/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#include <osg/GLExtensions>
#include <osg/Texture2D>
#include <osg/State>
#include <osg/Notify>
#include <osg/GLU>

using namespace osg;

Texture2D::Texture2D():
            _textureWidth(0),
            _textureHeight(0),
            _numMipmapLevels(0)
{
    setUseHardwareMipMapGeneration(true);
}

Texture2D::Texture2D(Image* image):
            _textureWidth(0),
            _textureHeight(0),
            _numMipmapLevels(0)
{
    setUseHardwareMipMapGeneration(true);
    setImage(image);
}

Texture2D::Texture2D(const Texture2D& text,const CopyOp& copyop):
            Texture(text,copyop),
            _image(copyop(text._image.get())),
            _textureWidth(text._textureWidth),
            _textureHeight(text._textureHeight),
            _numMipmapLevels(text._numMipmapLevels),
            _subloadCallback(text._subloadCallback)
{
}

Texture2D::~Texture2D()
{
}

int Texture2D::compare(const StateAttribute& sa) const
{
    // check the types are equal and then create the rhs variable
    // used by the COMPARE_StateAttribute_Paramter macro's below.
    COMPARE_StateAttribute_Types(Texture2D,sa)

    if (_image!=rhs._image) // smart pointer comparison.
    {
        if (_image.valid())
        {
            if (rhs._image.valid())
            {
                int result = _image->compare(*rhs._image);
                if (result!=0) return result;
            }
            else
            {
                return 1; // valid lhs._image is greater than null. 
            }
        }
        else if (rhs._image.valid()) 
        {
            return -1; // valid rhs._image is greater than null. 
        }
    }

    if (!_image && !rhs._image)
    {
        // no image attached to either Texture2D
        // but could these textures already be downloaded?
        // check the _textureObjectBuffer to see if they have been
        // downloaded

        int result = compareTextureObjects(rhs);
        if (result!=0) return result;
    }

    int result = compareTexture(rhs);
    if (result!=0) return result;

    // compare each paramter in turn against the rhs.
#if 1    
    if (_textureWidth != 0 && rhs._textureWidth != 0)
    {
        COMPARE_StateAttribute_Parameter(_textureWidth)
    }
    if (_textureHeight != 0 && rhs._textureHeight != 0)
    {
        COMPARE_StateAttribute_Parameter(_textureHeight)
    }
#endif
    COMPARE_StateAttribute_Parameter(_subloadCallback)

    return 0; // passed all the above comparison macro's, must be equal.
}

void Texture2D::setImage(Image* image)
{
    _image = image;
    _modifiedCount.setAllElementsTo(0);
}


void Texture2D::apply(State& state) const
{

    //state.setReportGLErrors(true);

    // get the contextID (user defined ID of 0 upwards) for the 
    // current OpenGL context.
    const unsigned int contextID = state.getContextID();

    // get the texture object for the current contextID.
    TextureObject* textureObject = getTextureObject(contextID);

    if (textureObject != 0)
    {
        textureObject->bind();
        
        if (getTextureParameterDirty(state.getContextID()))
            applyTexParameters(GL_TEXTURE_2D,state);

        if (_subloadCallback.valid())
        {
            _subloadCallback->subload(*this,state);
        }
        else if (_image.valid() && getModifiedCount(contextID) != _image->getModifiedCount())
        {
            applyTexImage2D_subload(state,GL_TEXTURE_2D,_image.get(),
                                    _textureWidth, _textureHeight, _internalFormat, _numMipmapLevels);
 
            // update the modified tag to show that it is up to date.
            getModifiedCount(contextID) = _image->getModifiedCount();
     
        }
        else if (_readPBuffer.valid())
        {
            _readPBuffer->bindPBufferToTexture(GL_FRONT);
        }

    }
    else if (_subloadCallback.valid())
    {

        _textureObjectBuffer[contextID] = textureObject = generateTextureObject(contextID,GL_TEXTURE_2D);

        textureObject->bind();

        applyTexParameters(GL_TEXTURE_2D,state);

