/*
   Copyright 2014 Outbrain Inc.

   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.
*/

package inst

import (
	"database/sql"
	"fmt"
	"github.com/outbrain/golib/math"
	"github.com/outbrain/orchestrator/go/config"
	"strconv"
	"strings"
)

// Instance represents a database instance, including its current configuration & status.
// It presents important replication configuration and detailed replication status.
type Instance struct {
	Key                    InstanceKey
	Uptime                 uint
	ServerID               uint
	ServerUUID             string
	Version                string
	ReadOnly               bool
	Binlog_format          string
	LogBinEnabled          bool
	LogSlaveUpdatesEnabled bool
	SelfBinlogCoordinates  BinlogCoordinates
	MasterKey              InstanceKey
	Slave_SQL_Running      bool
	Slave_IO_Running       bool
	HasReplicationFilters  bool
	SupportsOracleGTID     bool
	UsingOracleGTID        bool
	UsingMariaDBGTID       bool
	UsingPseudoGTID        bool
	ReadBinlogCoordinates  BinlogCoordinates
	ExecBinlogCoordinates  BinlogCoordinates
	IsDetached             bool
	RelaylogCoordinates    BinlogCoordinates
	LastSQLError           string
	LastIOError            string
	SecondsBehindMaster    sql.NullInt64
	SQLDelay               uint
	ExecutedGtidSet        string

	SlaveLagSeconds       sql.NullInt64
	SlaveHosts            InstanceKeyMap
	ClusterName           string
	SuggestedClusterAlias string
	DataCenter            string
	PhysicalEnvironment   string
	ReplicationDepth      uint
	IsCoMaster            bool

	IsLastCheckValid     bool
	IsUpToDate           bool
	IsRecentlyChecked    bool
	SecondsSinceLastSeen sql.NullInt64
	CountMySQLSnapshots  int

	IsCandidate          bool
	IsDowntimed          bool
	DowntimeReason       string
	DowntimeOwner        string
	DowntimeEndTimestamp string
	UnresolvedHostname   string
}

// NewInstance creates a new, empty instance
func NewInstance() *Instance {
	return &Instance{
		SlaveHosts: make(map[InstanceKey]bool),
	}
}

// Equals tests that this instance is the same instance as other. The function does not test
// configuration or status.
func (this *Instance) Equals(other *Instance) bool {
	return this.Key == other.Key
}

// MajorVersion returns this instance's major version number (e.g. for 5.5.36 it returns "5.5")
func (this *Instance) MajorVersion() []string {
	return strings.Split(this.Version, ".")[:2]
}

func (this *Instance) IsMySQL51() bool {
	return strings.Join(this.MajorVersion(), ".") == "5.1"
}

func (this *Instance) IsMySQL55() bool {
	return strings.Join(this.MajorVersion(), ".") == "5.5"
}

func (this *Instance) IsMySQL56() bool {
	return strings.Join(this.MajorVersion(), ".") == "5.6"
}

func (this *Instance) IsMySQL57() bool {
	return strings.Join(this.MajorVersion(), ".") == "5.7"
}

func (this *Instance) IsMySQL58() bool {
	return strings.Join(this.MajorVersion(), ".") == "5.8"
}

// IsSmallerMajorVersion tests this instance against another and returns true if this instance is of a smaller "major" varsion.
// e.g. 5.5.36 is NOT a smaller major version as comapred to 5.5.36, but IS as compared to 5.6.9
func (this *Instance) IsSmallerMajorVersion(other *Instance) bool {
	thisMajorVersion := this.MajorVersion()
	otherMajorVersion := other.MajorVersion()
	for i := 0; i < len(thisMajorVersion); i++ {
		this_token, _ := strconv.Atoi(thisMajorVersion[i])
		other_token, _ := strconv.Atoi(otherMajorVersion[i])
		if this_token < other_token {
			return true
		}
		if this_token > other_token {
			return false
		}
	}
	return false
}

// IsSmallerMajorVersionByString cehcks if this instance has a smaller major version number than given one
func (this *Instance) IsSmallerMajorVersionByString(otherVersion string) bool {
	other := &Instance{Version: otherVersion}
	return this.IsSmallerMajorVersion(other)
}

// IsMariaDB checkes whether this is any version of MariaDB
func (this *Instance) IsMariaDB() bool {
	return strings.Contains(this.Version, "MariaDB")
}

// isMaxScale checkes whether this is any version of MaxScale
func (this *Instance) isMaxScale() bool {
	return strings.Contains(this.Version, "maxscale")
}

// IsMaxScale checkes whether this is any type of a binlog server (currently only maxscale)
func (this *Instance) IsBinlogServer() bool {
	if this.isMaxScale() {
		return true
	}
	return false
}

