#include <stdio.h>
#include "bc_io.h"
#include "lib.h"

Filedesc _fdtable[16];
/* BASIC file descriptor table */
/* Channel assignment:
   -1		terminal IO
    0		data file
    1-15	user files
*/

int _chann = -1;
FILE* _chanrd = stdin;
FILE* _chanwr = stdout;

void _setchan(int index)
{
#ifdef DEBUG
	printf("setchannel %d\n", index);
#endif
	fflush(_chanwr);
	if (index == -1)
	{
		_chann = -1;
		_chanrd = stdin;
		_chanwr = stdout;
		return;
	}
	if (index < 0 || index > 15)
		error(27);
	_chann = index;
	_chanrd = _chanwr = _fdtable[index].fd;
}

void _asschn(void)
{
#ifdef DEBUG
	printf("_asschn %d\n", _chann);
#endif
	if (_chann == -1)
		return;
#ifdef DEBUG
	printf(" file %d\n", _fdtable[_chann].fd);
#endif
	if (_chann < 0 || _chann > 15)
		error(27);
	if (_fdtable[_chann].fd == 0)
		error(39);
	if (feof(_fdtable[_chann].fd))
		error(2);
}

void _clochn(int nr)
{
	if (nr < 1 || nr > 15 || _fdtable[nr].fd == 0)
		error(3);
	fclose(_fdtable[nr].fd);
	_fdtable[nr].fd = 0;
	_fdtable[nr].fname = 0;
}

void _opnchn(int reclen, String* fname, String* mode)
{
	/* channel has been set */
	FILE* f;
	int m;

#ifdef DEBUG
	printf("open %d %s %s \n", reclen, mode->strval, fname->strval);
#endif
	/* check for opened/closed file */
	if (_fdtable[_chann].fd)
		error(30);
	switch (*mode->strval)
	{
		case 'O':
		case 'o':
			if ((f = fopen(fname->strval, "wb")) == NULL)
				error(28);
			m = OMODE;
			break;
		case 'I':
		case 'i':
			if ((f = fopen(fname->strval, "rb")) == NULL)
				error(28);
			m = IMODE;
			break;
		case 'r':
		case 'R':
			if ((f = fopen(fname->strval, "ab")) == NULL)
				error(28);
			m = RMODE;
			break;
		default:
			printf("file mode %s\n", mode->strval);
			error(29);
	}
	_chanwr = _chanrd = _fdtable[_chann].fd = f;
	_fdtable[_chann].fname = fname->strval;
	_fdtable[_chann].reclength = reclen;
	_fdtable[_chann].mode = m;
#ifdef DEBUG
	printf("file descr %d\n", f);
#endif
}

int _ioeof(int channel)
{
	FILE* fd;
	char c;
	if (channel < 0 || channel > 15)
		error(3);
	fd = _fdtable[channel].fd;
	if (fd == 0)
		error(3);
	c = fgetc(fd);
	if (feof(_fdtable[channel].fd))
		return (-1);
	ungetc(c, fd);
	return (0);
}

void _closeall(void)
{
	/* close all open files */
	int i;
	for (i = 1; i < 16; i++)
		if (_fdtable[i].fd)
			_clochn(i);
}