/*
 * Copyright (C) 2021  Christopher J. Howard
 *
 * This file is part of Antkeeper source code.
 *
 * Antkeeper source code 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.
 *
 * Antkeeper source code 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 Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "game/graphics.hpp"
#include "gl/framebuffer.hpp"
#include "gl/texture-2d.hpp"
#include "gl/texture-wrapping.hpp"
#include "gl/texture-filter.hpp"
#include "debug/logger.hpp"
#include "utility/timestamp.hpp"
#include <glad/glad.h>
#include <stb/stb_image_write.h>
#include <thread>
#include <filesystem>

namespace game {
namespace graphics {

static void resize_framebuffer_attachment(gl::texture_2d& texture, const int2& resolution);

void create_framebuffers(game::context& ctx)
{
	ctx.logger->push_task("Creating framebuffers");
	
	// Load render resolution scale from config
	ctx.render_resolution_scale = 1.0f;
	if (ctx.config->contains("render_resolution"))
		ctx.render_resolution_scale = (*ctx.config)["render_resolution"].get<float>();
	
	// Calculate render resolution
	const int2& viewport_dimensions = ctx.app->get_viewport_dimensions();
	ctx.render_resolution = {static_cast<int>(viewport_dimensions.x * ctx.render_resolution_scale + 0.5f), static_cast<int>(viewport_dimensions.y * ctx.render_resolution_scale + 0.5f)};
	
	// Create HDR framebuffer (32F color, 32F depth)
	ctx.hdr_color_texture = new gl::texture_2d(ctx.render_resolution.x, ctx.render_resolution.y, gl::pixel_type::float_32, gl::pixel_format::rgb);
	ctx.hdr_color_texture->set_wrapping(gl::texture_wrapping::extend, gl::texture_wrapping::extend);
	ctx.hdr_color_texture->set_filters(gl::texture_min_filter::linear, gl::texture_mag_filter::linear);
	ctx.hdr_color_texture->set_max_anisotropy(0.0f);
	ctx.hdr_depth_texture = new gl::texture_2d(ctx.render_resolution.x, ctx.render_resolution.y, gl::pixel_type::float_32, gl::pixel_format::ds);
	ctx.hdr_depth_texture->set_wrapping(gl::texture_wrapping::extend, gl::texture_wrapping::extend);
	ctx.hdr_depth_texture->set_filters(gl::texture_min_filter::linear, gl::texture_mag_filter::linear);
	ctx.hdr_depth_texture->set_max_anisotropy(0.0f);
	ctx.hdr_framebuffer = new gl::framebuffer(ctx.render_resolution.x, ctx.render_resolution.y);
	ctx.hdr_framebuffer->attach(gl::framebuffer_attachment_type::color, ctx.hdr_color_texture);
	ctx.hdr_framebuffer->attach(gl::framebuffer_attachment_type::depth, ctx.hdr_depth_texture);
	ctx.hdr_framebuffer->attach(gl::framebuffer_attachment_type::stencil, ctx.hdr_depth_texture);
	
	// Calculate bloom resolution
	int2 bloom_resolution = ctx.render_resolution / 2;
	
	// Create bloom framebuffer (16F color, no depth)
	ctx.bloom_color_texture = new gl::texture_2d(bloom_resolution.x, bloom_resolution.y, gl::pixel_type::float_16, gl::pixel_format::rgb);
	ctx.bloom_color_texture->set_wrapping(gl::texture_wrapping::extend, gl::texture_wrapping::extend);
	ctx.bloom_color_texture->set_filters(gl::texture_min_filter::linear, gl::texture_mag_filter::linear);
	ctx.bloom_color_texture->set_max_anisotropy(0.0f);
	ctx.bloom_framebuffer = new gl::framebuffer(bloom_resolution.x, bloom_resolution.y);
	ctx.bloom_framebuffer->attach(gl::framebuffer_attachment_type::color, ctx.bloom_color_texture);
	
	// Load shadow map resolution from config
	int shadow_map_resolution = 4096;
	if (ctx.config->contains("shadow_map_resolution"))
		shadow_map_resolution = (*ctx.config)["shadow_map_resolution"].get<int>();
	
