/*
 * Copyright (C) 2023  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 <engine/gl/texture.hpp>
#include <engine/resources/deserialize-context.hpp>
#include <engine/resources/deserialize-error.hpp>
#include <engine/resources/resource-loader.hpp>
#include <engine/resources/resource-manager.hpp>

namespace {
	
	enum texture_type: std::uint8_t
	{
		texture_type_1d,
		texture_type_1d_array,
		texture_type_2d,
		texture_type_2d_array,
		texture_type_3d,
		texture_type_cube,
		texture_type_cube_array
	};
	
	[[nodiscard]] std::unique_ptr<gl::texture> load_texture(::resource_manager& resource_manager, deserialize_context& ctx, std::uint8_t texture_type)
	{
		// Read file format identifier
		std::uint32_t format_identifier{0};
		ctx.read32_le(reinterpret_cast<std::byte*>(&format_identifier), 1);
		
		// Validate file format identifier (U+1F5BC = framed picture)
		if (format_identifier != 0xbc969ff0)
		{
			throw deserialize_error("Invalid texture file.");
		}
		
		// Read file format version
		std::uint32_t format_version{0};
		ctx.read32_le(reinterpret_cast<std::byte*>(&format_version), 1);
		
		// Validate file format version
		if (format_version != 1)
		{
			throw deserialize_error("Unsupported texture file version.");
		}
		
		// Read image path
		std::uint32_t image_path_length{0};
		ctx.read32_le(reinterpret_cast<std::byte*>(&image_path_length), 1);
		std::string image_path(image_path_length, '\0');
		ctx.read8(reinterpret_cast<std::byte*>(image_path.data()), image_path_length);
		
		// Load image
		std::shared_ptr<gl::image> image;
		switch (texture_type)
		{
			case texture_type_1d:
			case texture_type_1d_array:
				image = resource_manager.load<gl::image_1d>(image_path);
				break;
			
			case texture_type_2d:
			case texture_type_2d_array:
				image = resource_manager.load<gl::image_2d>(image_path);
				break;
				
			case texture_type_3d:
				image = resource_manager.load<gl::image_3d>(image_path);
				break;
			
			case texture_type_cube:
			case texture_type_cube_array:
				image = resource_manager.load<gl::image_cube>(image_path);
				break;
			
			default:
				throw deserialize_error("Invalid texture type.");
		}
		
		// Read image view parameters
		gl::format format;
		std::uint32_t first_mip_level;
		std::uint32_t mip_level_count;
		std::uint32_t first_array_layer;
		std::uint32_t array_layer_count;
		ctx.read32_le(reinterpret_cast<std::byte*>(&format), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&first_mip_level), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&mip_level_count), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&first_array_layer), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&array_layer_count), 1);
		
		// Handle automatic mip level count (`0`)
		if (!mip_level_count)
		{
			mip_level_count = image->get_mip_levels();
		}
		
		// Handle automatic array layer count (`0`)
		if (!array_layer_count)
		{
			array_layer_count = image->get_array_layers();
		}
		
		// Read sampler parameters
		gl::sampler_filter mag_filter;
		gl::sampler_filter min_filter;
		gl::sampler_mipmap_mode mipmap_mode;
		gl::sampler_address_mode address_mode_u;
		gl::sampler_address_mode address_mode_v;
		gl::sampler_address_mode address_mode_w;
		float mip_lod_bias;
		float max_anisotropy;
		std::uint8_t compare_enabled;
		gl::compare_op compare_op;
		float min_lod;
		float max_lod;
		std::array<float, 4> border_color;
		ctx.read8(reinterpret_cast<std::byte*>(&mag_filter), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&min_filter), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&mipmap_mode), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&address_mode_u), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&address_mode_v), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&address_mode_w), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&mip_lod_bias), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&max_anisotropy), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&compare_enabled), 1);
		ctx.read8(reinterpret_cast<std::byte*>(&compare_op), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&min_lod), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(&max_lod), 1);
		ctx.read32_le(reinterpret_cast<std::byte*>(border_color.data()), 4);
		
