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/* ----------------------------------------------------------------------- *
 * This file is part of GEL, http://www.imm.dtu.dk/GEL
 * Copyright (C) the authors and DTU Informatics
 * For license and list of authors, see ../../doc/intro.pdf
 * ----------------------------------------------------------------------- */

#include "TriMesh.h"
#include "../CGLA/Vec3f.h"
#include <fstream>
#include <iostream>

using namespace std;
using namespace CGLA;

namespace Geometry {
    
        namespace
        {
                string get_path(const string& _filename)
                {
                        // Make sure we only have slashes and not backslashes
                        string filename = _filename;
                        replace(filename.begin(),filename.end(),'\\','/');
                        
                        // Find the last occurrence of slash.
                        // Everything before is path.
                        size_t n = filename.rfind("/");
                        if(n > filename.size())
                                return "./";
                        string pathname(filename,0,n);
                        pathname.append("/");
                        return pathname;
                }
        }
        class TriMeshObjLoader
        {
                TriMesh *mesh;
                std::string pathname;
        
                int get_vert(int i) {
                        assert(i!=0);
                        if (i<0) {
                                return mesh->geometry.no_vertices()+i;
                        } else
                                return i-1;
                }
        
                int get_normal(int i) {
                        if (i<0) {
                                return mesh->normals.no_vertices()+i;
                        } else
                                return i-1;
                }
        
                int get_texcoord(int i) {
                        if (i<0) {
                                return mesh->texcoords.no_vertices()+i;
                        } else
                                return i-1;
                }

    void read_material_library(const string& filename, vector<Material>& materials);

        public:
        
                TriMeshObjLoader(TriMesh *_mesh): mesh(_mesh) {}
                
                void load(const std::string& filename);
        
    void load_material_library(const string& filename, vector<Material>& materials)
    {
      pathname = get_path(filename);
      read_material_library(filename, materials);
    }        
        };
        
        void TriMeshObjLoader::read_material_library(const string& filename, vector<Material>& materials)
        {
    string fn = pathname + filename;
    ifstream material_file(fn.data());  
    if(!material_file)
    {
      cerr << "Could not open " << filename << endl;
      return;
    }

    string buf;
    unsigned int nummaterials=0;
    while(material_file >> buf)
    {
      switch(buf[0])
      {
      case 'n':
        ++nummaterials;
        mesh->materials.push_back(Material());
        material_file >> materials[nummaterials].name;
        break;
      case 'N':
        switch(buf[1])
        {
        case 's':
          material_file >> materials[nummaterials].shininess;
          materials[nummaterials].shininess *= 128.0f/1000.0f;
          break;
        case 'i':
          material_file >> materials[nummaterials].ior;
          break;
        }
        break;
      case 'K':
        switch(buf[1])
        {
        case 'd':
          material_file >> materials[nummaterials].diffuse[0]
                        >> materials[nummaterials].diffuse[1]
                        >> materials[nummaterials].diffuse[2];
          break;
        case 's':
          material_file >> materials[nummaterials].specular[0]
                        >> materials[nummaterials].specular[1]
                        >> materials[nummaterials].specular[2];
          break;
        case 'a':
          material_file >> materials[nummaterials].ambient[0]
                        >> materials[nummaterials].ambient[1]
                        >> materials[nummaterials].ambient[2];
          break;
        }
        break;
      case 'T':
        material_file >> materials[nummaterials].transmission[0]
                      >> materials[nummaterials].transmission[1]
                      >> materials[nummaterials].transmission[2];
        break;
      case 'i':
        material_file >> materials[nummaterials].illum;
        break;
      case 'm': // Map ... all maps are treated equally.
        material_file >> materials[nummaterials].tex_name;
        materials[nummaterials].has_texture = true;
        materials[nummaterials].tex_path = pathname;
        break;
      case '#':
      default:
        material_file.ignore(1024, '\n');
        break;
      }
    }
  }
    
  void TriMeshObjLoader::load(const std::string& filename)
  {
    pathname = get_path(filename);
    ifstream obj_file(filename.data());
    if(!obj_file)
    {
                        cerr << "File " << filename << " does not exist" << endl;
      exit(0);
    }

    mesh->materials.resize(1);
    string buf;
    int current_material=0;
    while(obj_file >> buf)
    {
      switch(buf[0])
      {
      case 'v': // v, vn, vt
        {
          if(buf == "v")
          {
            Vec3f v_geo;
            obj_file >> v_geo;
            mesh->geometry.add_vertex(v_geo);
          }
          else if(buf == "vn")
          {
            Vec3f v_norm;
            obj_file >> v_norm;
            mesh->normals.add_vertex(v_norm);
          }
          else if(buf == "vt")
          {
            Vec3f v_tex;
            obj_file >> v_tex[0] >> v_tex[1];
            v_tex[2]=1;
            mesh->texcoords.add_vertex(v_tex);
          }
        }
        break;
      case 'f':
        {
          char line[1024];
                        
          vector<int> v_indices;
          vector<int> t_indices;
          vector<int> n_indices;
                        
          obj_file.getline(line, 1022);
          char* pch = strtok(line, " \t");
          while(pch != 0)
          {
            int v,t,n;
            if(sscanf(pch, "%d/%d/%d", &v, &t, &n)==3)
            {
              v_indices.push_back(get_vert(v));
              t_indices.push_back(get_texcoord(t));
              n_indices.push_back(get_normal(n));
            }
            else if(sscanf(pch, "%d//%d", &v, &n)==2)
            {
              v_indices.push_back(get_vert(v));
              n_indices.push_back(get_normal(n));
            }
            else if(sscanf(pch, "%d/%d", &v, &t)==2)
            {
              v_indices.push_back(get_vert(v));
              t_indices.push_back(get_texcoord(t));
            }
            else if(sscanf(pch, "%d", &v)==1)
              v_indices.push_back(get_vert(v));
            pch = strtok(0, " \t");
          }
          if(v_indices.size()>=3)
            for(size_t i=0;i<=(v_indices.size()-3);++i)
            {
              int idx = mesh->geometry.add_face(Vec3i(v_indices[0], v_indices[i+1], v_indices[i+2]));
              if(t_indices.size())
              mesh->texcoords.add_face(Vec3i(t_indices[0], t_indices[i+1], t_indices[i+2]), idx);
              if(n_indices.size())
              mesh->normals.add_face(Vec3i(n_indices[0], n_indices[i+1], n_indices[i+2]), idx);
              mesh->mat_idx.push_back(current_material);
            }
        }
        break;
      case 'm':
        obj_file >> buf;
        read_material_library(buf, mesh->materials);
        break;
      case 'u':
        obj_file >> buf;
        current_material = mesh->find_material(buf);
        break;
      case '#':
      default:
        obj_file.ignore(1024, '\n');
        break;                        
      }
    }
  }
    
        void obj_load(const string& filename, TriMesh &mesh)
        {
                TriMeshObjLoader loader(&mesh);
                loader.load(filename);
        }
    
  /// Load materials from an MTL file
  void mtl_load(const std::string& filename, std::vector<Material>& materials)
  {
    TriMeshObjLoader loader(0);
    loader.load_material_library(filename, materials);
  }    
}