<?php
/* Copyright (C) 2014 Daniel Preussker <f0o@devilcode.org>
 * This program 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.
 * 
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>. */

/**
 * Alerts Tracking
 * @author Daniel Preussker <f0o@devilcode.org>
 * @copyright 2014 f0o, LibreNMS
 * @license GPL
 * @package LibreNMS
 * @subpackage Alerts
 */

include_once($config['install_dir'].'/includes/device-groups.inc.php');
include_once($config['install_dir'].'/html/includes/authentication/'.$config['auth_mechanism'].'.inc.php');

/**
 * Generate SQL from Rule
 * @param string $rule Rule to generate SQL for
 * @return string|boolean
 */
function GenSQL($rule) {
	$rule = RunMacros($rule);
	if( empty($rule) ) {
		//Cannot resolve Macros due to recursion. Rule is invalid.
		return false;
	}
	//Pretty-print rule to dissect easier
	$pretty = array('*'  => ' * ', '('  => ' ( ', ')'  => ' ) ', '/'  => ' / ', '&&' => ' && ', '||' => ' || ');
	$rule = str_replace(array_keys($pretty),$pretty,$rule);
	$tmp = explode(" ",$rule);
	$tables = array();
	foreach( $tmp as $opt ) {
		if( strstr($opt,'%') && strstr($opt,'.') ) {
			$tmpp = explode(".",$opt,2);
			$tmpp[0] = str_replace("%","",$tmpp[0]);
			$tables[] = mres(str_replace("(","",$tmpp[0]));
			$rule = str_replace($opt,$tmpp[0].'.'.$tmpp[1],$rule);
		}
	}
	$tables = array_keys(array_flip($tables));
	if( dbFetchCell('SELECT 1 FROM information_schema.COLUMNS WHERE TABLE_NAME = ? && COLUMN_NAME = ?',array($tables[0],'device_id')) != 1 ) {
		//Our first table has no valid glue, append the 'devices' table to it!
		array_unshift($tables, 'devices');
	}
	$x = sizeof($tables)-1;
	$i = 0;
	$join = "";
	while( $i < $x ) {
		if( isset($tables[$i+1]) ) {
			if( dbFetchCell('SELECT 1 FROM information_schema.COLUMNS WHERE TABLE_NAME = ? && COLUMN_NAME = ?',array($tables[$i+1],'device_id')) == 1 ) {
				//Found valid glue in definition.
				$join .= $tables[$i].".device_id = ".$tables[$i+1].".device_id && ";
			} else {
				//No valid glue, Resolve a glue-chain.
				$gtmp = ResolveGlues(array($tables[$i+1]),'device_id');
				if( $gtmp === false ) {
					//Cannot resolve glue-chain. Rule is invalid.
					return false;
				}
				$last = "";
				$qry = "";
				foreach( $gtmp as $glue ) {
					if( empty($last) ) {
						list($tmp,$last) = explode('.',$glue);
						$qry .= $glue.' = ';
					} else {
						list($tmp,$new) = explode('.',$glue);
						$qry .= $tmp.'.'.$last.' && '.$tmp.'.'.$new.' = ';
						$last = $new;
					}
					if( !in_array($tmp, $tables) ) {
						$tables[] = $tmp;
					}
				}
				$join .= "( ".$qry.$tables[0].".device_id ) && ";
			}
		}
		$i++;
	}
	$sql = "SELECT * FROM ".implode(",",$tables)." WHERE (".$join."".str_replace("(","",$tables[0]).".device_id = ?) && (".str_replace(array("%","@","!~","~"),array("","%","NOT LIKE","LIKE"),$rule).")";
	return $sql;
}

