// Package cluster provides functionality for monitoring etcd cluster health
// and recovering the cluster if quorum is lost.
package cluster

import (
	"context"
	"time"

	"go.etcd.io/etcd/api/v3/etcdserverpb"

	"edge-infra.dev/pkg/sds/lib/etcd/client/retry"
)

// Cluster represents an etcd cluster
type Cluster struct {
	endpoint     string
	maxUnhealthy time.Duration
	Status
}

// Status represents the health status of a resource
type Status struct {
	lastUnhealthy time.Time
	lastHealthy   time.Time
}

func New(endpoint string, maxUnhealthy time.Duration, status Status) Cluster {
	return Cluster{
		endpoint,
		maxUnhealthy,
		status,
	}
}

// InitializeStatus initializes the status times to ensure there are no inaccurate
// time comparrisons
func (c *Cluster) InitializeStatus() {
	c.ResetTimer()
}

// UpdateStatus checks the status of the etcd cluster and updates the last healthy/unhealthy time
// based on the result
func (c *Cluster) UpdateStatus(ctx context.Context, client retry.Retrier) {
	resp, err := client.SafeStatus(ctx, c.endpoint)
	if err != nil || len(resp.Errors) != 0 {
		c.lastUnhealthy = time.Now()
		return
	}

	c.lastHealthy = time.Now()
}

// IsResetRequired checks if the stored state for the etcd cluster indicates that a reset is required
func (c *Cluster) IsResetRequired() bool {
	if c.IsHealthy() {
		return false
	}
	return time.Since(c.lastHealthy) > c.maxUnhealthy
}

// IsHealthy checks if the stored state for the etcd cluster indicate that it is healthy
func (s *Status) IsHealthy() bool {
	return s.lastHealthy.After(s.lastUnhealthy)
}

// ResetTimer will reset the status timers so that both lastHealthy and lastUnhealthy
// are time.Now()
func (s *Status) ResetTimer() {
	now := time.Now()
	s.lastHealthy = now
	s.lastUnhealthy = now
}

// GetAlarms will retrieve all etcd cluster alarms of types: CORRUPT, NOSPACE
func GetAlarms(ctx context.Context, client retry.Retrier) []*etcdserverpb.AlarmMember {
	resp, err := client.SafeAlarmList(ctx)
	if err != nil {
		return []*etcdserverpb.AlarmMember{}
	}

	return resp.Alarms
}