////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2011, Computer Graphics Group RWTH Aachen University         //
// All rights reserved.                                                       //
////////////////////////////////////////////////////////////////////////////////

#ifndef ACGL_RESOURCE_TEXTURE_HH
#define ACGL_RESOURCE_TEXTURE_HH

#include <ACGL/ACGL.hh>

#include <ACGL/OpenGL/GL.hh>
#include <ACGL/OpenGL/Tools.hh>
#include <ACGL/Math/Math.hh>

#include <vector>
#include <tr1/memory>

namespace ACGL{
namespace OpenGL{

class Texture
{
    // ======================================================================================================== \/
    // ============================================================================================ GPU CONTEXT \/
    // ======================================================================================================== \/
private:
    static GLuint sTextureContext;

    // ========================================================================================================= \/
    // ============================================================================================ CONSTRUCTORS \/
    // ========================================================================================================= \/
public:
    Texture(
        GLenum _internalFormat = GL_RGBA,
        GLenum _target = GL_TEXTURE_2D,
        GLenum _format = GL_RGBA,
        GLenum _type = GL_UNSIGNED_BYTE)
    :   mContext(0),
        mWidth(0),
        mHeight(0),
        mDepth(0),
        mInternalFormat(_internalFormat),
        mTarget(_target),
        mFormat(_format),
        mType(_type)
    {
        glGenTextures(1, &mContext);
        if (openGLCriticalErrorOccured() ) {
            ACGL::Utils::error() << "could not generate texture!" << std::endl;
        }

    }

    virtual ~Texture(void)
    {
        // context 0 will get ignored by OpenGL
        glDeleteTextures(1, &mContext);
    }

    // ==================================================================================================== \/
    // ============================================================================================ GETTERS \/
    // ==================================================================================================== \/
public:
    inline GLuint  getContext        (void) const { return mContext;        }
    inline GLsizei getWidth          (void) const { return mWidth;          }
    inline GLsizei getHeight         (void) const { return mHeight;         }
    inline GLsizei getDepth          (void) const { return mDepth;          }
    inline GLenum  getInternalFormat (void) const { return mInternalFormat; }
    inline GLenum  getTarget         (void) const { return mTarget;         }
    inline GLenum  getFormat         (void) const { return mFormat;         }
    inline GLenum  getType           (void) const { return mType;           }

    // ==================================================================================================== \/
    // ============================================================================================ SETTERS \/
    // ==================================================================================================== \/
public:
    inline void setInternalFormat (GLenum _internalFormat) { mInternalFormat = _internalFormat; }
    inline void setTarget         (GLenum _target)         { mTarget = _target;                 }
    inline void setFormat         (GLenum _format)         { mFormat = _format;                 }
    inline void setType           (GLenum _type)           { mType = _type;                     }

    inline void setSize(
        GLsizei _width = 0,
        GLsizei _height = 0,
        GLsizei _depth = 0)
    {
        mWidth = _width;
        mHeight = _height;
        mDepth = _depth;
    }

    // ===================================================================================================== \/
    // ============================================================================================ WRAPPERS \/
    // ===================================================================================================== \/
public:
    //! Activate texture unit and bind this texture.
    inline void bind(GLenum _textureUnit) const
    {
        if(sTextureContext == mContext)
            return;
        glActiveTexture(GL_TEXTURE0 + _textureUnit);
        glBindTexture(mTarget, mContext);
        openGLRareError();
        sTextureContext = mContext;
    }
    
    //! Bind this texture.
    inline void bind(void) const
    {
        if(sTextureContext == mContext)
            return;
        glBindTexture(mTarget, mContext);
        openGLRareError();
        sTextureContext = mContext;
    }

    inline void setParameter(GLenum _parameter, GLint _value)
    {
        bind();
        glTexParameteri(mTarget, _parameter, _value);
        openGLRareError();
    }

    inline void setParameter(GLenum _parameter, GLfloat _value)
    {
        bind();
        glTexParameterf(mTarget, _parameter, _value);
        openGLRareError();
    }

    //! Set texture size for 1D, 2D or 3D textures and NULL data
    inline void setRenderTarget(
        GLsizei _width,
        GLsizei _height = 0,
        GLsizei _depth = 0)
    {
        bind();
        mWidth = _width;
        mHeight = _height;
        mDepth = _depth;
        if(mWidth > 0 && mHeight > 0 && mDepth > 0)
        {
            //3D
        }
        else if(mWidth > 0 && mHeight > 0)
        {
            glTexImage2D(
                mTarget,
                0,
                mInternalFormat,
                mWidth,
                mHeight,
                0,//no border
                mFormat,
                mType,
                NULL);
        }
        else if(mWidth > 0)
        {
            //1D
        }
    }

    //! Set texture size and NULL data
    inline void setRenderTarget2D(
        GLsizei _width,
        GLsizei _height)
    {
        bind();
        mWidth = _width;
        mHeight = _height;
        glTexImage2D(
            mTarget,
            0,
            mInternalFormat,
            mWidth,
            mHeight,
            0,//no border
            mFormat,
            mType,
            NULL);
    }

    //! Set texture data for some mipmap level.
    /*!
        If you upload a texture for a higher mipmap level, the function will automatically determine
        its size calculating (w,h)/2^level where w and h are the width and height of the base texture.
     */
    inline void setTexImage2D(
        const GLvoid* _pData)
    {
        bind();
        glTexImage2D(
            mTarget,
            0,
            mInternalFormat,
            mWidth,
            mHeight,
            0,//no border
            mFormat,
            mType,
            _pData);
    }

    //! Set texture data for some mipmap level.
    /*!
        If you upload a texture for a higher mipmap level, the function will automatically determine
        its size calculating (w,h)/2^level where w and h are the width and height of the base texture.
     */
    inline void setTexImage2D(
        const GLvoid* _pData,
        GLint         _mipmapLevel)
    {
        bind();
        glTexImage2D(
            mTarget,
            _mipmapLevel,
            mInternalFormat,
            mWidth  / GLsizei(Math::Functions::pow(2.0f, float(_mipmapLevel))),
            mHeight / GLsizei(Math::Functions::pow(2.0f, float(_mipmapLevel))),
            0,//no border
            mFormat,
            mType,
            _pData);
    }
    
    //! Generate mipmaps from the current base texture (i.e. the texture from level 0).
    void generateMipmaps(void) const
    {
        bind();
        glEnable(mTarget);
        glGenerateMipmap(mTarget);
        openGLRareError();
    } 

    // =================================================================================================== \/
    // ============================================================================================ FIELDS \/
    // =================================================================================================== \/
private:
    GLuint  mContext;
    GLsizei mWidth;
    GLsizei mHeight;
    GLsizei mDepth;
    GLenum  mInternalFormat;
    GLenum  mTarget;
    GLenum  mFormat;
    GLenum  mType;
};

typedef std::tr1::shared_ptr<Texture> SharedTexture;

} // OpenGL
} // ACGL

#endif // ACGL_RESOURCE_TEXTURE_HH