/*
 *
  ***** BEGIN LICENSE BLOCK *****
 
  Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren

  This file is part of CLIXON.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  Alternatively, the contents of this file may be used under the terms of
  the GNU General Public License Version 3 or later (the "GPL"),
  in which case the provisions of the GPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of the GPL, and not to allow others to
  use your version of this file under the terms of Apache License version 2, 
  indicate your decision by deleting the provisions above and replace them with
  the  notice and other provisions required by the GPL. If you do not delete
  the provisions above, a recipient may use your version of this file under
  the terms of any one of the Apache License version 2 or the GPL.

  ***** END LICENSE BLOCK *****

 */

#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <time.h>
#include <pwd.h>
#include <syslog.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/param.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <netinet/in.h>

/* cligen */
#include <cligen/cligen.h>

/* clicon */
#include <clixon/clixon.h>

#include "clixon_backend_transaction.h"
#include "backend_plugin.h"
#include "backend_handle.h"
#include "backend_commit.h"
#include "backend_client.h"

/*! Key values are checked for validity independent of user-defined callbacks
 *
 * Key values are checked as follows:
 * 1. If no value and default value defined, add it.
 * 2. If no value and mandatory flag set in spec, report error.
 * 3. Validate value versus spec, and report error if no match. Currently only int ranges and
 *    string regexp checked.
 * See also db_lv_set() where defaults are also filled in. The case here for defaults
 * are if code comes via XML/NETCONF.
 * @param[in]   yspec   Yang spec
 * @param[in]   td      Transaction data
 * @param[out]  cbret   Cligen buffer containing netconf error (if retval == 0)
 * @retval     -1       Error
 * @retval      0       Validation failed (with cbret set)
 * @retval      1       Validation OK       
 */
static int
generic_validate(yang_spec          *yspec,
		 transaction_data_t *td,
		 cbuf               *cbret)
{
    int             retval = -1;
    cxobj          *x1;
    cxobj          *x2;
    yang_stmt      *ys;
    int             i;
    int             ret;

    /* All entries */
    if ((ret = xml_yang_validate_all_top(td->td_target, cbret)) < 0) 
	goto done;
    if (ret == 0)
	goto fail;
    /* changed entries */
    for (i=0; i<td->td_clen; i++){
	x1 = td->td_scvec[i]; /* source changed */
	x2 = td->td_tcvec[i]; /* target changed */
	/* Should this be recursive? */
	if ((ret = xml_yang_validate_add(x2, cbret)) < 0)
	    goto done;
	if (ret == 0)
	    goto fail;
    }
    /* deleted entries */
    for (i=0; i<td->td_dlen; i++){
	x1 = td->td_dvec[i];
	ys = xml_spec(x1);
	if (ys && yang_mandatory(ys)){
	    if (netconf_missing_element(cbret, "protocol", xml_name(x1), "Removed mandatory variable") < 0)
		goto done;
	    goto fail;
	}
    }
    /* added entries */
    for (i=0; i<td->td_alen; i++){
	x2 = td->td_avec[i];
	if ((ret = xml_yang_validate_add(x2, cbret)) < 0)
	    goto done;
	if (ret == 0)
	    goto fail;
    }
    // ok:
    retval = 1;
 done:
    return retval;
 fail:
    retval = 0;
    goto done;
}

/*! Common code of candidate_validate and candidate_commit 
 * @param[in] h         Clicon handle
 * @param[in] candidate The candidate database. The wanted backend state
 * @retval   -1       Error - or validation failed (but cbret not set)
 * @retval    0       Validation failed (with cbret set)
 * @retval    1       Validation OK       
 * @note Need to differentiate between error and validation fail 
 *       (only done for generic_validate)
 */
static int
validate_common(clicon_handle       h, 
		char               *candidate,
	        transaction_data_t *td,
		cbuf               *cbret)
{
    int         retval = -1;
    yang_spec  *yspec;
    int         i;
    cxobj      *xn;
    int         ret;
    
    if ((yspec = clicon_dbspec_yang(h)) == NULL){
	clicon_err(OE_FATAL, 0, "No DB_SPEC");
	goto done;
    }	
    /* 2. Parse xml trees 
     * This is the state we are going from */
    if (xmldb_get(h, "running", "/", 1, &td->td_src) < 0)
	goto done;
    /* This is the state we are going to */
    if (xmldb_get(h, candidate, "/", 1, &td->td_target) < 0)
	goto done;

    /* Validate the target state. It is not completely clear this should be done 
     * here. It is being made in generic_validate below. 
     * But xml_diff requires some basic validation, at least check that yang-specs
     * have been assigned
     */
    if ((ret = xml_yang_validate_all_top(td->td_target, cbret)) < 0)
	goto done;
    if (ret == 0)
	goto fail;

