/*
* Not Thread Safe !
*/

#pragma once
#include <stddef.h>

class Filler
{
public:
	virtual size_t Read(void *dest, size_t len)=0;
};

class Drainer
{
public:
	virtual size_t Write(const void *dest, size_t len)=0;
};

class RingBuffer
{
public:
	RingBuffer();
	~RingBuffer();

	void Reset();
	bool reserve( size_t bytes ); // destructive.
	int expand( size_t bytes ); // like reserve, but only expands upward. non-destructive. returns an NError
	bool empty() const;
	size_t avail() const; // how much available for writing
	size_t size() const; // how much available for reading
	void clear();
	size_t read( void *dest, size_t len ); // returns amount actually read
	size_t advance( size_t len ); // same as read() but doesn't write the data any where.
	size_t peek( void *dest, size_t len ) const; // same as read() but doesn't advance the read pointer
	size_t write( const void *src, size_t len );
	size_t fill( Filler *filler, size_t max_bytes );
	size_t drain( Drainer *drainer, size_t max_bytes );
	size_t at( size_t offset, void *dest, size_t len ) const; // peeks() from offset. returns bytes read

	size_t write_position() const; // returns an integer representing a write position
	size_t read_position() const; // returns an integer representing the read position

	void get_read_buffer( size_t bytes, const void **buffer, size_t *bytes_available ) const; /* returns a pointer that you can read data from, call advance() when you are done */
	/* DO NOT USING THIS UNLESS YOU KNOW WHAT YOU'RE DOING
	you should only use it when the ring buffer is empty
	1) call clear() beforehand - very important!
	2) call LockBuffer(), it'll give you a buffer
	3) call UnlockBufer() with how much you've written
	4) you catch the man
	*/
	void *LockBuffer();
	void UnlockBuffer( size_t written );

private:
	volatile size_t ringBufferUsed;
	size_t ringBufferSize;
	char *ringBuffer;
	char *ringWritePosition;
	char *ringReadPosition;
};