/*
 *      cook - file construction tool
 *      Copyright (C) 2000, 2006, 2007 Peter Miller;
 *      All rights reserved.
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to manipulate flattens
 */

#include <common/str_list.h>

#include <c_incl/flatten.h>


static void
string_list_remove_nth(string_list_ty * slp, size_t n)
{
    if (n >= slp->nstrings)
        return;
    str_free(slp->string[n]);
    slp->nstrings--;
    while (n < slp->nstrings)
    {
        slp->string[n] = slp->string[n + 1];
        ++n;
    }
}


string_ty *
flatten(string_ty *filename)
{
    string_list_ty  sl;
    static string_ty *root;
    static string_ty *dot;
    static string_ty *dotdot;
    size_t          pos;
    size_t          start;
    size_t          j;
    string_ty       *s;

    /*
     * Create some things we are going to need.
     */
    if (!root)
    {
        root = str_from_c("");
        dot = str_from_c(".");
        dotdot = str_from_c("..");
    }

    /*
     * leading slash is special
     */
    pos = 0;
    string_list_constructor(&sl);
    if (filename->str_text[0] == '/')
    {
        ++pos;
        string_list_append(&sl, root);
    }

    /*
     * Break it into slash-separaed words.
     */
    for (;;)
    {
        while (pos < filename->str_length && filename->str_text[pos] == '/')
            ++pos;
        if (pos >= filename->str_length)
            break;
        start = pos;
        for (;;)
        {
            ++pos;
            if (pos >= filename->str_length || filename->str_text[pos] == '/')
                break;
        }

        /*
         * remember each word (except ".")
         */
        s = str_n_from_c(filename->str_text + start, pos - start);
        if (!str_equal(s, dot))
            string_list_append(&sl, s);
        str_free(s);
    }

    /*
     * Try as hard as possible to chuck out redundant stuff.
     */
    for (;;)
    {
        int             changed = 0;

        /*
         * "/.." -> "/"
         */
        if
        (
            sl.nstrings >= 2
        &&
            str_equal(sl.string[0], root)
        &&
            str_equal(sl.string[1], dotdot)
        )
        {
            string_list_remove_nth(&sl, 1);
            ++changed;
        }

        /*
         * "name/.." -> ""
         */
        for (j = 0; j + 1 < sl.nstrings; ++j)
        {
            if (str_equal(sl.string[j], root))
                continue;
            if (str_equal(sl.string[j], dotdot))
                continue;
            if (!str_equal(sl.string[j + 1], dotdot))
                continue;
            string_list_remove_nth(&sl, j);
            string_list_remove_nth(&sl, j);
            ++changed;
            --j;
        }

        /*
         * loop if anything changed,
         * bail if we can't find more to do
         */
        if (!changed)
            break;
    }

    /*
     * reassemble the "cleaned" path
     */
    s = wl2str_respect_empty(&sl, 0, sl.nstrings, "/", 1);
    string_list_destructor(&sl);
    return s;
}