/*
** gl_hwtexture.cpp
** GL texture abstraction
**
**---------------------------------------------------------------------------
** Copyright 2019 Christoph Oelckers
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. 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.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "gles_system.h"

#include "c_cvars.h"
#include "hw_material.h"

#include "hw_cvars.h"
#include "gles_renderer.h"
#include "gles_samplers.h"
#include "gles_renderstate.h"
#include "gles_hwtexture.h"

namespace OpenGLESRenderer
{


TexFilter_s TexFilter[] = {
	{GL_NEAREST,					GL_NEAREST,		false},
	{GL_NEAREST_MIPMAP_NEAREST,		GL_NEAREST,		true},
	{GL_LINEAR,						GL_LINEAR,		false},
	{GL_LINEAR_MIPMAP_NEAREST,		GL_LINEAR,		true},
	{GL_LINEAR_MIPMAP_LINEAR,		GL_LINEAR,		true},
	{GL_NEAREST_MIPMAP_LINEAR,		GL_NEAREST,		true},
	{GL_LINEAR_MIPMAP_LINEAR,		GL_NEAREST,		true},
};

//===========================================================================
// 
//	Static texture data
//
//===========================================================================
unsigned int FHardwareTexture::lastbound[FHardwareTexture::MAX_TEXTURES];

//===========================================================================
// 
//	Loads the texture image into the hardware
//
// NOTE: For some strange reason I was unable to find the source buffer
// should be one line higher than the actual texture. I got extremely
// strange crashes deep inside the GL driver when I didn't do it!
//
//===========================================================================

unsigned int FHardwareTexture::CreateTexture(unsigned char * buffer, int w, int h, int texunit, bool mipmap, const char *name)
{
	int rh,rw;
	int texformat = GL_RGBA;// TexFormat[gl_texture_format];
	bool deletebuffer=false;

	// When running in SW mode buffer will be null, so set it to the texBuffer already created
	// There could be other use cases I do not know about which means this is a bad idea..
	if (buffer == nullptr)
		buffer = texBuffer;

	bool firstCall = glTexID == 0;
	if (firstCall)
	{
		glGenTextures(1, &glTexID);
	}

	int textureBinding = UINT_MAX;
	if (texunit == -1)	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding);
	if (texunit > 0) glActiveTexture(GL_TEXTURE0+texunit);
	if (texunit >= 0) lastbound[texunit] = glTexID;
	glBindTexture(GL_TEXTURE_2D, glTexID);


	rw = GetTexDimension(w);
	rh = GetTexDimension(h);

	if (!buffer)
	{
		// The texture must at least be initialized if no data is present.
		mipmapped = false;
		buffer=(unsigned char *)calloc(4,rw * (rh+1));
		deletebuffer=true;
		//texheight=-h;	
	}
	else
	{
		if (rw < w || rh < h)
		{
			// The texture is larger than what the hardware can handle so scale it down.
			unsigned char * scaledbuffer=(unsigned char *)calloc(4,rw * (rh+1));
			if (scaledbuffer)
			{
				Resize(w, h, rw, rh, buffer, scaledbuffer);
				deletebuffer=true;
				buffer=scaledbuffer;
			}
		}


	}
	// store the physical size.

	int sourcetype;


#if USE_GLES2
	if (glTextureBytes == 1)
	{
		glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
		sourcetype = GL_ALPHA;
		texformat = GL_ALPHA;
	}
	else
	{
		sourcetype = GL_BGRA;
		texformat = GL_BGRA;
	}
#else
	if (glTextureBytes == 1)
	{
		glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
		sourcetype = GL_RED;
		texformat = GL_RED;
	}
	else
	{
		sourcetype = GL_BGRA;
		texformat = GL_RGBA;
	}
#endif

	glTexImage2D(GL_TEXTURE_2D, 0, texformat, rw, rh, 0, sourcetype, GL_UNSIGNED_BYTE, buffer);

