#include "lc_global.h"
#include <string.h>
#include <stdio.h>
#include "opengl.h"
#include "lc_glwidget.h"
#include "lc_mainwnd.h"
#include "preview.h"

GLBINDBUFFERARBPROC lcBindBufferARB;
GLDELETEBUFFERSARBPROC lcDeleteBuffersARB;
GLGENBUFFERSARBPROC lcGenBuffersARB;
GLISBUFFERARBPROC lcIsBufferARB;
GLBUFFERDATAARBPROC lcBufferDataARB;
GLBUFFERSUBDATAARBPROC lcBufferSubDataARB;
GLGETBUFFERSUBDATAARBPROC lcGetBufferSubDataARB;
GLMAPBUFFERARBPROC lcMapBufferARB;
GLUNMAPBUFFERARBPROC lcUnmapBufferARB;
GLGETBUFFERPARAMETERIVARBPROC lcGetBufferParameterivARB;
GLGETBUFFERPOINTERVARBPROC lcGetBufferPointervARB;

GLISRENDERBUFFERARBPROC lcIsRenderbufferARB;
GLBINDRENDERBUFFERARBPROC lcBindRenderbufferARB;
GLDELETERENDERBUFFERSARBPROC lcDeleteRenderbuffersARB;
GLGENRENDERBUFFERSARBPROC lcGenRenderbuffersARB;
GLRENDERBUFFERSTORAGEARBPROC lcRenderbufferStorageARB;
GLGETRENDERBUFFERPARAMETERIVARBPROC lcGetRenderbufferParameterivARB;
GLISFRAMEBUFFERARBPROC lcIsFramebufferARB;
GLBINDFRAMEBUFFERARBPROC lcBindFramebufferARB;
GLDELETEFRAMEBUFFERSARBPROC lcDeleteFramebuffersARB;
GLGENFRAMEBUFFERSARBPROC lcGenFramebuffersARB;
GLCHECKFRAMEBUFFERSTATUSARBPROC lcCheckFramebufferStatusARB;
GLFRAMEBUFFERTEXTURE1DARBPROC lcFramebufferTexture1DARB;
GLFRAMEBUFFERTEXTURE2DARBPROC lcFramebufferTexture2DARB;
GLFRAMEBUFFERTEXTURE3DARBPROC lcFramebufferTexture3DARB;
GLFRAMEBUFFERRENDERBUFFERARBPROC lcFramebufferRenderbufferARB;
GLGETFRAMEBUFFERATTACHMENTPARAMETERIVARBPROC lcGetFramebufferAttachmentParameterivARB;
GLGENERATEMIPMAPARBPROC lcGenerateMipmapARB;
GLBLITFRAMEBUFFERARBPROC lcBlitFramebufferARB;
GLRENDERBUFFERSTORAGEMULTISAMPLEARBPROC lcRenderbufferStorageMultisampleARB;
GLFRAMEBUFFERTEXTURELAYERARBPROC lcFramebufferTextureLayerARB;

bool GL_SupportsVertexBufferObject;
bool GL_UseVertexBufferObject;
bool GL_SupportsFramebufferObject;

bool GL_ExtensionSupported(const GLubyte* Extensions, const char* Name)
{
	const GLubyte *start;
	GLubyte *where, *terminator;

	where = (GLubyte*)strchr(Name, ' ');
	if (where || *Name == '\0')
		return false;

	if (!Extensions)
		return false;

	for (start = Extensions; ;)
	{
		where = (GLubyte*)strstr((const char*)start, Name);
		if (!where)
			break;

		terminator = where + strlen(Name);
		if (where == start || *(where - 1) == ' ')
			if (*terminator == ' ' || *terminator == '\0')
				return true;

		start = terminator;
	}

	return false;
}

void GL_InitializeSharedExtensions(lcGLWidget* Window)
{
	const GLubyte* Extensions = glGetString(GL_EXTENSIONS);

	if (GL_ExtensionSupported(Extensions, "GL_ARB_vertex_buffer_object"))
	{
		lcBindBufferARB = (GLBINDBUFFERARBPROC)Window->GetExtensionAddress("glBindBufferARB");
		lcDeleteBuffersARB = (GLDELETEBUFFERSARBPROC)Window->GetExtensionAddress("glDeleteBuffersARB");
		lcGenBuffersARB = (GLGENBUFFERSARBPROC)Window->GetExtensionAddress("glGenBuffersARB");
		lcIsBufferARB = (GLISBUFFERARBPROC)Window->GetExtensionAddress("glIsBufferARB");
		lcBufferDataARB = (GLBUFFERDATAARBPROC)Window->GetExtensionAddress("glBufferDataARB");
		lcBufferSubDataARB = (GLBUFFERSUBDATAARBPROC)Window->GetExtensionAddress("glBufferSubDataARB");
		lcGetBufferSubDataARB = (GLGETBUFFERSUBDATAARBPROC)Window->GetExtensionAddress("glGetBufferSubDataARB");
		lcMapBufferARB = (GLMAPBUFFERARBPROC)Window->GetExtensionAddress("glMapBufferARB");
		lcUnmapBufferARB = (GLUNMAPBUFFERARBPROC)Window->GetExtensionAddress("glUnmapBufferARB");
		lcGetBufferParameterivARB = (GLGETBUFFERPARAMETERIVARBPROC)Window->GetExtensionAddress("glGetBufferParameterivARB");
		lcGetBufferPointervARB = (GLGETBUFFERPOINTERVARBPROC)Window->GetExtensionAddress("glGetBufferPointervARB");

