/*
 * 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_SAMPLER_HPP
#define ANTKEEPER_GL_SAMPLER_HPP

#include <engine/gl/sampler-filter.hpp>
#include <engine/gl/sampler-mipmap-mode.hpp>
#include <engine/gl/sampler-address-mode.hpp>
#include <engine/gl/compare-op.hpp>
#include <array>

namespace gl {

/**
 * Sampler object.
 */
class sampler
{
public:
	/**
	 * Constructs a sampler object.
	 *
	 * @param mag_filter Magnification filter to apply to lookups.
	 * @param min_filter Minification filter to apply to lookups.
	 * @param mipmap_mode Mipmap filter to apply to lookups.
	 * @param address_mode_u Addressing mode for U-coordinates outside `[0, 1)`.
	 * @param address_mode_v Addressing mode for V-coordinates outside `[0, 1)`.
	 * @param address_mode_w Addressing mode for W-coordinates outside `[0, 1)`.
	 * @param mip_lod_bias Bias to be added to mipmap LOD calculation.
	 * @param max_anisotropy Anisotropy clamp value.
	 * @param compare_enabled `true` to enable comparison against a reference value during lookups, `false` otherwise.
	 * @param compare_op Comparison operator to apply to fetched data, if compare is enabled.
	 * @param min_lod Minimum clamp value of the computed LOD.
	 * @param max_lod Maximum clamp value of the computed LOD.
	 * @param border_color Border color used for texture lookups.
	 */
	explicit sampler
	(
		sampler_filter mag_filter = sampler_filter::linear,
		sampler_filter min_filter = sampler_filter::nearest,
		sampler_mipmap_mode mipmap_mode = sampler_mipmap_mode::linear,
		sampler_address_mode address_mode_u = sampler_address_mode::repeat,
		sampler_address_mode address_mode_v = sampler_address_mode::repeat,
		sampler_address_mode address_mode_w = sampler_address_mode::repeat,
		float mip_lod_bias = 0.0f,
		float max_anisotropy = 0.0f,
		bool compare_enabled = false,
		gl::compare_op compare_op = gl::compare_op::less,
		float min_lod = -1000.0f,
		float max_lod = 1000.0f,
		const std::array<float, 4>& border_color = {0.0f, 0.0f, 0.0f, 0.0f}
	);
	
	/// Destroys a sampler object.
	~sampler();
	
	sampler(const sampler&) = delete;
	sampler(sampler&&) = delete;
	sampler& operator=(const sampler&) = delete;
	sampler& operator=(sampler&&) = delete;
	
	/**
	 * Sets the magnification filter to apply to lookups.
	 *
	 * @param filter Magnification filter to apply to lookups.
	 */
	void set_mag_filter(sampler_filter filter);
	
	/**
	 * Sets the minification filter to apply to lookups.
	 *
	 * @param filter Minification filter to apply to lookups.
	 */
	void set_min_filter(sampler_filter filter);
	
	/**
	 * Sets the mipmap filter to apply to lookups.
	 *
	 * @param mode Mipmap filter to apply to lookups.
	 */
	void set_mipmap_mode(sampler_mipmap_mode mode);
	
	/**
	 * Sets the addressing mode for U-coordinates outside `[0, 1)`.
	 *
	 * @param Addressing mode for U-coordinates outside `[0, 1)`.
	 */
	void set_address_mode_u(sampler_address_mode mode);
	
	/**
	 * Sets the addressing mode for V-coordinates outside `[0, 1)`.
	 *
	 * @param Addressing mode for V-coordinates outside `[0, 1)`.
	 */
	void set_address_mode_v(sampler_address_mode mode);
	
	/**
	 * Sets the addressing mode for W-coordinates outside `[0, 1)`.
	 *
	 * @param Addressing mode for W-coordinates outside `[0, 1)`.
	 */
	void set_address_mode_w(sampler_address_mode mode);
	
	/**
	 * Sets the bias to be added to mipmap LOD calculation.
	 *
	 * @param bias Bias to be added to mipmap LOD calculation.
	 */
	void set_mip_lod_bias(float bias);
	
	/**
	 * Sets the anisotropy clamp value.
	 *
	 * @param anisotropy Anisotropy clamp value.
	 */
	void set_max_anisotropy(float anisotropy);
	
	/**
	 * Enables or disables a comparison against a reference value during lookups.
	 *
	 * @param enabled `true` to enable comparison against a reference value during lookups, `false` otherwise.
	 */
	void set_compare_enabled(bool enabled);
	