    /* 3. Compute differences */
    if (xml_diff(yspec, 
		 td->td_src,
		 td->td_target,
		 &td->td_dvec,      /* removed: only in running */
		 &td->td_dlen,
		 &td->td_avec,      /* added: only in candidate */
		 &td->td_alen,
		 &td->td_scvec,     /* changed: original values */
		 &td->td_tcvec,     /* changed: wanted values */
		 &td->td_clen) < 0)
	goto done;
    if (debug>1)
	transaction_print(stderr, td);
    /* Mark as changed in tree */
    for (i=0; i<td->td_dlen; i++){ /* Also down */
	xn = td->td_dvec[i];
	xml_flag_set(xn, XML_FLAG_DEL);
	xml_apply(xn, CX_ELMNT, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_DEL);
	xml_apply_ancestor(xn, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_CHANGE);
    }    
    for (i=0; i<td->td_alen; i++){ /* Also down */
	xn = td->td_avec[i];
	xml_flag_set(xn, XML_FLAG_ADD);
	xml_apply(xn, CX_ELMNT, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_ADD);
	xml_apply_ancestor(xn, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_CHANGE);
    }    
    for (i=0; i<td->td_clen; i++){ /* Also up */
	xn = td->td_scvec[i];
	xml_flag_set(xn, XML_FLAG_CHANGE);
	xml_apply_ancestor(xn, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_CHANGE);
	xn = td->td_tcvec[i];
	xml_flag_set(xn, XML_FLAG_CHANGE);
	xml_apply_ancestor(xn, (xml_applyfn_t*)xml_flag_set, (void*)XML_FLAG_CHANGE);
    }    

    /* 4. Call plugin transaction start callbacks */
    if (plugin_transaction_begin(h, td) < 0)
	goto done;

    /* 5. Make generic validation on all new or changed data.
       Note this is only call that uses 3-values */
    if ((ret = generic_validate(yspec, td, cbret)) < 0)
	goto done;
    if (ret == 0)
	goto fail;

    /* 6. Call plugin transaction validate callbacks */
    if (plugin_transaction_validate(h, td) < 0)
	goto done;

    /* 7. Call plugin transaction complete callbacks */
    if (plugin_transaction_complete(h, td) < 0)
	goto done;
    retval = 1;
 done:
    return retval;
 fail:
    retval = 0;
    goto done;
}

/*! Do a diff between candidate and running, then start a commit transaction
 *
 * The code reverts changes if the commit fails. But if the revert
 * fails, we just ignore the errors and proceed. Maybe we should
 * do something more drastic?
 * @param[in]  h         Clicon handle
 * @param[in]  candidate A candidate database, not necessarily "candidate"
 * @retval   -1       Error - or validation failed 
 * @retval    0       Validation failed (with cbret set)
 * @retval    1       Validation OK       
 * @note Need to differentiate between error and validation fail
 *       (only done for validate_common)
 */
int
candidate_commit(clicon_handle h, 
		 char         *candidate,
		 cbuf         *cbret)
{
    int                 retval = -1;
    transaction_data_t *td = NULL;
    int                 ret;

     /* 1. Start transaction */
    if ((td = transaction_new()) == NULL)
	goto done;

    /* Common steps (with validate). Load candidate and running and compute diffs
     * Note this is only call that uses 3-values
     */
    if ((ret = validate_common(h, candidate, td, cbret)) < 0)
	goto done;
    if (ret == 0)
	goto fail;

     /* 7. Call plugin transaction commit callbacks */
     if (plugin_transaction_commit(h, td) < 0)
	 goto done;

     /* Optionally write (potentially modified) tree back to candidate */
     if (clicon_option_bool(h, "CLICON_TRANSACTION_MOD")){
	 if ((ret = xmldb_put(h, candidate, OP_REPLACE, td->td_target, cbret)) < 0)
	     goto done;
	 if (ret == 0)
	     goto fail;
     }
     /* 8. Success: Copy candidate to running 
      */
     if (xmldb_copy(h, candidate, "running") < 0)
	 goto done;

    /* 9. Call plugin transaction end callbacks */
    plugin_transaction_end(h, td);

    /* 8. Copy running back to candidate in case end functions updated running */
    if (xmldb_copy(h, "running", candidate) < 0){
	/* ignore errors or signal major setback ? */
	clicon_log(LOG_NOTICE, "Error in rollback, trying to continue");
	goto done;
    } 
    retval = 1;
 done:
     /* In case of failure (or error), call plugin transaction termination callbacks */
     if (retval < 1 && td)
	 plugin_transaction_abort(h, td);
     if (td)
	 transaction_free(td);
    return retval;
 fail:
    retval = 0;
    goto done;
}