        _subloadCallback->load(*this,state);
        
        textureObject->setAllocated(_numMipmapLevels,_internalFormat,_textureWidth,_textureHeight,1,0);

        // in theory the following line is redundent, but in practice
        // have found that the first frame drawn doesn't apply the textures
        // unless a second bind is called?!!
        // perhaps it is the first glBind which is not required...
        //glBindTexture( GL_TEXTURE_2D, handle );

    }
    else if (_image.valid() && _image->data())
    {

        // keep the image around at least till we go out of scope.
        osg::ref_ptr<osg::Image> image = _image;

        // compute the internal texture format, this set the _internalFormat to an appropriate value.
        computeInternalFormat();
        
        // compute the dimensions of the texture.
        computeRequiredTextureDimensions(state,*image,_textureWidth, _textureHeight, _numMipmapLevels);
        
        
        _textureObjectBuffer[contextID] = textureObject = generateTextureObject(
                contextID,GL_TEXTURE_2D,_numMipmapLevels,_internalFormat,_textureWidth,_textureHeight,1,0);
        
        textureObject->bind();

        applyTexParameters(GL_TEXTURE_2D,state);

        if (textureObject->isAllocated())
        {
            //std::cout<<"Reusing texture object"<<std::endl;
            applyTexImage2D_subload(state,GL_TEXTURE_2D,image.get(),
                                 _textureWidth, _textureHeight, _internalFormat, _numMipmapLevels);
        }
        else
        {
            //std::cout<<"Creating new texture object"<<std::endl;
            applyTexImage2D_load(state,GL_TEXTURE_2D,image.get(),
                                 _textureWidth, _textureHeight, _numMipmapLevels);
                                 
            textureObject->setAllocated(true);
        }
        
        
        // update the modified tag to show that it is upto date.
        getModifiedCount(contextID) = image->getModifiedCount();


        if (_unrefImageDataAfterApply && areAllTextureObjectsLoaded() && image->getDataVariance()==STATIC)
        {
            Texture2D* non_const_this = const_cast<Texture2D*>(this);
            non_const_this->_image = 0;
        }

        // in theory the following line is redundent, but in practice
        // have found that the first frame drawn doesn't apply the textures
        // unless a second bind is called?!!
        // perhaps it is the first glBind which is not required...
        //glBindTexture( GL_TEXTURE_2D, handle );
        
    }
    else if ( (_textureWidth!=0) && (_textureHeight!=0) && (_internalFormat!=0) )
    {
        _textureObjectBuffer[contextID] = textureObject = generateTextureObject(
                contextID,GL_TEXTURE_2D,_numMipmapLevels,_internalFormat,_textureWidth,_textureHeight,1,0);
        
        textureObject->bind();

        applyTexParameters(GL_TEXTURE_2D,state);

        // no image present, but dimensions at set so lets create the texture
        glTexImage2D( GL_TEXTURE_2D, 0, _internalFormat,
                     _textureWidth, _textureHeight, _borderWidth,
                     _sourceFormat ? _sourceFormat : _internalFormat,
                     _sourceType ? _sourceType : GL_UNSIGNED_BYTE,
                     0);                
                     
        if (_readPBuffer.valid())
        {
            _readPBuffer->bindPBufferToTexture(GL_FRONT);
        }
        
    }
    else
    {
        glBindTexture( GL_TEXTURE_2D, 0 );
    }
}

void Texture2D::computeInternalFormat() const
{
    if (_image.valid()) computeInternalFormatWithImage(*_image); 
}


void Texture2D::copyTexImage2D(State& state, int x, int y, int width, int height )
{
    const unsigned int contextID = state.getContextID();
    
    if (_internalFormat==0) _internalFormat=GL_RGBA;

