// 
// ObjLoader.cpp -- modified for glm
//  modified from https://github.com/mortennobel/OpenGL_3_2_Utils
//
/*!
 * OpenGL 3.2 Utils - Extension to the Angel library (from the book Interactive Computer Graphics 6th ed
 * https://github.com/mortennobel/OpenGL_3_2_Utils
 *
 * New BSD License
 *
 * Copyright (c) 2011, Morten Nobel-Joergensen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
 * disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "ObjLoader.h"

#define GLM_ENABLE_EXPERIMENTAL
#include <glm/gtx/string_cast.hpp>
using namespace glm;

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <map>

using namespace std;

const int DEBUG = 1;

void printDebug(vector<vec3> &positions, vector<int> &indices);
void printDebug(Material *m);

vec3 toVec3(istringstream &iss){
    float x,y,z;
    iss >> x;
    iss >> y;
    iss >> z;
    return vec3(x,y,z);
}

vec2 toVec2(istringstream &iss){
    float x,y;
    iss >> x;
    iss >> y;
    return vec2(x,y);
}

struct TriangleIndex{
    // this is a vertex, represented as the indices into their
    // respective arrays of positions, normals, and texture coords
    int position;
    int normal;
    int uv;

    bool replace(std::string& str, const std::string& from, const std::string& to) {
        size_t start_pos = str.find(from);
        if(start_pos == std::string::npos)
            return false;
        str.replace(start_pos, from.length(), to);
        return true;
    }

    TriangleIndex(string p):position(-1),normal(-1),uv(-1) {
        // position/uv/normal
        replace(p, "//","/-1/");
        stringstream ss(p);
        char buffer[50];

        ss.getline(buffer,50, '/');
        position = atoi(buffer);
        if (ss.good()){
            ss.getline(buffer,50, '/');
            uv = atoi(buffer);
        }
        if (ss.good()){
            ss.getline(buffer,50, '/');
            normal = atoi(buffer);
        }
    }

    // needed to use TriangleIndex as key in map
    bool operator <(const TriangleIndex& Rhs) const {
        return (position < Rhs.position) ||
                (position == Rhs.position && normal < Rhs.normal) ||
                (position == Rhs.position && normal == Rhs.normal && uv < Rhs.uv);
    }
};

struct TriangleString{
    TriangleIndex v0;
    TriangleIndex v1;
    TriangleIndex v2;

    TriangleString(string v0, string v1, string v2):v0(v0),v1(v1),v2(v2){
    }

    TriangleIndex get(int index){
        if (index == 0) {
            return v0;
        } else if (index == 1) {
            return v1;
        }
        return v2;
    }
};



std::string
makeMtlFilename ( std::string mtlfile, std::string objfile )
{
  // pull off the path to the directory from the objfile
  size_t pos = objfile.rfind ('/');
  // tack the directory onto the materal "mtllib" filename
  if ( pos == std::string::npos ) {
    return mtlfile;
  }  else {
    std::string path;
    path = objfile.substr(0,pos);
    return path+"/"+mtlfile;
  }
}


bool loadMaterialLibrary ( string mtlText, map<string,Material*> &outMaterials)
{
    Material *mat = nullptr;
    stringstream ifs(mtlText);
    char buffer[512];
    while (ifs.good()) {
        ifs.getline(buffer,512);
        string line(buffer);
        istringstream iss(line);
        string token;
        vec3 color;
        iss >> token;
        if (token.compare("newmtl") ==0) {
            // create a new material and store in map
            mat = new Material;
            iss >> token;
            outMaterials[token] = mat;
        } else if (token.compare("Ka") == 0 && mat) {
            mat->ambient = toVec3 ( iss );
        } else if (token.compare("Kd") == 0 && mat) {
            mat->diffuse = toVec3 ( iss );
        } else if (token.compare("Ks") == 0 && mat) {
            mat->specular = toVec3 ( iss );
        } else if (token.compare("Ns") == 0 && mat) {
            iss >> mat->shininess;
        } else if (token.compare("map_Kd") == 0 && mat) {
            iss >> mat->diffuseTexture;
        } else if (token.compare("map_Disp") == 0 && mat) {
            iss >> mat->bumpTexture;
        }
    }

