/*
 *
  Copyright (C) 2009-2016 Olof Hagsand and Benny Holmgren

  This file is part of CLIXON.

  CLIXON 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 3 of the License, or
  (at your option) any later version.

  CLIXON 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 CLIXON; see the file LICENSE.  If not, see
  <http://www.gnu.org/licenses/>.

 */

#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   yspec   Yang spec
 * @param   td      Transaction data
 */
static int
generic_validate(yang_spec          *yspec,
		 transaction_data_t *td)
{
    int             retval = -1;
    cxobj          *x1;
    cxobj          *x2;
    int             i;
    yang_stmt      *ys;

    /* changed entries */
    for (i=0; i<td->td_clen; i++){
	x1 = td->td_scvec[i]; /* source changed */
	x2 = td->td_tcvec[i]; /* target changed */
	ys = xml_spec(x1);
	if (xml_yang_validate(x2, ys) < 0)
	    goto done;
    }
    /* deleted entries */
    for (i=0; i<td->td_dlen; i++){
	x1 = td->td_dvec[i];
	ys = xml_spec(x1);
	if (yang_mandatory(ys)){
	    clicon_err(OE_CFG, 0,"Removed mandatory variable: %s", 
		       xml_name(x1));
	    goto done;
	}
    }
    /* added entries */
    for (i=0; i<td->td_alen; i++){
	x2 = td->td_avec[i];
	if (xml_yang_validate(x2, xml_spec(x2)) < 0)
	    goto done;
	if (xml_apply(x2, CX_ELMNT, 
		      (xml_applyfn_t*)xml_yang_validate, NULL) < 0)
	    goto done;
    }
    retval = 0;
 done:
    return retval;
}

/*! 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] running   The current database. The original backend state
 * @param[in] candidate: The candidate database. The wanted backend state
*/
int
candidate_commit(clicon_handle h, 
		 char         *candidate, 
		 char         *running)
{
    int                retval = -1;
    int                i;
    cxobj             *xn;
    struct stat        sb;
    void              *firsterr = NULL;
    yang_spec         *yspec;
    transaction_data_t *td = NULL;

    if ((yspec = clicon_dbspec_yang(h)) == NULL){
	clicon_err(OE_FATAL, 0, "No DB_SPEC");
	goto done;
    }	
    /* Sanity checks that databases exists. */
    if (stat(running, &sb) < 0){
	clicon_err(OE_DB, errno, "%s", running);
	goto done;
    }
    if (stat(candidate, &sb) < 0){
	clicon_err(OE_DB, errno, "%s", candidate);
	goto done;
    }

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

     /* 2. Parse xml trees */
    if (xmldb_get(running, "/", yspec, &td->td_src) < 0)
	goto done;
    if (xmldb_get(candidate, "/", yspec, &td->td_target) < 0)
	goto done;

     /* 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)
	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);
    }    
    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);
    }    
    for (i=0; i<td->td_clen; i++){ /* Also up */
	xn = td->td_scvec[i];
	xml_flag(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. */
    if (generic_validate(yspec, td) < 0)
	 goto done;

    /* 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;

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

     /* 8. Success: Copy candidate to running */
     if (file_cp(candidate, running) < 0){
	 clicon_err(OE_UNIX, errno, "file_cp(candidate; running)");
	 goto done;
     }

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

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

/*! Do a diff between candidate and running, then start a validate transaction
 *
 * @param[in] h         Clicon handle
 * @param[in] running   The current database. The original backend state
 * @param[in] candidate: The candidate database. The wanted backend state
*/
int
candidate_validate(clicon_handle h, 
		   char         *candidate, 
		   char         *running)
 {
     int                 retval = -1;
     struct stat         sb;
     yang_spec          *yspec;
     transaction_data_t *td = NULL;
     int                i;
     cxobj             *xn;

     if ((yspec = clicon_dbspec_yang(h)) == NULL){
	clicon_err(OE_FATAL, 0, "No DB_SPEC");
	goto done;
    }	
     /* Sanity checks that databases exists. */
     if (stat(running, &sb) < 0){
	 clicon_err(OE_DB, errno, "%s", running);
	 goto done;
     }
     if (stat(candidate, &sb) < 0){
	 clicon_err(OE_DB, errno, "%s", candidate);
	 goto done;
     }

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

     /* 2. Parse xml trees */
    if (xmldb_get(running, "/", yspec, &td->td_src) < 0)
	goto done;
    if (xmldb_get(candidate, "/", yspec, &td->td_target) < 0)
	goto done;

