// EndMaintenance will terminate an active maintenance via maintenanceToken
func EndMaintenance(maintenanceToken int64) error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	res, err := sqlutils.Exec(db, `
			update
				database_instance_maintenance
			set  
				maintenance_active = NULL,
				end_timestamp = NOW()
			where
				database_instance_maintenance_id = ? 
			`,
		maintenanceToken,
	)
	if err != nil {
		return log.Errore(err)
	}
	if affected, _ := res.RowsAffected(); affected == 0 {
		err = errors.New(fmt.Sprintf("Instance is not in maintenance mode; token = %+v", maintenanceToken))
	} else {
		// success
		instanceKey, _ := ReadMaintenanceInstanceKey(maintenanceToken)
		AuditOperation("end-maintenance", instanceKey, fmt.Sprintf("maintenanceToken: %d", maintenanceToken))
	}
	return err
}

// EndMaintenanceByInstanceKey will terminate an active maintenance using given instanceKey as hint
func EndMaintenanceByInstanceKey(instanceKey *InstanceKey) error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	res, err := sqlutils.Exec(db, `
			update
				database_instance_maintenance
			set  
				maintenance_active = NULL,
				end_timestamp = NOW()
			where
				hostname = ? 
				and port = ?
				and maintenance_active = 1
			`,
		instanceKey.Hostname,
		instanceKey.Port,
	)
	if err != nil {
		return log.Errore(err)
	}

	if affected, _ := res.RowsAffected(); affected == 0 {
		err = errors.New(fmt.Sprintf("Instance is not in maintenance mode: %+v", instanceKey))
	} else {
		// success
		AuditOperation("end-maintenance", instanceKey, "")
	}
	return err
}

// submitSeedStateEntry submits a seed state: a single step in the overall seed process
func submitSeedStateEntry(seedId int64, action string, errorMessage string) (int64, error) {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return 0, log.Errore(err)
	}

	res, err := sqlutils.Exec(db, `
			insert 
				into agent_seed_state (
					agent_seed_id, state_timestamp, state_action, error_message
				) VALUES (
					?, NOW(), ?, ?
				)
			`,
		seedId,
		action,
		errorMessage,
	)
	if err != nil {
		return 0, log.Errore(err)
	}
	id, err := res.LastInsertId()

	return id, err
}

// UpdateAgentLastChecked updates the last_check timestamp in the orchestrator backed database
// for a given agent
func UpdateAgentInfo(hostname string, agent Agent) error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	_, err = sqlutils.Exec(db, `
        	update 
        		host_agent 
        	set
        		last_seen = NOW(),
        		mysql_port = ?,
        		count_mysql_snapshots = ?
			where 
				hostname = ?`,
		agent.MySQLPort,
		len(agent.LogicalVolumes),
		hostname,
	)
	if err != nil {
		return log.Errore(err)
	}

	return nil
}

// ReadOutdatedInstanceKeys reads and returns keys for all instances that are not up to date (i.e.
// pre-configured time has passed since they were last cheked)
func ReadOutdatedInstanceKeys() ([]InstanceKey, error) {
	res := []InstanceKey{}
	query := fmt.Sprintf(`
		select 
			hostname, port 
		from 
			database_instance 
		where
			last_checked < now() - interval %d second`,
		config.Config.InstancePollSeconds)
	db, err := db.OpenOrchestrator()
	if err != nil {
		goto Cleanup
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		instanceKey, merr := NewInstanceKeyFromStrings(m.GetString("hostname"), m.GetString("port"))
		if merr != nil {
			log.Errore(merr)
		} else {
			res = append(res, *instanceKey)
		}
		// We don;t return an error because we want to keep filling the outdated instances list.
		return nil
	})
Cleanup:

	if err != nil {
		log.Errore(err)
	}
	return res, err

}

// StopSlaveNicely stops a slave such that SQL_thread and IO_thread are aligned (i.e.
// SQL_thread consumes all relay log entries)
func StopSlaveNicely(instanceKey *InstanceKey) (*Instance, error) {
	instance, err := ReadTopologyInstance(instanceKey)
	if err != nil {
		return instance, log.Errore(err)
	}

	if !instance.IsSlave() {
		return instance, errors.New(fmt.Sprintf("instance is not a slave: %+v", instanceKey))
	}