		GL_UseVertexBufferObject = true;
		GL_SupportsVertexBufferObject = true;
	}

	if (GL_ExtensionSupported(Extensions, "GL_ARB_framebuffer_object"))
	{
		lcIsRenderbufferARB = (GLISRENDERBUFFERARBPROC)Window->GetExtensionAddress("glIsRenderbuffer");
		lcBindRenderbufferARB = (GLBINDRENDERBUFFERARBPROC)Window->GetExtensionAddress("glBindRenderbuffer");
		lcDeleteRenderbuffersARB = (GLDELETERENDERBUFFERSARBPROC)Window->GetExtensionAddress("glDeleteRenderbuffers");
		lcGenRenderbuffersARB = (GLGENRENDERBUFFERSARBPROC)Window->GetExtensionAddress("glGenRenderbuffers");
		lcRenderbufferStorageARB = (GLRENDERBUFFERSTORAGEARBPROC)Window->GetExtensionAddress("glRenderbufferStorage");
		lcGetRenderbufferParameterivARB = (GLGETRENDERBUFFERPARAMETERIVARBPROC)Window->GetExtensionAddress("glGetRenderbufferParameteriv");
		lcIsFramebufferARB = (GLISFRAMEBUFFERARBPROC)Window->GetExtensionAddress("glIsFramebuffer");
		lcBindFramebufferARB = (GLBINDFRAMEBUFFERARBPROC)Window->GetExtensionAddress("glBindFramebuffer");
		lcDeleteFramebuffersARB = (GLDELETEFRAMEBUFFERSARBPROC)Window->GetExtensionAddress("glDeleteFramebuffers");
		lcGenFramebuffersARB = (GLGENFRAMEBUFFERSARBPROC)Window->GetExtensionAddress("glGenFramebuffers");
		lcCheckFramebufferStatusARB = (GLCHECKFRAMEBUFFERSTATUSARBPROC)Window->GetExtensionAddress("glCheckFramebufferStatus");
		lcFramebufferTexture1DARB = (GLFRAMEBUFFERTEXTURE1DARBPROC)Window->GetExtensionAddress("glFramebufferTexture1D");
		lcFramebufferTexture2DARB = (GLFRAMEBUFFERTEXTURE2DARBPROC)Window->GetExtensionAddress("glFramebufferTexture2D");
		lcFramebufferTexture3DARB = (GLFRAMEBUFFERTEXTURE3DARBPROC)Window->GetExtensionAddress("glFramebufferTexture3D");
		lcFramebufferRenderbufferARB = (GLFRAMEBUFFERRENDERBUFFERARBPROC)Window->GetExtensionAddress("glFramebufferRenderbuffer");
		lcGetFramebufferAttachmentParameterivARB = (GLGETFRAMEBUFFERATTACHMENTPARAMETERIVARBPROC)Window->GetExtensionAddress("glGetFramebufferAttachmentParameteriv");
		lcGenerateMipmapARB = (GLGENERATEMIPMAPARBPROC)Window->GetExtensionAddress("glGenerateMipmap");
		lcBlitFramebufferARB = (GLBLITFRAMEBUFFERARBPROC)Window->GetExtensionAddress("glBlitFramebuffer");
		lcRenderbufferStorageMultisampleARB = (GLRENDERBUFFERSTORAGEMULTISAMPLEARBPROC)Window->GetExtensionAddress("glRenderbufferStorageMultisample");
		lcFramebufferTextureLayerARB = (GLFRAMEBUFFERTEXTURELAYERARBPROC)Window->GetExtensionAddress("glFramebufferTextureLayer");

		GL_SupportsFramebufferObject = true;
	}
}

static GLuint gFramebufferObject;
static GLuint gFramebufferTexture;
static GLuint gDepthRenderbufferObject;

bool GL_BeginRenderToTexture(int Width, int Height)
{
	if (!GL_SupportsFramebufferObject)
		return false;

	gMainWindow->mPreviewWidget->MakeCurrent();

	glGenFramebuffers(1, &gFramebufferObject);
	glGenTextures(1, &gFramebufferTexture);
	glGenRenderbuffers(1, &gDepthRenderbufferObject);

	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, gFramebufferObject);

	glBindTexture(GL_TEXTURE_2D, gFramebufferTexture);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, Width, Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gFramebufferTexture, 0);

	glBindRenderbuffer(GL_RENDERBUFFER, gDepthRenderbufferObject);
	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, Width, Height);
	glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, gDepthRenderbufferObject);

	glBindTexture(GL_TEXTURE_2D, 0);
	glBindFramebuffer(GL_FRAMEBUFFER, gFramebufferObject);

	if (glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
	{
		GL_EndRenderToTexture();
		return false;
	}

	return true;
}

void GL_EndRenderToTexture()
{
	glDeleteFramebuffers(1, &gFramebufferObject);
	gFramebufferObject = 0;
	glDeleteTextures(1, &gFramebufferTexture);
	gFramebufferTexture = 0;
	glDeleteRenderbuffers(1, &gDepthRenderbufferObject);
	gDepthRenderbufferObject = 0;
}