/*
 * 86Box    A hypervisor and IBM PC system emulator that specializes in
 *          running old operating systems and software designed for IBM
 *          PC systems and compatibles from 1981 through fairly recent
 *          system designs based on the PCI bus.
 *
 *          This file is part of the 86Box distribution.
 *
 *          Implementation POSIX OpenDir(3) and friends for Win32 API.
 *
 *          Based on old original code @(#)dir_win32.c 1.2.0 2007/04/19
 *
 * Authors: Fred N. van Kempen, <decwiz@yahoo.com>
 *
 *          Copyright 1998-2007 MicroWalt Corporation
 *          Copyright 2017 Fred N. van Kempen
 *          Copyright 2021-2023 Jasmine Iwanek.
 */
#include <io.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <wchar.h>
#include <86box/86box.h>
#include <86box/plat.h>
#include <86box/plat_dir.h>

#define SUFFIX    "\\*"
#define FINDATA   struct _finddata_t
#define FINDFIRST _findfirst
#define FINDNEXT  _findnext

/* Open a directory. */
DIR *
opendir(const char *name)
{
    DIR *p;

    /* Create a new control structure. */
    p = (DIR *) calloc(1, sizeof(DIR));
    if (p == NULL)
        return (NULL);
    p->flags  = (DIR_F_LOWER | DIR_F_SANE);
    p->offset = 0;
    p->sts    = 0;

    /* Create a work area. */
    p->dta = (char *) calloc(1, sizeof(FINDATA));
    if (p->dta == NULL) {
        free(p);
        return (NULL);
    }

    /* Add search filespec. */
    strcpy(p->dir, name);
    strcat(p->dir, SUFFIX);

    /* Special case: flag if we are in the root directory. */
    if (strlen(p->dir) == 3)
        p->flags |= DIR_F_ISROOT;

    /* Start the searching by doing a FindFirst. */
    p->handle = FINDFIRST(p->dir, (FINDATA *) p->dta);
    if (p->handle < 0L) {
        free(p->dta);
        free(p);
        return (NULL);
    }

    /* All OK. */
    return p;
}

/* Close an open directory. */
int
closedir(DIR *p)
{
    if (p == NULL)
        return 0;

    _findclose(p->handle);

    if (p->dta != NULL)
        free(p->dta);
    free(p);

    return 0;
}

/*
 * Read the next entry from a directory.
 * Note that the DOS (FAT), Windows (FAT, FAT32) and Windows NTFS
 * file systems do not have a root directory containing the UNIX-
 * standard "." and ".." entries.  Many applications do assume
 * this anyway, so we simply fake these entries.
 */
struct dirent *
readdir(DIR *p)
{
    FINDATA *ffp;

    if (p == NULL || p->sts == 1)
        return (NULL);

    /* Format structure with current data. */
    ffp           = (FINDATA *) p->dta;
    p->dent.d_ino = 1L;
    p->dent.d_off = p->offset++;
    switch (p->offset) {
        case 1: /* . */
            strncpy(p->dent.d_name, ".", MAXNAMLEN + 1);
            p->dent.d_reclen = 1;
            break;

        case 2: /* .. */
            strncpy(p->dent.d_name, "..", MAXNAMLEN + 1);
            p->dent.d_reclen = 2;
            break;

        default: /* regular entry. */
            strncpy(p->dent.d_name, ffp->name, MAXNAMLEN + 1);
            p->dent.d_reclen = (char) strlen(p->dent.d_name);
    }

    /* Read next entry. */
    p->sts = 0;

    /* Fake the "." and ".." entries here.. */
    if ((p->flags & DIR_F_ISROOT) && (p->offset <= 2))
        return (&(p->dent));

    /* Get the next entry if we did not fake the above. */
    if (FINDNEXT(p->handle, ffp) < 0)
        p->sts = 1;

    return (&(p->dent));
}

/* Report current position within the directory. */
long
telldir(DIR *p)
{
    return (p->offset);
}

void
seekdir(DIR *p, long newpos)
{
    short pos;

    /* First off, rewind to start of directory. */
    p->handle = FINDFIRST(p->dir, (FINDATA *) p->dta);
    if (p->handle < 0L) {
        p->sts = 1;
        return;
    }
    p->offset = 0;
    p->sts    = 0;

    /* If we are rewinding, that's all... */
    if (newpos == 0L)
        return;

    /* Nope.. read entries until we hit the right spot. */
    pos = (short) newpos;
    while (p->offset != pos) {
        p->offset++;
        if (FINDNEXT(p->handle, (FINDATA *) p->dta) < 0) {
            p->sts = 1;
            return;
        }
    }
}
