using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Globalization;
using System.IO;
using System.Text;
using CodeImp.DoomBuilder.Data;
using CodeImp.DoomBuilder.Geometry;
using CodeImp.DoomBuilder.Map;
using CodeImp.DoomBuilder.Rendering;
using CodeImp.DoomBuilder.Windows;

namespace CodeImp.DoomBuilder.BuilderModes.IO
{
	internal struct WavefrontExportSettings
	{
		public string Obj;
		public string ObjName;
		public string ObjPath;
		public float Scale;
		public bool FixScale;
		public bool ExportTextures;
		public bool Valid;
		public string[] Textures;

		public WavefrontExportSettings(string name, string path, float scale, bool fixScale, bool exportTextures) {
			ObjName = name;
			ObjPath = path;
			Scale = scale;
			FixScale = fixScale;
			ExportTextures = exportTextures;

			Valid = false;
			Obj = string.Empty;
			Textures = null;
		}
	}
	
	internal class WavefrontExporter
	{
		private const string DEFAULT = "Default";

		private struct VertexIndices
		{
			public int PositionIndex;
			public int UVIndex;
			public int NormalIndex;
		}

		public void Export(ICollection<Sector> sectors, WavefrontExportSettings settings) {
			createObjFromSelection(sectors, ref settings);

			if(!settings.Valid) {
				General.Interface.DisplayStatus(StatusType.Warning, "OBJ creation failed. Check 'Errors and Warnings' window for details.");
				return;
			}

			if(settings.ExportTextures) {
				//save all used textures
				if(settings.Textures != null) {
					foreach(string s in settings.Textures) {
						if(s == DEFAULT) continue;
						if(General.Map.Data.GetTextureExists(s)) {
							ImageData id = General.Map.Data.GetTextureImage(s);
							if(id.Width == 0 || id.Height == 0) {
								General.ErrorLogger.Add(ErrorType.Warning, "OBJ Exporter: texture '" + s + "' has invalid size (" + id.Width + "x" + id.Height + ")!");
								continue;
							}

							if(!id.IsImageLoaded)
								id.LoadImage();
							Bitmap bmp = id.GetBitmap();
							bmp.Save(Path.Combine(settings.ObjPath, s + ".PNG"), ImageFormat.Png);
						} else {
							General.ErrorLogger.Add(ErrorType.Warning, "OBJ Exporter: texture '" + s + "' does not exist!");
						}
					}
				}
			}

			//write obj
			string savePath = Path.Combine(settings.ObjPath, settings.ObjName);
			using(StreamWriter sw = new StreamWriter(savePath + ".obj", false))
				sw.Write(settings.Obj);

			//create mtl
			StringBuilder mtl = new StringBuilder();
			mtl.Append("# MTL for " + General.Map.FileTitle + ", map " + General.Map.Options.LevelName + Environment.NewLine);
			mtl.Append("# Created by GZDoom Builder " + GZBuilder.GZGeneral.Version.ToString(CultureInfo.InvariantCulture) + Environment.NewLine + Environment.NewLine);

			foreach(string s in settings.Textures) {
				if(s == DEFAULT) continue;
				mtl.Append("newmtl " + s.ToUpperInvariant() + Environment.NewLine);
				mtl.Append("Kd 1.0 1.0 1.0" + Environment.NewLine);
				if(settings.ExportTextures) mtl.Append("map_Kd " + Path.Combine(settings.ObjPath, s.ToUpperInvariant() + ".PNG") + Environment.NewLine);
				mtl.Append(Environment.NewLine);
			}

			//write mtl
			using(StreamWriter sw = new StreamWriter(savePath + ".mtl", false))
				sw.Write(mtl.ToString());

			//done
			General.Interface.DisplayStatus(StatusType.Warning, "Geometry exported to '" + savePath + ".obj'");
		}

		private void createObjFromSelection(ICollection<Sector> sectors, ref WavefrontExportSettings data) {
			BaseVisualMode mode = new BaseVisualMode();
			bool renderingEffectsDisabled = false;

			if(!BaseVisualMode.GZDoomRenderingEffects) {
				renderingEffectsDisabled = true;
				mode.ToggleGZDoomRenderingEffects();
			}

			mode.RebuildElementData();

			List<BaseVisualSector> visualSectors = new List<BaseVisualSector>();

			//create visual geometry
			foreach(Sector s in sectors) {
				BaseVisualSector bvs = mode.CreateBaseVisualSector(s);
				if(bvs != null) visualSectors.Add(bvs);
			}

			if(visualSectors.Count == 0) {
				General.ErrorLogger.Add(ErrorType.Error, "OBJ Exporter: no visual sectors to export!");
				return;
			}

			//sort geometry
			Dictionary<string, List<WorldVertex[]>> geometryByTexture = sortGeometry(visualSectors, data.ExportTextures);

