package cluster

import (
	"context"
	"errors"
)

// Cluster - The Cluster object manages the state of the cluster for a particular node
type Cluster struct {
	stateMachine FSM
	stop         chan struct{}
	done         chan struct{}
	Callbacks    LeaderCallbacks
}

type LeaderCallbacks struct {
	// OnStartedLeading is called when a LeaderElector client starts leading
	OnStartedLeading func(context.Context)
	// OnStoppedLeading is called when a LeaderElector client stops leading
	OnStoppedLeading func()
	// OnNewLeader is called when the client observes a leader that is
	// not the previously observed leader. This includes the first observed
	// leader when the client starts.
	OnNewLeader func(string)
}

// InitCluster - Will attempt to initialise all of the required settings for the cluster
func InitCluster(callbacks LeaderCallbacks) (*Cluster, error) {
	if callbacks.OnStartedLeading == nil {
		return nil, errors.New("OnStartedLeading is nil")
	}
	if callbacks.OnStoppedLeading == nil {
		return nil, errors.New("OnStoppedLeading is nil")
	}
	if callbacks.OnNewLeader == nil {
		return nil, errors.New("OnNewLeader is nil")
	}
	c := &Cluster{
		stop:      make(chan struct{}, 1),
		done:      make(chan struct{}, 1),
		Callbacks: callbacks,
	}

	return c, nil
}