package couchctl

import (
	"context"
	"fmt"
	"sync"
	"time"

	"edge-infra.dev/pkg/lib/fog"

	"github.com/go-logr/logr"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	coordinationv1client "k8s.io/client-go/kubernetes/typed/coordination/v1"
	"k8s.io/client-go/tools/leaderelection"
	"k8s.io/client-go/tools/leaderelection/resourcelock"
)

type PersistenceLeaderElector interface {
	IsLeader() bool
}

type PersistenceLeaderElectorFunc func() bool

func (r PersistenceLeaderElectorFunc) IsLeader() bool {
	return r()
}

type LeaderElection struct {
	mu     sync.RWMutex
	Lock   resourcelock.Interface
	log    logr.Logger
	id     string
	leader bool
}

func NewLeaderElection(cs *coordinationv1client.CoordinationV1Client, namespace, name, id string) *LeaderElection {
	return &LeaderElection{
		id: id,
		Lock: &resourcelock.LeaseLock{
			LeaseMeta: metav1.ObjectMeta{
				Name:      name,
				Namespace: namespace,
			},
			Client:     cs,
			LockConfig: resourcelock.ResourceLockConfig{Identity: id},
		},
		log: fog.WithLabels(fog.New(), "id", id),
	}
}

func (l *LeaderElection) IsLeader() bool {
	l.mu.RLock()
	defer l.mu.RUnlock()
	return l.leader
}

func (l *LeaderElection) OnNewLeader(ctx context.Context, cb func(leader bool)) {
	leaderelection.RunOrDie(ctx, leaderelection.LeaderElectionConfig{
		Lock:            l.Lock,
		ReleaseOnCancel: true,
		LeaseDuration:   15 * time.Second,
		RenewDeadline:   10 * time.Second,
		RetryPeriod:     2 * time.Second,
		Callbacks: leaderelection.LeaderCallbacks{
			OnStartedLeading: func(_ context.Context) {
				l.log.Info("leader election started")
			},
			OnStoppedLeading: func() {
				l.log.Info("leader election stopped")
			},
			OnNewLeader: func(identity string) {
				l.mu.Lock()
				defer l.mu.Unlock()
				leader := identity == l.id
				l.leader = leader
				if cb != nil {
					cb(leader)
				}
				l.log.Info(fmt.Sprintf("is new leader: %v", leader))
			},
		},
	})
}