/*
  Name:    pmuniq.c
  Purpose: Acts somewhat like the Unix "uniq" command
  Author:  Bill Slough
*/

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

struct args_t programArgs;

void output(char type, int count, char *s);

int main(int argc, char *argv[ ]) {
    FILE *fp;           /* file pointer for an input stream */
    char *previous;     /* previous line of input */
    char *current;      /* current line of input */
    int count;          /* number of times the previous line has appeared */

    /* process the command-line arguments */
    process_args(argc, argv, &programArgs);

    /* Try to open the input stream for reading */
    if (programArgs.inputFile == NULL)
        fp = stdin;
    else {
        fp = fopen(programArgs.inputFile, "r");
        if (fp == NULL) {
            fprintf(stderr,
                    "%s: %s: no such file\n",
                    argv[0], programArgs.inputFile);
            exit(EXIT_FAILURE);
        }
    }
    
    /* read the first line, if any, of the input file */
    previous = read_line(fp);
    count = 1;
    if (previous == NULL) {
        /* empty file: close the stream and exit */
        fclose(fp);
        return 0;
    }

    /* non-empty file: read all remaining lines */
    while ((current = read_line(fp)) != NULL) {
        if (strcmp(previous, current) == 0) {
            /* extends an existing run... */
            count++;
            free(current);
        }
        else {
            /* this line begins a new run */
            output(programArgs.option, count, previous);
            free(previous);
            previous = current;
            count = 1;
        }
    }
    output(programArgs.option, count, previous);
    free(previous);

    /* Close the stream */
    fclose(fp);
    return 0;
}

void output(char type, int count, char *s) {
    switch (type) {
    case 'n':
        printf("%s\n", s);             /* all unique lines, without frequency */
        break;
    case 'c':
        printf("%d %s\n", count, s);   /* all unique lines, with frequency */
        break;
    case 'd':
        if (count > 1)                 /* only repeated lines */
            printf("%s\n", s);
        break;  
    case 'u':
        if (count == 1) {              /* only non-repeated lines */
            printf("%s\n", s);
            break;
        }
    }
}