// -*-c++-*-

/*
 * Wavefront OBJ loader for Open Scene Graph
 *
 * Copyright (C) 2001 Ulrich Hertlein <u.hertlein@web.de>
 *
 * Modified by Robert Osfield to support per Drawable coord, normal and
 * texture coord arrays, bug fixes, and support for texture mapping.
 *
 * Writing support added 2007 by Stephan Huber, http://digitalmind.de, 
 * some ideas taken from the dae-plugin
 *
 * The Open Scene Graph (OSG) is a cross platform C++/OpenGL library for 
 * real-time rendering of large 3D photo-realistic models. 
 * The OSG homepage is http://www.openscenegraph.org/
 */

#include <osg/io_utils>
#include "OBJWriterNodeVisitor.h"
 


/** writes all values of an array out to a stream, applies a matrix beforehand if necessary */
class ValueVisitor : public osg::ValueVisitor {
    public:
        ValueVisitor(std::ostream& fout, const osg::Matrix& m = osg::Matrix::identity(), bool isNormal = false) :    
            osg::ValueVisitor(), 
            _fout(fout), 
            _m(m), 
            _isNormal(isNormal)
        { 
            _applyMatrix = (_m != osg::Matrix::identity());
            if (_isNormal) _origin = osg::Vec3(0,0,0) * _m;
        }
        
        virtual void apply (osg::Vec2 & inv) 
        { 
            _fout << inv[0] << ' ' << inv[1]; 
        }
        
        virtual void apply (osg::Vec3 & inv) 
        { 
            osg::Vec3 v(inv);
            if (_applyMatrix)  v = (_isNormal) ? (v * _m) - _origin : v * _m;
            _fout << v[0] << ' ' << v[1] << ' ' << v[2]; 
        }
        
        virtual void apply (osg::Vec2b & inv)
        { 
            _fout << inv[0] << ' ' << inv[1]; 
        }
        
        virtual void apply (osg::Vec3b & inv) 
        { 
            osg::Vec3 v(inv[0], inv[1], inv[2]);
            if (_applyMatrix)  v = (_isNormal) ? (v * _m) - _origin : v * _m;
            _fout << v[0] << ' ' << v[1] << ' ' << v[2]; 
        }
        
        virtual void apply (osg::Vec2s & inv) 
        {    
            _fout << inv[0] << ' ' << inv[1]; 
        }
        
        virtual void apply (osg::Vec3s & inv) 
        { 
            osg::Vec3 v(inv[0], inv[1], inv[2]);
            if (_applyMatrix)  v = (_isNormal) ? (v * _m) - _origin : v * _m;
            _fout << v[0] << ' ' << v[1] << ' ' << v[2]; 
        }
    private:

        ValueVisitor& operator = (const ValueVisitor&) { return *this; }

        std::ostream&    _fout;
        osg::Matrix        _m;
        bool            _applyMatrix, _isNormal;
        osg::Vec3        _origin;
};

/** writes all primitives of a primitive-set out to a stream, decomposes quads to triangles, line-strips to lines etc */
class ObjPrimitiveIndexWriter : public osg::PrimitiveIndexFunctor {
    
    public:
        ObjPrimitiveIndexWriter(std::ostream& fout,osg::Geometry* geo, unsigned int normalIndex, unsigned int lastVertexIndex, unsigned int  lastNormalIndex, unsigned int lastTexIndex) : 
            osg::PrimitiveIndexFunctor(), 
            _fout(fout),
            _lastVertexIndex(lastVertexIndex),
            _lastNormalIndex(lastNormalIndex),
            _lastTexIndex(lastTexIndex),
            _hasNormalCoords(geo->getNormalArray() != NULL),
            _hasTexCoords(geo->getTexCoordArray(0) != NULL),
            _geo(geo),
            _normalIndex(normalIndex)
        {
        }
        
        virtual void setVertexArray(unsigned int,const osg::Vec2*) {}

        virtual void setVertexArray(unsigned int ,const osg::Vec3* ) {}

        virtual void setVertexArray(unsigned int,const osg::Vec4* ) {}
        
        virtual void setVertexArray(unsigned int,const osg::Vec2d*) {}

        virtual void setVertexArray(unsigned int ,const osg::Vec3d* ) {}

        virtual void setVertexArray(unsigned int,const osg::Vec4d* ) {}
        
        void write(unsigned int i) 
        {
            _fout << (i + _lastVertexIndex) << "/";
            
            if (_hasTexCoords || _hasNormalCoords) 
            {
                if (_hasTexCoords)
                    _fout << (i + _lastTexIndex);
                _fout << "/";
                if (_hasNormalCoords) 
                {
                    if (_geo->getNormalBinding() == osg::Geometry::BIND_PER_VERTEX)
                        _fout << (i+_lastNormalIndex);
                    else
                        _fout << (_normalIndex + _lastNormalIndex);
                }
            }
            _fout << " ";
        }
        
