// Setting _DEFAULT_SOURCE is necessary to activate visibility of
// certain header file contents on GNU/Linux systems.
#define _DEFAULT_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <stdint.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fts.h>

// err.h contains various nonstandard BSD extensions, but they are
// very handy.
#include <err.h>

#include "histogram.h"

int global_histogram[8] = { 0 };

int fhistogram(char const *path) {
    FILE *f = fopen(path, "r");

    int local_histogram[8] = { 0 };

    if (f == NULL) {
        fflush(stdout);
        warn("failed to open %s", path);
        return -1;
    }

    int i = 0;

    char c;
    while (fread(&c, sizeof(c), 1, f) == 1) {
        i++;
        update_histogram(local_histogram, c);
        if ((i % 100000) == 0) {
            merge_histogram(local_histogram, global_histogram);
            print_histogram(global_histogram);
        }
    }

    fclose(f);

    merge_histogram(local_histogram, global_histogram);
    print_histogram(global_histogram);

    return 0;
}

int main(int argc, char * const *argv) {
    if (argc < 2) {
        err(1, "usage: paths...");
        exit(1);
    }

    char * const *paths = &argv[1];

    // FTS_LOGICAL = follow symbolic links
    // FTS_NOCHDIR = do not change the working directory of the process
    //
    // (These are not particularly important distinctions for our simple
    // uses.)
    int fts_options = FTS_LOGICAL | FTS_NOCHDIR;

    FTS *ftsp;
    if ((ftsp = fts_open(paths, fts_options, NULL)) == NULL) {
        err(1, "fts_open() failed");
        return -1;
    }

    FTSENT *p;
    while ((p = fts_read(ftsp)) != NULL) {
        switch (p->fts_info) {
        case FTS_D:
            break;
        case FTS_F:
            fhistogram(p->fts_path);
            break;
        default:
            break;
        }
    }

    fts_close(ftsp);

    move_lines(9);

    return 0;
}