	_, err = ExecInstance(instanceKey, `stop slave io_thread`)

	for up_to_date := false; !up_to_date; {
		instance, err = ReadTopologyInstance(instanceKey)
		if err != nil {
			return instance, log.Errore(err)
		}

		if instance.SQLThreadUpToDate() {
			up_to_date = true
		} else {
			time.Sleep(200 * time.Millisecond)
		}
	}
	_, err = ExecInstance(instanceKey, `stop slave`)
	if err != nil {
		return instance, log.Errore(err)
	}

	instance, err = ReadTopologyInstance(instanceKey)
	return instance, err
}

// AuditOperation creates and writes a new audit entry by given params
func AuditOperation(auditType string, instanceKey *InstanceKey, message string) error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	if instanceKey == nil {
		instanceKey = &InstanceKey{}
	}

	_, err = sqlutils.Exec(db, `
			insert 
				into audit (
					audit_timestamp, audit_type, hostname, port, message
				) VALUES (
					NOW(), ?, ?, ?, ?
				)
			`,
		auditType,
		instanceKey.Hostname,
		instanceKey.Port,
		message,
	)
	if err != nil {
		return log.Errore(err)
	}

	return err
}

// ReadClusterNameByMaster will return the cluster name for a given instance by looking at its master
// and getting it from there.
// It is a non-recursive function and so-called-recursion is performed upon periodic reading of
// instances.
func ReadClusterNameByMaster(instanceKey *InstanceKey, masterKey *InstanceKey) (string, error) {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return "", log.Errore(err)
	}

	var clusterName string
	err = db.QueryRow(`
       	select 
       		if (
       			cluster_name != '',
       			cluster_name,
	       		ifnull(concat(max(hostname), ':', max(port)), '')
	       	) as cluster_name
       	from database_instance 
		 	where hostname=? and port=?`,
		masterKey.Hostname, masterKey.Port).Scan(
		&clusterName,
	)
	if err != nil {
		return "", log.Errore(err)
	}
	if clusterName == "" {
		return fmt.Sprintf("%s:%d", instanceKey.Hostname, instanceKey.Port), nil
	}
	return clusterName, err
}

// BeginMaintenance will make new maintenance entry for given instanceKey.
func BeginMaintenance(instanceKey *InstanceKey, owner string, reason string) (int64, error) {
	db, err := db.OpenOrchestrator()
	var maintenanceToken int64 = 0
	if err != nil {
		return maintenanceToken, log.Errore(err)
	}

	res, err := sqlutils.Exec(db, `
			insert ignore
				into database_instance_maintenance (
					hostname, port, maintenance_active, begin_timestamp, end_timestamp, owner, reason
				) VALUES (
					?, ?, 1, NOW(), NULL, ?, ?
				)
			`,
		instanceKey.Hostname,
		instanceKey.Port,
		owner,
		reason,
	)
	if err != nil {
		return maintenanceToken, log.Errore(err)
	}

	if affected, _ := res.RowsAffected(); affected == 0 {
		err = errors.New(fmt.Sprintf("Cannot begin maintenance for instance: %+v", instanceKey))
	} else {
		// success
		maintenanceToken, _ = res.LastInsertId()
		AuditOperation("begin-maintenance", instanceKey, fmt.Sprintf("maintenanceToken: %d, owner: %s, reason: %s", maintenanceToken, owner, reason))
	}
	return maintenanceToken, err
}

// ReadClustersInfo reads names of all known clusters and some aggregated info
func ReadClustersInfo() ([]ClusterInfo, error) {
	clusters := []ClusterInfo{}

	db, err := db.OpenOrchestrator()
	if err != nil {
		return clusters, log.Errore(err)
	}

	query := fmt.Sprintf(`
		select 
			cluster_name,
			count(*) as count_instances
		from 
			database_instance 
		group by
			cluster_name`)

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		clusterInfo := ClusterInfo{
			ClusterName:    m.GetString("cluster_name"),
			CountInstances: m.GetUint("count_instances"),
		}
		for pattern, _ := range config.Config.ClusterNameToAlias {
			if matched, _ := regexp.MatchString(pattern, clusterInfo.ClusterName); matched {
				clusterInfo.ClusterAlias = config.Config.ClusterNameToAlias[pattern]
			}
		}

		clusters = append(clusters, clusterInfo)
		return nil
	})

	return clusters, err
}

// MasterPosWait issues a MASTER_POS_WAIT() an given instance according to given coordinates.
func MasterPosWait(instanceKey *InstanceKey, binlogCoordinates *BinlogCoordinates) (*Instance, error) {
	instance, err := ReadTopologyInstance(instanceKey)
	if err != nil {
		return instance, log.Errore(err)
	}

