#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>

#include <getopt.h>

#define	OPTLIST		"clLw"

//  TRACK WHICH THINGS WE SHOULD DISPLAY.
bool	display_bytes	= false;
bool	display_lines	= false;
bool	display_words	= false;
bool	display_longest	= false;

//  THINGS WE SHOULD COUNT
typedef struct {
    int		bytes;
    int		lines;
    int		longest;
    int		words;
} COUNTS;

// ------------------------------------------------------------------------

void report_counts(COUNTS what, char *filename)
{
//  JUST DISPLAY THE REQUESTED COUNTS
    if(display_lines) {
	printf("%8d", what.lines);
    }
    if(display_words) {
	printf("%8d", what.words);
    }
    if(display_bytes) {
	printf("%8d", what.bytes);
    }
    if(display_longest) {
	printf("%8d", what.longest);
    }
//  ONLY DISPLAY THE FILENAME IF IT'S NOT NULL
    if(filename != NULL) {
	printf("\t\t%s", filename);
    }
    printf("\n");
}

void counter(FILE *fp, char *filename, COUNTS *totals)
{
    COUNTS	this	= { 0, 0, 0, 0 };
    char	line[BUFSIZ];

//  FOREACH LINE READ FROM THE FILE-POINTER....
    while( fgets(line, sizeof line, fp) != NULL) {
	int	len		= 0;
	bool	inside_word	= false;
	char	*s		= line;

	++this.lines;
//  UNTIL WE HAVE REACHED THE END OF THIS LINE....
	while(*s) {
	    ++this.bytes;

//  FOR THE LONGEST LINE, TABS ARE EXPANDED TO A MULTIPLE OF 8 SPACES
	    if(*s == '\t') {
		len	= (len+8) / 8 * 8;
	    }
	    else if(*s != '\n') {
		++len;
	    }

//  KEP TRACK OF WHETHER WE'RE INSIDE A WORD, OR NOT
	    if(inside_word && isspace(*s)) {
		inside_word	= false;
	    }
	    else if(!inside_word && !isspace(*s)) {
		++this.words;
		inside_word	= true;
	    }
//  'WALK' ALONG THE LINE
	    ++s;
	}

//  SEE IF WE'VE FOUND A NEW LONGEST LINE
	if(this.longest < len) {
	    this.longest	= len;
	}
    }
    report_counts(this, filename);

//  UPDATE OUR GLOBAL TOTALS AND LONGEST LINE
    totals->bytes		+= this.bytes;
    totals->lines		+= this.lines;
    totals->words		+= this.words;
    if(totals->longest < this.longest)
	totals->longest	= this.longest;
}

// ------------------------------------------------------------------------

//  PROVIDE A 'USAGE' MESSAGE IF AN INVALID SWITCH PROVIDED
void usage(char *argv0)
{
    fprintf(stderr, "Usage: %s [-clLw] [file ...]\n", argv0);
    exit(EXIT_FAILURE);
}

int main(int argc, char *argv[])
{
    COUNTS	totals	= { 0, 0, 0, 0 };
    int		opt;

//  DETERMINE WHICH, IF ANY, COMMAND-LINE SWITCHES WERE PROVIDED
    while( (opt = getopt(argc, argv, OPTLIST)) != -1) {
	switch (opt) {
	case 'c' :	display_bytes	= true;
			break;

	case 'l' :	display_lines	= true;
			break;

	case 'L' :	display_longest	= true;
			break;

	case 'w' :	display_words	= true;
			break;

//  PROVIDE A 'USAGE' MESSAGE IF AN INVALID SWITCH PROVIDED
	default :	usage(argv[0]);
			break;
	}
    }

//  IF NO OPTIONS PROVIDED, USE THESE DEFAULTS:
    if(display_bytes == false && display_words == false &&
       display_lines == false && display_longest == false) {
	display_bytes = true;
	display_lines = true;
	display_words = true;
    }

//  IF NO ARGUMENTS PROVIDED, READ FROM stdin (e.g. KEYBOARD, PIPE, REDIRECTION)
    if(optind == argc) {
         counter(stdin, NULL, &totals);
    }

    else {
//  ARGUMENTS PROVIDED, ITERATE OVER EACH TREATING IT AS A FILENAME
        for(int a=optind ; a<argc ; ++a) {

//  ATTEMPT TO OPEN EACH FILENAME
            FILE *fp = fopen(argv[a], "r");

//  REPORT AN ERROR IF OPENING FAILS
            if(fp == NULL) {
                fprintf(stderr, "Cannot open %s\n", argv[a]);
                exit(EXIT_FAILURE);
            }
//  FILE OPENED, COUNT ITS CONTENTS
            counter(fp, argv[a], &totals);
	    fclose(fp);
        }

//  IF WE HAVE MORE THAN ONE FILE, REPORT THE TOTALS
	if(argc > optind)
	    report_counts(totals, "total");
    }

    exit(EXIT_SUCCESS);
    return 0;
}