			//restore vm settings
			if(renderingEffectsDisabled)
				mode.ToggleGZDoomRenderingEffects();

			mode.Dispose();
			mode = null;

			//create obj
			StringBuilder obj = createObjGeometry(geometryByTexture, data);

			if(obj.Length == 0) {
				General.ErrorLogger.Add(ErrorType.Error, "OBJ Exporter: failed to create geometry!");
				return;
			}

			//add header
			obj.Insert(0, "o " + General.Map.Options.LevelName + Environment.NewLine); //name
			obj.Insert(0, "# Created by GZDoom Builder " + GZBuilder.GZGeneral.Version.ToString(CultureInfo.InvariantCulture) + Environment.NewLine + Environment.NewLine);
			obj.Insert(0, "# " + General.Map.FileTitle + ", map " + General.Map.Options.LevelName + Environment.NewLine);
			data.Obj = obj.ToString();

			string[] textures = new string[geometryByTexture.Keys.Count];
			geometryByTexture.Keys.CopyTo(textures, 0);
			Array.Sort(textures);
			data.Textures = textures;

			data.Valid = true;
		}

		private Dictionary<string, List<WorldVertex[]>> sortGeometry(List<BaseVisualSector> visualSectors, bool exportTextures) {
			Dictionary<string, List<WorldVertex[]>> geo = new Dictionary<string, List<WorldVertex[]>>();
			geo.Add(DEFAULT, new List<WorldVertex[]>());
			string texture;

			foreach(BaseVisualSector vs in visualSectors) {
				//floor
				if(vs.Floor != null) {
					texture = vs.Sector.FloorTexture;
					checkTextureName(ref geo, ref texture);
					geo[texture].AddRange(optimizeSector(vs.Floor.Vertices, vs.Floor.GeometryType));
				}

				//ceiling
				if(vs.Ceiling != null) {
					texture = vs.Sector.CeilTexture;
					checkTextureName(ref geo, ref texture);
					geo[texture].AddRange(optimizeSector(vs.Ceiling.Vertices, vs.Ceiling.GeometryType));
				}

				//walls
				if(vs.Sides != null) {
					foreach(VisualSidedefParts part in vs.Sides.Values) {
						//upper
						if(part.upper != null && part.upper.Vertices != null) {
							texture = part.upper.Sidedef.HighTexture;
							checkTextureName(ref geo, ref texture);
							geo[texture].Add(optimizeWall(part.upper.Vertices));
						}

						//middle single
						if(part.middlesingle != null && part.middlesingle.Vertices != null) {
							texture = part.middlesingle.Sidedef.MiddleTexture;
							checkTextureName(ref geo, ref texture);
							geo[texture].Add(optimizeWall(part.middlesingle.Vertices));
						}

						//middle double
						if(part.middledouble != null && part.middledouble.Vertices != null) {
							texture = part.middledouble.Sidedef.MiddleTexture;
							checkTextureName(ref geo, ref texture);
							geo[texture].Add(optimizeWall(part.middledouble.Vertices));
						}

						//middle3d
						if(part.middle3d != null && part.middle3d.Count > 0) {
							foreach(VisualMiddle3D m3d in part.middle3d) {
								if(m3d.Vertices == null) continue;
								texture = m3d.Sidedef.MiddleTexture;
								checkTextureName(ref geo, ref texture);
								geo[texture].Add(optimizeWall(m3d.Vertices));
							}
						}

						//backsides(?)

						//lower
						if(part.lower != null && part.lower.Vertices != null) {
							texture = part.lower.Sidedef.LowTexture;
							checkTextureName(ref geo, ref texture);
							geo[texture].Add(optimizeWall(part.lower.Vertices));
						}
					}
				}

				//3d ceilings
				foreach(VisualCeiling vc in vs.ExtraCeilings) {
					texture = vc.GetControlSector().FloorTexture;
					checkTextureName(ref geo, ref texture);
					geo[texture].AddRange(optimizeSector(vc.Vertices, vc.GeometryType));
				}

				//3d floors
				foreach(VisualFloor vf in vs.ExtraFloors) {
					texture = vf.GetControlSector().FloorTexture;
					checkTextureName(ref geo, ref texture);
					geo[texture].AddRange(optimizeSector(vf.Vertices, vf.GeometryType));
				}

				//backsides(?)
			}

			return geo;
		}

		private void checkTextureName(ref Dictionary<string, List<WorldVertex[]>> geo, ref string texture) {
			if(!string.IsNullOrEmpty(texture) && texture != "-") {
				if(!geo.ContainsKey(texture))
					geo.Add(texture, new List<WorldVertex[]>());
			} else {
				texture = DEFAULT;
			}
		}

//SURFACE OPTIMIZATION
		//it's either quad, or triangle
		private WorldVertex[] optimizeWall(WorldVertex[] verts) {
			if (verts.Length == 6) {
				return new[] { verts[5], verts[2], verts[1], verts[0] };
			}