        // operator for triangles
        void writeTriangle(unsigned int i1, unsigned int i2, unsigned int i3)
         {
            _fout << "f ";
            write(i1);
            write(i2);
            write(i3);
            _fout << std::endl;
            // not sure if this is correct?
            if(_geo->getNormalBinding() && _geo->getNormalBinding() == osg::Geometry::BIND_PER_PRIMITIVE) ++_normalIndex;
        }
        
        // operator for lines
        void writeLine(unsigned int i1, unsigned int i2) 
        {
            _fout << "l ";
            write(i1);
            write(i2);
            _fout << std::endl;
            // not sure if this is correct?
            if(_geo->getNormalBinding() && _geo->getNormalBinding() == osg::Geometry::BIND_PER_PRIMITIVE) ++_normalIndex;
        }
        
        // operator for points
        void writePoint(unsigned int i1) 
        {
            _fout << "p ";
            write(i1);
            _fout << std::endl;
            // not sure if this is correct?
            if(_geo->getNormalBinding() && _geo->getNormalBinding() == osg::Geometry::BIND_PER_PRIMITIVE) ++_normalIndex;
        }

        virtual void begin(GLenum mode)
        {
            _modeCache = mode;
            _indexCache.clear();
        }

        virtual void vertex(unsigned int vert)
        {
            _indexCache.push_back(vert);
        }

        virtual void end()
        {
            if (!_indexCache.empty())
            {
                drawElements(_modeCache,_indexCache.size(),&_indexCache.front());
            }
        }

        virtual void drawArrays(GLenum mode,GLint first,GLsizei count);                    
        
        virtual void drawElements(GLenum mode,GLsizei count,const GLubyte* indices)
        {
            drawElementsImplementation<GLubyte>(mode, count, indices);
        }
        virtual void drawElements(GLenum mode,GLsizei count,const GLushort* indices)
        {
            drawElementsImplementation<GLushort>(mode, count, indices);
        }    

        virtual void drawElements(GLenum mode,GLsizei count,const GLuint* indices)
        {
            drawElementsImplementation<GLuint>(mode, count, indices);
        }    

    protected:
        
        template<typename T>void drawElementsImplementation(GLenum mode, GLsizei count, const T* indices) 
        {
            if (indices==0 || count==0) return;

            typedef const T* IndexPointer;
        
            switch(mode)
            {
                case(GL_TRIANGLES):
                {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=3)
                        writeTriangle(*iptr,*(iptr+1),*(iptr+2));
    
                    break;
                }
                case(GL_TRIANGLE_STRIP):
                {
                    IndexPointer iptr = indices;
                    for(GLsizei i=2;i<count;++i,++iptr)
                    {
                        if ((i%2)) writeTriangle(*(iptr),*(iptr+2),*(iptr+1));
                        else       writeTriangle(*(iptr),*(iptr+1),*(iptr+2));
                    }
                    break;
                }
                case(GL_QUADS):
                {
                    IndexPointer iptr = indices;
                    for(GLsizei i=3;i<count;i+=4,iptr+=4)
                    {
                        writeTriangle(*(iptr),*(iptr+1),*(iptr+2));
                        writeTriangle(*(iptr),*(iptr+2),*(iptr+3));
                    }
                    break;
                }
                case(GL_QUAD_STRIP):
                {
                    IndexPointer iptr = indices;
                    for(GLsizei i=3;i<count;i+=2,iptr+=2)
                    {
                        writeTriangle(*(iptr),*(iptr+1),*(iptr+2));
                        writeTriangle(*(iptr+1),*(iptr+3),*(iptr+2));
                    }
                    break;
                }
                case(GL_POLYGON): // treat polygons as GL_TRIANGLE_FAN
                case(GL_TRIANGLE_FAN):
                {
                    IndexPointer iptr = indices;
                    unsigned int first = *iptr;
                    ++iptr;
                    for(GLsizei i=2;i<count;++i,++iptr)
                    {
                        writeTriangle(first,*(iptr),*(iptr+1));
                    }
                    break;
                }
                case(GL_POINTS):
                {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;++iptr)
                    
                    {
                        writePoint(*iptr);
                    }
                    break;
                }

                case(GL_LINES):
                {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=2)
                    {
                        writeLine(*iptr, *(iptr+1));
                    }
                    break;
                }
                case(GL_LINE_STRIP):
                {
                    
