// Purge removes the Agent's state from the Registry
func (a *Agent) Purge() {
	// Continue heartbeating the agent's machine state while attempting to
	// stop all the locally-running jobs
	purged := make(chan bool)
	go a.heartbeatAgent(a.ttl, purged)

	a.state.Lock()
	scheduled := a.state.ScheduledJobs()
	a.state.Unlock()

	machID := a.Machine.State().ID
	for _, jobName := range scheduled {
		log.Infof("Unloading Job(%s) from local machine", jobName)
		a.unloadJob(jobName)
		log.Infof("Unscheduling Job(%s) from local machine", jobName)
		a.registry.ClearJobTarget(jobName, machID)
	}

	// Jobs have been stopped, the heartbeat can stop
	close(purged)

	log.Info("Removing Agent from Registry")
	if err := a.registry.RemoveMachineState(machID); err != nil {
		log.Errorf("Failed to remove Machine %s from Registry: %s", machID, err.Error())
	}
}

func (eh *EventHandler) HandleEventJobOffered(ev event.Event) {
	jo := ev.Payload.(job.JobOffer)
	log.Infof("EventJobOffered(%s): verifying ability to run Job", jo.Job.Name)

	if !jo.OfferedTo(eh.agent.Machine().State().ID) {
		log.Infof("EventJobOffered(%s): not offered to this machine", jo.Job.Name)
		return
	}

	eh.agent.state.Lock()
	defer eh.agent.state.Unlock()

	// Everything we check against could change over time, so we track all
	// offers starting here for future bidding even if we can't bid now
	eh.agent.state.TrackOffer(jo)
	eh.agent.state.TrackJob(&jo.Job)

	if !eh.agent.AbleToRun(&jo.Job) {
		log.Infof("EventJobOffered(%s): not all criteria met, not bidding", jo.Job.Name)
		return
	}

	log.Infof("EventJobOffered(%s): passed all criteria, submitting JobBid", jo.Job.Name)
	eh.agent.Bid(jo.Job.Name)
}

func (eh *EventHandler) HandleEventMachineRemoved(ev event.Event) {
	machID := ev.Payload.(string)
	mutex := eh.engine.registry.LockMachine(machID, eh.engine.machine.State().ID)
	if mutex == nil {
		log.V(1).Infof("EventMachineRemoved(%s): failed to lock Machine, ignoring event", machID)
		return
	}
	defer mutex.Unlock()

	jobs := getJobsScheduledToMachine(eh.engine.registry, machID)

	for _, j := range jobs {
		log.Infof("EventMachineRemoved(%s): clearing UnitState(%s)", machID, j.Name)
		err := eh.engine.registry.RemoveUnitState(j.Name)
		if err != nil {
			log.Errorf("Failed removing UnitState(%s) from Registry: %v", j.Name, err)
		}

		log.Infof("EventMachineRemoved(%s): unscheduling Job(%s)", machID, j.Name)
		eh.engine.registry.ClearJobTarget(j.Name, machID)
	}

	for _, j := range jobs {
		log.Infof("EventMachineRemoved(%s): re-publishing JobOffer(%s)", machID, j.Name)
		eh.engine.OfferJob(j)
	}
	eh.engine.clust.machineRemoved(machID)
}

// JobScheduledLocally clears all state related to the indicated
// job's offers/bids before attempting to load and possibly start
// the job. The ability to run the job will be revalidated before
// loading, and unscheduled if such validation fails.
func (a *Agent) JobScheduledLocally(jobName string) {
	a.state.Lock()
	defer a.state.Unlock()

	log.Infof("Dropping offer and bid for Job(%s) from cache", jobName)
	a.state.PurgeOffer(jobName)

	j := a.fetchJob(jobName)
	if j == nil {
		log.Errorf("Failed to fetch Job(%s)", jobName)
		return
	}

	if !a.ableToRun(j) {
		log.Infof("Unable to run locally-scheduled Job(%s), unscheduling", jobName)
		a.registry.ClearJobTarget(jobName, a.Machine.State().ID)
		a.state.PurgeJob(jobName)
		return
	}

	a.loadJob(j)

