package leakybucket

import (
	"encoding/json"
	"fmt"
	"net"
	"strconv"
	"sync/atomic"
	"time"

	//"log"
	"github.com/crowdsecurity/crowdsec/pkg/time/rate"
	"github.com/crowdsecurity/crowdsec/pkg/types"

	//rate "time/rate"

	"github.com/davecgh/go-spew/spew"
	"github.com/goombaio/namegenerator"
	"github.com/prometheus/client_golang/prometheus"
	log "github.com/sirupsen/logrus"
	//"golang.org/x/time/rate"
)

const (
	LIVE = iota
	TIMEMACHINE
)

//the bucket itself
type Leaky struct {
	//action_overflow
	//OverflowAction string
	//bucket actions
	//Actions []string
	Name string
	Mode int //LIVE or TIMEMACHINE
	//the limiter is what holds the proper "leaky aspect", it determines when/if we can pour objects
	Limiter         rate.RateLimiter `json:"-"`
	SerializedState rate.Lstate
	//Queue is used to held the cache of objects in the bucket, it is used to know 'how many' objects we have in buffer.
	Queue *Queue
	//Leaky buckets are receiving message through a chan
	In chan types.Event `json:"-"`
	//Leaky buckets are pushing their overflows through a chan
	Out chan *Queue `json:"-"`
	// shared for all buckets (the idea is to kill this afterwards)
	AllOut     chan types.Event `json:"-"`
	KillSwitch chan bool        `json:"-"`
	//max capacity (for burst)
	Capacity int
	//CacheRatio is the number of elements that should be kept in memory (compared to capacity)
	CacheSize int
	//the unique identifier of the bucket (a hash)
	Mapkey string
	// chan for signaling
	Signal       chan bool `json:"-"`
	Reprocess    bool
	Uuid         string
	First_ts     time.Time
	Last_ts      time.Time
	Ovflw_ts     time.Time
	Total_count  int
	Leakspeed    time.Duration
	BucketConfig *BucketFactory
	Duration     time.Duration
	Pour         func(*Leaky, types.Event) `json:"-"`
	//Profiling when set to true enables profiling of bucket
	Profiling     bool
	timedOverflow bool
	logger        *log.Entry
	//as the rate-limiter is intended for http or such, we need to have a separate mechanism to track 'empty' bucket.
	//we use a go-routine that use waitN to know when the bucket is empty (N would be equal to bucket capacity)
	//as it try to reserves the capacity, we need to cancel it before we can pour in the bucket
	//reservation *rate.Reservation
}

var BucketsPour = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_bucket_pour",
		Help: "How many time an event was poured in this bucket.",
	},
	[]string{"source", "name"},
)

var BucketsOverflow = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_bucket_overflow",
		Help: "How many time this bucket overflowed.",
	},
	[]string{"name"},
)

var BucketsUnderflow = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_bucket_underflow",
		Help: "How many time this bucket has underflowed.",
	},
	[]string{"name"},
)

var BucketsInstanciation = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_bucket_create",
		Help: "How many time this bucket was instanciated.",
	},
	[]string{"name"},
)

func NewLeaky(g BucketFactory) *Leaky {
	g.logger.Tracef("Instantiating live bucket %s", g.Name)
	return FromFactory(g)
}

// Newleaky creates a new leaky bucket from a BucketFactory
// Events created by the bucket (overflow, bucket empty) are sent to a chan defined by BucketFactory
// The leaky bucket implementation is based on rate limiter (see https://godoc.org/golang.org/x/time/rate)
// There's a trick to have an event said when the bucket gets empty to allow its destruction
func FromFactory(g BucketFactory) *Leaky {
	var limiter rate.RateLimiter
	//golang rate limiter. It's mainly intended for http rate limiter
	Qsize := g.Capacity
	if g.CacheSize > 0 {
		//cache is smaller than actual capacity
		if g.CacheSize <= g.Capacity {
			Qsize = g.CacheSize
			//bucket might be counter (infinite size), allow cache limitation
		} else if g.Capacity == -1 {
			Qsize = g.CacheSize
		}
	}
	if g.Capacity == -1 {
		//In this case we allow all events to pass.
		//maybe in the future we could avoid using a limiter
		limiter = &rate.AlwaysFull{}
	} else {
		limiter = rate.NewLimiter(rate.Every(g.leakspeed), g.Capacity)
	}
	if g.Profiling {
		BucketsInstanciation.With(prometheus.Labels{"name": g.Name}).Inc()
	}
	//create the leaky bucket per se
	l := &Leaky{
		Name:         g.Name,
		Limiter:      limiter,
		Uuid:         namegenerator.NewNameGenerator(time.Now().UTC().UnixNano()).Generate(),
		Queue:        NewQueue(Qsize),
		CacheSize:    g.CacheSize,
		Out:          make(chan *Queue, 1),
		AllOut:       g.ret,
		Capacity:     g.Capacity,
		Leakspeed:    g.leakspeed,
		BucketConfig: &g,
		Pour:         Pour,
		Reprocess:    g.Reprocess,
		Profiling:    g.Profiling,
		Mode:         LIVE,
	}
	if l.BucketConfig.Capacity > 0 && l.BucketConfig.leakspeed != time.Duration(0) {
		l.Duration = time.Duration(l.BucketConfig.Capacity+1) * l.BucketConfig.leakspeed
	}
	if l.BucketConfig.duration != time.Duration(0) {
		l.Duration = l.BucketConfig.duration
		l.timedOverflow = true
	}

	return l
}

var LeakyRoutineCount int64

/* for now mimic a leak routine */
func LeakRoutine(l *Leaky) {

	var (
		durationTicker <-chan time.Time = make(<-chan time.Time)
	)

