/**
 * @file ObjModel.cpp
 * @author  Simone Gasparini <simone.gasparini@enseeiht.fr>
 * @version 1.0
 *
 * @section LICENSE
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * @section DESCRIPTION
 *
 * Simple Class to load and draw 3D objects from OBJ files
 * Using triangles and normals as static object. No texture mapping.
 * OBJ files must be triangulated!!!
 *
 */

#include "ObjModel.hpp"

#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
#include <cassert>
//#include <stdlib.h>

#include <sstream>
#include <string>
#include <vector>
#include <cmath>

using namespace std;

/**
 * Load the OBJ data from file
 * @param filename The name of the OBJ file
 * @return 0 if everything went well
 */
int ObjModel::load(char *filename)
{

    string line;
    ifstream objFile(filename);
    // ifstream objFile("../data/models/cube.obj");
    // ifstream objFile("../data/models/cow-nonormals.obj");
    // ifstream objFile("../data/models/triang.obj");

    // If obj file is open, continue
    if (objFile.is_open())
    {
        // Start reading file data
        while (!objFile.eof())
        {
            // Get a line from file
            getline(objFile, line);

            // If the first character is a simple 'v'...
            // PRINTVAR(line);
            if ((line.c_str()[0] == 'v') && (line.c_str()[1] == ' ')) // to drop all the vn and vn lines
            {
                // PRINTVAR(line);
                // Read 3 floats from the line:  X Y Z and store them in the corresponding place in _vertices
                point3d p;
                sscanf(line.c_str(), "v %f %f %f ", &p.x, &p.y, &p.z);

                //**************************************************
                // add the new point to the list of the vertices
                // and its normal to the list of normals: for the time
                // being it is a [0, 0 ,0] normal.
                //**************************************************
                _vertices.push_back(p);
                _normals.push_back(vec3d(0, 0, 0));

                // update the bounding box, if it is the first vertex simply
                // set the bb to it
                if (_vertices.size() == 1)
                {
                    _bb.set(p);
                }
                else
                {
                    // otherwise add the point
                    _bb.add(p);
                }
            }
            // If the first character is a 'f'...
            if (line.c_str()[0] == 'f')
            {

                face t;
                const auto ok = parseFaceString(line, t);
                if (!ok)
                    throw std::runtime_error("Error while reading line: " + line);

                //**************************************************
                // correct the indices: OBJ starts counting from 1, in C the arrays starts at 0...
                //**************************************************
                t.v1--;
                t.v2--;
                t.v3--;

                //**************************************************
                // add it to the mesh
                //**************************************************
                _mesh.push_back(t);

                //*********************************************************************
                //  Compute the normal of the face
                //*********************************************************************
                vec3d normal;
                computeNormal(_vertices[t.v1], _vertices[t.v2], _vertices[t.v3], normal);

                //*********************************************************************
                // Sum the normal of the face to each vertex normal
                //*********************************************************************
                _normals[t.v1] += normal * angleAtVertex(_vertices[t.v1], _vertices[t.v2], _vertices[t.v3]);
                _normals[t.v2] += normal * angleAtVertex(_vertices[t.v2], _vertices[t.v1], _vertices[t.v3]);
                _normals[t.v3] += normal * angleAtVertex(_vertices[t.v3], _vertices[t.v1], _vertices[t.v2]);
            }
        }

        cerr << "Found :\n\tNumber of triangles (_indices) " << _mesh.size() << "\n\tNumber of Vertices: " << _vertices.size() << "\n\tNumber of Normals: " << _normals.size() << endl;
        // PRINTVAR(_mesh);
        // PRINTVAR(_vertices);
        // PRINTVAR(_normals);

        //*********************************************************************
        // normalize the normals of each vertex
        //*********************************************************************
        for (vec3d n : _normals)
        {
            n.normalize();
        }

        // PRINTVAR(_normals);

        // Close OBJ file
        objFile.close();
    }
    else
    {
        cout << "Unable to open file";
    }

    cout << "Object loaded with " << _vertices.size() << " vertices and " << _mesh.size() << " faces" << endl;
    cout << "Bounding box : pmax=" << _bb.pmax << "  pmin=" << _bb.pmin << endl;
    return 0;
}

/**
 * Draw the wireframe of the model
 *
 * @param vertices The list of vertices
 * @param mesh The mesh as a list of faces, each face is a tripleIndex of vertex indices
 * @param params The rendering parameters
 */
void ObjModel::drawWireframe(const std::vector<point3d> &vertices, const std::vector<face> &mesh, const RenderingParameters &params) const
{
    //**************************************************
    // we first need to disable the lighting in order to
    // draw colored segments
    //**************************************************
    glDisable(GL_LIGHTING);

