#ifndef _POS_LOG_H_
#define _POS_LOG_H_
#include "sha1.h"
#include <list>
#include <string>
#include <stdint.h>

enum E_OBJ_TYPE { ET_TRANS, ET_HASH, ET_SALE, ET_REVERT };

struct __attribute__ ((packed)) UPC {
	uint64_t h, l;
};

class UPCLess {
public:
	bool operator()(const UPC & lhs, const UPC & rhs) const {
		if(lhs.h == rhs.h)
			return (lhs.l < rhs.l);
		else
			return (lhs.h < rhs.h);
	}
};

struct __attribute__ ((aligned (64), packed)) LogEntry
{
	uint64_t ts;
	uint64_t serial;
	E_OBJ_TYPE type;
	union {
		struct __attribute__ ((packed)) {
			uint32_t uid;
			int32_t delta;
		} Transaction;

		struct __attribute__ ((packed)) {
			char hash[20];
			uint32_t uid;
			bool add;
		} HashChange;

		struct __attribute__ ((packed)) {
			UPC upc;
			int32_t delta;
		} StockChange;

		struct __attribute__ ((packed)) {
			uint64_t revert_serial;
		} Revert;
	};
};

class Log {
public:
	Log(const char * fn);
	uint64_t writeEntry(LogEntry ent);
	uint64_t nextSerial();
	std::list<LogEntry>::const_iterator begin();
	std::list<LogEntry>::const_iterator end();

private:
	std::list<LogEntry> entries;
	std::string log_name;
	uint64_t serial;
};

#endif