     /* 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)
	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);
     }    
     for (i=0; i<td->td_alen; i++){ /* Also down */
	 xn = td->td_avec[i];
	 xml_flag_set(xn, XML_FLAG_ADD);
     }    
     for (i=0; i<td->td_clen; i++){ /* Also up */
	 xn = td->td_scvec[i];
	 xml_flag_set(xn, XML_FLAG_CHANGE);
	 xn = td->td_tcvec[i];
	 xml_flag(xn, XML_FLAG_CHANGE);
     }    

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

    /* 5. Make generic validation on all new or changed data. */
    if (generic_validate(yspec, td) < 0)
	 goto done;

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

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

     retval = 0;
   done:
     /* In case of failure, call plugin transaction termination callbacks */
     if (retval < 0 && td)
	 plugin_transaction_abort(h, td);
     if (td)
	 transaction_free(td);
     return retval;
 }


/*! Handle an incoming commit message from a client.
 * XXX: If commit succeeds and snapshot/startup fails, we have strange state:
 *   the commit has succeeded but an error message is returned.
 */
int
from_client_commit(clicon_handle h,
		   int s,
		   struct clicon_msg *msg,
		   const char *label)
{
    int        retval = -1;
    char      *candidate;
    char      *running;
    uint32_t   snapshot;
    uint32_t   startup;
    char      *snapshot_0;
    char      *archive_dir;
    char      *startup_config;

    if (clicon_msg_commit_decode(msg, &candidate, &running,
				&snapshot, &startup, label) < 0)
	goto err;

    if (candidate_commit(h, candidate, running) < 0){
	clicon_debug(1, "Commit %s failed",  candidate);
	retval = 0; /* We ignore errors from commit, but maybe
		       we should fail on fatal errors? */
	goto err;
    }
    clicon_debug(1, "Commit %s",  candidate);
    if (snapshot){
	if ((archive_dir = clicon_archive_dir(h)) == NULL){
	    clicon_err(OE_PLUGIN, 0, "snapshot set and clicon_archive_dir not defined");
	    goto err;
	}
	if (config_snapshot(h, running, archive_dir) < 0)
	    goto err;
    }

    if (startup){
	if ((archive_dir = clicon_archive_dir(h)) == NULL){
	    clicon_err(OE_PLUGIN, 0, "startup set but clicon_archive_dir not defined");
	    goto err;
	}
	if ((startup_config = clicon_startup_config(h)) == NULL){
	    clicon_err(OE_PLUGIN, 0, "startup set but startup_config not defined");
	    goto err;
	}
	snapshot_0 = chunk_sprintf(__FUNCTION__, "%s/0", archive_dir);
	if (file_cp(snapshot_0, startup_config) < 0){
	    clicon_err(OE_PROTO, errno, "%s: Error when creating startup",
		    __FUNCTION__);
		goto err;
	}
    }
    retval = 0;
    if (send_msg_ok(s) < 0)
	goto done;
    goto done;
  err:
    /* XXX: more elaborate errstring? */
    if (send_msg_err(s, clicon_errno, clicon_suberrno, "%s", clicon_err_reason) < 0)
	retval = -1;  
 done:
    unchunk_group(__FUNCTION__);

    return retval; /* may be zero if we ignoring errors from commit */
} /* from_client_commit */



/*
 * Call backend plugin
 */
int
from_client_validate(clicon_handle h,
		     int s,
		     struct clicon_msg *msg,
		     const char *label)
{
    char *dbname;
    char *running_db;
    int retval = -1;

    if (clicon_msg_validate_decode(msg, &dbname, label) < 0){
	send_msg_err(s, clicon_errno, clicon_suberrno,
		     clicon_err_reason);
	goto err;
    }

    clicon_debug(1, "Validate %s",  dbname);
    if ((running_db = clicon_running_db(h)) == NULL){
	clicon_err(OE_FATAL, 0, "running db not set");
	goto err;
    }
    if (candidate_validate(h, dbname, running_db) < 0){
	clicon_debug(1, "Validate %s failed",  dbname);
	retval = 0; /* We ignore errors from commit, but maybe
		       we should fail on fatal errors? */
	goto err;
    }
    retval = 0;
    if (send_msg_ok(s) < 0)
	goto done;
    goto done;
  err:
    /* XXX: more elaborate errstring? */
    if (send_msg_err(s, clicon_errno, clicon_suberrno, "%s", clicon_err_reason) < 0)
	retval = -1;
  done:
    unchunk_group(__FUNCTION__);
    return retval;
} /* from_client_validate */