/*
Program: UNIQ.C
Author : Kim Moser
Date   : 4/16/89
System : IBM PC / Borland Turbo-C 2.0
Descrip: Reads lines from stdin, copies unique lines (i.e. those with no
	 identical adjacent counterpart) to stdout.

Usage  : UNIQ [-switches]

	 SWITCH  MEANING
	      u  print unique lines
	      d  print lines that are duplicated (i.e. not unique)
*/

#include <stdio.h>
#include <string.h>

int MSG=1, WARN=1;

void credits(void)
{
	static int yet=0;

	if (!yet++ && MSG)
		fprintf( stderr, "UNIQ  v1.0 (4/16/89)  Copyright (c) Kim Moser  All Rights Reserved\n" );
}

void usage(void)
{
	if (!MSG) return;
	fprintf( stderr, "  Reads stdin, prints either unique lines (i.e. those without an identical\n" );
	fprintf( stderr, "  adjacent counterpart), or lines with duplicates (i.e. with an identical\n" );
	fprintf( stderr, "  adjacent counterpart), depending on switch.  Assumes no line > 512 chars.\n\n" );
	fprintf( stderr, "  SWITCH  MEANING\n" );
	fprintf( stderr, "       u  print unique lines (default)\n" );
	fprintf( stderr, "       d  print duplicate lines\n" );
	fprintf( stderr, "       M  suppress messages\n" );
	fprintf( stderr, "       W  suppress warnings\n" );
}

int getline(s)
/* Reads stdin into string 's', until '\n' or EOF encountered.
   Returns 0 if first char read was EOF, otherwise returns 1. */
char *s;
{
	int c;
	int i=0;

	while ((c=getchar())!=EOF && (c!='\n'))
		s[i++]=c;
	s[i]=0;  /* Terminate string */
	return !((c==EOF)&&(i==0));
}

void main(argc,argv)
int argc;
char **argv;
{
	int DUPE=0, UNIQUE=1;
	char line[512]={0}, prev[512]={0};
	int count=0;  /* How many lines read */
	int i;
	int isdiff=1;  /* Whether line differes from prev line */
	int wasdiff=1; /* Whether prev line differed from line before it */

	if (argc==2) {
		if (argv[1][0]=='-') {
			UNIQUE=0;
			for (i=1; argv[1][i]; i++) {
				switch(argv[1][i]) {
					case 'd':  /* Print dupes */
						DUPE=1;
						break;
					case 'u':  /* Print unique lines */
						UNIQUE=1;
						break;
					case 'M':  /* Suppress msgs */
						MSG=0;
						break;
					case 'W':  /* Suppress warnings */
						WARN=0;
						break;
					default:
						usage();
				}
			}
		}
	}

	if (!UNIQUE && !DUPE)
		usage();

	credits();
	if (MSG) {
		if (UNIQUE)
			fprintf( stderr, "Display unique lines\n" );
		if (DUPE)
			fprintf( stderr, "Display duplicate lines\n" );
	}

	while(getline(line)) {
		if (count++) {
			if (isdiff=strcmp(line,prev)) { /* It's different from prev line */
				if (DUPE && !wasdiff)
					printf( "%s\n", prev );
				if (UNIQUE && wasdiff)
					printf( "%s\n", prev );
			}

			wasdiff=isdiff;
		}
		strcpy(prev,line);
	}

	/* Only 1 line read (it can't be anything but unique), or
	   just last line: */
	if (((count==1)&&(UNIQUE)) || (!isdiff&&DUPE) || (isdiff&&UNIQUE))
		printf( "%s\n", line);

	if (MSG)
		fprintf( stderr, "\n%d lines read.\n", count );
}