/* fastopen.c -- Copyright 1996 Liam R. E. Quin.
 * All Rights Reserved.
 * This code is NOT in the public domain.
 * See the file COPYRIGHT for full details.
 */

/* fastopen --
 * read filenames and byte offsets on stdin, and
 * open the files, and read up to the byte offsets.
 *
 * input is
 * open _n_ _filename_
 * seek _n_ _position_
 * close _n_
 * requests may be interleaved, up to a max of 100.
 *
 * The program is intended to be run in the backgrund by lqaddfile, and hence
 * does not gnerally produce diagnostics unless called with the -d option.
 *
 * Format errors, attempts to close a file not opened, or to re-use an _n_
 * without closing it first are all fatal errors that are reported.
 *
 * $Id: fastopen.c,v 1.1 1996/08/14 17:02:12 lee Exp $
 */

static char *Version =
    "@(#) $Id: fastopen.c,v 1.1 1996/08/14 17:02:12 lee Exp $";

#include "globals.h" /* defines and declarations for database filenames */
#include "error.h"

#include <stdlib.h>

#include <stdio.h>
#include <ctype.h>

#include <sys/types.h>
#include <sys/stat.h>

#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif

#include <malloc.h>

#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#endif

#include "fileinfo.h"
#include "wordinfo.h"
#include "wordrules.h"
#include "emalloc.h"
#include "addfile.h"
#include "lqutil.h"
#include "liblqtext.h"
#include "filter.h"
#include "lqtrace.h"
#include "revision.h"

typedef struct {
    int n; /* -1 if not opened */
    int fd;
    long pos;
} t_oneFile;

#define MAXFILES 100
t_oneFile Files[MAXFILES];
int nFiles = 0;

static int
FindMe(n)
    int n;
{
    register int i;

    for (i = 0; i < nFiles; i++) {
	if (Files[i].n == n) {
	    return i;
	}
    }
    return -1;
}

int
main(argc, argv)
    int argc;
    char *argv[];
{
    char linebuffer[2000];
    int OK;
    t_LQTEXT_Database *db;
    t_lqdbOptions *Options;

    Options = LQT_InitFromArgv(argc, argv);

    db = LQT_OpenDatabase(Options, O_RDONLY, 0);
    if (!db) {
	Error(E_FATAL, "failed to open database.");
    }

    {
	int i;

	for (i = 0; i < nFiles; i++) {
	    Files[i].n = Files[i].fd = -1;
	}
    }

    while (fgets(linebuffer, sizeof(linebuffer), stdin) != (char *) NULL) {
	char *p;

	LQT_Trace(LQTRACE_DEBUG, "Line: %s", linebuffer);

	for (p = linebuffer; *p; p++) {
	    if (*p == '\n') {
		*p = '\0';
		break;
	    }
	}

	OK = 0; /* default = bad */

	switch (linebuffer[0]) {
	case 'o':
	    if (strncmp(linebuffer, "open ", 5) == 0) {
		OK = 1;
		if (nFiles == MAXFILES) {
		    fprintf(stderr, "%s: %d files already open\n", progname, nFiles);
		    exit(1);
		} else {
		    int n;

		    n = 0;
		    for (p = &linebuffer[5]; *p; p++) {
			if (!isdigit(*p)) {
			    break;
			}
			n *= 10;
			n += *p - '0';
		    }

		    if (*p != ' ' || !*++p) {
			OK = 0;
			fprintf(stderr, "%s: missing filename?\n", progname);
			break;
		    }

		    if (FindMe(n) != -1) {
			fprintf(stderr, "%s: %d already open!\n",
			    progname, n
			);
			exit(1);
		    }

		    /* p points to the start of the filename */
		    p = LQT_FindFile(db, p);
		    if (!p) {
			if (LQT_TraceFlagsSet(LQTRACE_VERBOSE|LQTRACE_DEBUG)) {
			    Error(E_WARN|E_SYS, "FindFile returned null...");
			}
			OK = 0;
			break;
		    }

		    Files[nFiles].fd = open(p, O_RDONLY, 0644);
		    if (Files[nFiles].fd < 0) {
			if (LQT_TraceFlagsSet(LQTRACE_VERBOSE|LQTRACE_DEBUG)) {
			    perror(p);
			    fprintf(stderr, "%s: failed to open %s\n",
				progname, p
			    );
			}
			OK = 0;
			break;
		    }

		    Files[nFiles].n = n;
		    Files[nFiles].pos = 0L;

		    /* read a single byte */
		    (void) read(Files[nFiles].fd, linebuffer, 1);

		    LQT_Trace(LQTRACE_DEBUG, "%s: OPEN %d -> %d, %s",
			progname, n, Files[nFiles].fd, p
		    );
		    nFiles++;

		} /* else */
	    }
	    break;
	case 's':
	    if (strncmp(linebuffer, "seek ", 5) == 0) {
		fprintf(stderr, "%s: unimplemented: %s\n",
		    progname, linebuffer
		);
		OK = 1;
	    }
	    break;
	case 'c':
	    OK = 0;
	    if (strncmp(linebuffer, "close ", 6) == 0) {
		int n;

		n = 0;
		for (p = &linebuffer[6]; *p; p++) {
		    if (!isdigit(*p)) {
			break;
		    }
		    n *= 10;
		    n += *p - '0';
		}

		if (*p) {
		    fprintf(stderr, "%s: close: usage: close number \\n\n",
			progname
		    );
		    break;
		} else {
		    int Me;

		    Me = FindMe(n);
		    if (Me < 0) {
			fprintf(stderr, "%s: %d not open\n", progname, n);
			break;
		    } else {
			int j;

			LQT_Trace(LQTRACE_DEBUG, "%s: CLOSE %d\n",
			    progname, n
			);

			(void) close(Files[Me].fd);

			/* move down */
			for (j = Me + 1; j < nFiles; j++, Me++) {
			    Files[Me] = Files[j];
			}
			nFiles--;
			OK = 1;
			break;
		    }
		}
	    }
	    break;
	default:
	    fprintf(stderr, "%s: unrecognised command...\n", progname);
	    OK = 0;
	}

	if (!OK) {
	    fprintf(stderr, "%s: bad input: %s", progname, linebuffer);
	}
    }
    return 0;
}