach(SurfaceEntry entry in set.Value.entries)
				{
					if(SurfaceEntryIsVisible(entry, viewport, skipHidden))
						AddSurfaceEntryForRendering(entry, entry.floortexture);
				}
			}
		}
		
		// This renders all sector ceilings
		internal void RenderSectorCeilings(RectangleF viewport, bool skipHidden)
		{
			surfaces = new Dictionary<ImageData, List<SurfaceEntry>>();
			surfacevertexoffsetmul = 1;
			
			// Go for all surfaces as they are sorted in the buffers, so that
			// they are automatically already sorted by vertexbuffer
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				foreach(SurfaceEntry entry in set.Value.entries)
				{
					if(SurfaceEntryIsVisible(entry, viewport, skipHidden))
						AddSurfaceEntryForRendering(entry, entry.ceiltexture);
				}
			}
		}

		// This renders all sector brightness levels
		internal void RenderSectorBrightness(RectangleF viewport, bool skipHidden)
		{
			surfaces = new Dictionary<ImageData, List<SurfaceEntry>>();
			surfacevertexoffsetmul = 0;
			
			// Go for all surfaces as they are sorted in the buffers, so that
			// they are automatically already sorted by vertexbuffer
			foreach(KeyValuePair<int, SurfaceBufferSet> set in sets)
			{
				foreach(SurfaceEntry entry in set.Value.entries)
				{
					if(SurfaceEntryIsVisible(entry, viewport, skipHidden))
						AddSurfaceEntryForRendering(entry, 0);
				}
			}
		}

		// Checks to see if a particular surface entry is visible in the viewport
		private bool SurfaceEntryIsVisible(SurfaceEntry entry, RectangleF viewport, bool skipHidden)
		{
			if (skipHidden && entry.hidden)
				return false;

			return entry.bbox.IntersectsWith(viewport);
		}

		// This adds a surface entry to the list of surfaces
		private void AddSurfaceEntryForRendering(SurfaceEntry entry, long longimagename)
		{
			// Determine texture to use
			ImageData img;
			if(longimagename == 0)
			{
				img = General.Map.Data.WhiteTexture;
			}
			else
			{
				if(longimagename == MapSet.EmptyLongName) 
				{
					img = General.Map.Data.MissingTexture3D;
				}
				else 
				{
					img = General.Map.Data.GetFlatImage(longimagename);

					if(img is UnknownImage)
					{
						img = General.Map.Data.UnknownTexture3D;
					}
					else
					{
						if(!img.IsImageLoaded || img.LoadFailed) 
						{
							img = General.Map.Data.WhiteTexture;
						}
					}
				}
			}
			
			// Store by texture
			if(!surfaces.ContainsKey(img)) surfaces.Add(img, new List<SurfaceEntry>());
			surfaces[img].Add(entry);
		}
		
		// This renders the sorted sector surfaces
		internal void RenderSectorSurfaces(RenderDevice graphics)
		{
			if(!resourcesunloaded)
			{
				ShaderName pass = Renderer.FullBrightness ? ShaderName.display2d_fullbright : ShaderName.display2d_normal; //mxd
				foreach(KeyValuePair<ImageData, List<SurfaceEntry>> imgsurfaces in surfaces)
				{
                    graphics.SetShader(pass);
                    graphics.SetTexture(imgsurfaces.Key.Texture);
					
					// Go for all surfaces
					VertexBuffer lastbuffer = null;
					foreach(SurfaceEntry entry in imgsurfaces.Value)
					{
                        graphics.SetUniform(UniformName.desaturation, (float)entry.desaturation);
                        
						// Set the vertex buffer
						SurfaceBufferSet set = sets[entry.numvertices];
						if(set.buffers[entry.bufferindex] != lastbuffer)
						{
							lastbuffer = set.buffers[entry.bufferindex];
							graphics.SetVertexBuffer(lastbuffer);
						}

						// Draw
						graphics.Draw(PrimitiveType.TriangleList, entry.vertexoffset + (entry.numvertices * surfacevertexoffsetmul), entry.numvertices / 3);
					}
				}
                graphics.SetUniform(UniformName.desaturation, 0.0f);
            }
		}
		
		#endregion
	}
}