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices+1;iptr<ilast;iptr+=2)

                    {
                        writeLine(*(iptr-1), *iptr);
                    }
                    break;
                }
                case(GL_LINE_LOOP):
                {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices+1;iptr<ilast;iptr+=2)
                    {
                        writeLine(*(iptr-1), *iptr);
                    }
                    writeLine(*ilast, *indices);
                    break;
                }

                default:
                    // uhm should never come to this point :)
                    break;
            }
        }    
    
    private:

        ObjPrimitiveIndexWriter& operator = (const ObjPrimitiveIndexWriter&) { return *this; }

        std::ostream&         _fout;
        GLenum               _modeCache;
        std::vector<GLuint>  _indexCache;
        unsigned int         _lastVertexIndex, _lastNormalIndex, _lastTexIndex;
        bool                 _hasNormalCoords, _hasTexCoords;
        osg::Geometry*         _geo;
        unsigned int         _normalIndex;
};


void ObjPrimitiveIndexWriter::drawArrays(GLenum mode,GLint first,GLsizei count)
{
    switch(mode)
    {
        case(GL_TRIANGLES):
        {
            unsigned int pos=first;
            for(GLsizei i=2;i<count;i+=3,pos+=3)
            {
                writeTriangle(pos,pos+1,pos+2);
            }
            break;
        }
        case(GL_TRIANGLE_STRIP):
         {
            unsigned int pos=first;
            for(GLsizei i=2;i<count;++i,++pos)
            {
                if ((i%2)) writeTriangle(pos,pos+2,pos+1);
                else       writeTriangle(pos,pos+1,pos+2);
            }
            break;
        }
        case(GL_QUADS):
        {
            unsigned int pos=first;
            for(GLsizei i=3;i<count;i+=4,pos+=4)
            {
                writeTriangle(pos,pos+1,pos+2);
                writeTriangle(pos,pos+2,pos+3);
            }
            break;
        }
        case(GL_QUAD_STRIP):
        {
            unsigned int pos=first;
            for(GLsizei i=3;i<count;i+=2,pos+=2)
            {
                writeTriangle(pos,pos+1,pos+2);
                writeTriangle(pos+1,pos+3,pos+2);
            }
            break;
        }
        case(GL_POLYGON): // treat polygons as GL_TRIANGLE_FAN
        case(GL_TRIANGLE_FAN):
        {
            unsigned int pos=first+1;
            for(GLsizei i=2;i<count;++i,++pos)
            {
                writeTriangle(first,pos,pos+1);
            }
            break;
        }
        case(GL_POINTS):
        {
            
            for(GLsizei i=0;i<count;++i)
            {
                writePoint(i);
            }
            break;
        }

        case(GL_LINES):
        {
            for(GLsizei i=0;i<count;i+=2)
            {
                writeLine(i, i+1);
            }
            break;
        }
        case(GL_LINE_STRIP):
        {
            for(GLsizei i=1;i<count;++i)
            {
                writeLine(i-1, i);
            }
            break;
        }
        case(GL_LINE_LOOP):
        {
            for(GLsizei i=1;i<count;++i)
            {
                writeLine(i-1, i);
            }
            writeLine(count-1, 0);
            break;
        }
        default:
            OSG_WARN << "OBJWriterNodeVisitor :: can't handle mode " << mode << std::endl; 
            break;
    }
}
                    

OBJWriterNodeVisitor::OBJMaterial::OBJMaterial(osg::Material* mat, osg::Texture* tex) :
    diffuse(1,1,1,1),
    ambient(0.2,0.2,0.2,1),
    specular(0,0,0,1),
    image("")
{
    static unsigned int s_objmaterial_id = 0;
    ++s_objmaterial_id;
    std::stringstream ss; 
    ss << "material_" << s_objmaterial_id;
    name = ss.str();
    
    if (mat) {
        diffuse = mat->getDiffuse(osg::Material::FRONT);
        ambient = mat->getAmbient(osg::Material::FRONT);
        specular = mat->getSpecular(osg::Material::FRONT);
    }
    
    if (tex) {
        osg::Image* img = tex->getImage(0);
        if ((img) && (!img->getFileName().empty()))
            image = img->getFileName();
        
    }
        
}

std::ostream& operator<<(std::ostream& fout, const OBJWriterNodeVisitor::OBJMaterial& mat) {
    
    fout << "newmtl " << mat.name << std::endl;
    fout << "       " << "Ka " << mat.ambient << std::endl;
    fout << "       " << "Kd " << mat.diffuse << std::endl;
    fout << "       " << "Ks " << mat.specular << std::endl;
    
    if(!mat.image.empty())
        fout << "       " << "map_Kd " << mat.image << std::endl;
    
    return fout;
    