		// Construct sampler
		std::shared_ptr<gl::sampler> sampler = std::make_shared<gl::sampler>
		(
			mag_filter,
			min_filter,
			mipmap_mode,
			address_mode_u,
			address_mode_v,
			address_mode_w,
			mip_lod_bias,
			max_anisotropy,
			compare_enabled,
			compare_op,
			min_lod,
			max_lod,
			border_color
		);
		
		// Construct image view and texture
		switch (texture_type)
		{
			case texture_type_1d:
			{
				auto image_view = std::make_shared<gl::image_view_1d>(image, format, first_mip_level, mip_level_count, first_array_layer);
				return std::make_unique<gl::texture_1d>(std::move(image_view), std::move(sampler));
			}
			
			case texture_type_1d_array:
			{
				auto image_view = std::make_shared<gl::image_view_1d_array>(image, format, first_mip_level, mip_level_count, first_array_layer, array_layer_count);
				return std::make_unique<gl::texture_1d_array>(std::move(image_view), std::move(sampler));
			}
				
			case texture_type_2d:
			{
				auto image_view = std::make_shared<gl::image_view_2d>(image, format, first_mip_level, mip_level_count, first_array_layer);
				return std::make_unique<gl::texture_2d>(std::move(image_view), std::move(sampler));
			}
			
			case texture_type_2d_array:
			{
				auto image_view = std::make_shared<gl::image_view_2d_array>(image, format, first_mip_level, mip_level_count, first_array_layer, array_layer_count);
				return std::make_unique<gl::texture_2d_array>(std::move(image_view), std::move(sampler));
			}
				
			case texture_type_3d:
			{
				auto image_view = std::make_shared<gl::image_view_3d>(image, format, first_mip_level, mip_level_count);
				return std::make_unique<gl::texture_3d>(std::move(image_view), std::move(sampler));
			}
			
			case texture_type_cube:
			{
				auto image_view = std::make_shared<gl::image_view_cube>(image, format, first_mip_level, mip_level_count, first_array_layer);
				return std::make_unique<gl::texture_cube>(std::move(image_view), std::move(sampler));
			}
			
			case texture_type_cube_array:
			{
				auto image_view = std::make_shared<gl::image_view_cube_array>(image, format, first_mip_level, mip_level_count, first_array_layer, array_layer_count);
				return std::make_unique<gl::texture_cube_array>(std::move(image_view), std::move(sampler));
			}
			
			default:
				return nullptr;
		}
	}

}

template <>
std::unique_ptr<gl::texture_1d> resource_loader<gl::texture_1d>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_1d>(static_cast<gl::texture_1d*>(load_texture(resource_manager, ctx, texture_type_1d).release()));
}

template <>
std::unique_ptr<gl::texture_1d_array> resource_loader<gl::texture_1d_array>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_1d_array>(static_cast<gl::texture_1d_array*>(load_texture(resource_manager, ctx, texture_type_1d_array).release()));
}

template <>
std::unique_ptr<gl::texture_2d> resource_loader<gl::texture_2d>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_2d>(static_cast<gl::texture_2d*>(load_texture(resource_manager, ctx, texture_type_2d).release()));
}

template <>
std::unique_ptr<gl::texture_2d_array> resource_loader<gl::texture_2d_array>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_2d_array>(static_cast<gl::texture_2d_array*>(load_texture(resource_manager, ctx, texture_type_2d_array).release()));
}

template <>
std::unique_ptr<gl::texture_3d> resource_loader<gl::texture_3d>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_3d>(static_cast<gl::texture_3d*>(load_texture(resource_manager, ctx, texture_type_3d).release()));
}

template <>
std::unique_ptr<gl::texture_cube> resource_loader<gl::texture_cube>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_cube>(static_cast<gl::texture_cube*>(load_texture(resource_manager, ctx, texture_type_cube).release()));
}

template <>
std::unique_ptr<gl::texture_cube_array> resource_loader<gl::texture_cube_array>::load(::resource_manager& resource_manager, deserialize_context& ctx)
{
	return std::unique_ptr<gl::texture_cube_array>(static_cast<gl::texture_cube_array*>(load_texture(resource_manager, ctx, texture_type_cube_array).release()));
}