/*
 * 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/>.
 */

#ifndef ANTKEEPER_GL_SHADER_OBJECT_HPP
#define ANTKEEPER_GL_SHADER_OBJECT_HPP

#include <engine/gl/shader-stage.hpp>
#include <cstddef>
#include <string>

namespace gl {
	
class shader_program;

/**
 * Shader object which can be compiled and linked to a shader program.
 *
 * @see gl::shader_program
 * @see gl::shader_stage
 */
class shader_object
{
public:
	/**
	 * Creates an empty shader object for the specified shader stage.
	 *
	 * @param stage Shader stage in which this shader object will be used.
	 *
	 * @exception std::runtime_error An error occurred while creating an OpenGL shader object.
	 */
	shader_object(shader_stage stage);
	
	/**
	 * Destroys a shader object.
	 */
	~shader_object();
	
	/**
	 * Replaces the source code of the shader object.
	 *
	 * @param source_code String containing shader object source code.
	 *
	 * @exception std::runtime_error Shader object handle is not a value generated by OpenGL.
	 * @exception std::runtime_error Shader object handle is not a shader object.
	 */
	void source(const std::string& source_code);
	
	/**
	 * Compiles the shader object.
	 *
	 * @return `true` if the shader object was compiled successfully, `false` otherwise. If compilation fails, check the info log via shader_object::get_info_log() for more information.
	 *
	 * @exception std::runtime_error Shader object handle is not a value generated by OpenGL.
	 * @exception std::runtime_error Shader object handle is not a shader object.
	 *
	 * @see shader_object::get_info_log()
	 */
	bool compile();
	
	/// Returns the shader stage of this shader object.
	shader_stage get_stage() const;
	
	/// Returns the shader object info log, which is updated when the shader object is compiled.
	const std::string& get_info_log() const;
	
	/// Returns `true` if the shader object has been successfully compiled, `false` otherwise.
	bool was_compiled() const;
	
	shader_object(const shader_object&) = delete;
	shader_object& operator=(const shader_object&) = delete;

private:
	friend class shader_program;
	
	unsigned int gl_shader_id;
	shader_stage stage;
	std::string info_log;
	bool compiled;
};

inline shader_stage shader_object::get_stage() const
{
	return stage;
}

inline const std::string& shader_object::get_info_log() const
{
	return info_log;
}

inline bool shader_object::was_compiled() const
{
	return compiled;
}

} // namespace gl

#endif // ANTKEEPER_GL_SHADER_OBJECT_HPP