    // get the globj for the current contextID.
    TextureObject* textureObject = getTextureObject(contextID);
    
    if (textureObject)
    {
        if (width==(int)_textureWidth && height==(int)_textureHeight)
        {
            // we have a valid texture object which is the right size
            // so lets play clever and use copyTexSubImage2D instead.
            // this allows use to reuse the texture object and avoid
            // expensive memory allocations.
            copyTexSubImage2D(state,0 ,0, x, y, width, height);
            return;
        }
        // the relevent texture object is not of the right size so
        // needs to been deleted    
        // remove previously bound textures. 
        dirtyTextureObject();
        // note, dirtyTextureObject() dirties all the texture objects for
        // this texture, is this right?  Perhaps we should dirty just the
        // one for this context.  Note sure yet will leave till later.
        // RO July 2001.
    }
    
    
    // remove any previously assigned images as these are nolonger valid.
    _image = NULL;

    // switch off mip-mapping.
    //
    _textureObjectBuffer[contextID] = textureObject = generateTextureObject(contextID,GL_TEXTURE_2D);

    textureObject->bind();
    
    applyTexParameters(GL_TEXTURE_2D,state);


    bool needHardwareMipMap = (_min_filter != LINEAR && _min_filter != NEAREST);
    bool hardwareMipMapOn = false;
    if (needHardwareMipMap)
    {
        const Extensions* extensions = getExtensions(contextID,true);
        bool generateMipMapSupported = extensions->isGenerateMipMapSupported();

        hardwareMipMapOn = _useHardwareMipMapGeneration && generateMipMapSupported;
        
        if (!hardwareMipMapOn)
        {
            // have to swtich off mip mapping
            notify(NOTICE)<<"Warning: Texture2D::copyTexImage2D(,,,,) switch of mip mapping as hardware support not available."<<std::endl;
            _min_filter = LINEAR;
        }
    }
    
    if (hardwareMipMapOn) glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,GL_TRUE);

    glCopyTexImage2D( GL_TEXTURE_2D, 0, _internalFormat, x, y, width, height, 0 );

    if (hardwareMipMapOn) glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,GL_FALSE);


    _textureWidth = width;
    _textureHeight = height;
    _numMipmapLevels = 1;
    
    textureObject->setAllocated(_numMipmapLevels,_internalFormat,_textureWidth,_textureHeight,1,0);


    // inform state that this texture is the current one bound.
    state.haveAppliedTextureAttribute(state.getActiveTextureUnit(), this);
}

void Texture2D::copyTexSubImage2D(State& state, int xoffset, int yoffset, int x, int y, int width, int height )
{
    const unsigned int contextID = state.getContextID();

    if (_internalFormat==0) _internalFormat=GL_RGBA;

    // get the texture object for the current contextID.
    TextureObject* textureObject = getTextureObject(contextID);
    
    if (textureObject)
    {
        // we have a valid image
        textureObject->bind();
        
        applyTexParameters(GL_TEXTURE_2D,state);

        bool needHardwareMipMap = (_min_filter != LINEAR && _min_filter != NEAREST);
        bool hardwareMipMapOn = false;
        if (needHardwareMipMap)
        {
            const Extensions* extensions = getExtensions(contextID,true);
            bool generateMipMapSupported = extensions->isGenerateMipMapSupported();

            hardwareMipMapOn = _useHardwareMipMapGeneration && generateMipMapSupported;

            if (!hardwareMipMapOn)
            {
                // have to swtich off mip mapping
                notify(NOTICE)<<"Warning: Texture2D::copyTexImage2D(,,,,) switch of mip mapping as hardware support not available."<<std::endl;
                _min_filter = LINEAR;
            }
        }

        if (hardwareMipMapOn) glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,GL_TRUE);

        glCopyTexSubImage2D( GL_TEXTURE_2D, 0, xoffset, yoffset, x, y, width, height);

        if (hardwareMipMapOn) glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,GL_FALSE);

        // inform state that this texture is the current one bound.
        state.haveAppliedTextureAttribute(state.getActiveTextureUnit(), this);

    }
    else
    {
        // no texture object already exsits for this context so need to
        // create it upfront - simply call copyTexImage2D.
        copyTexImage2D(state,x,y,width,height);
    }
}