/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "common/textconsole.h"
#include "common/util.h"

#if (defined(USE_OPENGL_GAME) || defined(USE_OPENGL_SHADERS)) && !defined(AMIGAOS) && !defined(__MORPHOS__)

#if defined(SDL_BACKEND) && !defined(USE_GLAD) && !defined(USE_GLES2)
#define GL_GLEXT_PROTOTYPES // For the GL_EXT_framebuffer_object extension
#include "graphics/opengl/framebuffer.h"
#ifndef GL_ARB_framebuffer_object
#define GL_COLOR_ATTACHMENT0 GL_COLOR_ATTACHMENT0_EXT
#define GL_DEPTH_ATTACHMENT GL_DEPTH_ATTACHMENT_EXT
#define GL_FRAMEBUFFER GL_FRAMEBUFFER_EXT
#define GL_FRAMEBUFFER_COMPLETE GL_FRAMEBUFFER_COMPLETE_EXT
#define GL_RENDERBUFFER GL_RENDERBUFFER_EXT
#define GL_STENCIL_ATTACHMENT GL_STENCIL_ATTACHMENT_EXT
#define GL_STENCIL_INDEX8 GL_STENCIL_INDEX8_EXT
#define GL_DEPTH24_STENCIL8 0x88F0
#define GL_READ_FRAMEBUFFER 0x8CA8
#define GL_DRAW_FRAMEBUFFER 0x8CA9
#endif // defined(GL_ARB_framebuffer_object)
#include "backends/platform/sdl/sdl-sys.h"
#else
#include "graphics/opengl/framebuffer.h"
#endif

#include "graphics/opengl/context.h"

#ifdef USE_GLES2
#define GL_DEPTH24_STENCIL8 GL_DEPTH24_STENCIL8_OES
#define GL_DEPTH_COMPONENT24 GL_DEPTH_COMPONENT24_OES
#endif

namespace OpenGL {

#if defined(SDL_BACKEND) && !defined(USE_GLAD) && !defined(USE_GLES2)
static bool framebuffer_object_functions = false;
static PFNGLBINDFRAMEBUFFEREXTPROC glBindFramebuffer;
static PFNGLBINDRENDERBUFFEREXTPROC glBindRenderbuffer;
static PFNGLCHECKFRAMEBUFFERSTATUSEXTPROC glCheckFramebufferStatus;
static PFNGLDELETEFRAMEBUFFERSEXTPROC glDeleteFramebuffers;
static PFNGLDELETERENDERBUFFERSEXTPROC glDeleteRenderbuffers;
static PFNGLFRAMEBUFFERRENDERBUFFEREXTPROC glFramebufferRenderbuffer;
static PFNGLFRAMEBUFFERTEXTURE2DEXTPROC glFramebufferTexture2D;
static PFNGLGENFRAMEBUFFERSEXTPROC glGenFramebuffers;
static PFNGLGENRENDERBUFFERSEXTPROC glGenRenderbuffers;
static PFNGLRENDERBUFFERSTORAGEEXTPROC glRenderbufferStorage;
typedef void (* PFNGLRENDERBUFFERSTORAGEMULTISAMPLEEXTPROC) (GLenum target, GLsizei samples, GLenum internalformat, GLsizei width, GLsizei height);
static PFNGLRENDERBUFFERSTORAGEMULTISAMPLEEXTPROC glRenderbufferStorageMultisample;
typedef void (* PFNGLBLITFRAMEBUFFEREXTPROC) (GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask, GLenum filter);
static PFNGLBLITFRAMEBUFFEREXTPROC glBlitFramebuffer;


static void grabFramebufferObjectPointers() {
	if (framebuffer_object_functions)
		return;
	framebuffer_object_functions = true;

