/* hist.c - display histogram of letters in input
 * Andrew Ho (andrew@zeuscat.com)
 *
 * Displays a human readable histogram of the distribution of letters
 * in the input text. Letters are normalized to lowercase. If no filename
 * is specified, tries to read /usr/dict/words.
 *
 * Build: gcc -lm -o hist hist.c
 * Usage: hist [filename]
 */

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <math.h>

#define BUFSIZE 1024
#define COLUMNS 80
#define LETTERS 26

int main(int argc, char **argv) {
    FILE *fh;
    char buf[BUFSIZE], *fmt;
    int max, b, i, j;
    int hist[LETTERS];

    for(i = 0; i < LETTERS; i++) hist[i] = 0;

    if(argc > 1) {
        fh = fopen(argv[1], "r");
    } else {
        fprintf(stderr, "hist: opening default /usr/dict/words file\n");
        fh = fopen("/usr/dict/words", "r");
    }
    if(!fh) {
        perror("hist: could not open input");
        return 1;
    }
    while( (b = fread(buf, sizeof(char), BUFSIZE, fh)) )
        for(i = 0; i < b; i++)
            if(isalpha((unsigned char)buf[i])) hist[tolower(buf[i]) - 'a']++;
    fclose(fh);

    max = 0;
    for(i = 0; i < LETTERS; i++)
        if(max < hist[i]) max = hist[i];

    fmt = (char *)malloc(COLUMNS * sizeof(char));
    sprintf(fmt, "%%c %%%dd ", (int)(log(max) / log(10)) + 1);

    for(i = 0; i < LETTERS; i++) {
        fprintf(stdout, fmt, i + 'a', hist[i]);
        for(j = 0; j < hist[i] * (int)(COLUMNS * 0.8) / max; j++)
            fputs("*", stdout);
        fputs("\n", stdout);
    }

    return 0;
}