#pragma once
#include "filewatcher.hh"
#include "utilities.hh"


/*= INPUT FILES ==============================================================*/

// Type of input chunk
enum class E_ShaderInputChunk {
	CODE ,
	INCLUDE
};

// Input chunk data
struct T_ShaderInputChunk
{
	E_ShaderInputChunk type;
	std::string text;
	uint32_t lines;

	T_ShaderInputChunk( ) = default;
	T_ShaderInputChunk(
			__rd__ const E_ShaderInputChunk type ,
			__rd__ std::string text ,
			__rd__ const uint32_t lines )
		: type( type ) , text( std::move( text ) ) , lines( lines )
	{ }
};

// Input file type
enum class E_ShaderInput {
	CHUNK ,			// Chunk that may be repeated
	LIBRARY ,		// Library (will only be loaded once)

	// "Main" shader source files
	VERTEX , FRAGMENT , GEOMETRY ,
	COMPUTE
};

// Preprocessing errors
struct T_ShaderInputError
{
	uint32_t line;
	std::string error;
};

// Source file
struct T_ShaderInput
{
	E_ShaderInput type = E_ShaderInput::CHUNK;
	std::vector< T_ShaderInputChunk > chunks;
	std::vector< T_ShaderInputError > errors;

	bool load( __rd__ std::string const& path );
};
using P_ShaderInput = std::unique_ptr< T_ShaderInput >;


// Type of shader
enum class E_ShaderType {
	VERTEX , FRAGMENT , GEOMETRY ,
	COMPUTE ,
	__COUNT__
};


// Errors in shader code - the errors it represents may come from either
// the input loader, the shader loader or the driver.
struct T_ShaderError
{
	std::string source;
	uint32_t line;
	std::string error;
};


struct T_ShaderManager;

struct T_ShaderPipeline
{
	friend struct T_ShaderManager;

	T_ShaderPipeline( );
	COPY( T_ShaderPipeline );
	MOVE( T_ShaderPipeline );
	~T_ShaderPipeline( );

	bool valid( ) const noexcept;
	void enable( ) const;

	GLuint program( __rd__ const E_ShaderType program ) const;

    private:
	explicit T_ShaderPipeline(
			__rd__ const int32_t index );
	int32_t smIndex_;
};


struct T_ShaderManager
{
	friend struct T_ShaderPipeline;

	struct T_ShaderCode
	{
		E_ShaderType type;
		std::vector< uint32_t > starts;		// Position of chunk in source file
		std::vector< uint32_t > counts;		// Chunk lengths
		std::vector< std::string > sources;	// Chunk source files
		std::string code;
		std::vector< T_ShaderError > errors;
		std::map< std::string , bool > files;
	};

	T_ShaderPipeline pipeline(
			__rd__ std::initializer_list< std::string > shaders );

	void update( );

    private:
	struct T_Pipeline_
	{
		uint32_t references;
		std::string idString;
		GLuint id;
		std::vector< std::string > programs;
	};

	struct T_Program_
	{
		std::string name;
		std::set< uint32_t > references;
		T_ShaderCode code;
		GLuint id;
		std::unique_ptr< T_WatchedFiles > watch;
	};

	std::vector< T_Pipeline_ > pipelines_;
	std::map< std::string , uint32_t > pipelineIndex_;

	std::vector< T_Program_ > programs_;
	std::map< std::string , uint32_t > programIndex_;

	std::map< std::string , P_ShaderInput > inputs_;

	std::map< std::string , std::set< std::string > > missing_;
	std::set< std::string > updates_;

	uint32_t newPipelineRecord( );
	uint32_t newProgramRecord( );

	void loadProgram(
			__rd__ const uint32_t pipeline ,
			__rd__ std::string const& name );
	bool useExistingProgram(
			__rd__ const uint32_t pipeline ,
			__rd__ std::string const& name );

	T_ShaderInput const* getInput(
			__rd__ std::string const& name );

	void dereferencePipeline(
			__rd__ const uint32_t index );
	void dereferenceProgram(
			__rd__ const uint32_t index ,
			__rd__ const uint32_t pipeline );

	void initPipeline(
			__rw__ T_Pipeline_& pipeline ) const;
	void initProgram(
			__rw__ T_Program_& program );

	void parseGLSLError(
			__rw__ T_ShaderCode& code ,
			__rd__ char const* errorLine );

	void programUpdated(
			__rd__ std::string const& name );

	void resetProgram(
			__rw__ T_Program_& program );
};