	/*todo : we create a logger at runtime while we want leakroutine to be up asap, might not be a good idea*/
	l.logger = l.BucketConfig.logger.WithFields(log.Fields{"capacity": l.Capacity, "partition": l.Mapkey, "bucket_id": l.Uuid})

	l.Signal <- true
	atomic.AddInt64(&LeakyRoutineCount, 1)
	defer atomic.AddInt64(&LeakyRoutineCount, -1)

	for _, f := range l.BucketConfig.processors {
		err := f.OnBucketInit(l.BucketConfig)
		if err != nil {
			l.logger.Errorf("Problem at bucket initializiation. Bail out %T : %v", f, err)
			close(l.Signal)
			return
		}
	}

	l.logger.Debugf("Leaky routine starting, lifetime : %s", l.Duration)
	defer l.logger.Debugf("Leaky routine exiting")
	for {
		select {
		/*receiving an event*/
		case msg := <-l.In:
			/*the msg var use is confusing and is redeclared in a different type :/*/
			for _, f := range l.BucketConfig.processors {
				msg := f.OnBucketPour(l.BucketConfig)(msg, l)
				// if &msg == nil we stop processing
				if msg == nil {
					goto End
				}
			}
			l.logger.Tracef("Pour event: %s", spew.Sdump(msg))
			l.logger.Debugf("Pouring event.")

			if l.Profiling {
				BucketsPour.With(prometheus.Labels{"name": l.Name, "source": msg.Line.Src}).Inc()
			}
			l.Pour(l, msg) // glue for now
			//Clear cache on behalf of pour
			tmp := time.NewTicker(l.Duration)
			durationTicker = tmp.C
			l.Signal <- true
			defer tmp.Stop()
		/*a kill chan to allow externally killing the leaky routines*/
		case <-l.KillSwitch:
			close(l.Signal)
			return
		/*we overflowed*/
		case ofw := <-l.Out:
			close(l.Signal)
			sig := FormatOverflow(l, ofw)
			l.logger.Tracef("Overflow hooks time : %v", l.BucketConfig.processors)
			for _, f := range l.BucketConfig.processors {
				sig, ofw = f.OnBucketOverflow(l.BucketConfig)(l, sig, ofw)
				if ofw == nil {
					l.logger.Debugf("Overflow has been discard (%T)", f)
					break
				}
			}
			l.logger.Tracef("Overflow event: %s", spew.Sdump(types.Event{Overflow: sig}))
			mt, _ := l.Ovflw_ts.MarshalText()
			l.logger.Tracef("overflow time : %s", mt)
			if l.Profiling {
				BucketsOverflow.With(prometheus.Labels{"name": l.Name}).Inc()
			}
			l.AllOut <- types.Event{Overflow: sig, Type: types.OVFLW, MarshaledTime: string(mt)}
			return
			/*we underflow or reach bucket deadline (timers)*/
		case <-durationTicker:
			l.Ovflw_ts = time.Now()
			close(l.Signal)
			ofw := l.Queue
			sig := types.SignalOccurence{MapKey: l.Mapkey}

			if l.timedOverflow {
				if l.Profiling {
					BucketsOverflow.With(prometheus.Labels{"name": l.Name}).Inc()
				}
				sig = FormatOverflow(l, ofw)
				for _, f := range l.BucketConfig.processors {
					sig, ofw = f.OnBucketOverflow(l.BucketConfig)(l, sig, ofw)
					if ofw == nil {
						l.logger.Debugf("Overflow has been discard (%T)", f)
						break
					}
				}
				l.logger.Infof("Timed Overflow")
			} else {
				l.logger.Debugf("bucket underflow, destroy")
				BucketsUnderflow.With(prometheus.Labels{"name": l.Name}).Inc()

