/*
    LA: linear algebra C++ interface library
    Copyright (C) 2008 Jiri Pittner <jiri.pittner@jh-inst.cas.cz> or <jiri@pittnerovi.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _AUXSTORAGE_H_
#define _AUXSTORAGE_H_

#include "vec.h"
#include "mat.h"
#include "smat.h"

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

namespace LA {

//CAUTION:
//it will not work if T is itself a class with dynamically allocated components
//it cannot be implemented for SparseMat, which lacks fixed record length
//for more complex I/O use put() and get() methods of the individual classes



template<typename T>
class AuxStorage
	{
	char filename[32];
	int fd;
	bool deleteme;
	size_t recl;
public:
	AuxStorage(void);
	AuxStorage(const char *name);
	~AuxStorage(void) {close(fd); if(deleteme) unlink(filename);};
	AuxStorage(const AuxStorage &) = delete; //a copy would close the file twice
	AuxStorage & operator=(const AuxStorage &) = delete;
	void get(NRVec<T> &x, const int pos) const;
	void put(const NRVec<T> &x, const int pos);
        void get(NRMat<T> &x, const int pos) const;
        void put(const NRMat<T> &x, const int pos);
        void get(NRSMat<T> &x, const int pos) const;
        void put(const NRSMat<T> &x, const int pos);
	};

template<typename T>
AuxStorage<T>::AuxStorage(void)
{
//mkostemp creates and opens the file atomically (unlike mktemp+open), additional flags like O_LARGEFILE can be given
strcpy(filename,"AUX_XXXXXX");
fd=mkostemp(filename,O_LARGEFILE);
if(fd<0) {perror(""); laerror("mkostemp failed in AuxStorage");}
recl=0;
deleteme=1;
}

template<typename T>
AuxStorage<T>::AuxStorage(const char *name)
{
if(strlen(name)>=sizeof(filename)) laerror("file name too long in AuxStorage");
strcpy(filename,name);
unlink(filename);
fd=open(filename,O_CREAT|O_LARGEFILE|O_RDWR,0777);
if(fd<0) {perror(""); laerror("open failed in AuxStorage");}
recl=0;
deleteme=0;
}


//vectors
template<typename T>
void AuxStorage<T>::get(NRVec<T> &x, const int pos) const
{
if(recl==0) laerror("get from an empty file in AuxStorage");
if(recl!=x.size()*sizeof(T)) laerror("size mismatch in AuxStorage::get");
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
x.copyonwrite();
if((ssize_t)recl!=read(fd,&x[0],recl)) {perror(""); laerror("read failed in AuxStorage");}
}

template<typename T>
void AuxStorage<T>::put(const NRVec<T> &x, const int pos)
{
if(recl) {if(recl!=x.size()*sizeof(T)) laerror("attempt to write objects of different size to one AuxStorage");}
else recl=x.size()*sizeof(T);
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
if(0>write(fd,&x[0],recl)) {perror(""); laerror("write failed in AuxStorage");}
}

//matrices
template<typename T>
void AuxStorage<T>::get(NRMat<T> &x, const int pos) const
{
if(recl==0) laerror("get from an empty file in AuxStorage");
if(recl!=(size_t)x.nrows()*x.ncols()*sizeof(T)) laerror("size mismatch in AuxStorage::get");
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
x.copyonwrite();
if((ssize_t)recl!=read(fd,&x(0,0),recl)) {perror(""); laerror("read failed in AuxStorage");}
}

template<typename T>
void AuxStorage<T>::put(const NRMat<T> &x, const int pos)
{
if(recl) {if(recl!=x.nrows()*x.ncols()*sizeof(T)) laerror("attempt to write objects of different size to one AuxStorage");}
else recl=x.nrows()*x.ncols()*sizeof(T);
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
if(0>write(fd,&x(0,0),recl)) {perror(""); laerror("write failed in AuxStorage");}
}

//packed symmetric matrices
template<typename T>
void AuxStorage<T>::get(NRSMat<T> &x, const int pos) const
{
if(recl==0) laerror("get from an empty file in AuxStorage");
if(recl!=(size_t)x.nrows()*(x.nrows()+1)/2*sizeof(T)) laerror("size mismatch in AuxStorage::get");
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
x.copyonwrite();
if((ssize_t)recl!=read(fd,&x(0,0),recl)) {perror(""); laerror("read failed in AuxStorage");}
}

template<typename T>
void AuxStorage<T>::put(const NRSMat<T> &x, const int pos)
{
if(recl) {if(recl!=x.nrows()*(x.nrows()+1)/2*sizeof(T)) laerror("attempt to write objects of different size to one AuxStorage");}
else recl=x.nrows()*(x.nrows()+1)/2*sizeof(T);
if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
if(0>write(fd,&x(0,0),recl)) {perror(""); laerror("write failed in AuxStorage");}
}


}//namespace

#endif