/* mdfrm.c -- mdfrm(1) for maildir.
 *
 * $Id$
 *
 * This program is in the public domain.
 */

#include <sys/types.h>

#include <ctype.h>
#include <dirent.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

/* Note that PATH_MAX is supposed to include the terminating null. */
#ifndef PATH_MAX
#ifndef MAXPATHLEN
#define PATH_MAX 65
#else
#define PATH_MAX MAXPATHLEN
#endif
#endif

enum {
    FROMLEN = 5,                /* "From:" */
    SUBJLEN = 8,                /* "Subject:" */

    /* Number of characters for each field we actually output.  This
     * must also be changed in the printf functions at the end of the
     * frm function.
     */
    FROMCOUNT = 24,
    SUBJCOUNT = 53
};

static char ident[] = "$Id$";

static void
err(int exitcode, char *format, ...)
{
    va_list ap;

    va_start(ap, format);
    vfprintf(stderr, format, ap);
    va_end(ap);

    perror(" ");

    exit(exitcode);
}

static void
errx(int exitcode, char *format, ...)
{
    va_list ap;

    va_start(ap, format);
    vfprintf(stderr, format, ap);
    va_end(ap);

    fputs("\n", stderr);

    exit(exitcode);
}

static void
sanitize(char *str, size_t len)
{
    int i;

    for (i = 0; i < len; i++) {
        if (isprint(str[i]) == 0) {
            str[i] = '?';
        }
    }
}

static void
scan_message(char *filename, char *fromheader, char *subjheader)
{
    FILE *file;
    char *line;
    size_t len, fromcount, subjcount;

    if (!(file = fopen(filename, "r"))) {
        err(EX_OSERR, "Failed fopen(%s)", filename);
    }

    fromcount = subjcount = 0;
    fromheader[0] = subjheader[0] = '\0';
    while ((line = fgetln(file, &len))) {
        if (len <= 1) {
            break;
        }
        --len;

        if (len > FROMLEN && strncasecmp(line, "From:", FROMLEN) == 0) {
            line += FROMLEN;
            len -= FROMLEN;
            while (len > 0 && isspace(line[0])) {
                line++;
                len--;
            }
            if (len < FROMCOUNT) {
                fromcount = len;
            } else {
                fromcount = FROMCOUNT;
            }
            strncpy(fromheader, line, fromcount);
            fromheader[fromcount] = '\0';
            sanitize(fromheader, fromcount);
        } else if (len > SUBJLEN && strncasecmp(line, "Subject:", SUBJLEN) == 0) {
            line += SUBJLEN;
            len -= SUBJLEN;
            while (len > 0 && isspace(line[0])) {
                line++;
                len--;
            }
            if (len < SUBJCOUNT) {
                subjcount = len;
            } else {
                subjcount = SUBJCOUNT;
            }
            strncpy(subjheader, line, subjcount);
            subjheader[subjcount] = '\0';
            sanitize(subjheader, subjcount);
        }
    }

    fclose(file);
}

static void
frm(char *dirname, int showfn)
{
    DIR *dir;
    struct dirent *dirent;
    char *filename;
    char fromheader[FROMCOUNT + 1] = { '\0' };
    char subjheader[SUBJCOUNT + 1] = { '\0' };

    if (chdir(dirname) != 0) {
        err(EX_OSERR, "Failed chdir(%s)", dirname);
    }

    if (chdir("new") != 0) {
        err(EX_OSERR, "Failed chdir(%s/new)", dirname);
    }

    dir = opendir(".");
    if (!dir) {
        err(EX_OSERR, "Failed opendir(%s/new)", dirname);
    }

    for (dirent = readdir(dir); dirent; dirent = readdir(dir)) {
        filename = dirent->d_name;
        if (filename[0] == '.') {
            continue;
        }

        scan_message(filename, fromheader, subjheader);

        if (showfn) {
            printf("%s  ", filename);
        }
        printf("%-24s  ", fromheader);
        printf("%s\n", subjheader);
    }
}

int
main(int argc, char *argv[])
{
    char *dirname;
    char buf[PATH_MAX];
    int showfn = 0;

    if (argv[1] && argv[1][0] == '-' && argv[1][1] == 'v') {
        puts(ident);
        return 0;
    }

    if (argv[1] && argv[1][0] == '-' && argv[1][1] == 'f') {
        showfn = 1;
        argv++;
    }

    if (!(dirname = argv[1])) {
        if (!(dirname = getenv("MAILDIR"))) {
            if (!(dirname = getenv("HOME"))) {
                errx(EX_UNAVAILABLE, "Could not find maildir.");
            } else {
                snprintf(buf, PATH_MAX, "%s/Maildir", dirname);
                dirname = buf;
            }
        }
    }

    frm(dirname, showfn);

    return 0;
}