	log.Infof("Bidding for all possible peers of Job(%s)", j.Name)
	a.bidForPossiblePeers(j.Name)

	ts, _ := a.registry.GetJobTargetState(j.Name)
	if ts == nil || *ts != job.JobStateLaunched {
		return
	}

	log.Infof("Job(%s) loaded, now starting it", j.Name)
	a.startJobUnlocked(j.Name)
}

func (m *SystemdManager) removeUnit(name string) {
	log.Infof("Unlinking systemd unit %s from target %s", name, m.Target.Name())
	link := m.getLocalPath(path.Join(m.Target.Name()+".wants", name))
	syscall.Unlink(link)

	file := m.getLocalPath(name)
	log.Infof("Removing systemd unit file %s", file)
	syscall.Unlink(file)
}

func (eh *EventHandler) HandleEventJobBidSubmitted(ev event.Event) {
	jb := ev.Payload.(job.JobBid)

	err := eh.engine.ResolveJobOffer(jb.JobName, jb.MachineID)
	if err == nil {
		log.Infof("EventJobBidSubmitted(%s): successfully scheduled Job to Machine(%s)", jb.JobName, jb.MachineID)
	} else {
		log.Infof("EventJobBidSubmitted(%s): failed to schedule Job to Machine(%s)", jb.JobName, jb.MachineID)
	}
}

func (eh *EventHandler) HandleCommandLoadJob(ev event.Event) {
	jobName := ev.Payload.(string)

	j := eh.engine.registry.GetJob(jobName)
	if j == nil {
		log.Infof("CommandLoadJob(%s): asked to offer job that could not be found")
		return
	}

	log.Infof("CommandLoadJob(%s): publishing JobOffer", jobName)
	eh.engine.OfferJob(*j)
}

func (eh *EventHandler) HandleEventJobScheduled(ev event.Event) {
	jobName := ev.Payload.(string)
	target := ev.Context.(string)

	if target != eh.agent.Machine.State().ID {
		log.Infof("EventJobScheduled(%s): Job scheduled to other Machine(%s), informing Agent", jobName, target)
		eh.agent.JobScheduledElsewhere(jobName)
	} else {
		log.Infof("EventJobScheduled(%s): Job scheduled here, informing Agent", jobName)
		eh.agent.JobScheduledLocally(jobName)
	}
}

// JobScheduledElsewhere clears all state related to the indicated
// job before bidding for all oustanding jobs that can be run locally.
func (a *Agent) JobScheduledElsewhere(jobName string) {
	a.state.Lock()
	defer a.state.Unlock()

	log.Infof("Dropping offer and bid for Job(%s) from cache", jobName)
	a.state.PurgeOffer(jobName)

	log.Infof("Purging Job(%s) data from cache", jobName)
	a.state.PurgeJob(jobName)

	log.Infof("Checking outstanding job offers")
	a.bidForPossibleJobs()
}

// JobUnscheduled attempts to unload the indicated job only
// if it were scheduled here in the first place, otherwise
// the event is ignored. If unloading is necessary, all jobs
// that can be run locally will also be bid upon.
func (a *Agent) JobUnscheduled(jobName string) {
	a.state.Lock()
	defer a.state.Unlock()

	if !a.state.ScheduledHere(jobName) {
		log.V(1).Infof("Job(%s) not scheduled here, ignoring", jobName)
		return
	}

	log.Infof("Unloading Job(%s)", jobName)
	a.unloadJob(jobName)

	log.Infof("Checking outstanding JobOffers")
	a.bidForPossibleJobs()
}

func getConfig(flagset *flag.FlagSet, file string) (*config.Config, error) {
	if _, err := os.Stat(file); err != nil {
		glog.Infof("Config file %s does not appear to exist - ignoring")
		file = ""
	}

	opts := globalconf.Options{
		EnvPrefix:  "FLEET_",
		ConfigFile: file,
	}
	gconf, err := globalconf.NewWithOptions(opts)
	if err != nil {
		return nil, err
	}

	gconf.ParseSet("", flagset)