			Array.Reverse(verts);
			return verts;
		}

		private List<WorldVertex[]> optimizeSector(WorldVertex[] verts, VisualModes.VisualGeometryType visualGeometryType) {
			List<WorldVertex[]> groups = new List<WorldVertex[]>();

			if(verts.Length == 6) { //rectangle surface
				if (visualGeometryType == VisualModes.VisualGeometryType.FLOOR) {
					verts = new[] { verts[5], verts[2], verts[1], verts[0] };
				} else {
					verts = new[] { verts[2], verts[5], verts[1], verts[0] };
				}
				groups.Add(verts);
			} else {
				for (int i = 0; i < verts.Length; i += 3) {
					groups.Add(new[] { verts[i + 2], verts[i + 1], verts[i] });
				}
			}

			return groups;
		}

//OBJ Creation
		private StringBuilder createObjGeometry(Dictionary<string, List<WorldVertex[]>> geometryByTexture, WavefrontExportSettings data) {
			StringBuilder obj = new StringBuilder();
			const string vertexFormatter = "{0} {2} {1}\n";

			List<Vector3D> uniqueVerts = new List<Vector3D>();
			List<Vector3D> uniqueNormals = new List<Vector3D>();
			List<PointF> uniqueUVs = new List<PointF>();

			Dictionary<string, Dictionary<WorldVertex, VertexIndices>> vertexDataByTexture = new Dictionary<string, Dictionary<WorldVertex, VertexIndices>>();
			int ni, pi, uvi;

			//optimize geometry
			foreach(KeyValuePair<string, List<WorldVertex[]>> group in geometryByTexture) {
				Dictionary<WorldVertex, VertexIndices> vertsData = new Dictionary<WorldVertex, VertexIndices>();
				foreach(WorldVertex[] verts in group.Value) {
					//vertex normals
					Vector3D n = new Vector3D(verts[0].nx, verts[0].ny, verts[0].nz).GetNormal();
					ni = uniqueNormals.IndexOf(n);
					if (ni == -1) {
						uniqueNormals.Add(n);
						ni = uniqueNormals.Count;
					} else {
						ni++;
					}
					
					foreach(WorldVertex v in verts){
						if(vertsData.ContainsKey(v)) continue;
						VertexIndices indices = new VertexIndices();
						indices.NormalIndex = ni;

						//vertex coords
						Vector3D vc = new Vector3D(v.x, v.y, v.z);
						pi = uniqueVerts.IndexOf(vc);
						if (pi == -1) {
							uniqueVerts.Add(vc);
							pi = uniqueVerts.Count;
						} else {
							pi++;
						}

						//uv
						PointF uv = new PointF(v.u, v.v);
						uvi = uniqueUVs.IndexOf(uv);
						if(uvi == -1) {
							uniqueUVs.Add(uv);
							uvi = uniqueUVs.Count;
						} else {
							uvi++;
						}

						indices.PositionIndex = pi;
						indices.UVIndex = uvi;

						vertsData.Add(v, indices);
					}
				}

				vertexDataByTexture.Add(group.Key, vertsData);
			}

			//write geometry
			//write vertices
			if(data.FixScale) {
				foreach(Vector3D v in uniqueVerts)
					obj.Append(string.Format(CultureInfo.InvariantCulture, "v " + vertexFormatter, -v.x * data.Scale, v.y * data.Scale, v.z * data.Scale * 1.2f));
			} else {
				foreach(Vector3D v in uniqueVerts)
					obj.Append(string.Format(CultureInfo.InvariantCulture, "v " + vertexFormatter, -v.x * data.Scale, v.y * data.Scale, v.z * data.Scale));
			}

			//write normals
			foreach(Vector3D v in uniqueNormals)
				obj.Append(string.Format(CultureInfo.InvariantCulture, "vn " + vertexFormatter, v.x, v.y, v.z));

			//write UV coords
			foreach(PointF p in uniqueUVs)
				obj.Append(string.Format(CultureInfo.InvariantCulture, "vt {0} {1}\n", p.X, -p.Y));

			//write material library
			obj.Append("mtllib ").Append(data.ObjName + ".mtl").Append("\n");

			//write materials and surface indices
			foreach(KeyValuePair<string, List<WorldVertex[]>> group in geometryByTexture) {
				//material
				obj.Append("usemtl ").Append(group.Key).Append("\n");
				
				foreach(WorldVertex[] verts in group.Value) {
					//surface indices
					obj.Append("f");
					foreach(WorldVertex v in verts) {
						VertexIndices vi = vertexDataByTexture[group.Key][v];
						obj.Append(" " + vi.PositionIndex + "/" + vi.UVIndex + "/" + vi.NormalIndex);
					}
					obj.Append("\n");
				}
			}

			return obj;
		}
	}
}