/*******************************************************************************

 Copyright (c) 2009, Charles McGarvey
 All rights reserved.
 
 Redistribution   and   use  in  source  and  binary  forms,  with  or  without
 modification, are permitted provided that the following conditions are met:
 
   * Redistributions  of  source  code  must retain the above copyright notice,
     this list of conditions and the following disclaimer.
   * Redistributions  in binary form must reproduce the above copyright notice,
     this  list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
 THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*******************************************************************************/

#include <cstring>		// memcpy

#include <boost/bind.hpp>

#include <SDL/SDL.h>
#include <SDL/SDL_image.h>

#include "Dispatcher.hh"
#include "Library.hh"
#include "Log.hh"
#include "OpenGL.hh"
#include "Texture.hh"


namespace Mf {


/**
 * The texture implementation just contains all the information about the image
 * which is worth having in memory.  The image data itself is not worth keeping
 * in memory if the texture has been loaded to GL, but the name of the resource
 * is retained so that it can be reloaded if necessary.  The implementation is a
 * mippleton so that multiple texture objects can share the same internal
 * objects and avoid having duplicate textures loaded to GL.
 */

class Texture::Impl : public Library<Impl>
{

	/**
	 * Delete the texture (if it is loaded) from GL.
	 */

	void unloadFromGL()
	{
		if (mObject)
		{
			if (mObject == globalObject_)
			{
				globalObject_ = 0;
			}

			glDeleteTextures(1, &mObject);
			mObject = 0;
		}
	}

	/**
	 * If the GL context was recreated, we need to reload the texture.  This may
	 * involve reading it from disk again, but hopefully the OS was smart enough
	 * to cache it if the client has plenty of RAM.
	 */

	void contextRecreated(const Notification* note)
	{
		mObject = globalObject_ = 0;
		uploadToGL();
	}

	/**
	 * This is a helper method used by some of the texture loading code.  It
	 * returns the first power of two which is greater than the input value.
	 */

	static int powerOfTwo(int input)
	{
		int value = 1;

		while (value < input)
		{
			value <<= 1;
		}
		return value;
	}


	static void flipSurface(SDL_Surface* image)
	{
		unsigned char*	pixels = (Uint8*)(image->pixels);

		unsigned		pitch = image->pitch;
		unsigned char	line[pitch];

		int		yBegin = 0;
		int		yEnd = image->h - 1;

		if (SDL_MUSTLOCK(image)) SDL_LockSurface(image);
		while (yBegin < yEnd)
		{
			memcpy(line,                    pixels + pitch * yBegin, pitch);
			memcpy(pixels + pitch * yBegin,	pixels + pitch * yEnd,   pitch);
			memcpy(pixels + pitch * yEnd,   line,                    pitch);
			yBegin++;
			yEnd--;
		}
		if (SDL_MUSTLOCK(image)) SDL_UnlockSurface(image);
	}

public:

	/**
	 * Construction is initialization.
	 */

	explicit Impl(const std::string& name) :
		Library<Impl>(name),
		mContext(0),
		mWidth(0),
		mHeight(0),
		mMode(0),
		mMinFilter(GL_NEAREST),
		mMagFilter(GL_NEAREST),
		mWrapS(GL_CLAMP),
		mWrapT(GL_CLAMP),
		mObject(0)
	{
		loadFromFile();

		// we want to know when the GL context is recreated
		Dispatcher::getInstance().addHandler("video.context_recreated",
				boost::bind(&Impl::contextRecreated, this, _1), this);
	}

	~Impl()
	{
		if (mContext)
		{
			SDL_FreeSurface(mContext);
		}

		unloadFromGL();

		Dispatcher::getInstance().removeHandler(this);
	}


	/**
	 * Adapted from some public domain code.  This stuff is common enough that
	 * it really should be included in SDL_image...  We need this because images
	 * loaded with SDL_image aren't exactly GL-ready right out of the box.  This
	 * method makes them ready.
	 */

	static SDL_Surface* prepareImageForGL(SDL_Surface* surface)
	{
		int w = powerOfTwo(surface->w);
		int h = powerOfTwo(surface->h);

		// 2. OpenGL textures make more sense within the coordinate system when
		// they are "upside down," so let's flip it.

		flipSurface(surface);

		// 1. OpenGL images must (generally) have dimensions of a power-of-two.
		// If this one doesn't, we can at least be more friendly by expanding
		// the dimensions so that they are, though there will be some empty
		// space within the range of normal texture coordinates.  It's better if
		// textures are the right size to begin with.

