/* Program kcd.c
**
** Change Directory for 4DOS
**
** Original code by: ?
**
** Modified and corrected by S. E. Kohn
**
** Requires 4DOS environmental variable CDPATH be set to list of
** primary directories to search.
** Program will work for partial directory names
**
** Use 4DOS alias   cd=`<drive>:\<directory>\kcd.com`
**
*/
#include <stdio.h>
#include <stdlib.h>
#include <dos.h>
#include <direct.h>
#include <string.h>
#include <ctype.h>

#define  CDPATH  "CDPATH"
#define  MAX_DIR 66
#define  PROG    "cd"

/* ##################### IS_ROOT_DIR ######################## */
int is_root_dir (char try[])
{
    char *ptr;

    if ((ptr = strchr(try, ':')) != NULL)
        ptr++;
    else
        ptr = try;
    if (strchr("\\/", *ptr) != NULL && *(ptr+1) == '\0')
        return 1;
    if (strchr("\\/", *ptr) != NULL && *(ptr+1) == '.' && *(ptr+2) == '\0')
        return 1;
    return 0;
}

/* ####################### ISDIR ##################### */
int isdir (char try[])
{
    struct find_t find;
    char *ptr, test[MAX_DIR];

    if (is_root_dir(try))
        return 1;
    if ((_dos_findfirst(try, 0xffff, &find) == 0) && (find.attrib & _A_SUBDIR))
         return 1;
    strcpy(test, try);
    strcat(test, "*");
    if (_dos_findfirst(test, 0xffff, &find) == 0)
    {
        if (find.attrib & _A_SUBDIR)
        {
            ptr = strrchr(try, '\\');
            if (ptr != (char *)NULL)
                strcpy(++ptr, find.name);
            else
                strcpy(try, find.name);
            return 1;
        }
        while (_dos_findnext(&find) == 0)
        {
            if (find.attrib & _A_SUBDIR)
            {
                ptr = strrchr(try, '\\');
                if (ptr != (char *)NULL)
                    strcpy(++ptr, find.name);
                else
                    strcpy(try, find.name);
                return 1;
            }
        }
    }
    if (try[strlen(try)-2] == ':' && try[strlen(try)-1] == '.')
    {
        try[strlen(try)-1] = '\\';
        return 1;
    }
    return 0;
}

/* ######################## ISABSOLUTEPATH ################### */
int isabsolutepath(char try[])
{
    return strchr("\\/", try[0]) != NULL ||
        (try[1] == ':' && strchr("\\/", try[2]) != NULL);
}

/* ###################### KCD ##################### */
int main (int argc, char *argv[])
{
    char *cdpath, dir[MAX_DIR], *nxt, drv='\0', *check,
            try[MAX_DIR], *ptr, root[MAX_DIR];
    unsigned orig_drive, trg_drive, tmp;
    int fnd, cdpathno = 0;

    /* get current default drive */
    _dos_getdrive (&orig_drive);
    strcpy(root, "c:\\");
    root[0] = 'a' + orig_drive - 1;

    if (argc == 1)
    {
        /* if no arguments, print current directory */
        getcwd(dir, MAX_DIR);
        strlwr(dir);
        printf("%s\n", dir);
        return 0;
    }

    strcpy (try, argv[1]);
    if (try[0] == '-')
            strcpy(dir, getenv("LASTDIR"));
    else
    {
        while ((ptr = strchr(try, '/')) != (char *)NULL) *ptr = '\\';
        if (try[strlen(try)-1] == ':')
            strcat (try, ".");
        if ((cdpath = getenv(CDPATH)) == NULL ||
            isdir(try) || isabsolutepath(try) ||
            try[0] == '.')

        /*
         * if either cdpath not defined, valid subdir given, or ".." used in
         * relative path, don't bother searching cdpath
        */
            strcpy (dir, try);
        else
        {
            strcpy (dir, ".\\");
            strcat (dir, try);

            do
            {
                root[3] = '\0';
                /*
                 * if dir given on command line is subdirectory of current directory,
                 * no need to search cdpath
                 */
                if (!isdir(dir) &&
                    ((nxt = strtok(cdpath, ";")) != NULL))
                {
                    /* if drive is part of dir, save */
                    if ((check = strchr(try, ':')) != NULL)
                    {
                        drv = *(check-1);
                        check++;
                    }
                    else
                        check = try;

                    strcat(root, try);
                    fnd = isdir(root);
                    /*
                     * search each entry in cdpath (left to right) to find first for
                     * which argv[1] is a subdirectory or until cdpath exhausted
                     */
                    do
                    {
                        if (fnd)
                        {
                            strcpy(dir, root);
                            break;
                        }
                        strcpy(dir, nxt);
                        if (dir[strlen(dir)-1] != '\\')
                            strcat(dir, "\\");
                        strcat(dir, check);
                        if(isdir(dir) &&
                            (drv == '\0' || strchr(dir, ':') == NULL
                            ||  drv == dir[0]))
                            fnd = 1;
                    }
                    while(!fnd && ((nxt = strtok(NULL, ";")) != NULL));
                }
                cdpathno++;
                if (!fnd) sprintf(cdpath, "CDPATH%d", cdpathno);
            }
            while(!fnd && ((cdpath = getenv(cdpath)) != (char *)NULL));

            /* print error if directory not found in cdpath */
            if (!fnd)
            {
                fprintf (stderr, "%s: Directory %s not found.\n", PROG, argv[1]);
                return -1;
            }
        }
    }

    /*
     * if directory ends in '\' and is NOT the root directory of a drive, strip
     * off the '\'
     */
    if((dir[strlen(dir)-1] == '\\' || dir[strlen(dir)-1] == '/') &&
        !is_root_dir(dir))
        dir[strlen(dir)-1] = '\0';

    /*
     * if drive is part of target directory and it differs from the current
     * default, set drive before performing chdir
     */
    if (strchr(dir, ':') != NULL &&
        (trg_drive = dir[0] + 1 - (isupper(dir[0]) ? 'A' : 'a')) != orig_drive)
            _dos_setdrive(trg_drive, &tmp);
    while (strncmp(dir, "...", 3) == 0)
    {
        getcwd(try, MAX_DIR);
        if (is_root_dir(try) == 0)
                chdir("..");
        strcpy(dir, dir + 1);
    }
    getcwd(try, MAX_DIR);
    if (is_root_dir(try) && (strcmp(dir, "..") == 0)) return 0;

    if (chdir(dir) != 0)
    {
        fprintf (stderr, "%s: Invalid directory %s.\n", PROG, argv[1]);
        exit (1);
    }
    return 0;
}