//
// dod -- show most recent files in current directory.
//
// - optional -N argument (default 10) to set the number of files displayed
// - optional filename wildcard expression to limit types of files
// - dod is short for "dir /od | tail"
//
// 20-Jan-2006 Tom Van Baak (tvb) www.LeapSecond.com/tools
//

#include <direct.h>
#include <io.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

// Sort files by modification time.

int fd_cmp (const struct _finddata_t **ap, const struct _finddata_t **bp)
{
    time_t a = (*ap)->time_write;
    time_t b = (*bp)->time_write;
    return a < b ? -1 : a > b ? 1 : 0;
}

void main (int argc, char *argv[])
{
    long fh, files, files_max, i, tail, start;
    struct _finddata_t **list, fd;
    char *pattern;

    // Get optional file count.

    tail = 10;
    if (argc > 1 && argv[1][0] == '-') {
        tail = atoi(&argv[1][1]);
        argc -= 1;
        argv += 1;
    }

    // Get optional filename pattern.

    pattern = (argc > 1) ? argv[1] : "*";

    // Read all file names in directory and sort by mod time.

    if ((fh = _findfirst(pattern, &fd)) == -1) {
        fprintf(stderr, "no files matching \"%s\"\n", pattern);
        exit(1);
    }
    files_max = 100;
    if (NULL == (list = malloc(files_max * sizeof list[0]))) {
        fprintf(stderr, "malloc failed\n");
        exit(1);
    }
    files = 0;
    do {
        if ((fd.attrib & _A_SUBDIR) == 0) {
            if (files == files_max) {
                files_max *= 2;
                if (NULL == (list = realloc(list, files_max * sizeof list[0]))) {
                    fprintf(stderr, "malloc failed\n");
                    exit(1);
                }
            }
            if (NULL == (list[files] = malloc(sizeof fd))) {
                fprintf(stderr, "malloc failed\n");
                exit(1);
            }
            memcpy(list[files], &fd, sizeof fd);
            files += 1;
        }
    } while (_findnext(fh, &fd) != -1);

    _findclose(fh);
    qsort(list, files, sizeof list[0], fd_cmp);

    // Display most recent files in directory.

    start = (tail <= 0 || tail > files) ? 0 : (files - tail);
    for (i = start; i < files; i += 1) {
        char *decimal (unsigned long n);
        struct tm *tm;

        if (NULL == (tm = localtime(&list[i]->time_write))) {
            static struct tm tm0 = { 0, 0, 0, 0, -1, -1900 };
            tm = &tm0;
        }
        printf("%.4d-%.2d-%.2d %.2d:%.2d:%.2d %13s %s\n",
               tm->tm_year + 1900,
               tm->tm_mon + 1,
               tm->tm_mday,
               tm->tm_hour,
               tm->tm_min,
               tm->tm_sec,
               decimal(list[i]->size),
               list[i]->name);
    }
}

// Format decimal numbers with thousands separators.

char *decimal (unsigned long n)
{
    unsigned long base, E3 = 1000;
    static char s[100];

    for (base = E3 * E3 * E3; n < base && base > 1; base /= E3) {}
    sprintf(s, "%ld", n / base);
    while (base > 1) {
        n %= base;
        base /= E3;
        sprintf(s + strlen(s), ",%.3ld", n / base);
    }
    return s; // WARNING: static
}