	// Create shadow map framebuffer
	ctx.shadow_map_depth_texture = new gl::texture_2d(shadow_map_resolution, shadow_map_resolution, gl::pixel_type::float_32, gl::pixel_format::d);
	ctx.shadow_map_depth_texture->set_wrapping(gl::texture_wrapping::extend, gl::texture_wrapping::extend);
	ctx.shadow_map_depth_texture->set_filters(gl::texture_min_filter::linear, gl::texture_mag_filter::linear);
	ctx.shadow_map_depth_texture->set_max_anisotropy(0.0f);
	ctx.shadow_map_framebuffer = new gl::framebuffer(shadow_map_resolution, shadow_map_resolution);
	ctx.shadow_map_framebuffer->attach(gl::framebuffer_attachment_type::depth, ctx.shadow_map_depth_texture);
	
	ctx.logger->pop_task(EXIT_SUCCESS);
}

void destroy_framebuffers(game::context& ctx)
{
	ctx.logger->push_task("Destroying framebuffers");
	
	// Delete HDR framebuffer and its attachments
	delete ctx.hdr_framebuffer;
	ctx.hdr_framebuffer = nullptr;
	delete ctx.hdr_color_texture;
	ctx.hdr_color_texture = nullptr;
	delete ctx.hdr_depth_texture;
	ctx.hdr_depth_texture = nullptr;
	
	// Delete bloom framebuffer and its attachments
	delete ctx.bloom_framebuffer;
	ctx.bloom_framebuffer = nullptr;
	delete ctx.bloom_color_texture;
	ctx.bloom_color_texture = nullptr;
	
	// Delete shadow map framebuffer and its attachments
	delete ctx.shadow_map_framebuffer;
	ctx.shadow_map_framebuffer = nullptr;
	delete ctx.shadow_map_depth_texture;
	ctx.shadow_map_depth_texture = nullptr;
	
	ctx.logger->pop_task(EXIT_SUCCESS);
}

void change_render_resolution(game::context& ctx, float scale)
{
	ctx.logger->push_task("Changing render resolution");
	
	// Update render resolution scale
	ctx.render_resolution_scale = scale;
	
	// Recalculate render resolution
	const int2& viewport_dimensions = ctx.app->get_viewport_dimensions();
	ctx.render_resolution = {static_cast<int>(viewport_dimensions.x * ctx.render_resolution_scale + 0.5f), static_cast<int>(viewport_dimensions.y * ctx.render_resolution_scale + 0.5f)};
	
	// Resize HDR framebuffer and attachments
	ctx.hdr_framebuffer->resize({ctx.render_resolution.x, ctx.render_resolution.y});
	resize_framebuffer_attachment(*ctx.hdr_color_texture, ctx.render_resolution);
	resize_framebuffer_attachment(*ctx.hdr_depth_texture, ctx.render_resolution);
	
	// Recalculate bloom resolution
	int2 bloom_resolution = ctx.render_resolution / 2;
	
	// Resize bloom framebuffer and attachments
	ctx.bloom_framebuffer->resize({bloom_resolution.x, bloom_resolution.y});
	resize_framebuffer_attachment(*ctx.bloom_color_texture, bloom_resolution);
	
	ctx.logger->pop_task(EXIT_SUCCESS);
}

void resize_framebuffer_attachment(gl::texture_2d& texture, const int2& resolution)
{
	texture.resize(resolution.x, resolution.y, texture.get_pixel_type(), texture.get_pixel_format(), texture.get_color_space(), nullptr);
}

void save_screenshot(game::context& ctx)
{
	// Determine screenshot path
	std::string filename = "antkeeper-" + timestamp() + ".png";
	std::filesystem::path path = ctx.config_path / "gallery" / filename;
	
	ctx.logger->push_task("Saving screenshot to \"" + path.string() + "\"");
	
	const int2& viewport_dimensions = ctx.app->get_viewport_dimensions();
	
	// Allocate image
	std::shared_ptr<image> frame = std::make_shared<image>();
	frame->format(1, 3);
	frame->resize(viewport_dimensions.x, viewport_dimensions.y);
	
	// Read pixel data from backbuffer into image
	glReadBuffer(GL_BACK);
	glReadPixels(0, 0, viewport_dimensions.x, viewport_dimensions.y, GL_RGB, GL_UNSIGNED_BYTE, frame->get_pixels());
	
	// Write screenshot file in separate thread
	std::thread
	(
		[frame, path]
		{
			stbi_flip_vertically_on_write(1);
			stbi_write_png(path.string().c_str(), frame->get_width(), frame->get_height(), frame->get_channel_count(), frame->get_pixels(), frame->get_width() * frame->get_channel_count());
		}
	).detach();
	
	ctx.logger->pop_task(EXIT_SUCCESS);
}

} // namespace graphics
} // namespace game