// 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
}

// 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
}

// 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
}

// 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

}

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
}

// 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
}

// 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
}

// 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
}

// 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
}

func readAgentBasicInfo(hostname string) (Agent, string, error) {
	agent := Agent{}
	token := ""
	query := fmt.Sprintf(`
		select 
			hostname,
			port,
			token,
			last_submitted,
			mysql_port
		from 
			host_agent
		where
			hostname = '%s'
		`, hostname)
	db, err := db.OpenOrchestrator()
	if err != nil {
		return agent, "", err
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		agent.Hostname = m.GetString("hostname")
		agent.Port = m.GetInt("port")
		agent.LastSubmitted = m.GetString("last_submitted")
		agent.MySQLPort = m.GetInt64("mysql_port")
		token = m.GetString("token")

		return nil
	})

	if token == "" {
		return agent, "", log.Errorf("Cannot get agent/token: %s", hostname)
	}
	return agent, token, nil
}

// 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
}

// 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
}

// 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
}

// 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
}

// 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
}

// 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
}

// ForgetLongUnseenInstances will remove entries of all instacnes that have long since been last seen.
func ForgetLongUnseenAgents() error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	_, err = sqlutils.Exec(db, `
			delete 
				from host_agent 
			where 
				last_submitted < NOW() - interval ? hour`,
		config.Config.UnseenAgentForgetHours,
	)
	return err
}

// ForgetLongUnseenInstances will remove entries of all instacnes that have long since been last seen.
func ForgetLongUnseenInstances() error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	_, err = sqlutils.Exec(db, `
			delete 
				from database_instance 
			where 
				last_seen < NOW() - interval ? hour`,
		config.Config.UnseenInstanceForgetHours,
	)
	AuditOperation("forget-unseen", nil, "")
	return err
}

// ReadActiveMaintenance returns the list of currently active maintenance entries
func ReadActiveMaintenance() ([]Maintenance, error) {
	res := []Maintenance{}
	query := fmt.Sprintf(`
		select 
			database_instance_maintenance_id,
			hostname,
			port,
			begin_timestamp,
			timestampdiff(second, begin_timestamp, now()) as seconds_elapsed,
			maintenance_active,
			owner,
			reason
		from 
			database_instance_maintenance
		where
			maintenance_active = 1
		order by
			database_instance_maintenance_id
		`)
	db, err := db.OpenOrchestrator()
	if err != nil {
		goto Cleanup
	}

	err = sqlutils.QueryRowsMap(db, query, func(m sqlutils.RowMap) error {
		maintenance := Maintenance{}
		maintenance.MaintenanceId = m.GetUint("database_instance_maintenance_id")
		maintenance.Key.Hostname = m.GetString("hostname")
		maintenance.Key.Port = m.GetInt("port")
		maintenance.BeginTimestamp = m.GetString("begin_timestamp")
		maintenance.SecondsElapsed = m.GetUint("seconds_elapsed")
		maintenance.IsActive = m.GetBool("maintenance_active")
		maintenance.Owner = m.GetString("owner")
		maintenance.Reason = m.GetString("reason")

		res = append(res, maintenance)
		return err
	})
Cleanup:

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

}

// ForgetInstance removes an instance entry from the orchestrator backed database.
// It may be auto-rediscovered through topology or requested for discovery by multiple means.
func ForgetInstance(instanceKey *InstanceKey) error {
	db, err := db.OpenOrchestrator()
	if err != nil {
		return log.Errore(err)
	}

	_, err = sqlutils.Exec(db, `
			delete 
				from database_instance 
			where 
				hostname = ? and port = ?`,
		instanceKey.Hostname,
		instanceKey.Port,
	)
	AuditOperation("forget", instanceKey, "")
	return err
}