/*
 * This source file is part of libRocket, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://www.librocket.com
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "RocketLibSystemRenderInterfaceOpenGL.h"
#include <Rocket/Core.h>

#define GL_CLAMP_TO_EDGE 0x812F

RocketLibSystemRenderInterfaceOpenGL::RocketLibSystemRenderInterfaceOpenGL()
{
}

// Called by Rocket when it wants to render geometry that it does not wish to optimise.
void RocketLibSystemRenderInterfaceOpenGL::RenderGeometry(Rocket::Core::Vertex* vertices, int ROCKET_UNUSED(num_vertices), int* indices, int num_indices, const Rocket::Core::TextureHandle texture, const Rocket::Core::Vector2f& translation)
{
	glPushMatrix();
	glTranslatef(translation.x, translation.y, 0);

	glVertexPointer(2, GL_FLOAT, sizeof(Rocket::Core::Vertex), &vertices[0].position);
	glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(Rocket::Core::Vertex), &vertices[0].colour);

	if (texture == NULL)
	{
		glDisable(GL_TEXTURE_2D);
		glDisableClientState(GL_TEXTURE_COORD_ARRAY);
	}
	else
	{
		glEnable(GL_TEXTURE_2D);
		glBindTexture(GL_TEXTURE_2D, (GLuint) texture);
		glEnableClientState(GL_TEXTURE_COORD_ARRAY);
		glTexCoordPointer(2, GL_FLOAT, sizeof(Rocket::Core::Vertex), &vertices[0].tex_coord);
	}

	glDrawElements(GL_TRIANGLES, num_indices, GL_UNSIGNED_INT, indices);

	glPopMatrix();
}

// Called by Rocket when it wants to compile geometry it believes will be static for the forseeable future.		
Rocket::Core::CompiledGeometryHandle RocketLibSystemRenderInterfaceOpenGL::CompileGeometry(Rocket::Core::Vertex* ROCKET_UNUSED(vertices), int ROCKET_UNUSED(num_vertices), int* ROCKET_UNUSED(indices), int ROCKET_UNUSED(num_indices), const Rocket::Core::TextureHandle ROCKET_UNUSED(texture))
{
	return (Rocket::Core::CompiledGeometryHandle) NULL;
}

// Called by Rocket when it wants to render application-compiled geometry.		
void RocketLibSystemRenderInterfaceOpenGL::RenderCompiledGeometry(Rocket::Core::CompiledGeometryHandle ROCKET_UNUSED(geometry), const Rocket::Core::Vector2f& ROCKET_UNUSED(translation))
{
}

// Called by Rocket when it wants to release application-compiled geometry.		
void RocketLibSystemRenderInterfaceOpenGL::ReleaseCompiledGeometry(Rocket::Core::CompiledGeometryHandle ROCKET_UNUSED(geometry))
{
}

// Called by Rocket when it wants to enable or disable scissoring to clip content.		
void RocketLibSystemRenderInterfaceOpenGL::EnableScissorRegion(bool enable)
{
	if (enable)
		glEnable(GL_SCISSOR_TEST);
	else
		glDisable(GL_SCISSOR_TEST);
}

// Called by Rocket when it wants to change the scissor region.		
void RocketLibSystemRenderInterfaceOpenGL::SetScissorRegion(int x, int y, int width, int height)
{
	int windowSize[4];
	glGetIntegerv( GL_VIEWPORT, windowSize);
	glScissor(x, windowSize[3] - (y + height), width, height);
}

// Set to byte packing, or the compiler will expand our struct, which means it won't read correctly from file
#pragma pack(1) 
struct TGAHeader 
{
	char  idLength;
	char  colourMapType;
	char  dataType;
	short int colourMapOrigin;
	short int colourMapLength;
	char  colourMapDepth;
	short int xOrigin;
	short int yOrigin;
	short int width;
	short int height;
	char  bitsPerPixel;
	char  imageDescriptor;
};
// Restore packing
#pragma pack()

// Called by Rocket when a texture is required by the library.		
bool RocketLibSystemRenderInterfaceOpenGL::LoadTexture(Rocket::Core::TextureHandle& texture_handle, Rocket::Core::Vector2i& texture_dimensions, const Rocket::Core::String& source)
{
	Rocket::Core::FileInterface* file_interface = Rocket::Core::GetFileInterface();
	Rocket::Core::FileHandle file_handle = file_interface->Open(source);
	if (file_handle == NULL)
		return false;

	file_interface->Seek(file_handle, 0, SEEK_END);
	size_t buffer_size = file_interface->Tell(file_handle);
	file_interface->Seek(file_handle, 0, SEEK_SET);
	
	char* buffer = new char[buffer_size];
	file_interface->Read(buffer, buffer_size, file_handle);
	file_interface->Close(file_handle);

	TGAHeader header;
	memcpy(&header, buffer, sizeof(TGAHeader));
	
	int color_mode = header.bitsPerPixel / 8;
	int image_size = header.width * header.height * 4; // We always make 32bit textures 
	
	if (header.dataType != 2)
	{
		Rocket::Core::Log::Message(Rocket::Core::Log::LT_ERROR, "Only 24/32bit uncompressed TGAs are supported.");
		return false;
	}
	
	// Ensure we have at least 3 colors
	if (color_mode < 3)
	{
		Rocket::Core::Log::Message(Rocket::Core::Log::LT_ERROR, "Only 24 and 32bit textures are supported");
		return false;
	}
	
	const char* image_src = buffer + sizeof(TGAHeader);
	unsigned char* image_dest = new unsigned char[image_size];
	
	// Targa is BGR, swap to RGB and flip Y axis
	for (long y = 0; y < header.height; y++)
	{
		long read_index = y * header.width * color_mode;
		long write_index = ((header.imageDescriptor & 32) != 0) ? read_index : (header.height - y - 1) * header.width * color_mode;
		for (long x = 0; x < header.width; x++)
		{
			image_dest[write_index] = image_src[read_index+2];
			image_dest[write_index+1] = image_src[read_index+1];
			image_dest[write_index+2] = image_src[read_index];
			if (color_mode == 4)
				image_dest[write_index+3] = image_src[read_index+3];
			else
				image_dest[write_index+3] = 255;
			
			write_index += 4;
			read_index += color_mode;
		}
	}

	texture_dimensions.x = header.width;
	texture_dimensions.y = header.height;
	
	bool success = GenerateTexture(texture_handle, image_dest, texture_dimensions);
	
	delete [] image_dest;
	delete [] buffer;
	
	return success;
}

// Called by Rocket when a texture is required to be built from an internally-generated sequence of pixels.
bool RocketLibSystemRenderInterfaceOpenGL::GenerateTexture(Rocket::Core::TextureHandle& texture_handle, const Rocket::Core::byte* source, const Rocket::Core::Vector2i& source_dimensions)
{
	GLuint texture_id;
	glGenTextures(1, &texture_id);
	glBindTexture(GL_TEXTURE_2D, texture_id);

	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, source_dimensions.x, source_dimensions.y, 0, GL_RGBA, GL_UNSIGNED_BYTE, source);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	texture_handle = (Rocket::Core::TextureHandle) texture_id;

	return true;
}

// Called by Rocket when a loaded texture is no longer required.		
void RocketLibSystemRenderInterfaceOpenGL::ReleaseTexture(Rocket::Core::TextureHandle texture_handle)
{
	glDeleteTextures(1, (GLuint*) &texture_handle);
}