    // if we are displaying the object with colored faces
    if (params.solid)
    {
        // use black ticker lines
        glColor3f(0, 0, 0);
        glLineWidth(2);
    }
    else
    {
        // otherwise use white thinner lines for wireframe only
        glColor3f(.8, .8, .8);
        glLineWidth(.21);
    }

    //**************************************************
    // for each face of the mesh...
    //**************************************************
    for (auto &face : mesh)
    {
        //**************************************************
        // draw the contour of the face as a GL_LINE_LOOP
        //**************************************************
        glBegin(GL_LINE_LOOP);
        glVertex3fv((float *)&vertices[face.v1]);
        glVertex3fv((float *)&vertices[face.v2]);
        glVertex3fv((float *)&vertices[face.v3]);
        glEnd();
    }

    //**************************************************
    // re-enable the lighting
    //**************************************************
    glEnable(GL_LIGHTING);
}

/**
 * Calculate the normal of a triangular face defined by three points
 *
 * @param[in] v1 the first vertex
 * @param[in] v2 the second vertex
 * @param[in] v3 the third vertex
 * @param[out] norm the normal
 */
void ObjModel::computeNormal(const point3d &v1, const point3d &v2, const point3d &v3, vec3d &norm) const
{
    //**************************************************
    // compute the cross product between two edges of the triangular face
    //**************************************************
    norm = (v2 - v1).cross(v3 - v1);

    //**************************************************
    // remember to normalize the result
    //**************************************************
    norm.normalize();
}

/**
 * Draw the faces using the computed normal of each face
 *
 * @param vertices The list of vertices
 * @param mesh The list of face, each face containing the indices of the vertices
 * @param params The rendering parameters
 */
void ObjModel::drawFlatFaces(const std::vector<point3d> &vertices, const std::vector<face> &mesh, const RenderingParameters &params) const
{
    // shading model to use
    if (params.smooth)
    {
        glShadeModel(GL_SMOOTH);
    }
    else
    {
        glShadeModel(GL_FLAT);
    }

    //**************************************************
    // for each face
    //**************************************************
    for (auto &face : mesh)
    {
        //**************************************************
        // Compute the normal to the face and then draw the
        // faces as GL_TRIANGLES assigning the proper normal
        //**************************************************
        vec3d normal;
        computeNormal(vertices[face.v1], vertices[face.v2], vertices[face.v3], normal);
        glNormal3fv((float *)&normal);

        glBegin(GL_TRIANGLES);
        glVertex3fv((float *)&vertices[face.v1]);
        glVertex3fv((float *)&vertices[face.v2]);
        glVertex3fv((float *)&vertices[face.v3]);
        glEnd();
    }
}

/**
 * Draw the model using the vertex indices
 *
 * @param vertices The vertices
 * @param indices The list of the faces, each face containing the 3 indices of the vertices
 * @param vertexNormals The list of normals associated to each vertex
 * @param params The rendering parameters
 */
void ObjModel::drawSmoothFaces(const std::vector<point3d> &vertices,
                               const std::vector<face> &mesh,
                               std::vector<vec3d> &vertexNormals,
                               const RenderingParameters &params) const
{
    if (params.smooth)
    {
        glShadeModel(GL_SMOOTH);
    }
    else
    {
        glShadeModel(GL_FLAT);
    }
    //****************************************
    // Enable vertex arrays
    //****************************************
    glEnableClientState(GL_VERTEX_ARRAY);

    //****************************************
    // Enable normal arrays
    //****************************************
    glEnableClientState(GL_NORMAL_ARRAY);

    //****************************************
    // Normal pointer to normal array
    //****************************************
    glNormalPointer(GL_FLOAT, 0, &vertexNormals[0]);

    //****************************************
    // Vertex pointer to Vertex array
    //****************************************
    glVertexPointer(3, GL_FLOAT, 0, &vertices[0]);

    //****************************************
    // Draw the faces
    //****************************************
    glDrawElements(GL_TRIANGLES, 3 * mesh.size(), GL_UNSIGNED_INT, &mesh[0]);

    //****************************************
    // Disable vertex arrays
    //****************************************
    glDisableClientState(GL_VERTEX_ARRAY);

    //****************************************
    // Disable normal arrays
    //****************************************
    glDisableClientState(GL_NORMAL_ARRAY);
}