	cfg := config.NewConfig()
	cfg.Verbosity = (*flagset.Lookup("verbosity")).Value.(flag.Getter).Get().(int)
	cfg.EtcdServers = (*flagset.Lookup("etcd_servers")).Value.(flag.Getter).Get().(stringSlice)
	cfg.BootId = (*flagset.Lookup("boot_id")).Value.(flag.Getter).Get().(string)
	cfg.PublicIP = (*flagset.Lookup("public_ip")).Value.(flag.Getter).Get().(string)
	cfg.RawMetadata = (*flagset.Lookup("metadata")).Value.(flag.Getter).Get().(string)
	cfg.UnitPrefix = (*flagset.Lookup("unit_prefix")).Value.(flag.Getter).Get().(string)
	cfg.AgentTTL = (*flagset.Lookup("agent_ttl")).Value.(flag.Getter).Get().(string)

	return cfg, nil
}

// Instruct the Agent to stop the provided Job and
// all of its peers
func (a *Agent) StopJob(jobName string) {
	log.Infof("Stopping Job(%s)", jobName)
	a.systemd.StopJob(jobName)
	a.ReportJobState(jobName, nil)

	a.state.Lock()
	reversePeers := a.state.GetJobsByPeer(jobName)
	a.state.DropPeersJob(jobName)
	a.state.DropJobConflicts(jobName)
	a.state.Unlock()

	for _, peer := range reversePeers {
		log.Infof("Stopping Peer(%s) of Job(%s)", peer, jobName)
		a.registry.StopJob(peer)
	}
}

func (e *Engine) ResolveJobOffer(jobName string, machID string) error {
	log.V(1).Infof("Attempting to lock JobOffer(%s)", jobName)
	mutex := e.registry.LockJobOffer(jobName, e.machine.State().ID)

	if mutex == nil {
		log.V(1).Infof("Could not lock JobOffer(%s)", jobName)
		return errors.New("Could not lock JobOffer")
	}
	defer mutex.Unlock()

	log.V(1).Infof("Claimed JobOffer(%s)", jobName)

	err := e.registry.ResolveJobOffer(jobName)
	if err != nil {
		log.Errorf("Failed resolving JobOffer(%s): %v", jobName, err)
		return err
	}

	err = e.registry.ScheduleJob(jobName, machID)
	if err != nil {
		log.Errorf("Failed scheduling Job(%s): %v", jobName, err)
		return err
	}

	log.Infof("Scheduled Job(%s) to Machine(%s)", jobName, machID)
	return nil
}

func (e *Engine) OfferJob(j job.Job) error {
	log.V(1).Infof("Attempting to lock Job(%s)", j.Name)

	mutex := e.registry.LockJob(j.Name, e.machine.State().ID)
	if mutex == nil {
		log.V(1).Infof("Could not lock Job(%s)", j.Name)
		return errors.New("Could not lock Job")
	}
	defer mutex.Unlock()

	log.V(1).Infof("Claimed Job(%s)", j.Name)

	machineIDs, err := e.partitionCluster(&j)
	if err != nil {
		log.Errorf("Failed partitioning cluster for Job(%s): %v", j.Name, err)
		return err
	}

	offer := job.NewOfferFromJob(j, machineIDs)

	err = e.registry.CreateJobOffer(offer)
	if err == nil {
		log.Infof("Published JobOffer(%s)", offer.Job.Name)
	}

	return err
}

func (self *Engine) OfferJob(j job.Job) error {
	log.V(2).Infof("Attempting to lock Job(%s)", j.Name)

	mutex := self.lockJob(j.Name)
	if mutex == nil {
		log.V(1).Infof("Could not lock Job(%s)", j.Name)
		return errors.New("Could not lock Job")
	}
	defer mutex.Unlock()

	log.V(1).Infof("Claimed Job", j.Name)

	machineBootIds, err := self.partitionCluster(&j)
	if err != nil {
		log.Errorf("Failed partitioning cluster for Job(%s): %v", j.Name, err)
		return err
	}

	offer := job.NewOfferFromJob(j, machineBootIds)

	log.V(2).Infof("Publishing JobOffer(%s)", offer.Job.Name)
	self.registry.CreateJobOffer(offer)
	log.Infof("Published JobOffer(%s)", offer.Job.Name)

