#pragma once
#ifndef REAL_BUILD
# include "externals.hh"
#endif


enum class E_TexType {
	RGBA8 ,
	RGBA16F ,
	RGB8 ,
	RGB16F ,
	R8 ,
	R16F ,
};

enum class E_TexSampling {
	NEAREST ,
	LINEAR ,
};

enum class E_TexWrap {
	REPEAT ,
	CLAMP_EDGE ,
	CLAMP_BORDER
};

struct T_Texture
{
	T_Texture( ) = delete;
	T_Texture( T_Texture const& ) = delete;
	T_Texture( T_Texture&& ) = delete;

	T_Texture(
			__rd__ const uint32_t width ,
			__rd__ const uint32_t height ,
			__rd__ const E_TexType type ,
			__rd__ const uint32_t levels = 1 );
	~T_Texture( );

	T_Texture& samplingMode(
			__rd__ const E_TexSampling mode );
	T_Texture& wrap(
			__rd__ const E_TexWrap mode );

	GLuint id( ) const noexcept { return id_; }
	uint32_t levels( ) const noexcept { return levels_; }
	uint32_t width( ) const noexcept { return width_; }
	uint32_t height( ) const noexcept { return height_; }

    private:
	GLuint id_;
	uint32_t levels_ , width_ , height_;
};


struct T_TextureSampler
{
	T_TextureSampler( T_TextureSampler const& ) = delete;

	// --------------------------------------------------------------------
	// Initialisation, destruction & move

	T_TextureSampler( );
	T_TextureSampler(
			__rw__ T_TextureSampler&& other ) noexcept;
	T_TextureSampler& operator=(
			__rw__ T_TextureSampler&& other ) noexcept;
	~T_TextureSampler( );

	// --------------------------------------------------------------------
	// Configuration

	T_TextureSampler& sampling(
			__rd__ const E_TexSampling mode );

	T_TextureSampler& noMipmap( );
	T_TextureSampler& mipmap(
			__rd__ const E_TexSampling mode );

	T_TextureSampler& wrap(
			__rd__ const E_TexWrap mode );

	T_TextureSampler& lod(
			__rd__ const float min ,
			__rd__ const float max );

	// --------------------------------------------------------------------
	// Usage

	GLuint id( ) const noexcept { return id_; }

	// unused
	void bind( __rd__ const GLuint unit )
		{ glBindSampler( unit , id_ ); }

    private:
	void setSamplingMode( ) const;

	GLuint id_ = 0;
	E_TexSampling sampling_ = E_TexSampling::NEAREST;
	E_TexSampling lodSampling_ = E_TexSampling::NEAREST;
	bool hasLOD_ = false;
};


struct T_TextureManagement
{
	static constexpr uint32_t MaxUnits = 8;

	NO_COPY( T_TextureManagement );
	NO_MOVE( T_TextureManagement );

	static T_TextureManagement& TM( );
	static void Shutdown( );

	void reset( );
	T_TextureSampler const* sampler(
			__rd__ std::string const& name ) const;

	void bind( __rd__ const uint32_t unit ,
			__rd__ T_Texture const& texture );
	void bind( __rd__ const uint32_t unit ,
			__rd__ T_Texture const& texture ,
			__rd__ T_TextureSampler const& sampler );

    private:
	static std::unique_ptr< T_TextureManagement > instance_;

	T_TextureManagement( );

	struct T_Binding_
	{
		GLuint texture = 0;
		GLuint sampler = 0;
	};

	std::map< std::string , std::shared_ptr< T_TextureSampler > > samplers_;
	T_Binding_ bindings_[ MaxUnits ];
};