	union {
		void *obj_ptr;
		void (APIENTRY *func_ptr)();
	} u;
	// We're casting from an object pointer to a function pointer, the
	// sizes need to be the same for this to work.
	assert(sizeof(u.obj_ptr) == sizeof(u.func_ptr));
	u.obj_ptr = SDL_GL_GetProcAddress("glBlitFramebuffer");
	glBlitFramebuffer = (PFNGLBLITFRAMEBUFFEREXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glBindFramebuffer");
	glBindFramebuffer = (PFNGLBINDFRAMEBUFFEREXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glBindRenderbuffer");
	glBindRenderbuffer = (PFNGLBINDRENDERBUFFEREXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glCheckFramebufferStatus");
	glCheckFramebufferStatus = (PFNGLCHECKFRAMEBUFFERSTATUSEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glDeleteFramebuffers");
	glDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glDeleteRenderbuffers");
	glDeleteRenderbuffers = (PFNGLDELETERENDERBUFFERSEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glFramebufferRenderbuffer");
	glFramebufferRenderbuffer = (PFNGLFRAMEBUFFERRENDERBUFFEREXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glFramebufferTexture2D");
	glFramebufferTexture2D = (PFNGLFRAMEBUFFERTEXTURE2DEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glGenFramebuffers");
	glGenFramebuffers = (PFNGLGENFRAMEBUFFERSEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glGenRenderbuffers");
	glGenRenderbuffers = (PFNGLGENRENDERBUFFERSEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glRenderbufferStorage");
	glRenderbufferStorage = (PFNGLRENDERBUFFERSTORAGEEXTPROC)u.func_ptr;
	u.obj_ptr = SDL_GL_GetProcAddress("glRenderbufferStorageMultisample");
	glRenderbufferStorageMultisample = (PFNGLRENDERBUFFERSTORAGEMULTISAMPLEEXTPROC)u.func_ptr;
}
#endif // defined(SDL_BACKEND) && !defined(USE_GLAD) && !defined(USE_GLES2)



static bool usePackedBuffer() {
	return OpenGLContext.packedDepthStencilSupported;
}
static bool useDepthComponent24() {
	return OpenGLContext.OESDepth24;
}

FrameBuffer::FrameBuffer(uint width, uint height) :
		TextureGL(width, height) {
	if (!OpenGLContext.framebufferObjectSupported) {
		error("FrameBuffer Objects are not supported by the current OpenGL context");
	}

#if defined(SDL_BACKEND) && !defined(USE_GLAD) && !defined(USE_GLES2)
	grabFramebufferObjectPointers();
#endif

	init();
}

FrameBuffer::FrameBuffer(GLuint texture_name, uint width, uint height, uint texture_width, uint texture_height) :
		TextureGL(texture_name, width, height, texture_width, texture_height) {
	init();
}

FrameBuffer::~FrameBuffer() {
	glDeleteRenderbuffers(2, _renderBuffers);
	glDeleteFramebuffers(1, &_frameBuffer);
}

void FrameBuffer::init() {
	glGenFramebuffers(1, &_frameBuffer);
	glGenRenderbuffers(2, _renderBuffers);

	glBindFramebuffer(GL_FRAMEBUFFER, _frameBuffer);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _texture, 0);

	if (usePackedBuffer()) {
		glBindRenderbuffer(GL_RENDERBUFFER, _renderBuffers[0]);
		glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, _texWidth, _texHeight);
		glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _renderBuffers[0]);
		glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _renderBuffers[0]);
		glBindRenderbuffer(GL_RENDERBUFFER, 0);
	} else {
		glBindRenderbuffer(GL_RENDERBUFFER, _renderBuffers[0]);

		const char *glVersion = (const char *)glGetString(GL_VERSION);
		if (strstr(glVersion, "WebGL 1.0") != NULL) {
			// See https://www.khronos.org/registry/webgl/specs/latest/1.0/#FBO_ATTACHMENTS
			// and https://github.com/emscripten-core/emscripten/issues/4832
#ifndef GL_DEPTH_STENCIL
#define GL_DEPTH_STENCIL 0x84F9
#endif
			glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_STENCIL, _texWidth, _texHeight);