	return nil
}

func (self *Engine) ResolveJobOffer(jobName string, machBootId string) error {
	log.V(2).Infof("Attempting to lock JobOffer(%s)", jobName)
	mutex := self.lockJobOffer(jobName)

	if mutex == nil {
		log.V(2).Infof("Could not lock JobOffer(%s)", jobName)
		return errors.New("Could not lock JobOffer")
	}
	defer mutex.Unlock()

	log.V(2).Infof("Claimed JobOffer(%s)", jobName)

	log.V(2).Infof("Resolving JobOffer(%s), scheduling to Machine(%s)", jobName, machBootId)
	err := self.registry.ResolveJobOffer(jobName)
	if err != nil {
		log.Errorf("Failed resolving JobOffer(%s): %v", jobName, err)
		return err
	}

	err = self.registry.ScheduleJob(jobName, machBootId)
	if err != nil {
		log.Errorf("Failed scheduling Job(%s): %v", jobName, err)
		return err
	}

	log.Infof("Scheduled Job(%s) to Machine(%s)", jobName, machBootId)
	return nil
}

func (m *SystemdManager) stopUnit(name string) {
	if stat, err := m.Systemd.StopUnit(name, "replace"); err != nil {
		log.Errorf("Failed to stop systemd unit %s: %v", name, err)
	} else {
		log.Infof("Stopped systemd unit %s(%s)", name, stat)
	}
}

func (eh *EventHandler) HandleEventUnitStateUpdated(ev event.Event) {
	jobName := ev.Context.(string)
	state := ev.Payload.(*unit.UnitState)

	if state == nil {
		log.Infof("EventUnitStateUpdated(%s): received nil UnitState object", jobName)
		state, _ = eh.agent.systemd.GetUnitState(jobName)
	}

	log.Infof("EventUnitStateUpdated(%s): pushing state (loadState=%s, activeState=%s, subState=%s) to Registry", jobName, state.LoadState, state.ActiveState, state.SubState)

	// FIXME: This should probably be set in the underlying event-generation code
	ms := eh.agent.Machine().State()
	state.MachineState = &ms

	eh.agent.ReportUnitState(jobName, state)
}

// Determine if the Agent can run the provided Job
func (a *Agent) ableToRun(j *job.Job) bool {
	if !a.verifyJob(j) {
		log.V(1).Infof("Failed to verify Job(%s)", j.Name)
		return false
	}

	requirements := j.Requirements()
	if len(requirements) == 0 {
		log.V(1).Infof("Job(%s) has no requirements", j.Name)
	}

	log.Infof("Job(%s) has requirements: %s", j.Name, requirements)

	metadata := j.RequiredTargetMetadata()
	log.V(1).Infof("Job(%s) requires machine metadata: %v", j.Name, metadata)
	ms := a.Machine.State()
	if !machine.HasMetadata(&ms, metadata) {
		log.Infof("Unable to run Job(%s), local Machine metadata insufficient", j.Name)
		return false
	}

	if tgt, ok := j.RequiredTarget(); ok && !a.Machine.State().MatchID(tgt) {
		log.Infof("Agent does not meet machine target requirement for Job(%s)", j.Name)
		return false
	}

	peers := j.Peers()
	if len(peers) > 0 {
		log.V(1).Infof("Asserting required Peers %v of Job(%s) are scheduled locally", peers, j.Name)
		for _, peer := range peers {
			if !a.peerScheduledHere(j.Name, peer) {
				log.Infof("Required Peer(%s) of Job(%s) is not scheduled locally", peer, j.Name)
				return false
			}
		}
	} else {
		log.V(1).Infof("Job(%s) has no peers to worry about", j.Name)
	}

	if conflicted, conflictedJobName := a.HasConflict(j.Name, j.Conflicts()); conflicted {
		log.Infof("Job(%s) has conflict with Job(%s)", j.Name, conflictedJobName)
		return false
	}

	return true
}

// Submit a bid for the given Job
func (a *Agent) bid(jobName string) {
	log.Infof("Submitting JobBid for Job(%s)", jobName)

	jb := job.NewBid(jobName, a.Machine.State().ID)
	a.registry.SubmitJobBid(jb)

	a.state.TrackBid(jb.JobName)
}