GeanyLua: get selected filename: geany.selfile()

/*
 * Return the selected filename in the active Geany document (like as
 *   "Open selected file" (Ctrl+Shift+O) but without opening).
 * Based on "on_menu_open_selected_file1_activate" (geany/src/callbacks.c)
 */
static gint glspi_selfile(lua_State* L)
{
    DOC_REQUIRED
    gchar *sel = NULL;
    gchar *filename = NULL;
    const gchar *wc;

#ifdef G_OS_WIN32
    wc = GEANY_WORDCHARS "./-" "\\";
#else
    wc = GEANY_WORDCHARS "./-";
#endif

    if (sci_has_selection(doc->editor->sci))
    {
        if (sci_get_selected_text_length(doc->editor->sci) < GEANY_MAX_WORD_LENGTH)
            sel = sci_get_selection_contents(doc->editor->sci);
    }
    else
        sel = editor_get_word_at_pos(doc->editor, sci_get_current_position(doc->editor->sci), wc);

    if (sel == NULL)
        return 0;

    SETPTR(sel, utils_get_locale_from_utf8(sel));
    if (g_path_is_absolute(sel))
        filename = g_strdup(sel);
    else
    {   /* relative filename, add the path of the current file */
        gchar *path;
        if (doc->file_name != NULL)
            path = g_path_get_dirname(doc->file_name); /* returns "." if no path */
        else
            path = g_get_current_dir();
        SETPTR(path, utils_get_locale_from_utf8(path));

        filename = g_build_path(G_DIR_SEPARATOR_S, path, sel, NULL);

        if (! g_file_test(filename, G_FILE_TEST_EXISTS) &&
                geany->app->project != NULL && !EMPTY(geany->app->project->base_path))
        {
            /* try the project's base path */
            if (g_path_is_absolute(geany->app->project->base_path))
                SETPTR(path, utils_get_locale_from_utf8(geany->app->project->base_path));
            else
            {
                /* build base_path out of project file name's dir and base_path */
                gchar *tmp;
                tmp = g_path_get_dirname(geany->app->project->file_name);
                if (utils_str_equal(geany->app->project->base_path, "./"))
                    SETPTR(path, utils_get_locale_from_utf8(tmp));
                else
                    SETPTR(path, utils_get_locale_from_utf8(g_build_filename(tmp, geany->app->project->base_path, NULL)));
                g_free(tmp);
            }
            SETPTR(filename, g_build_path(G_DIR_SEPARATOR_S, path, sel, NULL));
        }
        g_free(path);
#ifdef G_OS_UNIX
        if (! g_file_test(filename, G_FILE_TEST_EXISTS))
            SETPTR(filename, g_build_path(G_DIR_SEPARATOR_S, "/usr/local/include", sel, NULL));

        if (! g_file_test(filename, G_FILE_TEST_EXISTS))
            SETPTR(filename, g_build_path(G_DIR_SEPARATOR_S, "/usr/include", sel, NULL));
#endif
    }

    if (g_file_test(filename, G_FILE_TEST_EXISTS))
    {
        /* remove relative junk */
        utils_tidy_path(filename);

        lua_pushstring(L, (const gchar *) filename);
        g_free(filename);
        g_free(sel);
        return 1;
    }
    else
    {
        g_free(filename);
        g_free(sel);
        return 0;
    }
}