/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 4 -*- */

/* $Id$ */

/* Copyright (C) 1998-99 Martin Baulig
   This file is part of LibGTop 1.0.

   Contributed by Martin Baulig <martin@home-of-linux.org>, April 1998.

   LibGTop 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.

   LibGTop 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 LibGTop; see the file COPYING. If not, write to the
   Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.
*/

#include <glibtop.h>
#include <glibtop/global.h>
#include <glibtop/xmalloc.h>

#include <glibtop/backend.h>

#if LIBGTOP_USE_GMODULE

#include <gmodule.h>

static void
unload_module (gpointer data, gpointer user_data)
{
    g_module_close (data);
}

static int
load_extra_libs (glibtop *server, glibtop_backend_entry *entry)
{
    GSList *list;
    GSList *loaded_here = NULL;

    for (list = entry->extra_libs; list; list = list->next) {
	const gchar *filename = list->data;
	GModule *module;

	module = g_module_open (filename, G_MODULE_BIND_LAZY);
	if (!module) {
	    glibtop_warn_r (server, "Cannot open extra shared library `%s' "
			    "for backend `%s' (%s)", filename, entry->name,
			    g_module_error ());
	    g_slist_foreach (loaded_here, unload_module, NULL);
	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
	}

	loaded_here = g_slist_prepend (loaded_here, module);
    }

    entry->_priv->extra_modules = g_slist_concat
	(loaded_here, entry->_priv->extra_modules);

    return 0;
}

#else /* not LIBGTOP_USE_GMODULE */

extern glibtop_backend_info LibGTopBackendInfo_Sysdeps;
extern glibtop_backend_info LibGTopBackendInfo_Common;
extern glibtop_backend_info LibGTopBackendInfo_Server;

typedef struct {
    const char *name;
    glibtop_backend_info *backend_info;
} backend_init_table_entry;

static backend_init_table_entry backend_init_table [] = {
#ifdef LIBGTOP_HAVE_SYSDEPS
    { "glibtop-backend-sysdeps", &LibGTopBackendInfo_Sysdeps },
#endif
    { "glibtop-backend-common", &LibGTopBackendInfo_Common },
#ifdef LIBGTOP_NEED_SERVER
    { "glibtop-backend-server", &LibGTopBackendInfo_Server },
#endif
    { NULL, NULL }
};

static glibtop_backend_info *
find_backend_by_name (const char *backend_name)
{
    backend_init_table_entry *table;

    for (table = backend_init_table; table->name; table++)
	if (!strcmp (backend_name, table->name))
	    return table->backend_info;

    return NULL;
}

#endif /* LIBGTOP_USE_GMODULE */

int
glibtop_open_backend_l (glibtop *server, const char *backend_name,
			u_int64_t features, const char **backend_args)
{
    const glibtop_backend_info *info;
    glibtop_backend_entry *entry;
    glibtop_backend *backend;

    entry = glibtop_backend_by_name (backend_name);
    if (!entry) return -GLIBTOP_ERROR_NO_SUCH_BACKEND;

    if (!entry->_priv) {
	entry->_priv = g_new0 (glibtop_backend_module, 1);

#if LIBGTOP_USE_GMODULE
	if (entry->extra_libs) {
	    int retval;

	    retval = load_extra_libs (server, entry);
	    if (retval < 0) return retval;
	}

	entry->_priv->module = g_module_open (entry->shlib_name,
					      G_MODULE_BIND_LAZY);
	if (!entry->_priv->module) {
	    glibtop_warn_r (server, "Cannot open shared library `%s' "
			    "for backend `%s' (%s)", entry->shlib_name,
			    entry->name, g_module_error ());
	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
	}

	if (!g_module_symbol (entry->_priv->module,
			      "LibGTopBackendInfo",
			      (gpointer*) &entry->info)) {
	    glibtop_warn_r (server, "Library `%s' is not a valid "
			    "LibGTop Backend library (start symbol not found)",
			    entry->shlib_name);

	    g_module_close (entry->_priv->module);
	    g_free (entry->_priv);
	    entry->_priv = NULL;

	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
	}
#else /* not LIBGTOP_USE_GMODULE */
	entry->info = find_backend_by_name (backend_name);
	if (!entry->info)
	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
#endif /* not LIBGTOP_USE_GMODULE */
    }

    entry->_priv->refcount++;

    info = entry->info;
    if (!info) return -GLIBTOP_ERROR_NO_SUCH_BACKEND;

    backend = glibtop_calloc_r (server, 1, sizeof (glibtop_backend));
    backend->_priv_module = entry->_priv;
    backend->info = info;

    if (!server->_priv)
	server->_priv = glibtop_calloc_r
	    (server, 1, sizeof (glibtop_server_private));

    if (info->open) {
	int retval;

	retval = info->open (server, backend, features, backend_args);
	if (retval) {
	    glibtop_free_r (server, backend->_priv);
	    glibtop_free_r (server, backend);
	    return retval;
	}
    }

    server->_priv->backend_list = g_slist_append
	(server->_priv->backend_list, backend);

    return 0;
}