/**
 * Compute the subdivision of the input mesh by applying one step of the Loop algorithm
 *
 * @param[in] origVert The list of the input vertices
 * @param[in] origMesh The input mesh (the vertex indices for each face/triangle)
 * @param[out] destVert The list of the new vertices for the subdivided mesh
 * @param[out] destMesh The new subdivided mesh (the vertex indices for each face/triangle)
 * @param[out] destNorm The new list of normals for each new vertex of the subdivided mesh
 */
void ObjModel::loopSubdivision(const std::vector<point3d> &origVert, //!< the original vertices
                               const std::vector<face> &origMesh,    //!< the original mesh
                               std::vector<point3d> &destVert,       //!< the new vertices
                               std::vector<face> &destMesh,          //!< the new mesh
                               std::vector<vec3d> &destNorm) const   //!< the new normals
{
    // copy the original vertices in destVert
    destVert = origVert;

    // start fresh with the new mesh
    destMesh.clear();

    // PRINTVAR(destVert);
    // PRINTVAR(origVert);

    // create a list of the new vertices creates with the reference to the edge
    EdgeList newVertices;

    //*********************************************************************
    // for each face
    //*********************************************************************
    for (auto &f : origMesh)
    {
        //*********************************************************************
        // get the indices of the triangle vertices
        //*********************************************************************
        uint v1 = f.v1;
        uint v2 = f.v2;
        uint v3 = f.v3;

        //*********************************************************************
        // for each edge get the index of the vertex of the midpoint using getNewVertex
        //*********************************************************************
        const uint a = getNewVertex(edge{v1, v2}, destVert, origMesh, newVertices);
        const uint b = getNewVertex(edge{v2, v3}, destVert, origMesh, newVertices);
        const uint c = getNewVertex(edge{v3, v1}, destVert, origMesh, newVertices);

        //*********************************************************************
        // create the four new triangles
        // BE CAREFUL WITH THE VERTEX ORDER!!
        //               v2
        //               /\
        //              /  \
        //             /    \
        //            a ---- b
        //           / \     /\
        //          /   \   /  \
        //         /     \ /    \
        //        v1 ---- c ---- v3
        //
        // the original triangle was v1-v2-v3, use the same clock-wise order for the other
        // hence v1-a-c, a-b-c and so on
        //*********************************************************************
        destMesh.push_back(face{v1, a, c});
        destMesh.push_back(face{a, b, c});
        destMesh.push_back(face{c, b, v3});
        destMesh.push_back(face{a, v2, b});
    }

    //*********************************************************************
    // Update each "old" vertex using the Loop coefficients. A smart way to do
    // so is to think in terms of faces than the single vertex: for each face
    // we update each of the 3 vertices using the Loop formula wrt the other 2 and
    // sum it to a temporary copy tmp of the vertices (which is initialized to
    // [0 0 0] at the beginning). We also keep a record of the occurrence of each vertex.
    // At then end, to get the final vertices we just need to divide each vertex
    // in tmp by its occurrence
    //*********************************************************************

    // A list containing the occurrence of each vertex
    vector<size_t> occurrences(origVert.size(), 0.0f);

    // A list of the same size as origVert with all the elements initialized to [0 0 0]
    vector<point3d> tmp(origVert.size());

    //*********************************************************************
    // for each face
    //*********************************************************************
    for (auto &face : origMesh)
    {
        //*********************************************************************
        // consider each of the 3 vertices:
        // 1) increment its occurrence
        // 2) apply Loop update with the other 2 vertices of the face
        // BE CAREFUL WITH THE COEFFICIENT OF THE OTHER 2 VERTICES!... consider
        // how many times each vertex is summed in the general case...
        //*********************************************************************

        // 1) increment occurrences
        occurrences[face.v1] += 2;
        occurrences[face.v2] += 2;
        occurrences[face.v3] += 2;

        // 2) apply Loop update
        tmp[face.v1] += (destVert[face.v2] + destVert[face.v3]);
        tmp[face.v2] += (destVert[face.v1] + destVert[face.v3]);
        tmp[face.v3] += (destVert[face.v1] + destVert[face.v2]);
    }

    //*********************************************************************
    //  To obtain the new vertices, divide each vertex by its occurrence value
    //*********************************************************************
    for (int i = 0; i < tmp.size(); i++)
    {
        assert(occurrences[i] != 0);
        destVert[i] = 5.0f / 8.0f * destVert[i] + 3.0f / 8.0f / occurrences[i] * tmp[i];
    }
    // PRINTVAR(destVert);