// IsOracleMySQL checkes whether this is an Oracle MySQL distribution
func (this *Instance) IsOracleMySQL() bool {
	if this.IsMariaDB() {
		return false
	}
	if this.isMaxScale() {
		return false
	}
	if this.IsBinlogServer() {
		return false
	}
	return true
}

// IsSlave makes simple heuristics to decide whether this insatnce is a slave of another instance
func (this *Instance) IsSlave() bool {
	return this.MasterKey.Hostname != "" && this.MasterKey.Hostname != "_" && this.MasterKey.Port != 0 && (this.ReadBinlogCoordinates.LogFile != "" || this.UsingGTID())
}

// SlaveRunning returns true when this instance's status is of a replicating slave.
func (this *Instance) SlaveRunning() bool {
	return this.IsSlave() && this.Slave_SQL_Running && this.Slave_IO_Running
}

// SQLThreadUpToDate returns true when the instance had consumed all relay logs.
func (this *Instance) SQLThreadUpToDate() bool {
	return this.ReadBinlogCoordinates.Equals(&this.ExecBinlogCoordinates)
}

// UsingGTID returns true when this slave is currently replicating via GTID (either Oracle or MariaDB)
func (this *Instance) UsingGTID() bool {
	return this.UsingOracleGTID || this.UsingMariaDBGTID
}

// NextGTID returns the next (Oracle) GTID to be executed. Useful for skipping queries
func (this *Instance) NextGTID() (string, error) {
	if this.ExecutedGtidSet == "" {
		return "", fmt.Errorf("No value found in Executed_Gtid_Set; cannot compute NextGTID")
	}

	firstToken := func(s string, delimiter string) string {
		tokens := strings.Split(s, delimiter)
		return tokens[0]
	}
	lastToken := func(s string, delimiter string) string {
		tokens := strings.Split(s, delimiter)
		return tokens[len(tokens)-1]
	}
	// executed GTID set: 4f6d62ed-df65-11e3-b395-60672090eb04:1,b9b4712a-df64-11e3-b391-60672090eb04:1-6
	executedGTIDsFromMaster := lastToken(this.ExecutedGtidSet, ",")
	// executedGTIDsFromMaster: b9b4712a-df64-11e3-b391-60672090eb04:1-6
	executedRange := lastToken(executedGTIDsFromMaster, ":")
	// executedRange: 1-6
	lastExecutedNumberToken := lastToken(executedRange, "-")
	// lastExecutedNumber: 6
	lastExecutedNumber, err := strconv.Atoi(lastExecutedNumberToken)
	if err != nil {
		return "", err
	}
	nextNumber := lastExecutedNumber + 1
	nextGTID := fmt.Sprintf("%s:%d", firstToken(executedGTIDsFromMaster, ":"), nextNumber)
	return nextGTID, nil
}

// AddSlaveKey adds a slave to the list of this instance's slaves.
func (this *Instance) AddSlaveKey(slaveKey *InstanceKey) {
	this.SlaveHosts.AddKey(*slaveKey)
}

// GetNextBinaryLog returns the successive, if any, binary log file to the one given
func (this *Instance) GetNextBinaryLog(binlogCoordinates BinlogCoordinates) (BinlogCoordinates, error) {
	if binlogCoordinates.LogFile == this.SelfBinlogCoordinates.LogFile {
		return binlogCoordinates, fmt.Errorf("Cannot find next binary log for %+v", binlogCoordinates)
	}
	return binlogCoordinates.NextFileCoordinates()
}

// IsSlaveOf returns true if this instance claims to replicate from given master
func (this *Instance) IsSlaveOf(master *Instance) bool {
	return this.MasterKey.Equals(&master.Key)
}

// IsSlaveOf returns true if this i supposed master of given slave
func (this *Instance) IsMasterOf(slave *Instance) bool {
	return slave.IsSlaveOf(this)
}

// CanReplicateFrom uses heursitics to decide whether this instacne can practically replicate from other instance.
// Checks are made to binlog format, version number, binary logs etc.
func (this *Instance) CanReplicateFrom(other *Instance) (bool, error) {
	if this.Key.Equals(&other.Key) {
		return false, fmt.Errorf("instance cannot replicate from itself: %+v", this.Key)
	}
	if !other.LogBinEnabled {
		return false, fmt.Errorf("instance does not have binary logs enabled: %+v", other.Key)
	}
	if other.IsSlave() {
		if !other.LogSlaveUpdatesEnabled {
			return false, fmt.Errorf("instance does not have log_slave_updates enabled: %+v", other.Key)
		}
		// OK for a master to not have log_slave_updates
		// Not OK for a slave, for it has to relay the logs.
	}
	if this.IsSmallerMajorVersion(other) && !this.IsBinlogServer() {
		return false, fmt.Errorf("instance %+v has version %s, which is lower than %s on %+v ", this.Key, this.Version, other.Version, other.Key)
	}
	if this.LogBinEnabled && this.LogSlaveUpdatesEnabled {
		if this.Binlog_format == "STATEMENT" && (other.Binlog_format == "ROW" || other.Binlog_format == "MIXED") {
			return false, fmt.Errorf("Cannot replicate from ROW/MIXED binlog format on %+v to STATEMENT on %+v", other.Key, this.Key)
		}
		if this.Binlog_format == "MIXED" && other.Binlog_format == "ROW" {
			return false, fmt.Errorf("Cannot replicate from ROW binlog format on %+v to MIXED on %+v", other.Key, this.Key)
		}
	}
	if config.Config.VerifyReplicationFilters {
		if other.HasReplicationFilters && !this.HasReplicationFilters {
			return false, fmt.Errorf("%+v has replication filters", other.Key)
		}
	}
	if this.ServerID == other.ServerID && !this.IsBinlogServer() {
		return false, fmt.Errorf("Identical server id: %+v, %+v both have %d", other.Key, this.Key, this.ServerID)
	}
	return true, nil
}

