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

/*= Utilities ================================================================*/

// Disable next ImGui button(s)
void disableButton( );
// Re-enable ImGui buttons
inline void reenableButtons( )
{
	ImGui::PopStyleColor( 3 );
}

/*----------------------------------------------------------------------------*/

// Add some value to an angle, keeping it in [-180;180]
void updateAngle(
		__rw__	float& initial ,
		__rd__	const float delta
	);
// Make a rotation matrix from three YPR angles (in degrees)
void anglesToMatrix(
		__rd__	float const* angles ,
		__wr__	float* matrix );

/*----------------------------------------------------------------------------*/

// Helpers for finding entries in collections
template< typename T , typename I >
inline auto find(
		__rd__ T const& collection ,
		__rd__ I const& item )
{
	return std::find( collection.begin( ) , collection.end( ) , item );
}

template< typename T , typename I >
inline auto find(
		__rw__ T& collection ,
		__rd__ I const& item )
{
	return std::find( collection.begin( ) , collection.end( ) , item );
}


/*= T_FilesWatcher / T_WatchedFiles ==========================================*/

struct T_FilesWatcher;
struct T_WatchedFiles;
using F_OnFileChanges = std::function< void( void ) >;

struct T_FilesWatcher
{
	friend struct T_WatchedFiles;

	T_FilesWatcher( T_FilesWatcher const& ) = delete;

	T_FilesWatcher( );
	T_FilesWatcher( T_FilesWatcher&& ) noexcept;
	~T_FilesWatcher( );

	void check( );

    private:
	int fd;
	std::vector< T_WatchedFiles* > watched;
};

/*----------------------------------------------------------------------------*/

struct T_WatchedFiles
{
	friend struct T_FilesWatcher;

	T_WatchedFiles( ) = delete;
	T_WatchedFiles( T_WatchedFiles const& ) = delete;

	T_WatchedFiles( T_WatchedFiles&& ) noexcept;
	T_WatchedFiles(
			__rw__ T_FilesWatcher& watcher ,
			__rd__ const F_OnFileChanges callback );

	~T_WatchedFiles( );

	void clear( );
	bool watch( __rd__ std::string const& file );

    private:
	T_FilesWatcher* watcher;
	const F_OnFileChanges callback;
	bool triggered;
	std::vector< int > identifiers;
};


/*= T_ShaderCode =============================================================*/

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

	explicit T_ShaderCode( __rd__ const int nparts );
	~T_ShaderCode( );

	void setPart(
			__rd__	const int index ,
			__rd__	char const* const string );
	void setPart(
			__rd__	const int index ,
			__rd__	void const* const data ,
			__rd__	const int size );
	bool loadPart(
			__rd__	const int index ,
			__rd__	std::string const& source ,
			__rw__	std::vector< std::string >& errors );

	GLuint createProgram(
			__rd__	GLenum type ,
			__rw__	std::vector< std::string >& errors ) const;

    private:
	std::vector< char* > code;
};

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

	T_ShaderProgram(
			__rd__ GLenum programType ,
			__rw__ T_FilesWatcher& watcher );
	~T_ShaderProgram( );

	void addChunk( __rd__ std::string const& string );
	void addFile( __rd__ std::string const& source );

	void load( );
	bool activate( ) const;

    private:
	T_WatchedFiles files_;

	std::vector< bool > chunksOrFiles_;
	std::vector< std::string > parts_;

	std::vector< std::string > errors_;

	GLenum programType_;
	GLuint program_;
};


/*= T_Camera =================================================================*/

struct T_Camera
{
	glm::vec3 lookAt;
	glm::vec3 angles;
	float distance = 10;
	float fov = 90;

	// Everything below is updated by update()
	glm::vec3 dir;
	glm::vec3 up;
	glm::vec3 pos;
	float np;

	T_Camera()
		{ update( ); }

	void handleDND(
			__rd__	ImVec2 const& move ,
			__rd__	const bool hasCtrl ,
			__rd__	const bool hasShift ,
			__rd__	const bool lmb		// Left mouse button
		);
	void handleWheel(
			__rd__	const float wheel ,
			__rd__	const bool hasCtrl ,
			__rd__	const bool hasShift
		);

	void makeUI( );

    private:
	glm::mat3x3 rotMat;
	float rotationMatrix[ 9 ];
	void update( );
};