    // redo the normals, reset and create a list of normals of the same size as
    // the vertices, each normal set to [0 0 0]
    destNorm.clear();
    destNorm = vector<vec3d>(destVert.size());

    //*********************************************************************
    //  Recompute the normals for each face
    //*********************************************************************
    for (auto &f : destMesh)
    {
        //*********************************************************************
        //  Calculate the normal of the triangles, it will be the same for each vertex
        //*********************************************************************
        vec3d n;
        computeNormal(destVert[f.v1], destVert[f.v2], destVert[f.v3], n);

        //*********************************************************************
        // Sum the normal of the face to each vertex normal using the angleAtVertex as weight
        //*********************************************************************
        destNorm[f.v1] += n * angleAtVertex(destVert[f.v1], destVert[f.v2], destVert[f.v3]);
        destNorm[f.v2] += n * angleAtVertex(destVert[f.v2], destVert[f.v1], destVert[f.v3]);
        destNorm[f.v3] += n * angleAtVertex(destVert[f.v3], destVert[f.v2], destVert[f.v1]);
    }
    //*********************************************************************
    // normalize the normals of each vertex
    //*********************************************************************
    for (vec3d n : destNorm)
    {
        n.normalize();
    }
}

/**
 * For a given edge it returns the index of the new vertex created on its middle point.
 * If such vertex already exists it just returns the its index; if it does not exist
 * it creates it in vertList along it's normal and return the index
 *
 * @param[in] e the edge
 * @param[in,out] vertList the list of vertices
 * @param[in] mesh the list of triangles
 * @param[in,out] newVertList The list of the new vertices added so far
 * @return the index of the new vertex or the one that has been already created for that edge
 * @see EdgeList
 */
idxtype ObjModel::getNewVertex(const edge &e,
                               std::vector<point3d> &vertList,
                               const std::vector<face> &mesh,
                               EdgeList &newVertList) const
{
    // PRINTVAR(e);
    // PRINTVAR(newVertList);

    //*********************************************************************
    // if the egde is NOT contained in the new vertex list (see EdgeList.contains() method)
    //*********************************************************************
    if (!newVertList.contains(e))
    {
        //*********************************************************************
        // generate new index (vertex.size)
        //*********************************************************************
        int newIndex = vertList.size();

        //*********************************************************************
        // add the edge and index to the newVertList
        //*********************************************************************
        newVertList.add(e, newIndex);

        // generate new vertex
        point3d nvert; //!< this will contain the new vertex
        idxtype oppV1; //!< the index of the first "opposite" vertex
        idxtype oppV2; //!< the index of the second "opposite" vertex (if it exists)

        //*********************************************************************
        // check if it is a boundary edge, ie check if there is another triangle
        // sharing this edge and if so get the index of its "opposite" vertex
        //*********************************************************************
        if (!isBoundaryEdge(e, mesh, oppV1, oppV2))
        {
            // if it is not a boundary edge create the new vertex

            //*********************************************************************
            // the new vertex is the linear combination of the two extrema of
            // the edge V1 and V2 and the two opposite vertices oppV1 and oppV2
            // Using the loop coefficient the new vertex is
            // nvert = 3/8 (V1+V2) + 1/8(oppV1 + oppV2)
            //
            // REMEMBER THAT IN THE CODE OPPV1 AND OPPV2 ARE INDICES, NOT VERTICES!!!
            //*********************************************************************
            nvert = 3.0f / 8.0f * (vertList[e.first] + vertList[e.second]) + 1.0f / 8.0f * (vertList[oppV1] + vertList[oppV2]);
        }
        else
        {
            //*********************************************************************
            // otherwise it is a boundary edge then the vertex is the linear combination of the
            // two extrema
            //*********************************************************************
            nvert = 0.5f * vertList[e.first] + 0.5f * vertList[e.second];
        }
        //*********************************************************************
        // append the new vertex to the list of vertices
        //*********************************************************************
        vertList.push_back(nvert);

        //*********************************************************************
        // return the index of the new vertex
        //*********************************************************************
        return newIndex;
    }
    else
    // else we don't need to do anything, just return the associated index of the
    // already existing vertex
    {
        //*********************************************************************
        // get and return the index of the vertex
        //*********************************************************************
        return newVertList.getIndex(e);
    }

    // this is just to avoid compilation errors at the beginning
    // execution should normally never reach here
    // the return instructions go inside each branch of the if - else above
    std::cerr << "WARNING: the subdivision may not be implemented correctly" << std::endl;
    return 0;
}

#include "ObjModel.cxx"