// HasReasonableMaintenanceReplicationLag returns true when the slave lag is reasonable, and maintenance operations should have a green light to go.
func (this *Instance) HasReasonableMaintenanceReplicationLag() bool {
	// Slaves with SQLDelay are a special case
	if this.SQLDelay > 0 {
		return math.AbsInt64(this.SecondsBehindMaster.Int64-int64(this.SQLDelay)) <= int64(config.Config.ReasonableMaintenanceReplicationLagSeconds)
	}
	return this.SecondsBehindMaster.Int64 <= int64(config.Config.ReasonableMaintenanceReplicationLagSeconds)
}

// CanMove returns true if this instance's state allows it to be repositioned. For example,
// if this instance lags too much, it will not be moveable.
func (this *Instance) CanMove() (bool, error) {
	if !this.IsLastCheckValid {
		return false, fmt.Errorf("%+v: last check invalid", this.Key)
	}
	if !this.IsRecentlyChecked {
		return false, fmt.Errorf("%+v: not recently checked", this.Key)
	}
	if !this.Slave_SQL_Running {
		return false, fmt.Errorf("%+v: instance is not replicating", this.Key)
	}
	if !this.Slave_IO_Running {
		return false, fmt.Errorf("%+v: instance is not replicating", this.Key)
	}
	if !this.SecondsBehindMaster.Valid {
		return false, fmt.Errorf("%+v: cannot determine slave lag", this.Key)
	}
	if !this.HasReasonableMaintenanceReplicationLag() {
		return false, fmt.Errorf("%+v: lags too much", this.Key)
	}
	return true, nil
}

// CanMoveAsCoMaster returns true if this instance's state allows it to be repositioned.
func (this *Instance) CanMoveAsCoMaster() (bool, error) {
	if !this.IsLastCheckValid {
		return false, fmt.Errorf("%+v: last check invalid", this.Key)
	}
	if !this.IsRecentlyChecked {
		return false, fmt.Errorf("%+v: not recently checked", this.Key)
	}
	return true, nil
}

// CanMoveViaMatch returns true if this instance's state allows it to be repositioned via pseudo-GTID matching
func (this *Instance) CanMoveViaMatch() (bool, error) {
	if !this.IsLastCheckValid {
		return false, fmt.Errorf("%+v: last check invalid", this.Key)
	}
	if !this.IsRecentlyChecked {
		return false, fmt.Errorf("%+v: not recently checked", this.Key)
	}
	return true, nil
}

// StatusString returns a human readable description of this instance's status
func (this *Instance) StatusString() string {
	if !this.IsLastCheckValid {
		return "last check invalid"
	}
	if !this.IsRecentlyChecked {
		return "not recently checked"
	}
	if this.IsSlave() && !(this.Slave_SQL_Running && this.Slave_IO_Running) {
		return "not replicating"
	}
	if this.IsSlave() && !this.SecondsBehindMaster.Valid {
		return "cannot determine slave lag"
	}
	if this.IsSlave() && this.SecondsBehindMaster.Int64 > int64(config.Config.ReasonableMaintenanceReplicationLagSeconds) {
		return "lags too much"
	}
	return "OK"
}

// HumanReadableDescription returns a simple readable string describing the status, version,
// etc. properties of this instance
func (this *Instance) HumanReadableDescription() string {
	tokens := []string{}
	tokens = append(tokens, this.StatusString())
	tokens = append(tokens, this.Version)
	tokens = append(tokens, this.Binlog_format)
	if this.LogSlaveUpdatesEnabled {
		tokens = append(tokens, ">>")
	}
	if this.UsingGTID() {
		tokens = append(tokens, "GTID")
	}
	if this.UsingPseudoGTID {
		tokens = append(tokens, "P-GTID")
	}
	description := fmt.Sprintf("[%s]", strings.Join(tokens, ","))
	return description
}