#ifndef GL_DEPTH_STENCIL_ATTACHMENT
#define GL_DEPTH_STENCIL_ATTACHMENT 0x821A
#endif
			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _renderBuffers[0]);
		} else {
			glRenderbufferStorage(GL_RENDERBUFFER, useDepthComponent24() ? GL_DEPTH_COMPONENT24 : GL_DEPTH_COMPONENT16, _texWidth, _texHeight);
			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _renderBuffers[0]);

			glBindRenderbuffer(GL_RENDERBUFFER, _renderBuffers[1]);
			glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, _texWidth, _texHeight);
			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _renderBuffers[1]);
		}
		glBindRenderbuffer(GL_RENDERBUFFER, 0);
	}

	glBindFramebuffer(GL_FRAMEBUFFER, _frameBuffer);
	GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
	if (status != GL_FRAMEBUFFER_COMPLETE)
		error("Framebuffer is not complete! status: %d", status);

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

void FrameBuffer::attach() {
	glBindFramebuffer(GL_FRAMEBUFFER, _frameBuffer);
	glGetIntegerv(GL_VIEWPORT, _prevStateViewport);
	glViewport(0, 0, _width, _height);
}

void FrameBuffer::detach() {
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	glViewport(_prevStateViewport[0], _prevStateViewport[1], _prevStateViewport[2], _prevStateViewport[3]);
}

#if !defined(USE_GLES2) && !defined(AMIGAOS) && !defined(__MORPHOS__)
MultiSampleFrameBuffer::MultiSampleFrameBuffer(uint width, uint height, int samples)
		: FrameBuffer(width,height) {
	if (!OpenGLContext.framebufferObjectMultisampleSupported) {
		error("The current OpenGL context does not support multisample framebuffer objects!");
	}

	if (samples > OpenGLContext.multisampleMaxSamples) {
		warning("Requested anti-aliasing with '%d' samples, but the current OpenGL context supports '%d' samples at most",
		        samples, OpenGLContext.multisampleMaxSamples);
	}

	_msSamples = MIN(samples, OpenGLContext.multisampleMaxSamples);

	init();
}

MultiSampleFrameBuffer::~MultiSampleFrameBuffer() {
	glDeleteRenderbuffers(1, &_msColorId);
	glDeleteRenderbuffers(1, &_msDepthId);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	glDeleteFramebuffers(1, &_msFrameBufferId);
}

void MultiSampleFrameBuffer::init() {
	glGenFramebuffers(1, &_msFrameBufferId);
	glBindFramebuffer(GL_FRAMEBUFFER, _msFrameBufferId);

	glGenRenderbuffers(1, &_msColorId);
	glBindRenderbuffer(GL_RENDERBUFFER, _msColorId);
	glRenderbufferStorageMultisample(GL_RENDERBUFFER, _msSamples, GL_RGBA8, getTexWidth(), getTexHeight());

	glGenRenderbuffers(1, &_msDepthId);
	glBindRenderbuffer(GL_RENDERBUFFER, _msDepthId);
	glRenderbufferStorageMultisample(GL_RENDERBUFFER, _msSamples, GL_DEPTH24_STENCIL8, getTexWidth(), getTexHeight());

	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _msColorId);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _msDepthId);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _msDepthId);

	GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
	if (status != GL_FRAMEBUFFER_COMPLETE)
		error("Framebuffer is not complete! status: %d", status);

	glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void MultiSampleFrameBuffer::attach() {
	glBindFramebuffer(GL_READ_FRAMEBUFFER, getFrameBufferName());
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, _msFrameBufferId);
	glGetIntegerv(GL_VIEWPORT, _prevStateViewport);
	glViewport(0, 0, getWidth(), getHeight());
}

void MultiSampleFrameBuffer::detach() {
	glBindFramebuffer(GL_READ_FRAMEBUFFER, _msFrameBufferId);
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, getFrameBufferName());
	glBlitFramebuffer(0, 0, getWidth(), getHeight(), 0, 0, getWidth(), getHeight(), GL_COLOR_BUFFER_BIT, GL_NEAREST);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	glViewport(_prevStateViewport[0], _prevStateViewport[1], _prevStateViewport[2], _prevStateViewport[3]);
}

#endif // !defined(USE_GLES2) && !defined(AMIGAOS) && !defined(__MORPHOS__)

} // End of namespace OpenGL

#endif