    return (mat != nullptr);
}

bool loadObject(string objText,
                vector<vec3> &outPositions,
                vector<vec3> &outNormal,
                vector<vec2> &outUv,
                vector<unsigned int> &outIndices,
                std::string &outMtlfilename
                )
{
    vector<vec3> positions;
    vector<vec3> normals;
    vector<vec2> uvs;
    vector<TriangleString> triangles;

    stringstream ifs(objText);
    char buffer[512];
    while (ifs.good()){
        ifs.getline(buffer,512);

        string line(buffer);
        istringstream iss(line);
        string token;
        iss >> token;
        if (token.compare("o")==0){
            // does not support multiple objects
        } else if (token.compare("g")==0){
        } else if (token.compare("mtllib")==0){
            // read the name of .mtl file
            iss >> outMtlfilename;
        } else if (token.compare("usemtl")==0){
            // does not support multiple materials
        } else if (token.compare("v")==0){
            positions.push_back( toVec3(iss));
        } else if (token.compare("vn")==0){
            normals.push_back( toVec3(iss));
        } else if (token.compare("vt")==0){
            uvs.push_back( toVec2(iss));
        } else if (token.compare("f")==0){
            vector<string> polygon;
            do {
                string index;
                iss >> index;
                if (index.length() > 0) {
                    polygon.push_back(index);
                }
            } while (iss);

            // triangulate polygon (assumes convex )
            TriangleString triangle(polygon[0], polygon[1], polygon[2]);
            triangles.push_back(triangle);
            for (int i=3;i<polygon.size();i++){
                TriangleString triangle2(polygon[i-1], polygon[i], polygon[0]);
                triangles.push_back(triangle2);
            }
        }
    }

    map<TriangleIndex,int> cache;
    for (int i=0;i<triangles.size();i++){
        TriangleString triangleString = triangles[i];
        for (int j=0;j<3;j++){
            TriangleIndex index = triangleString.get(j);
            map<TriangleIndex,int>::iterator cachedIndex = cache.find(index);
            if (cachedIndex != cache.end()) {
                outIndices.push_back(cachedIndex->second);
            } else {
                int vertexIndex = outPositions.size();
                outPositions.push_back(positions[index.position-1]);
                if (index.normal != -1){
                    outNormal.push_back(normals[index.normal-1]);
                }
                if (index.uv != -1) {
                    outUv.push_back(uvs[index.uv-1]);
                }
                outIndices.push_back(vertexIndex);
                cache[index] = vertexIndex;
            }
        }
    }

    return (outPositions.size()>0);
}


struct Group {
    vector<TriangleString> triangles;
    Material *mat;
};

//
// loadObjectGroups loads a .obj file containing materials and textures,
// creating a ModelNode that draws it.
bool loadObjectGroups ( string filename,
                        vector<vec3> &outPositions,
                        vector<vec3> &outNormal,
                        vector<vec2> &outUv,
                        vector< vector<unsigned int> > &outIndices, // per group
                        vector< Material* >&outMaterials // per group
                       )
{
    map<string,Material*> materials;
    vector<vec3> positions;
    vector<vec3> normals;
    vector<vec2> uvs;

    map<string,Group*> groups;
    string currentGroupName("");
    static int groupnum = 1;

    string path = std::string( filename );
    ifstream ifs ( path.c_str() , ifstream::in );
    char buffer[512];
    while (ifs.good()){
        ifs.getline(buffer,512);

        string line(buffer);
        istringstream iss(line);
        string token;
        iss >> token;
        if (token.compare("o")==0){
            // does not support multiple objects
        } else if (token.compare("g")==0){
            // for a new group of faces (eg with a diff material)
            // create a group
            iss >> currentGroupName;
            groups[currentGroupName] = new Group;
        } else if (token.compare("mtllib")==0){
            // read the .mtl file and create the Materials
            string mtlfile;
            iss >> mtlfile;
//            loadMaterialLibrary( mtlfile.c_str(),
//                                  filename,
//                                  materials);
        } else if (token.compare("usemtl")==0){
            // create group if none exists, or if this is a "usemtl" line without a preceding "g" line
            if ( currentGroupName=="" || groups[currentGroupName]->triangles.size() ) {
                string name;
                ostringstream oss(name);
                //	static int groupnum = 1;
                oss << "dummy" << groupnum++;
                currentGroupName=oss.str();
                groups[currentGroupName] = new Group;
            }
            iss >> token;
            if (token=="usemtl") {
                if (DEBUG)
                    std::cout << "null token" << std::endl;
                token = "dummy1";
            }
            if (DEBUG) {
                std::cout << "group is " << currentGroupName << std::endl;
                std::cout << "usemtl " << token << std::endl;
                std::cout << "materials[token] == " << materials[token] << std::endl;
            }
            if ( materials[token] == 0 ) {
                materials[token] = new Material;
            }
            printDebug ( materials[token] );
            groups[currentGroupName]->mat = materials[token];
            outMaterials.push_back((materials[token]));

