package core

import (
	"container/heap"
	"github.com/reugn/go-streams"
	ext "github.com/reugn/go-streams/extension"
	"github.com/reugn/go-streams/flow"
	"github.com/sirupsen/logrus"
	"runtime"
	"sort"
	"sync"
	"time"
)

type pipelineReplay struct {
	stopChan   chan struct{}
	replayChan chan interface{}
}

func (r pipelineReplay) Stop() {
	r.stopChan <- struct{}{}
	close(r.replayChan)
}

func NewReplayPipeline(p Publisher, t *Tracking) *pipelineReplay {
	r := &pipelineReplay{make(chan struct{}), nil}
	// set pipeline up and wire it together
	r.replayChan = r.channelFromTracking(t)
	collNet := ext.NewChanSource(r.replayChan)
	dataSanitizer := flow.NewMap(replaySanitizeFunc(), 1)
	//flowReorder := NewRearranger()

	flowJson := flow.NewMap(jsonFunc, 1)
	sinkPub := newPublishSink(p)

	// wire up and execute
	//go collNet.Via(dataSanitizer).Via(flowJson).To(sinkPub)
	go collNet.Via(dataSanitizer).Via(flowJson).To(sinkPub)
	return r
}

func logFunc() flow.MapFunc {
	return func(i interface{}) interface{} {
		//s := i.(SensorData)
		logrus.Debugln("logfunc", i)
		return i
	}
}

func (p *pipelineReplay) channelFromTracking(t *Tracking) chan interface{} {
	ch := make(chan interface{})
	sort.Slice(t.Data, func(i, j int) bool { return t.Data[i].Servertime.Before(t.Data[j].Servertime) })
	go func() {
		lastTs := t.Data[0].Servertime.UnixNano()
		lastTsNow := time.Now().UTC().UnixNano()
		i := 0
	br:
		for i <= len(t.Data)-1 {
			durationSinceLastEvent := t.Data[i].Servertime.UnixNano() - lastTs
			timeCounter := time.Now().UTC().UnixNano() - lastTsNow
			if timeCounter >= durationSinceLastEvent {
				select {
				case <-p.stopChan:
					logrus.Debugln("replay stopped")
					break br
				case ch <- &(t.Data[i]):
				}
				logrus.Traceln("replay tracking: ", t.Data[i])
				lastTs = t.Data[i].Servertime.UnixNano()
				lastTsNow = time.Now().UTC().UnixNano()
				i++
			}
		}

		logrus.Infoln("replay: tracking replay finished")
	}()
	return ch
}

func replaySanitizeFunc() flow.MapFunc {
	var lastTimeOffsetIphone int64
	var lastTimeOffsetUblox int64

	return func(i interface{}) interface{} {
		sd := i.(*SensorData)

		if !(sd.Timestamp.IsZero() || sd.Timestamp.Nanosecond() == 0) {
			lastOffset := sd.Servertime.UnixNano() - sd.Timestamp.UnixNano()
			if sd.Source() == SOURCE_TCP {
				lastTimeOffsetIphone = lastOffset
			}
			if sd.Source() == SOURCE_SERIAL {
				lastTimeOffsetUblox = lastOffset
			}
		} else {
			var lastOff int64
			if sd.Source() == SOURCE_TCP {
				lastOff = lastTimeOffsetIphone
			}
			if sd.Source() == SOURCE_SERIAL {
				lastOff = lastTimeOffsetUblox
			}
			sd.Timestamp = sd.Servertime.Add(time.Duration(lastOff))
		}
		if sd.Servertime.Before(time.Unix(1608422400, 0)) && sd.Speed != 0 && sd.Source() == SOURCE_SERIAL {
			sd.Speed = sd.Speed * 3.6
		}
		return sd
	}
}

func NewRearranger() *rearranger {
	rearran := &rearranger{
		queue: &flow.PriorityQueue{},
		in:    make(chan interface{}),
		out:   make(chan interface{}),
		done:  make(chan struct{}),
	}
	go rearran.receive()
	go rearran.emit()
	return rearran
}

type rearranger struct {
	sync.RWMutex
	queue           *flow.PriorityQueue
	in              chan interface{}
	out             chan interface{}
	done            chan struct{}
	lastTimestamp   int64
	lastTimeNanoNow int64
}

// Verify rearranger satisfies the Flow interface.
var _ streams.Flow = (*rearranger)(nil)

func (r *rearranger) In() chan<- interface{} {
	return r.in
}

func (r *rearranger) Out() <-chan interface{} {
	return r.out
}

func (r *rearranger) Via(flow streams.Flow) streams.Flow {
	go r.transmit(flow)
	return flow
}

func (r *rearranger) To(sink streams.Sink) {
	r.transmit(sink)
}

// submit emitted windows to the next Inlet
func (r *rearranger) transmit(inlet streams.Inlet) {
	for elem := range r.Out() {
		inlet.In() <- elem
	}
	close(inlet.In())
}

func (r *rearranger) receive() {
	for elem := range r.in {
		ts := r.timestamp(elem)
		//if r.lastTimestamp == 0 {
		//	r.lastTimestamp = ts //- (500 * 1e+6) // Delay
		//	r.lastTimeNanoNow = time.Now().UTC().UnixNano()
		//}
		item := flow.NewItem(elem, ts, 0)
		r.Lock()
		heap.Push(r.queue, item)
		r.Unlock()
		logrus.Debugln("item recieved.")
		runtime.Gosched()
	}
	close(r.done)
	close(r.out)
}

// emit pops data from ordered priority queue
func (r *rearranger) emit() {
	for {
		if r.queue.Len() <= 10 {
			continue
		}
		tnow := time.Now().UTC().UnixNano()
		logrus.Debugln("popping item: ")

		r.Lock()
		item := heap.Pop(r.queue).(*flow.Item)
		r.Unlock()
		v := item.Msg.(*SensorData)
		r.out <- v
		r.lastTimestamp = v.Timestamp.UnixNano()
		r.lastTimeNanoNow = tnow
		select {
		case <-r.done:
			return
		default:
		}
	}
}

func (r *rearranger) timestamp(elem interface{}) int64 {
	v := elem.(*SensorData)
	return v.Timestamp.UnixNano()
}