/*!
 *	readTraFile.cpp
 *
 *	Created on: 20.11.2012
 *		Author: Gereon Kremer
 */

#include "parser.h"

#include "src/parser/readTraFile.h"
#include "src/exceptions/file_IO_exception.h"
#include "src/exceptions/wrong_file_format.h"
#include "boost/integer/integer_mask.hpp"
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <clocale>
#include <iostream>
#include <errno.h>
#include <time.h>
#include <sys/stat.h>
#if defined LINUX || defined MACOSX
	#include <sys/mman.h>
#elif defined WINDOWS
#endif
#include <fcntl.h>
#include <locale.h>

namespace mrmc {
namespace parser{

/*!
 *	@brief	Perform first pass through the file and obtain number of
 *	non-zero cells and maximum node id.
 *
 *	This method does the first pass through the .tra file and computes
 *	the number of non-zero elements that are not diagonal elements,
 *	which correspondents to the number of transitions that are not
 *	self-loops.
 *	(Diagonal elements are treated in a special way).
 *	It also calculates the maximum node id and stores it in maxnode.
 *
 *	@return The number of non-zero elements that are not on the diagonal
 *	@param buf Data to scan. Is expected to be some char array.
 *	@param maxnode Is set to highest id of all nodes.
 */
static uint_fast32_t makeFirstPass(char* buf, uint_fast32_t &maxnode)
{
	uint_fast32_t non_zero = 0;
	
	/*
	 *	check file header and extract number of transitions
	 */
	if (strncmp(buf, "STATES ", 7) != 0) return 0;
	buf += 7; // skip "STATES "
	if (strtol(buf, &buf, 10) == 0) return 0;
	buf = skipWS(buf);
	if (strncmp(buf, "TRANSITIONS ", 12) != 0) return 0;
	buf += 12; // skip "TRANSITIONS "
	if ((non_zero = strtol(buf, &buf, 10)) == 0) return 0;
	
	/*
	 *	check all transitions for non-zero diagonal entrys
	 */
	uint_fast32_t row, col;
	double val;
	maxnode = 0;
	while (buf[0] != '\0')
	{
		/*
		 *	read row and column
		 */
		row = checked_strtol(buf, &buf);
		col = checked_strtol(buf, &buf);
		/*
		 *	check if one is larger than the current maximum id
		 */
		if (row > maxnode) maxnode = row;
		if (col > maxnode) maxnode = col;
		/*
		 *	read value. if value is zero, we have reached the end of the file.
		 *	if row == col, we have a diagonal element which is treated seperately and this non_zero must be decreased.
		 */
		val = strtod(buf, &buf);
		if (val == 0.0) break;
		if (row == col) non_zero--;
		buf = skipWS(buf);
	}

	return non_zero;
}



/*!
 *	Reads a .tra file and produces a sparse matrix representing the described Markov Chain.
 *
 *	Matrices created with this method have to be freed with the delete operator.
 *	@param filename input .tra file's name.
 *	@return a pointer to the created sparse matrix.
 */

mrmc::storage::SquareSparseMatrix<double> * readTraFile(const char * filename) {
	/*
	*	enforce locale where decimal point is '.'
	*/
	setlocale( LC_NUMERIC, "C" );
	
	/*
	 *	open file
	 */
	MappedFile file(filename);
	char* buf = file.data;
	
	/*
	 *	perform first pass, i.e. count entries that are not zero and not on the diagonal
	 */
	uint_fast32_t maxnode;
	uint_fast32_t non_zero = makeFirstPass(file.data, maxnode);
	/*
	 *	if first pass returned zero, the file format was wrong
	 */
	if (non_zero == 0) throw mrmc::exceptions::wrong_file_format();
	
	/*
	 *	perform second pass
	 *	
	 *	from here on, we already know that the file header is correct
	 */
	mrmc::storage::SquareSparseMatrix<double> *sp = NULL;

	/*
	 *	read file header, extract number of states
	 */
	buf += 7; // skip "STATES "
	checked_strtol(buf, &buf);
	buf = skipWS(buf);
	buf += 12; // skip "TRANSITIONS "
	checked_strtol(buf, &buf);
	
	/*
	 *	Creating matrix
	 *	Memory for diagonal elements is automatically allocated, hence only the number of non-diagonal
	 *	non-zero elements has to be specified (which is non_zero, computed by make_first_pass)
	 */
	sp = new mrmc::storage::SquareSparseMatrix<double>(maxnode + 1);
	if (sp == NULL)	throw std::bad_alloc();
	sp->initialize(non_zero);

	uint_fast64_t row, col;
	double val;

	/*
	 *	read all transitions from file
	 */
	while (buf[0] != '\0')
	{
		/*
		 *	read row, col and value.
		 */
		row = checked_strtol(buf, &buf);
		col = checked_strtol(buf, &buf);
		val = strtod(buf, &buf);
		
		/*
		 *	only values in (0, 1] are meaningful
		 */
		if ((val <= 0.0) || (val > 1.0)) throw mrmc::exceptions::wrong_file_format();
		sp->addNextValue(row,col,val);
		buf = skipWS(buf);
	}
	
	/*
	 * clean up
	 */	
	sp->finalize();
	return sp;
}

} //namespace parser
} //namespace mrmc