/*
 * \- prepend dated input to file specified by option
 * usage: %note  [-f filename, -c "date_string", -n, -s]
 * prepend input to file specified by option or parm, 
 * with date heading each line
 * -c preprends to calendar, -n to notes, -s to shop, and 
 * -f to filename in $home or $home/memos
 * -n is default
 * j.a. rupley, tucson, arizona
 *
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

char	usage[2000] = 
	{
"\n\
usage:  note  [ {-f filename, -c \"date_string\", -n, -s} ]\n\
\n\
        no argument implies -n\n\
        {-c, -n, -s} imply files {calendar, notes, shop}\n\
\n\
        the target file is looked for in $HOME/memos, and if not found,\n\
        the file is created there (except, $HOME is the calendar directory);\n\
\n\
       	text input is by line, with a date string heading each line;\n\
	input is terminated with ^D = EOF\n\
	input is first to a temporary file;\n\
	at the end of input, the target file is copied to target.bak, \n\
	and the temporary is preprepended to the target\n\
\n\
        \"date_string\" for -c option:\n\n\
        {now | weekday | month day[, year] | mm/dd[/yy[yy]] | \n\
	    {month|mm} number weekday } \n\
	        [ +-number  { {d | w | m | y} | weekday } [....] ]\n\
"
	};


int
main(argc, argv)
int argc;
char **argv;
{
	extern char    *strcat();
	extern char    *strcpy();
	extern void	exit();
	extern void	perror();
	extern char    *optarg;
	extern int      optind, opterr;
	extern int      getopt();
	extern int	getpid();
	extern FILE	*fopen();
	extern char	*fgets();
	extern char	*mktemp();
	extern char	*getenv();
	extern char	*getdate();
	
	FILE	*fptrtemp;
	FILE	*fptrfname;
	char	*datestring;
	char	*homestring;
	char	*tempfile;
	char	tempbuf[80];
	char	*fname;
	char	fnamebuf[80];
	char	fnamebak[80];
	char	linebuf[200];
	int	c;

	fname = "notes";
	/* notes is the default file */
	/* add more options = hard-wired note files, to your heart's content */
	while ((c = getopt(argc, argv, "?zenscf:")) != EOF) {
		switch (c) {
		case 'n':
			fname = "notes";
			break;
		case 's':
			fname = "shop";
			break;
		case 'c':
			fname = "calendar";
			break;
		case 'f':
			fname = optarg;
			break;
		case '?':
		case 'z':
			fprintf(stderr, "%s", usage);
			exit(-1);
		}
	}

	/* set up file pathnames (in ~/memos, except calendar in ~) */
	if ((homestring = getenv("HOME")) == NULL) {
		perror("Cannot get HOME from environment");
		exit (1);
	} else {
		if (strcmp(fname, "calendar")) {
			sprintf(fnamebuf, "%s/memos/%s", homestring, fname);
			fname = &fnamebuf[0];
		} else {
			sprintf(fnamebuf, "%s/%s", homestring, fname);
			fname = &fnamebuf[0];
		}
		sprintf(tempbuf, "%s/tmp/noteXXXXXX",homestring);
	}

	/* get date string = today's date for -n, -s, and -f options */
	/* and for -c, a calculated date based on the arguments */
	/* remaining after optarg processing */
	if ((datestring = getdate(0, optind, argc, argv)) == NULL) {
		perror("No datestring returned");
		exit (1);
	}

	/* open the temporary file; write dated input line by line into it */
	if ((tempfile = mktemp(tempbuf)) == NULL) {
		(void )perror("Cannot create tempfile");
		exit (1);
	}
	if ((fptrtemp = fopen(tempfile, "w+")) == NULL) {
		(void )perror("Cannot open tempfile");
		exit (1);
	}
	if (isatty(fileno(stdin)))
		fprintf(stdout, "\n%s: ", datestring);
	while (fgets(linebuf, sizeof(linebuf), stdin) != NULL) {
		fprintf(fptrtemp, "%s: %s", datestring, linebuf);
		if (isatty(fileno(stdin)))
			fprintf(stdout, "%s: ", datestring);
	}

	/* this gives a blank line between records on the output files */
	/* comment out the next line if you do not want it */
	fputc('\n', fptrtemp);
	if (isatty(fileno(stdin)))
		fputc('\n', stdout);

	/* append old target file onto temporary */
	/* and if successful, mv old target to target.bak */
	if ((fptrfname = fopen(fname, "r")) == NULL) {
		perror("Warning: cannot open old target file");
	} else {
		while (fgets(linebuf, sizeof(linebuf), fptrfname) != NULL) {
			if (fputs(linebuf, fptrtemp) == -1) {
				perror("Fatal: cannot append old target file to tempfile");
				exit (1);
			}
		}
		fclose(fptrfname);
		strcpy(fnamebak, fname);
		strcat(fnamebak, ".bak");
		if (unlink(fnamebak) == -1) {
			perror("Warning: cannot unlink old backup file ");
		}
		if (link(fname, fnamebak) == -1) {
			perror("Fatal: cannot link old target file to backup file");
			exit (1);
		}
	}

	/* mv new temporary file = new information prepended to old target */
	/* to old target */
	fclose(fptrtemp);
	if (unlink(fname) == -1) {
		perror("Warning: cannot unlink old target file");
	}
	if (link(tempfile, fname) == -1) {
		perror("Fatal: cannot link tempfile to target file");
		exit (1);
	}
	unlink(tempfile);

	return (0);
}