		SDL_Surface* image = SDL_CreateRGBSurface
		(
			SDL_SWSURFACE,
			w, h,
			32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			0x000000FF,
			0x0000FF00,
			0x00FF0000,
			0xFF000000
#else
			0xFF000000,
			0x00FF0000,
			0x0000FF00,
			0x000000FF
#endif
		);

		if (!image)
		{
			return 0;
		}

		Uint32 savedFlags = surface->flags&(SDL_SRCALPHA|SDL_RLEACCELOK);
		Uint8  savedAlpha = surface->format->alpha;
		if (savedFlags & SDL_SRCALPHA)
		{
			SDL_SetAlpha(surface, 0, 0);
		}

		SDL_Rect srcArea, destArea;
		srcArea.x = 0; destArea.x = 0;
		srcArea.y = 0; destArea.y = h - surface->h;
		srcArea.w = surface->w;
		srcArea.h = surface->h;
		SDL_BlitSurface(surface, &srcArea, image, &destArea);

		if (savedFlags & SDL_SRCALPHA)
		{
			SDL_SetAlpha(surface, savedFlags, savedAlpha);
		}

		return image;
	}

	/**
	 * Use SDL_image to load images from file.  A surface with the image data is
	 * returned.
	 * @return Image data.
	 */

	void loadFromFile()
	{
		SDL_Surface* surface;

		surface = IMG_Load(Texture::getPath(getName()).c_str());

		if (!surface)
		{
			logWarning("texture not found: %s", getName().c_str());
			throw Exception(Exception::FILE_NOT_FOUND);
		}

		SDL_Surface* temp = prepareImageForGL(surface);
		SDL_FreeSurface(surface);

		if (!temp)
		{
			throw Exception(Exception::OPENGL_ERROR);
		}

		if (temp->format->BytesPerPixel == 3)
		{
			mMode = GL_RGB;
		}
		else if (temp->format->BytesPerPixel == 4)
		{
			mMode = GL_RGBA;
		}
		else
		{
			SDL_FreeSurface(temp);
			throw Exception(Exception::BAD_IMAGE_FORMAT);
		}

		mWidth = temp->w;
		mHeight = temp->h;

		mContext = temp;
	}


	/**
	 * Upload the image to GL so that it will be accessible by a much more
	 * manageable handle and hopefully reside in video memory.
	 */

	void uploadToGL()
	{
		if (mObject)
		{
			// already loaded
			return;
		}

		if (!mContext) loadFromFile();

		glGenTextures(1, &mObject);
		glBindTexture(GL_TEXTURE_2D, mObject);

		glTexImage2D
		//gluBuild2DMipmaps
		(
			GL_TEXTURE_2D,
			0,
			mMode,
			//3,
			mContext->w,
			mContext->h,
			0,
			mMode,
			GL_UNSIGNED_BYTE,
			mContext->pixels
		);

		setProperties();

		SDL_FreeSurface(mContext);
		mContext = 0;
	}


	/**
	 * Sets some texture properties such as the filters and external coordinate
	 * behavior.
	 */

	void setProperties()
	{
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, mMinFilter);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mMagFilter);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, mWrapS);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, mWrapT);
	}

	inline void setMinFilter(GLuint filter)
	{
		bind();
		mMinFilter = filter;
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, mMinFilter);
	}

	inline void setMagFilter(GLuint filter)
	{
		bind();
		mMagFilter = filter;
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mMagFilter);
	}

	inline void setWrapS(GLuint wrap)
	{
		bind();
		mWrapS = wrap;
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, mWrapS);
	}

	inline void setWrapT(GLuint wrap)
	{
		bind();
		mWrapT = wrap;
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, mWrapT);
	}


	inline void bind()
	{
		if (mObject == 0)
		{
			uploadToGL();
		}
		if (mObject != globalObject_)
		{
			glBindTexture(GL_TEXTURE_2D, mObject);
			globalObject_ = mObject;
		}
	}


	SDL_Surface*	mContext;
	unsigned		mWidth;			///< Horizontal dimension of the image.
	unsigned		mHeight;		///< Vertical dimension.

	GLuint			mMode;			///< Depth of the image, GL_RGB or GL_RGBA.
	GLuint			mMinFilter;		///< Minifcation filter.
	GLuint			mMagFilter;		///< Magnification filter.
	GLuint			mWrapS;			///< Wrapping behavior horizontally.
	GLuint			mWrapT;			///< Wrapping behavior vertically.

	GLuint			mObject;		///< GL texture handle.
	static GLuint	globalObject_;	///< Global GL texture handle.
};

GLuint Texture::Impl::globalObject_ = 0;


Texture::Texture(const std::string& name) :
	// pass through
	mImpl(Texture::Impl::getInstance(name)) {}


/**
 * Bind the GL texture for mapping, etc.
 */

void Texture::bind() const
{
	// pass through
	mImpl->bind();
}


/**
 * Get the texture object, for the curious.
 */

GLuint Texture::getObject() const
{
	// pass through
	return mImpl->mObject;
}


void Texture::resetBind()
{
	glBindTexture(GL_TEXTURE_2D, 0);
	Impl::globalObject_ = 0;
}


unsigned Texture::getWidth() const
{
	// pass through
	return mImpl->mWidth;
}

unsigned Texture::getHeight() const
{
	// pass through
	return mImpl->mHeight;
}


void Texture::setMinFilter(GLuint filter)
{
	// pass through
	mImpl->setMinFilter(filter);
}

void Texture::setMagFilter(GLuint filter)
{
	// pass through
	mImpl->setMagFilter(filter);
}

void Texture::setWrapS(GLuint wrap)
{
	// pass through
	mImpl->setWrapS(wrap);
}

void Texture::setWrapT(GLuint wrap)
{
	// pass through
	mImpl->setWrapT(wrap);
}


std::string Texture::getPath(const std::string& name)
{
	std::string path = Resource::getPath("textures/" + name + ".png");
	return path;
}


} // namespace Mf

/** vim: set ts=4 sw=4 tw=80: *************************************************/