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/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2008-2010 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#ifndef OSGEARTH_IMAGEUTILS_H
#define OSGEARTH_IMAGEUTILS_H

#include <osgEarth/Common>
#include <osg/Image>
#include <osg/GL>

//These formats were not added to OSG until after 2.8.3 so we need to define them to use them.
#ifndef GL_EXT_texture_compression_rgtc
  #define GL_COMPRESSED_RED_RGTC1_EXT                0x8DBB
  #define GL_COMPRESSED_SIGNED_RED_RGTC1_EXT         0x8DBC
  #define GL_COMPRESSED_RED_GREEN_RGTC2_EXT          0x8DBD
  #define GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT   0x8DBE
#endif

#ifndef GL_IMG_texture_compression_pvrtc
    #define GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG      0x8C00
    #define GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG      0x8C01
    #define GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG     0x8C02
    #define GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG     0x8C03
#endif

namespace osgEarth
{
    class OSGEARTH_EXPORT ImageUtils
    {
    public:
        static osg::Image* cloneImage( const osg::Image* image );

        static void normalizeImage( osg::Image* image );

        static bool copyAsSubImage(
            const osg::Image* src, 
            osg::Image* dst, 
            int dst_start_col, int dst_start_row, int dst_start_img=0 );

        static bool resizeImage(
            const osg::Image* input, 
            unsigned int new_s, unsigned int new_t,
            osg::ref_ptr<osg::Image>& output,
            unsigned int mipmapLevel =0 );

        static osg::Image* cropImage(
            const osg::Image* image,
            double src_minx, double src_miny, double src_maxx, double src_maxy,
            double &dst_minx, double &dst_miny, double &dst_maxx, double &dst_maxy);

        static osg::Image* createMipmapBlendedImage(
            const osg::Image* primary,
            const osg::Image* secondary );

        static bool mix( osg::Image* dest, const osg::Image* src, float a );

        static osg::Image* sharpenImage( const osg::Image* image );

        static bool isPowerOfTwo(const osg::Image* image);

        static osg::Image* createEmptyImage();

        static bool canConvert(const osg::Image* image, GLenum pixelFormat, GLenum dataType);

        static osg::Image* convert(const osg::Image* image, GLenum pixelFormat, GLenum dataType);

                static osg::Image* convertToRGB8(const osg::Image* image);

                static osg::Image* convertToRGBA8(const osg::Image* image);

                static bool areEquivalent(const osg::Image *lhs, const osg::Image *rhs);

        static bool areRGBEquivalent( const osg::Vec4& lhs, const osg::Vec4& rhs, float epsilon =0.01f ) {
            return
                fabs(lhs.r() - rhs.r()) < epsilon &&
                fabs(lhs.g() - rhs.g()) < epsilon &&
                fabs(lhs.b() - rhs.b()) < epsilon;
        }

        static bool hasAlphaChannel( const osg::Image* image );

        static bool isCompressed( const osg::Image* image );

        class OSGEARTH_EXPORT PixelReader
        {
        public:
            PixelReader(const osg::Image* image);

            static bool supports( GLenum pixelFormat, GLenum dataType );

            static bool supports( const osg::Image* image ) {
                return image && supports(image->getPixelFormat(), image->getDataType() );
            }

            osg::Vec4 operator()(int s, int t, int r=0, int m=0) const {
                return (*_reader)(this, s, t, r, m);
            }

            // internals:
            const unsigned char* data(int s=0, int t=0, int r=0, int m=0) const {
                return m == 0 ?
                    _image->data() + s*_colMult + t*_rowMult + r*_imageSize :
                    _image->getMipmapData(m) + s*_colMult + t*(_rowMult >> m) + r*(_imageSize>>m) ;
            }

            typedef osg::Vec4 (*ReaderFunc)(const PixelReader* ia, int s, int t, int r, int m);
            ReaderFunc _reader;
            const osg::Image* _image;
            unsigned _colMult;
            unsigned _rowMult;
            unsigned _imageSize;
        };
        
        class OSGEARTH_EXPORT PixelWriter
        {
        public:
            PixelWriter(osg::Image* image);

            static bool supports( GLenum pixelFormat, GLenum dataType );

            static bool supports( const osg::Image* image ) {
                return image && supports(image->getPixelFormat(), image->getDataType() );
            }

            void operator()(const osg::Vec4& c, int s, int t, int r=0, int m=0) {
                (*_writer)(this, c, s, t, r, m );
            }

            // internals:
            osg::Image* _image;
            unsigned _colMult;
            unsigned _rowMult;
            unsigned _imageSize;

            unsigned char* data(int s=0, int t=0, int r=0, int m=0) const {
                return m == 0 ?
                    _image->data() + s*_colMult + t*_rowMult + r*_imageSize :
                    _image->getMipmapData(m) + s*_colMult + t*(_rowMult >> m) + r*(_imageSize>>m);
            }

            typedef void (*WriterFunc)(const PixelWriter* iw, const osg::Vec4& c, int s, int t, int r, int m);
            WriterFunc _writer;
        };

        template<typename T>
        struct PixelVisitor : public T
        {
            void accept( osg::Image* image ) {
                PixelReader _reader( image );
                PixelWriter _writer( image );
                for( int r=0; r<image->r(); ++r ) {
                    for( int t=0; t<image->t(); ++t ) {
                        for( int s=0; s<image->s(); ++s ) {
                            osg::Vec4f pixel = _reader(s,t,r);
                            if ( (*this)(pixel) )
                                _writer(pixel,s,t,r);
                        }
                    }
                }
            }          

            void accept( const osg::Image* src, osg::Image* dest ) {
                PixelReader _readerSrc( src );
                PixelReader _readerDest( dest );
                PixelWriter _writerDest( dest );
                for( int r=0; r<src->r(); ++r ) {
                    for( int t=0; t<src->t(); ++t ) {
                        for( int s=0; s<src->s(); ++s ) {
                            const osg::Vec4f pixelSrc = _readerSrc(s,t,r);
                            osg::Vec4f pixelDest = _readerDest(s,t,r);
                            if ( (*this)(pixelSrc, pixelDest) )
                                _writerDest(pixelDest,s,t,r);
                        }
                    }
                }
            }
        };

        struct CopyImage {
            bool operator()( const osg::Vec4f& src, osg::Vec4f& dest ) {
                dest = src;
                return true;
            }
        };
    };
}

#endif //OSGEARTH_IMAGEUTILS_H