}

void OBJWriterNodeVisitor::writeMaterials(std::ostream& fout) 
{
    for(MaterialMap::iterator i = _materialMap.begin(); i != _materialMap.end(); ++i)
    {
        fout << (*i).second << std::endl;
    }
}


std::string OBJWriterNodeVisitor::getUniqueName(const std::string& defaultvalue) {
    
    std::string name = "";
    for(std::list<std::string>::iterator i = _nameStack.begin(); i != _nameStack.end(); ++i) {
        if (!name.empty()) name+="_";
        name += (*i);
    }
    
    if (!defaultvalue.empty())
        name += "_" +defaultvalue;
    
    if (_nameMap.find(name) == _nameMap.end())
        _nameMap.insert(std::make_pair(name, 0u));
        
    std::stringstream ss;
    ss << name << "_" << _nameMap[name];
    ++(_nameMap[name]);
    return ss.str();

}

void OBJWriterNodeVisitor::processArray(const std::string& key, osg::Array* array, const osg::Matrix& m, bool isNormal)
{
    if (array == NULL)
        return;
    
    ValueVisitor vv(_fout, m, isNormal);
    _fout << std::endl;
    for(unsigned int i = 0; i < array->getNumElements(); ++i) {
        _fout << key << ' ';
        array->accept(i, vv);
        _fout << std::endl;
    }
    
    _fout << "# " << array->getNumElements() << " elements written" << std::endl;
    
}

void OBJWriterNodeVisitor::processStateSet(osg::StateSet* ss) 
{
    if (_materialMap.find(ss) != _materialMap.end()) {
        _fout << "usemtl " << _materialMap[ss].name << std::endl;
        return;
    }
    
    osg::Material* mat = dynamic_cast<osg::Material*>(ss->getAttribute(osg::StateAttribute::MATERIAL));
    osg::Texture* tex = dynamic_cast<osg::Texture*>(ss->getTextureAttribute(0, osg::StateAttribute::TEXTURE));
    
    if (mat || tex) 
    {
        _materialMap.insert(std::make_pair(osg::ref_ptr<osg::StateSet>(ss), OBJMaterial(mat, tex)));
        _fout << "usemtl " << _materialMap[ss].name << std::endl;
    }
    
}


void OBJWriterNodeVisitor::processGeometry(osg::Geometry* geo, osg::Matrix& m) {
    _fout << std::endl;
    _fout << "o " << getUniqueName( geo->getName().empty() ? geo->className() : geo->getName() ) << std::endl;
    
    processStateSet(_currentStateSet.get());
    
    processArray("v", geo->getVertexArray(), m, false);
    processArray("vn", geo->getNormalArray(), m, true);
    processArray("vt", geo->getTexCoordArray(0)); // we support only tex-unit 0
    unsigned int normalIndex = 0;
    for(unsigned int i = 0; i < geo->getNumPrimitiveSets(); ++i) 
    {
        osg::PrimitiveSet* ps = geo->getPrimitiveSet(i);
        
        ObjPrimitiveIndexWriter pif(_fout, geo, normalIndex, _lastVertexIndex, _lastNormalIndex, _lastTexIndex);
        ps->accept(pif);
        
        if(geo->getNormalArray() && geo->getNormalBinding() == osg::Geometry::BIND_PER_PRIMITIVE_SET)
            ++normalIndex;
    }
    if (geo->getVertexArray()) 
        _lastVertexIndex += geo->getVertexArray()->getNumElements();
    if (geo->getNormalArray())
        _lastNormalIndex += geo->getNormalArray()->getNumElements();
    if(geo->getTexCoordArray(0))
        _lastTexIndex += geo->getTexCoordArray(0)->getNumElements();
    
}

void OBJWriterNodeVisitor::apply( osg::Geode &node )
{

    pushStateSet(node.getStateSet());
    _nameStack.push_back(node.getName());
    osg::Matrix m = osg::computeLocalToWorld(getNodePath());
    unsigned int count = node.getNumDrawables();
    for ( unsigned int i = 0; i < count; i++ )
    {
        osg::Geometry *g = node.getDrawable( i )->asGeometry();
        if ( g != NULL )
        {
            pushStateSet(g->getStateSet());
            
            processGeometry(g,m);
            
            popStateSet(g->getStateSet());
        }
    }


    popStateSet(node.getStateSet());
    _nameStack.pop_back();
}