/**
 * Create a glue-chain
 * @param array $tables Initial Tables to construct glue-chain
 * @param string $target Glue to find (usual device_id)
 * @param int $x Recursion Anchor
 * @param array $hist History of processed tables
 * @param array $last Glues on the fringe
 * @return string|boolean
 */
function ResolveGlues($tables,$target,$x=0,$hist=array(),$last=array()) {
	if( sizeof($tables) == 1 && $x != 0 ) {
		if( dbFetchCell('SELECT 1 FROM information_schema.COLUMNS WHERE TABLE_NAME = ? && COLUMN_NAME = ?',array($tables[0],$target)) == 1 ) {
			return array_merge($last,array($tables[0].'.'.$target));
		} else {
			return false;
		}
	} else {
		$x++;
		if( $x > 30 ) {
			//Too much recursion. Abort.
			return false;
		}
		foreach( $tables as $table ) {
			$glues = dbFetchRows('SELECT COLUMN_NAME FROM information_schema.COLUMNS WHERE TABLE_NAME = ? && COLUMN_NAME LIKE "%\_id"',array($table));
			if( sizeof($glues) == 1 && $glues[0]['COLUMN_NAME'] != $target ) {
				//Search for new candidates to expand
				$tmp = dbFetchRows('SELECT TABLE_NAME FROM information_schema.TABLES WHERE TABLE_NAME LIKE "'.substr($table,0,-1).'_%" && TABLE_NAME != "'.$table.'"');
				$ntables = array();
				foreach( $tmp as $expand ) {
					$ntables[] = $expand['TABLE_NAME'];
				}
				$tmp = ResolveGlues($ntables,$target,$x++,array_merge($tables,$ntables),array_merge($last,array($table.'.'.$glues[0]['COLUMN_NAME'])));
				if( is_array($tmp) ) {
					return $tmp;
				}
			} else {
				foreach( $glues as $glue ) {
					if( $glue['COLUMN_NAME'] == $target ) {
						return array_merge($last,array($table.'.'.$target));
					} else {
						list($tmp) = explode('_',$glue['COLUMN_NAME']);
						$tmp .= 's';
						if( !in_array($tmp,$tables) && !in_array($tmp,$hist) ) {
							//Expand table
							$tmp = ResolveGlues(array($tmp),$target,$x++,array_merge($tables,array($tmp)),array_merge($last,array($table.'.'.$glue['COLUMN_NAME'])));
							if( is_array($tmp) ) {
								return $tmp;
							}
						}
					}
				}
			}
		}
	}
	//You should never get here.
	return false;
}

/**
 * Process Macros
 * @param string $rule Rule to process
 * @param int $x Recursion-Anchor
 * @return string|boolean
 */
function RunMacros($rule,$x=1) {
	global $config;
	krsort($config['alert']['macros']['rule']);
	foreach( $config['alert']['macros']['rule'] as $macro=>$value ) {
		if( !strstr($macro," ") ) {
			$rule = str_replace('%macros.'.$macro,$value,$rule);
		}
	}
	if( strstr($rule,"%macros") ) {
		if( ++$x < 30 ) {
			$rule = RunMacros($rule,$x);
		} else {
			return false;
		}
	}
	return $rule;
}

/**
 * Get Alert-Rules for Devices
 * @param int $device Device-ID
 * @return array
 */
function GetRules($device) {
	$groups = GetGroupsFromDevice($device);
	$params = array($device,$device);
	$where = "";
	foreach( $groups as $group ) {
		$where .= " || alert_map.target = ?";
		$params[] = 'g'.$group;
	}
	return dbFetchRows('SELECT alert_rules.* FROM alert_rules LEFT JOIN alert_map ON alert_rules.id=alert_map.rule WHERE alert_rules.disabled = 0 && ( (alert_rules.device_id = -1 || alert_rules.device_id = ? ) || alert_map.target = ? '.$where.' )',$params);
}

/**
 * Check if device is under maintenance
 * @param int $device Device-ID
 * @return int
 */
function IsMaintenance( $device ) {
	$groups = GetGroupsFromDevice($device);
	$params = array($device);
	$where = "";
	foreach( $groups as $group ) {
		$where .= " || alert_schedule_items.target = ?";
		$params[] = 'g'.$group;
	}
	return dbFetchCell('SELECT DISTINCT(alert_schedule.schedule_id) FROM alert_schedule LEFT JOIN alert_schedule_items ON alert_schedule.schedule_id=alert_schedule_items.schedule_id WHERE ( alert_schedule_items.target = ?'.$where.' ) && NOW() BETWEEN alert_schedule.start AND alert_schedule.end LIMIT 1',$params);
}