	_, err = ExecInstance(instanceKey, fmt.Sprintf("select master_pos_wait('%s', %d)",
		binlogCoordinates.LogFile, binlogCoordinates.LogPos))
	if err != nil {
		return instance, log.Errore(err)
	}
	log.Infof("Instance %+v has reached coordinates: %+v", instanceKey, binlogCoordinates)

	instance, err = ReadTopologyInstance(instanceKey)
	return instance, err
}

// ReadClusterInstances reads all instances of a given cluster
func ReadClusterInstances(clusterName string) ([](*Instance), error) {
	instances := [](*Instance){}

	db, err := db.OpenOrchestrator()
	if err != nil {
		return instances, log.Errore(err)
	}
	if strings.Index(clusterName, "'") >= 0 {
		return instances, log.Errorf("Invalid cluster name: %s", clusterName)
	}

	query := fmt.Sprintf(`
		select 
			*,
			timestampdiff(second, last_checked, now()) as seconds_since_last_checked,
			(last_checked <= last_seen) is true as is_last_check_valid,
			timestampdiff(second, last_seen, now()) as seconds_since_last_seen
		from 
			database_instance 
		where
			cluster_name = '%s'
		order by
			hostname, port`, clusterName)

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		instance := readInstanceRow(m)
		instances = append(instances, instance)
		return nil
	})

	return instances, err
}

// ReadMaintenanceInstanceKey will return the instanceKey for active maintenance by maintenanceToken
func ReadMaintenanceInstanceKey(maintenanceToken int64) (*InstanceKey, error) {
	var res *InstanceKey
	query := fmt.Sprintf(`
		select 
			hostname, port 
		from 
			database_instance_maintenance 
		where
			database_instance_maintenance_id = %d `,
		maintenanceToken)
	db, err := db.OpenOrchestrator()
	if err != nil {
		goto Cleanup
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		instanceKey, merr := NewInstanceKeyFromStrings(m.GetString("hostname"), m.GetString("port"))
		if merr != nil {
			return merr
		}

		res = instanceKey
		return nil
	})
Cleanup:

	if err != nil {
		log.Errore(err)
	}
	return res, err
}

func ReadOutdatedAgentsHosts() ([]string, error) {
	res := []string{}
	query := fmt.Sprintf(`
		select 
			hostname 
		from 
			host_agent 
		where
			IFNULL(last_checked < now() - interval %d minute, true)
			`,
		config.Config.AgentPollMinutes)
	db, err := db.OpenOrchestrator()
	if err != nil {
		goto Cleanup
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		hostname := m.GetString("hostname")
		res = append(res, hostname)
		return nil
	})
Cleanup:

	if err != nil {
		log.Errore(err)
	}
	return res, err
}

func executeAgentCommand(hostname string, command string, onResponse *func([]byte)) (Agent, error) {
	agent, token, err := readAgentBasicInfo(hostname)
	if err != nil {
		return agent, err
	}

	// All seems to be in order. Now make some inquiries from orchestrator-agent service:
	uri := baseAgentUri(agent.Hostname, agent.Port)

	var fullCommand string
	if strings.Contains(command, "?") {
		fullCommand = fmt.Sprintf("%s&token=%s", command, token)
	} else {
		fullCommand = fmt.Sprintf("%s?token=%s", command, token)
	}
	log.Debugf("orchestrator-agent command: %s", fullCommand)
	agentCommandUri := fmt.Sprintf("%s/%s", uri, fullCommand)
	body, err := readResponse(http.Get(agentCommandUri))
	if err != nil {
		return agent, log.Errore(err)
	}
	if onResponse != nil {
		(*onResponse)(body)
	}

	return agent, err
}

// MakeCoMaster will attempt to make an instance co-master with its master, by making its master a slave of its own.
// This only works out if the master is not replicating; the master does not have a known master (it may have an unknown master).
func MakeCoMaster(instanceKey *InstanceKey) (*Instance, error) {
	instance, err := ReadTopologyInstance(instanceKey)
	if err != nil {
		return instance, err
	}
	master, err := GetInstanceMaster(instance)
	if err != nil {
		return instance, err
	}

	rinstance, _, _ := ReadInstance(&master.Key)
	if canMove, merr := rinstance.CanMoveAsCoMaster(); !canMove {
		return instance, merr
	}
	rinstance, _, _ = ReadInstance(instanceKey)
	if canMove, merr := rinstance.CanMove(); !canMove {
		return instance, merr
	}