        } else if (token.compare("v")==0){
            positions.push_back( toVec3(iss));
        } else if (token.compare("vn")==0){
            normals.push_back( toVec3(iss));
        } else if (token.compare("vt")==0){
            uvs.push_back( toVec2(iss));
        } else if (token.compare("f")==0){
            // assign face to current group
            vector<string> polygon;
            do {
                string index;
                iss >> index;
                if (index.length() > 0) {
                    polygon.push_back(index);
                }
            } while (iss);

            // oops no usemtl or mtllib or group seen
            //      if ( currentGroupName=="" || groups[currentGroupName]->triangles.size()==0 ) {
            if ( currentGroupName=="" ) {
                string name;
                ostringstream oss(name);
                //	static int groupnum = 1;
                oss << "dummy" << groupnum++;
                currentGroupName=oss.str();
                groups[currentGroupName] = new Group;
                outMaterials.push_back( groups[currentGroupName]->mat = new Material );
            }


            // triangulate polygon
            if ( polygon.size() >= 3 ) {
                TriangleString triangle(polygon[0], polygon[1], polygon[2]);
                groups[currentGroupName]->triangles.push_back(triangle);
                for (int i=3;i<polygon.size();i++){
                    TriangleString triangle2(polygon[i-1], polygon[i], polygon[0]);
                    groups[currentGroupName]->triangles.push_back(triangle2);
                }
            }
        }
    }
    ifs.close();

    // XXX
    // repeat this for each group.
    // return vectors must be made vectors of vectors (or maybe just the indices?)
    // for each group
    //  deref and pack the vertex positions, normal, and uv,
    //  pack the element array for each group separately
    map<TriangleIndex,int> cache;
    for ( map<string,Group*>::iterator g = groups.begin(); g != groups.end();g++ ) {
        // each group gets its own element array
        vector<unsigned int> groupIndices;
        for (int i=0;i<g->second->triangles.size();i++){
            TriangleString triangleString = g->second->triangles[i];
            for (int j=0;j<3;j++){
                TriangleIndex index = triangleString.get(j);
                map<TriangleIndex,int>::iterator cachedIndex = cache.find(index);
                if (cachedIndex != cache.end()) {
                    groupIndices.push_back(cachedIndex->second);
                } else {
                    int vertexIndex = outPositions.size();
                    outPositions.push_back(positions[index.position-1]);
                    if (index.normal != -1){
                        outNormal.push_back(normals[index.normal-1]);
                    }
                    if (index.uv != -1) {
                        outUv.push_back(uvs[index.uv-1]);
                    }
                    groupIndices.push_back(vertexIndex);
                    cache[index] = vertexIndex;
                }
            }
        }
        // pack the indices for this group
        outIndices.push_back(groupIndices);
    }
    //cout <<"Indices "<< outIndices.size() << endl;
    //cout <<"Positions "<< outPositions.size() << endl;
    //printDebug(outPositions, outIndices);
    return true;
}


void printDebug(vector<vec3> &positions, vector<int> &indices){
    if (!DEBUG)
        return;
    for (int i=0;i<indices.size();i++){
        //		cout << positions[indices[i]] <<" ";
        cout << positions[indices[i]].x <<",";
        cout << positions[indices[i]].y <<",";
        cout << positions[indices[i]].z <<" ";
        if ((i+1)%3==0){
            cout << endl;
        }
    }
}

void printDebug(Material *m){
    if (!DEBUG) return;
    cout << "ambient " << glm::to_string(m->ambient) << endl;
    cout << "diffuse " << glm::to_string(m->diffuse) << endl;
    cout << "specular " << glm::to_string(m->specular) << endl;
    cout << "shininess " << m->shininess << endl;
    cout << "diffuse texture " << m->diffuseTexture << endl;
    cout << "bump texture " << m->bumpTexture << endl;
}