/**
 * Run all rules for a device
 * @param int $device Device-ID
 * @return void
 */
function RunRules($device) {
	global $debug;
	if( IsMaintenance($device) > 0 ) {
		echo "Under Maintenance, Skipping alerts.\r\n";
		return false;
	}
	foreach( GetRules($device) as $rule ) {
		echo " #".$rule['id'].":";
		$inv = json_decode($rule['extra'],true);
		if( isset($inv['invert']) ) {
			$inv = (bool) $inv['invert'];
		} else {
			$inv = false;
		}
		$chk = dbFetchRow("SELECT state FROM alerts WHERE rule_id = ? && device_id = ? ORDER BY id DESC LIMIT 1", array($rule['id'], $device));
		$sql = GenSQL($rule['rule']);
		$qry = dbFetchRows($sql,array($device));
		$s = sizeof($qry);
		if( $s == 0 && $inv === false ) {
			$doalert = false;
		} elseif( $s > 0 && $inv === false ) {
			$doalert = true;
		} elseif( $s == 0 && $inv === true ) {
			$doalert = true;
		} else { //( $s > 0 && $inv == false ) {
			$doalert = false;
		}
		if( $doalert ) {
			if( $chk['state'] === "2" ) {
				echo " SKIP  ";
			} elseif( $chk['state'] >= "1" ) {
				echo " NOCHG ";
			} else {
				$extra = gzcompress(json_encode(array('contacts' => GetContacts($qry), 'rule'=>$qry)),9);
				if( dbInsert(array('state' => 1, 'device_id' => $device, 'rule_id' => $rule['id'], 'details' => $extra),'alert_log') ) {
					if( !dbUpdate(array('state' => 1, 'open' => 1),'alerts','device_id = ? && rule_id = ?', array($device,$rule['id'])) ) {
						dbInsert(array('state' => 1, 'device_id' => $device, 'rule_id' => $rule['id'], 'open' => 1),'alerts');
					}
					echo " ALERT ";
				}
			}
		} else {
			if( $chk['state'] === "0" ) {
				echo " NOCHG ";
			} else {
				if( dbInsert(array('state' => 0, 'device_id' => $device, 'rule_id' => $rule['id']),'alert_log') ){
					if( !dbUpdate(array('state' => 0, 'open' => 1),'alerts','device_id = ? && rule_id = ?', array($device,$rule['id'])) ) {
						dbInsert(array('state' => 0, 'device_id' => $device, 'rule_id' => $rule['id'], 'open' => 1),'alerts');
					}
					echo " OK    ";
				}
			}
		}
	}
}

/**
 * Find contacts for alert
 * @param array $results Rule-Result
 * @return array
 */
function GetContacts($results) {
	global $config;
	if( sizeof($results) == 0 ) {
		return array();
	}
	if( $config['alert']['default_only'] == true || $config['alerts']['email']['default_only'] == true ) {
		return array(''.($config['alert']['default_mail'] ? $config['alert']['default_mail'] : $config['alerts']['email']['default']) => 'NOC');
	}
	$users = get_userlist();
	$contacts = array();
	$uids = array();
	foreach( $results as $result ) {
		$tmp  = NULL;
		if( is_numeric($result["bill_id"]) ) {
			$tmpa = dbFetchRows("SELECT user_id FROM bill_perms WHERE bill_id = ?",array($result["bill_id"]));
			foreach( $tmpa as $tmp ) {
				$uids[$tmp['user_id']] = $tmp['user_id'];
			}
		}
		if( is_numeric($result["port_id"]) ) {
			$tmpa = dbFetchRows("SELECT user_id FROM ports_perms WHERE access_level >= 0 AND port_id = ?",array($result["port_id"]));
			foreach( $tmpa as $tmp ) {
				$uids[$tmp['user_id']] = $tmp['user_id'];
			}
		}
		if( is_numeric($result["device_id"]) ) {
			$tmpa = dbFetchRow("SELECT sysContact FROM devices WHERE device_id = ?",array($result["device_id"]));
			$contacts[$tmpa["sysContact"]] = "NOC";
			$tmpa = dbFetchRows("SELECT user_id FROM devices_perms WHERE access_level >= 0 AND device_id = ?", array($result["device_id"]));
			foreach( $tmpa as $tmp ) {
				$uids[$tmp['user_id']] = $tmp['user_id'];
			}
		}
	}
	foreach( $users as $user ) {
		if( empty($user['email']) ) {
			continue;
		} elseif( empty($user['realname']) ) {
			$user['realname'] = $user['username'];
		}
		$user['level'] = get_userlevel($user['username']);
		if( $config["alert"]["globals"] && ( $user['level'] >= 5 && $user['level'] < 10 ) ) {
			$contacts[$user['email']] = $user['realname'];
		} elseif( $config["alert"]["admins"] && $user['level'] == 10 ) {
			$contacts[$user['email']] = $user['realname'];
		} elseif( in_array($user['user_id'],$uids) ) {
			$contacts[$user['email']] = $user['realname'];
		}
	}
	return $contacts;
}
?>