			}
			l.logger.Tracef("Overflow event: %s", spew.Sdump(types.Event{Overflow: sig}))

			l.AllOut <- types.Event{Overflow: sig, Type: types.OVFLW}
			l.logger.Tracef("Returning from leaky routine.")
			return
		}
	End:
	}
}

func Pour(l *Leaky, msg types.Event) {

	l.Total_count += 1
	if l.First_ts.IsZero() {
		l.First_ts = time.Now()
	}
	l.Last_ts = time.Now()
	if l.Limiter.Allow() {
		l.Queue.Add(msg)
	} else {
		l.Ovflw_ts = time.Now()
		l.logger.Debugf("Last event to be poured, bucket overflow.")
		l.Queue.Add(msg)
		l.Out <- l.Queue
	}
}

func FormatOverflow(l *Leaky, queue *Queue) types.SignalOccurence {
	var am string

	l.logger.Debugf("Overflow (start: %s, end: %s)", l.First_ts, l.Ovflw_ts)

	sig := types.SignalOccurence{
		Scenario:      l.Name,
		Bucket_id:     l.Uuid,
		Alert_message: am,
		Start_at:      l.First_ts,
		Stop_at:       l.Ovflw_ts,
		Events_count:  l.Total_count,
		Capacity:      l.Capacity,
		Reprocess:     l.Reprocess,
		Leak_speed:    l.Leakspeed,
		MapKey:        l.Mapkey,
		Sources:       make(map[string]types.Source),
		Labels:        l.BucketConfig.Labels,
	}

	for _, evt := range queue.Queue {
		//either it's a collection of logs, or a collection of past overflows being reprocessed.
		//one overflow can have multiple sources for example
		if evt.Type == types.LOG {
			if _, ok := evt.Meta["source_ip"]; !ok {
				continue
			}
			source_ip := evt.Meta["source_ip"]
			if _, ok := sig.Sources[source_ip]; !ok {
				src := types.Source{}
				src.Ip = net.ParseIP(source_ip)
				if v, ok := evt.Enriched["ASNNumber"]; ok {
					src.AutonomousSystemNumber = v
				}
				if v, ok := evt.Enriched["IsoCode"]; ok {
					src.Country = v
				}
				if v, ok := evt.Enriched["ASNOrg"]; ok {
					src.AutonomousSystemOrganization = v
				}
				if v, ok := evt.Enriched["Latitude"]; ok {
					src.Latitude, _ = strconv.ParseFloat(v, 32)
				}
				if v, ok := evt.Enriched["Longitude"]; ok {
					src.Longitude, _ = strconv.ParseFloat(v, 32)
				}
				if v, ok := evt.Meta["SourceRange"]; ok {
					_, ipNet, err := net.ParseCIDR(v)
					if err != nil {
						l.logger.Errorf("Declared range %s of %s can't be parsed", v, src.Ip.String())
					} else if ipNet != nil {
						src.Range = *ipNet
						l.logger.Tracef("Valid range from %s : %s", src.Ip.String(), src.Range.String())
					}
				}
				sig.Sources[source_ip] = src
				if sig.Source == nil {
					sig.Source = &src
					sig.Source_ip = src.Ip.String()
					sig.Source_AutonomousSystemNumber = src.AutonomousSystemNumber
					sig.Source_AutonomousSystemOrganization = src.AutonomousSystemOrganization
					sig.Source_Country = src.Country
					sig.Source_range = src.Range.String()
					sig.Source_Latitude = src.Latitude
					sig.Source_Longitude = src.Longitude
				}
			}
		} else if evt.Type == types.OVFLW {
			for _, src := range evt.Overflow.Sources {
				if _, ok := sig.Sources[src.Ip.String()]; !ok {
					sig.Sources[src.Ip.String()] = src
					if sig.Source == nil {
						l.logger.Tracef("populating overflow with source : %+v", src)
						src := src //src will be reused, copy before giving pointer
						sig.Source = &src
						sig.Source_ip = src.Ip.String()
						sig.Source_AutonomousSystemNumber = src.AutonomousSystemNumber
						sig.Source_AutonomousSystemOrganization = src.AutonomousSystemOrganization
						sig.Source_Country = src.Country
						sig.Source_range = src.Range.String()
						sig.Source_Latitude = src.Latitude
						sig.Source_Longitude = src.Longitude
					}
				}

			}

		}

		strret, err := json.Marshal(evt.Meta)
		if err != nil {
			l.logger.Errorf("failed to marshal ret : %v", err)
			continue
		}
		if sig.Source != nil {
			sig.Events_sequence = append(sig.Events_sequence, types.EventSequence{
				Source:                              *sig.Source,
				Source_ip:                           sig.Source_ip,
				Source_AutonomousSystemNumber:       sig.Source.AutonomousSystemNumber,
				Source_AutonomousSystemOrganization: sig.Source.AutonomousSystemOrganization,
				Source_Country:                      sig.Source.Country,
				Serialized:                          string(strret),
				Time:                                l.First_ts})
		} else {
			l.logger.Warningf("Event without source ?!")
		}
	}

	if len(sig.Sources) > 1 {
		am = fmt.Sprintf("%d IPs", len(sig.Sources))
	} else if len(sig.Sources) == 1 {
		if sig.Source != nil {
			am = fmt.Sprintf("%s", sig.Source.Ip.String())
		} else {
			am = fmt.Sprintf("??")
		}
	} else {
		am = "UNKNOWN"
	}

	am += fmt.Sprintf(" performed '%s' (%d events over %s) at %s", l.Name, l.Total_count, l.Ovflw_ts.Sub(l.First_ts), l.Ovflw_ts)
	sig.Alert_message = am
	return sig
}