// InitMaster breaks slaves replication, get the current MySQL replication
// position, insert a row in the reparent_journal table, and returns
// the replication position
func (agent *ActionAgent) InitMaster(ctx context.Context) (string, error) {
	// we need to insert something in the binlogs, so we can get the
	// current position. Let's just use the mysqlctl.CreateReparentJournal commands.
	cmds := mysqlctl.CreateReparentJournal()
	if err := agent.MysqlDaemon.ExecuteSuperQueryList(cmds); err != nil {
		return "", err
	}

	// get the current replication position
	pos, err := agent.MysqlDaemon.MasterPosition()
	if err != nil {
		return "", err
	}

	// Set the server read-write, from now on we can accept real
	// client writes. Note that if semi-sync replication is enabled,
	// we'll still need some slaves to be able to commit
	// transactions.
	if err := agent.MysqlDaemon.SetReadOnly(false); err != nil {
		return "", err
	}

	// Change our type to master if not already
	if _, err := agent.TopoServer.UpdateTabletFields(ctx, agent.TabletAlias, func(tablet *topodatapb.Tablet) error {
		tablet.Type = topodatapb.TabletType_MASTER
		tablet.HealthMap = nil
		return nil
	}); err != nil {
		return "", err
	}

	agent.initReplication = true
	return replication.EncodePosition(pos), nil
}

// PopulateReparentJournal adds an entry into the reparent_journal table.
func (agent *ActionAgent) PopulateReparentJournal(ctx context.Context, timeCreatedNS int64, actionName string, masterAlias *topodatapb.TabletAlias, position string) error {
	pos, err := replication.DecodePosition(position)
	if err != nil {
		return err
	}
	cmds := mysqlctl.CreateReparentJournal()
	cmds = append(cmds, mysqlctl.PopulateReparentJournal(timeCreatedNS, actionName, topoproto.TabletAliasString(masterAlias), pos))

	return agent.MysqlDaemon.ExecuteSuperQueryList(cmds)
}

// InitMaster enables writes and returns the replication position.
func (agent *ActionAgent) InitMaster(ctx context.Context) (string, error) {
	if err := agent.lock(ctx); err != nil {
		return "", err
	}
	defer agent.unlock()

	// Initializing as master implies undoing any previous "do not replicate".
	agent.setSlaveStopped(false)

	// we need to insert something in the binlogs, so we can get the
	// current position. Let's just use the mysqlctl.CreateReparentJournal commands.
	cmds := mysqlctl.CreateReparentJournal()
	if err := agent.MysqlDaemon.ExecuteSuperQueryList(ctx, cmds); err != nil {
		return "", err
	}

	// get the current replication position
	pos, err := agent.MysqlDaemon.MasterPosition()
	if err != nil {
		return "", err
	}

	// If using semi-sync, we need to enable it before going read-write.
	if *enableSemiSync {
		if err := agent.enableSemiSync(true); err != nil {
			return "", err
		}
	}

	// Set the server read-write, from now on we can accept real
	// client writes. Note that if semi-sync replication is enabled,
	// we'll still need some slaves to be able to commit transactions.
	if err := agent.MysqlDaemon.SetReadOnly(false); err != nil {
		return "", err
	}

	// Change our type to master if not already
	if _, err := agent.TopoServer.UpdateTabletFields(ctx, agent.TabletAlias, func(tablet *topodatapb.Tablet) error {
		tablet.Type = topodatapb.TabletType_MASTER
		return nil
	}); err != nil {
		return "", err
	}

	// and refresh our state
	agent.initReplication = true
	if err := agent.refreshTablet(ctx, "InitMaster"); err != nil {
		return "", err
	}
	return replication.EncodePosition(pos), nil
}

// PopulateReparentJournal adds an entry into the reparent_journal table.
func (agent *ActionAgent) PopulateReparentJournal(ctx context.Context, timeCreatedNS int64, actionName string, masterAlias *pb.TabletAlias, pos myproto.ReplicationPosition) error {
	cmds := mysqlctl.CreateReparentJournal()
	cmds = append(cmds, mysqlctl.PopulateReparentJournal(timeCreatedNS, actionName, topoproto.TabletAliasString(masterAlias), pos))

	return agent.MysqlDaemon.ExecuteSuperQueryList(cmds)
}