/*
  Name:    arg.c
  Purpose: provides support for processing command-line arguments
  Author:  Bill Slough
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "util.h"
#include "arg.h"

/* Process the arguments from a given command line, checking for errors,
   summarizing the results in an args_t structure */
void process_args(int argc, char *argv[ ], struct args_t *argument) {
    int opt;
    int nr_non_options;
    int countFlag;
    int repeatedFlag;
    int notRepeatedFlag;

    /* initializations... */
    countFlag = 0;
    repeatedFlag = 0;
    notRepeatedFlag = 0;
    
    opterr = 0;    /* we are responsible for error diagnostics */
    while ((opt = getopt (argc, argv, "cdu")) != -1)
        switch (opt) {
        case 'c':
            countFlag = 1;
            break;
        case 'd':
            repeatedFlag = 1;
            break;
        case 'u':
            notRepeatedFlag = 1;
            break;
        case '?':    
            fprintf (stderr, "%s: illegal option `-%c'.\n", argv[0], optopt);
            display_usage(argv[0]);
        default:
            abort();
        }
    /* Was just one option provided? */
    if (countFlag + repeatedFlag + notRepeatedFlag > 1) {
        fprintf(stderr, "%s: conflicting options\n", argv[0]);
        display_usage(argv[0]);
    }

    /* set the appropriate option */
    if (countFlag == 1)
        argument->option = 'c';
    else if (repeatedFlag == 1)
        argument->option = 'd';
    else if (notRepeatedFlag == 1)
        argument->option = 'u';
    else
        argument->option = 'n';

    /* how many non-options appear on the command line? */
    nr_non_options = argc - optind;
    if (nr_non_options == 0)
        /* none: no input file name was given */
        argument->inputFile = NULL;
    else if (nr_non_options == 1) {
        /* one: presumably, the name of an input file */
        argument->inputFile = (char *) safe_malloc(strlen(argv[optind]) + 1);
        strcpy(argument->inputFile, argv[optind]);
    }
    else {
        /* two or more: violates the syntax for pmuniq */
        fprintf(stderr, "%s: too many arguments\n", argv[0]);
        display_usage(argv[0]);
    }
}

/* Tell the user how to use this program */
void display_usage(char *pname) {
    fprintf(stderr, "usage: %s [-c | -d | -u] [input]\n", pname);
    exit(EXIT_FAILURE);
}