#if !(USE_GLES2)
	// The shader is using the alpha channel instead of red, this work on GLES but not on GL
	// So the texture uses GL_RED and this swizzels the red channel into the alpha channel
	if (glTextureBytes == 1)
	{
		GLint swizzleMask[] = { GL_ZERO, GL_ZERO, GL_ZERO, GL_RED };
		glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_RGBA, swizzleMask);
	}
#endif

	if (deletebuffer && buffer) free(buffer);

	if (mipmap && TexFilter[gl_texture_filter].mipmapping)
	{
		glGenerateMipmap(GL_TEXTURE_2D);
		mipmapped = true;
	}

	if (texunit > 0) glActiveTexture(GL_TEXTURE0);
	else if (texunit == -1) glBindTexture(GL_TEXTURE_2D, textureBinding);
	return glTexID;
}


void FHardwareTexture::AllocateBuffer(int w, int h, int texelsize) 
{	
	if (texelsize < 1 || texelsize > 4) texelsize = 4;
	glTextureBytes = texelsize;
	bufferpitch = w;

	if (texBuffer)
		delete[] texBuffer;

	texBuffer = new uint8_t[(w * h) * texelsize];
	return;
}

uint8_t* FHardwareTexture::MapBuffer()
{
	return texBuffer;
}

//===========================================================================
// 
//	Destroys the texture
//
//===========================================================================
FHardwareTexture::~FHardwareTexture() 
{ 
	if (glTexID != 0) glDeleteTextures(1, &glTexID);

	if (texBuffer)
		delete[] texBuffer;
}


//===========================================================================
// 
//	Binds this patch
//
//===========================================================================
unsigned int FHardwareTexture::Bind(int texunit, bool needmipmap)
{
	if (glTexID != 0)
	{
		if (lastbound[texunit] == glTexID) return glTexID;
		lastbound[texunit] = glTexID;
		if (texunit != 0) glActiveTexture(GL_TEXTURE0 + texunit);
		glBindTexture(GL_TEXTURE_2D, glTexID);
		// Check if we need mipmaps on a texture that was creted without them.
		if (needmipmap && !mipmapped && TexFilter[gl_texture_filter].mipmapping)
		{
			glGenerateMipmap(GL_TEXTURE_2D);
			mipmapped = true;
		}
		if (texunit != 0) glActiveTexture(GL_TEXTURE0);
		return glTexID;
	}
	return 0;
}

void FHardwareTexture::Unbind(int texunit)
{
	if (lastbound[texunit] != 0)
	{
		if (texunit != 0) glActiveTexture(GL_TEXTURE0+texunit);
		glBindTexture(GL_TEXTURE_2D, 0);
		if (texunit != 0) glActiveTexture(GL_TEXTURE0);
		lastbound[texunit] = 0;
	}
}

void FHardwareTexture::UnbindAll()
{
	for(int texunit = 0; texunit < 16; texunit++)
	{
		Unbind(texunit);
	}
}

//===========================================================================
// 
//	Creates a depth buffer for this texture
//
//===========================================================================

int FHardwareTexture::GetDepthBuffer(int width, int height)
{
	if (glDepthID == 0)
	{
		glGenRenderbuffers(1, &glDepthID);
		glBindRenderbuffer(GL_RENDERBUFFER, glDepthID);
		glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 
			GetTexDimension(width), GetTexDimension(height));
		glBindRenderbuffer(GL_RENDERBUFFER, 0);
	}
	return glDepthID;
}


//===========================================================================
// 
//	Binds this texture's surfaces to the current framrbuffer
//
//===========================================================================

void FHardwareTexture::BindToFrameBuffer(int width, int height)
{
	width = GetTexDimension(width);
	height = GetTexDimension(height);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, glTexID, 0);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, GetDepthBuffer(width, height));
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, GetDepthBuffer(width, height));
}


//===========================================================================
// 
//	Binds a texture to the renderer
//
//===========================================================================

bool FHardwareTexture::BindOrCreate(FTexture *tex, int texunit, int clampmode, int translation, int flags)
{
	bool needmipmap = (clampmode <= CLAMP_XY) && !forcenofilter;

	// Bind it to the system.
	if (!Bind(texunit, needmipmap))
	{
		if (flags & CTF_Indexed)
		{
			glTextureBytes = 1;
			forcenofilter = true;
			needmipmap = false;
		}
		int w = 0, h = 0;

		// Create this texture

		FTextureBuffer texbuffer;

		if (!tex->isHardwareCanvas())
		{
			texbuffer = tex->CreateTexBuffer(translation, flags | CTF_ProcessData);
			w = texbuffer.mWidth;
			h = texbuffer.mHeight;
		}
		else
		{
			w = tex->GetWidth();
			h = tex->GetHeight();
		}
		if (!CreateTexture(texbuffer.mBuffer, w, h, texunit, needmipmap, "FHardwareTexture.BindOrCreate"))
		{
			// could not create texture
			return false;
		}
	}
	if (forcenofilter && clampmode <= CLAMP_XY) clampmode += CLAMP_NOFILTER - CLAMP_NONE;
	GLRenderer->mSamplerManager->Bind(texunit, clampmode, 255);
	return true;
}

}