/* 
   ldb database library

   Copyright (C) Simo Sorce  2004-2006
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   Copyright (C) Andrew Tridgell 2005

     ** NOTE! The following LGPL license applies to the ldb
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

/*
 *  Name: ldb
 *
 *  Component: ldb objectguid module
 *
 *  Description: add a unique objectGUID onto every new record
 *
 *  Author: Simo Sorce
 */

#include "includes.h"
#include "ldb/include/ldb_includes.h"
#include "librpc/gen_ndr/ndr_misc.h"
#include "param/param.h"

static struct ldb_message_element *objectguid_find_attribute(const struct ldb_message *msg, const char *name)
{
	int i;

	for (i = 0; i < msg->num_elements; i++) {
		if (ldb_attr_cmp(name, msg->elements[i].name) == 0) {
			return &msg->elements[i];
		}
	}

	return NULL;
}

/*
  add a time element to a record
*/
static int add_time_element(struct ldb_message *msg, const char *attr, time_t t)
{
	struct ldb_message_element *el;
	char *s;

	if (ldb_msg_find_element(msg, attr) != NULL) {
		return 0;
	}

	s = ldb_timestring(msg, t);
	if (s == NULL) {
		return -1;
	}

	if (ldb_msg_add_string(msg, attr, s) != 0) {
		return -1;
	}

	el = ldb_msg_find_element(msg, attr);
	/* always set as replace. This works because on add ops, the flag
	   is ignored */
	el->flags = LDB_FLAG_MOD_REPLACE;

	return 0;
}

/*
  add a uint64_t element to a record
*/
static int add_uint64_element(struct ldb_message *msg, const char *attr, uint64_t v)
{
	struct ldb_message_element *el;

	if (ldb_msg_find_element(msg, attr) != NULL) {
		return 0;
	}

	if (ldb_msg_add_fmt(msg, attr, "%llu", (unsigned long long)v) != 0) {
		return -1;
	}

	el = ldb_msg_find_element(msg, attr);
	/* always set as replace. This works because on add ops, the flag
	   is ignored */
	el->flags = LDB_FLAG_MOD_REPLACE;

	return 0;
}

/* add_record: add objectGUID attribute */
static int objectguid_add(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_request *down_req;
	struct ldb_message_element *attribute;
	struct ldb_message *msg;
	struct ldb_val v;
	struct GUID guid;
	uint64_t seq_num;
	enum ndr_err_code ndr_err;
	int ret;
	time_t t = time(NULL);

	ldb_debug(module->ldb, LDB_DEBUG_TRACE, "objectguid_add_record\n");

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(req->op.add.message->dn)) {
		return ldb_next_request(module, req);
	}

	if ((attribute = objectguid_find_attribute(req->op.add.message, "objectGUID")) != NULL ) {
		return ldb_next_request(module, req);
	}

	down_req = talloc(req, struct ldb_request);
	if (down_req == NULL) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	*down_req = *req;

	/* we have to copy the message as the caller might have it as a const */
	down_req->op.add.message = msg = ldb_msg_copy_shallow(down_req, req->op.add.message);
	if (msg == NULL) {
		talloc_free(down_req);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	/* a new GUID */
	guid = GUID_random();

	ndr_err = ndr_push_struct_blob(&v, msg, 
				       lp_iconv_convenience(ldb_get_opaque(module->ldb, "loadparm")),
				       &guid,
				       (ndr_push_flags_fn_t)ndr_push_GUID);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(down_req);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	ret = ldb_msg_add_value(msg, "objectGUID", &v, NULL);
	if (ret) {
		talloc_free(down_req);
		return ret;
	}
	
	if (add_time_element(msg, "whenCreated", t) != 0 ||
	    add_time_element(msg, "whenChanged", t) != 0) {
		talloc_free(down_req);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	/* Get a sequence number from the backend */
	ret = ldb_sequence_number(module->ldb, LDB_SEQ_NEXT, &seq_num);
	if (ret == LDB_SUCCESS) {
		if (add_uint64_element(msg, "uSNCreated", seq_num) != 0 ||
		    add_uint64_element(msg, "uSNChanged", seq_num) != 0) {
			talloc_free(down_req);
			return LDB_ERR_OPERATIONS_ERROR;
		}
	}

	ldb_set_timeout_from_prev_req(module->ldb, req, down_req);

	/* go on with the call chain */
	ret = ldb_next_request(module, down_req);

	/* do not free down_req as the call results may be linked to it,
	 * it will be freed when the upper level request get freed */
	if (ret == LDB_SUCCESS) {
		req->handle = down_req->handle;
	}

	return ret;
}

/* modify_record: update timestamps */
static int objectguid_modify(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_request *down_req;
	struct ldb_message *msg;
	int ret;
	time_t t = time(NULL);
	uint64_t seq_num;

	ldb_debug(module->ldb, LDB_DEBUG_TRACE, "objectguid_add_record\n");

	/* do not manipulate our control entries */
	if (ldb_dn_is_special(req->op.add.message->dn)) {
		return ldb_next_request(module, req);
	}

	down_req = talloc(req, struct ldb_request);
	if (down_req == NULL) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	*down_req = *req;

	/* we have to copy the message as the caller might have it as a const */
	down_req->op.mod.message = msg = ldb_msg_copy_shallow(down_req, req->op.mod.message);
	if (msg == NULL) {
		talloc_free(down_req);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	if (add_time_element(msg, "whenChanged", t) != 0) {
		talloc_free(down_req);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	/* Get a sequence number from the backend */
	ret = ldb_sequence_number(module->ldb, LDB_SEQ_NEXT, &seq_num);
	if (ret == LDB_SUCCESS) {
		if (add_uint64_element(msg, "uSNChanged", seq_num) != 0) {
			talloc_free(down_req);
			return LDB_ERR_OPERATIONS_ERROR;
		}
	}

	ldb_set_timeout_from_prev_req(module->ldb, req, down_req);

	/* go on with the call chain */
	ret = ldb_next_request(module, down_req);

	/* do not free down_req as the call results may be linked to it,
	 * it will be freed when the upper level request get freed */
	if (ret == LDB_SUCCESS) {
		req->handle = down_req->handle;
	}

	return ret;
}

_PUBLIC_ const struct ldb_module_ops ldb_objectguid_module_ops = {
	.name          = "objectguid",
	.add           = objectguid_add,
	.modify        = objectguid_modify,
};