	if instanceKey.Equals(&master.MasterKey) {
		return instance, errors.New(fmt.Sprintf("instance  %+v is already co master of %+v", instanceKey, master.Key))
	}
	if _, found, _ := ReadInstance(&master.MasterKey); found {
		return instance, errors.New(fmt.Sprintf("master %+v already has known master: %+v", master.Key, master.MasterKey))
	}
	if canReplicate, err := master.CanReplicateFrom(instance); !canReplicate {
		return instance, err
	}
	log.Infof("Will make %+v co-master of %+v", instanceKey, master.Key)

	if maintenanceToken, merr := BeginMaintenance(instanceKey, "orchestrator", fmt.Sprintf("make co-master of %+v", master.Key)); merr != nil {
		err = errors.New(fmt.Sprintf("Cannot begin maintenance on %+v", *instanceKey))
		goto Cleanup
	} else {
		defer EndMaintenance(maintenanceToken)
	}
	if maintenanceToken, merr := BeginMaintenance(&master.Key, "orchestrator", fmt.Sprintf("%+v turns into co-master of this", *instanceKey)); merr != nil {
		err = errors.New(fmt.Sprintf("Cannot begin maintenance on %+v", master.Key))
		goto Cleanup
	} else {
		defer EndMaintenance(maintenanceToken)
	}

	// the coMaster used to be merely a slave. Just point master into *some* position
	// within coMaster...
	master, err = ChangeMasterTo(&master.Key, instanceKey, &instance.SelfBinlogCoordinates)
	if err != nil {
		goto Cleanup
	}

Cleanup:
	master, _ = StartSlave(&master.Key)
	if err != nil {
		return instance, log.Errore(err)
	}
	// and we're done (pending deferred functions)
	AuditOperation("make-co-master", instanceKey, fmt.Sprintf("%+v made co-master of %+v", *instanceKey, master.Key))

	return instance, err
}

// ReadAgents returns a list of all known agents
func ReadCountMySQLSnapshots(hostnames []string) (map[string]int, error) {
	res := make(map[string]int)
	query := fmt.Sprintf(`
		select 
			hostname,
			count_mysql_snapshots
		from 
			host_agent
		where
			hostname in (%s)
		order by
			hostname
		`, sqlutils.InClauseStringValues(hostnames))
	db, err := db.OpenOrchestrator()
	if err != nil {
		goto Cleanup
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		res[m.GetString("hostname")] = m.GetInt("count_mysql_snapshots")
		return nil
	})
Cleanup:

	if err != nil {
		log.Errore(err)
	}
	return res, err
}

// ReadProblemInstances reads all instances with problems
func ReadProblemInstances() ([](*Instance), error) {
	instances := [](*Instance){}

	db, err := db.OpenOrchestrator()
	if err != nil {
		return instances, log.Errore(err)
	}

	query := fmt.Sprintf(`
		select 
			*,
			timestampdiff(second, last_checked, now()) as seconds_since_last_checked,
			(last_checked <= last_seen) is true as is_last_check_valid,
			timestampdiff(second, last_seen, now()) as seconds_since_last_seen
		from 
			database_instance 
		where
			(last_seen < last_checked)
			or (not ifnull(timestampdiff(second, last_checked, now()) <= %d, false))
			or (not slave_sql_running)
			or (not slave_io_running)
			or (seconds_behind_master > 10)
		order by
			hostname, port`, config.Config.InstancePollSeconds)

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		instance := readInstanceRow(m)
		instances = append(instances, instance)
		return nil
	})

	return instances, err
}

// FailStaleSeeds marks as failed seeds where no progress have been seen recently
func FailStaleSeeds() error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	_, err = sqlutils.Exec(db, `
				update 
						agent_seed 
					set 
						is_complete=1, 
						is_successful=0 
					where 
						is_complete=0 
						and (
							select 
									max(state_timestamp) as last_state_timestamp 
								from 
									agent_seed_state 
								where 
									agent_seed.agent_seed_id = agent_seed_state.agent_seed_id
						) < now() - interval ? minute`,
		config.Config.StaleSeedFailMinutes,
	)
	return err
}

// QueryRowsMap is a convenience function allowing querying a result set while poviding a callback
// function activated per read row.
func QueryRowsMap(db *sql.DB, query string, on_row func(RowMap) error) error {
	rows, err := db.Query(query)
	defer rows.Close()
	if err != nil && err != sql.ErrNoRows {
		return log.Errore(err)
	}
	err = ScanRowsToMaps(rows, on_row)
	return err
}