// Package tracer is responsible for tracing the events that occur in the honeypots
package tracer

import (
	log "github.com/sirupsen/logrus"
	"sync"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
)

// Workers is the number of workers that will
const Workers = 5

type Event struct {
	DateTime        string
	RemoteAddr      string
	Protocol        string
	Command         string
	CommandOutput   string
	Status          string
	Msg             string
	ID              string
	Environ         string
	User            string
	Password        string
	Client          string
	Headers         string
	Cookies         string
	UserAgent       string
	HostHTTPRequest string
	Body            string
	HTTPMethod      string
	RequestURI      string
	Description     string
	SourceIp        string
	SourcePort      string
}

type (
	Protocol int
	Status   int
)

const (
	HTTP Protocol = iota
	SSH
	TCP
)

func (protocol Protocol) String() string {
	return [...]string{"HTTP", "SSH", "TCP"}[protocol]
}

const (
	Start Status = iota
	End
	Stateless
	Interaction
)

func (status Status) String() string {
	return [...]string{"Start", "End", "Stateless", "Interaction"}[status]
}

type Strategy func(event Event)

type Tracer interface {
	TraceEvent(event Event)
}

type tracer struct {
	strategy        Strategy
	eventsChan      chan Event
	eventsTotal     prometheus.Counter
	eventsSSHTotal  prometheus.Counter
	eventsTCPTotal  prometheus.Counter
	eventsHTTPTotal prometheus.Counter
}

var lock = &sync.Mutex{}
var singleton *tracer

func GetInstance(defaultStrategy Strategy) *tracer {
	if singleton == nil {
		lock.Lock()
		defer lock.Unlock()
		// This is to prevent expensive lock operations every time the GetInstance method is called
		if singleton == nil {
			singleton = &tracer{
				strategy:   defaultStrategy,
				eventsChan: make(chan Event, Workers),
				eventsTotal: promauto.NewCounter(prometheus.CounterOpts{
					Namespace: "beelzebub",
					Name:      "events_total",
					Help:      "The total number of events",
				}),
				eventsSSHTotal: promauto.NewCounter(prometheus.CounterOpts{
					Namespace: "beelzebub",
					Name:      "ssh_events_total",
					Help:      "The total number of SSH events",
				}),
				eventsTCPTotal: promauto.NewCounter(prometheus.CounterOpts{
					Namespace: "beelzebub",
					Name:      "tcp_events_total",
					Help:      "The total number of TCP events",
				}),
				eventsHTTPTotal: promauto.NewCounter(prometheus.CounterOpts{
					Namespace: "beelzebub",
					Name:      "http_events_total",
					Help:      "The total number of HTTP events",
				}),
			}

			for i := 0; i < Workers; i++ {
				go func(i int) {
					log.Debug("Trace worker: ", i)
					for event := range singleton.eventsChan {
						singleton.strategy(event)
					}
				}(i)
			}
		}
	}

	return singleton
}

func (tracer *tracer) setStrategy(strategy Strategy) {
	tracer.strategy = strategy
}

func (tracer *tracer) TraceEvent(event Event) {
	event.DateTime = time.Now().UTC().Format(time.RFC3339)

	tracer.eventsChan <- event

	tracer.updatePrometheusCounters(event.Protocol)
}

func (tracer *tracer) updatePrometheusCounters(protocol string) {
	switch protocol {
	case HTTP.String():
		tracer.eventsHTTPTotal.Inc()
	case SSH.String():
		tracer.eventsSSHTotal.Inc()
	case TCP.String():
		tracer.eventsTCPTotal.Inc()
	}
	tracer.eventsTotal.Inc()
}