	/**
	 * Sets the comparison operator to apply to fetched data, if compare is enabled.
	 *
	 * @param op Comparison operator to apply to fetched data, if compare is enabled.
	 */
	void set_compare_op(gl::compare_op op);
	
	/**
	 * Sets the minimum clamp value of the computed LOD.
	 *
	 * @param lod Minimum clamp value of the computed LOD.
	 */
	void set_min_lod(float lod);
	
	/**
	 * Sets the maximum clamp value of the computed LOD.
	 *
	 * @param lod Maximum clamp value of the computed LOD.
	 */
	void set_max_lod(float lod);
	
	/**
	 * Sets the border color used for texture lookups.
	 *
	 * @param color Border color used for texture lookups.
	 */
	void set_border_color(const std::array<float, 4>& color);
	
	/// Returns the magnification filter to apply to lookups.
	[[nodiscard]] inline constexpr sampler_filter get_mag_filter() const noexcept
	{
		return m_mag_filter;
	}
	
	/// Returns the minification filter to apply to lookups.
	[[nodiscard]] inline constexpr sampler_filter get_min_filter() const noexcept
	{
		return m_min_filter;
	}
	
	/// Returns the mipmap filter to apply to lookups.
	[[nodiscard]] inline constexpr sampler_mipmap_mode get_mipmap_mode() const noexcept
	{
		return m_mipmap_mode;
	}
	
	/// Returns the addressing mode for U-coordinates outside `[0, 1)`.
	[[nodiscard]] inline constexpr sampler_address_mode get_address_mode_u() const noexcept
	{
		return m_address_mode_u;
	}
	
	/// Returns the addressing mode for V-coordinates outside `[0, 1)`.
	[[nodiscard]] inline constexpr sampler_address_mode get_address_mode_v() const noexcept
	{
		return m_address_mode_v;
	}
	
	/// Returns the addressing mode for W-coordinates outside `[0, 1)`.
	[[nodiscard]] inline constexpr sampler_address_mode get_address_mode_w() const noexcept
	{
		return m_address_mode_w;
	}
	
	/// Returns the bias to be added to mipmap LOD calculation.
	[[nodiscard]] inline constexpr float get_mip_lod_bias() const noexcept
	{
		return m_mip_lod_bias;
	}
	
	/// Returns the anisotropy clamp value.
	[[nodiscard]] inline constexpr float get_max_anisotropy() const noexcept
	{
		return m_max_anisotropy;
	}
	
	/// Returns `true` if comparison against a reference value during lookups is enabled, `false` otherwise. 
	[[nodiscard]] inline constexpr float get_compare_enabled() const noexcept
	{
		return m_compare_enabled;
	}
	
	/// Returns the comparison operator to apply to fetched data, if compare is enabled.
	[[nodiscard]] inline constexpr compare_op get_compare_op() const noexcept
	{
		return m_compare_op;
	}
	
	/// Returns the minimum clamp value of the computed LOD.
	[[nodiscard]] inline constexpr float get_min_lod() const noexcept
	{
		return m_min_lod;
	}
	
	/// Returns the maximum clamp value of the computed LOD.
	[[nodiscard]] inline constexpr float get_max_lod() const noexcept
	{
		return m_max_lod;
	}
	
	/// Returns the border color used for texture lookups.
	[[nodiscard]] inline constexpr const std::array<float, 4>& get_border_color() const noexcept
	{
		return m_border_color;
	}

private:
	friend class pipeline;
	friend class gl_shader_texture_1d;
	friend class gl_shader_texture_2d;
	friend class gl_shader_texture_3d;
	friend class gl_shader_texture_cube;
	
	unsigned int m_gl_named_sampler{0};
	
	sampler_filter m_mag_filter{sampler_filter::linear};
	sampler_filter m_min_filter{sampler_filter::nearest};
	sampler_mipmap_mode m_mipmap_mode{sampler_mipmap_mode::linear};
	sampler_address_mode m_address_mode_u{sampler_address_mode::repeat};
	sampler_address_mode m_address_mode_v{sampler_address_mode::repeat};
	sampler_address_mode m_address_mode_w{sampler_address_mode::repeat};
	float m_mip_lod_bias{0.0f};
	float m_max_anisotropy{0.0f};
	bool m_compare_enabled{false};
	gl::compare_op m_compare_op{gl::compare_op::less};
	float m_min_lod{-1000.0f};
	float m_max_lod{1000.0f};
	std::array<float, 4> m_border_color{0.0f, 0.0f, 0.0f, 0.0f};
};

} // namespace gl

#endif // ANTKEEPER_GL_SAMPLER_HPP