#ifndef KIMODEM_ARENA_H
#define KIMODEM_ARENA_H


#include <iostream>
#include <sys/stat.h>
#include <cstddef>
#include <cstdint>


namespace klib {


enum ArenaType : uint8_t {
	ARENA_UNINIT,
	ARENA_STATIC,
	ARENA_ALLOC,
	ARENA_MMAP,
};

class Arena {
public:
	Arena();

	~Arena();

	/*
	 * InitializeArena is intended for use only with systems that
	 * do not initialize new variables to zero. It should be called
	 * exactly once, at the start of the program. Any other time the
	 * arena needs to be reset, it should be called with Clear or
	 * Destroy.
	 */
	void Initialize();

	int SetStatic(uint8_t *, size_t);

	int SetAlloc(size_t allocSize);

#if defined(__linux__)
	int 	 MemoryMap(int fd); // Arena will own fd.
	int	 Create(const char *path, size_t size, mode_t mode);
	int 	 Open(const char *, size_t);
#endif

	uint8_t *NewCursor() const { return this->store; }
	uint8_t *End() { return this->store + this->size; }
	bool	 CursorInArena(uint8_t *cursor);

	size_t Size() const
	{ return this->size; }

	uint8_t Type() const
	{ return this->arenaType; }

	bool Ready() const { return this->Type() != ARENA_UNINIT; };
	void Clear();
	void Destroy(); /* dispose of any memory used by arena */

	/*
	 * DANGER: if arena is file backed (mmap or open), DO NOT WRITE TO THE
	 * BACKING FILE!
	 */
	int Write(const char *path);

	uint8_t &operator[](size_t index)
	{ return this->store[index]; }

private:
	uint8_t *store;
	size_t size;
	int fd;
	ArenaType arenaType;
};


std::ostream &operator<<(std::ostream& os, Arena arena);


} // namespace klib


#endif