/*! Commit changes from candidate to running
 * @param[in]  h     Clicon handle
 * @param[out] cbret Return xml value cligen buffer
 * @retval  0   OK. This may indicate both ok and err msg back to client
 * @retval  -1  (Local) Error
 */
int
from_client_commit(clicon_handle h,
		   int           mypid,
		   cbuf         *cbret)
{
    int        retval = -1;
    int        piddb;
    cbuf      *cbx = NULL; /* Assist cbuf */
    int        ret;

    /* Check if target locked by other client */
    piddb = xmldb_islocked(h, "running");
    if (piddb && mypid != piddb){
	if ((cbx = cbuf_new()) == NULL){
	    clicon_err(OE_XML, errno, "cbuf_new");
	    goto done;
	}	
	cprintf(cbx, "<session-id>%d</session-id>", piddb);
	if (netconf_lock_denied(cbret, cbuf_get(cbx), "Operation failed, lock is already held") < 0)
	    goto done;
	goto ok;
    }
    if ((ret = candidate_commit(h, "candidate", cbret)) < 0){ /* Assume validation fail, nofatal */
	clicon_debug(1, "Commit candidate failed");
	if (ret < 0)
	    if (netconf_operation_failed(cbret, "application", clicon_err_reason)< 0)
		goto done;
        goto ok;
    }
    cprintf(cbret, "<rpc-reply><ok/></rpc-reply>");
 ok:
    retval = 0;
 done:
    if (cbx)
	cbuf_free(cbx);
    return retval; /* may be zero if we ignoring errors from commit */
} /* from_client_commit */

/*! Discard all changes in candidate / revert to running
 * @param[in]  h     Clicon handle
 * @param[in]  mypid  Process/session id of calling client
 * @param[out] cbret Return xml value cligen buffer
 * @retval  0  OK. This may indicate both ok and err msg back to client
 * @retval  -1 (Local) Error
 */
int
from_client_discard_changes(clicon_handle h,
			    int           mypid,
			    cbuf         *cbret)
{
    int   retval = -1;
    int   piddb;
    cbuf *cbx = NULL; /* Assist cbuf */
    
    /* Check if target locked by other client */
    piddb = xmldb_islocked(h, "candidate");
    if (piddb && mypid != piddb){
	if ((cbx = cbuf_new()) == NULL){
	    clicon_err(OE_XML, errno, "cbuf_new");
	    goto done;
	}	
	cprintf(cbx, "<session-id>%d</session-id>", piddb);
	if (netconf_lock_denied(cbret, cbuf_get(cbx), "Operation failed, lock is already held") < 0)
	    goto done;
	goto ok;
    }
    if (xmldb_copy(h, "running", "candidate") < 0){
	if (netconf_operation_failed(cbret, "application", clicon_err_reason)< 0)
	    goto done;
	goto ok;
    }
    cprintf(cbret, "<rpc-reply><ok/></rpc-reply>");
 ok:
    retval = 0;
 done:
    if (cbx)
	cbuf_free(cbx);
    return retval; /* may be zero if we ignoring errors from commit */
}

/*! Handle an incoming validate message from a client.
 * @param[in]  h     Clicon handle
 * @param[in]  db    Database name
 * @param[out] cbret Return xml value cligen buffer
 * @retval  0   OK. This may indicate both ok and err msg back to client (eg invalid)
 * @retval  -1  (Local) Error
 */
int
from_client_validate(clicon_handle h,
		     char         *db,
		     cbuf         *cbret)
{
    int                 retval = -1;
    transaction_data_t *td = NULL;
    int                 ret;

    if (strcmp(db, "candidate") != 0 && strcmp(db, "tmp") != 0){
	if (netconf_invalid_value(cbret, "protocol", "No such database")< 0)
	    goto done;
	goto ok;
    }
    clicon_debug(1, "Validate %s",  db);

     /* 1. Start transaction */
    if ((td = transaction_new()) == NULL)
	goto done;
    /* Common steps (with commit) */
    if ((ret = validate_common(h, db, td, cbret)) < 1){
	clicon_debug(1, "Validate %s failed",  db);
	if (ret < 0){
	    if (netconf_operation_failed(cbret, "application", clicon_err_reason)< 0)
		goto done;
	}
	goto ok;
    }
    /* Optionally write (potentially modified) tree back to candidate */
    if (clicon_option_bool(h, "CLICON_TRANSACTION_MOD")){
	if ((ret = xmldb_put(h, "candidate", OP_REPLACE, td->td_target, cbret)) < 0)
	    goto done;
	goto ok;
    }
    cprintf(cbret, "<rpc-reply><ok/></rpc-reply>");
 ok:
    retval = 0;
 done:
     if (retval < 0 && td)
	 plugin_transaction_abort(h, td);
     if (td)
	 transaction_free(td);
    return retval;
} /* from_client_validate */