package pktqueue

import (
	"github.com/nareix/av"
)

type timePacket struct {
	time float64
	av.Packet
}

type stream struct {
	pkts []timePacket
	lastDuration float64
}

func (self *stream) Read(flush bool) (ok bool, pkt timePacket) {
	if len(self.pkts) > 1 {
		ok = true
		pkt := self.pkts[0]
		pkt.Duration = self.pkts[1].time - self.pkts[0].time
		self.lastDuration = pkt.Duration
		self.pkts = self.pkts[1:]
	} else if len(self.pkts) == 1 && flush {
		ok = true
		pkt := self.pkts[0]
		pkt.Duration = self.lastDuration
		self.pkts = self.pkts[1:]
	}
	return
}

type Queue struct {
	streams []*stream
	Poll func() error
	err error
	time float64
}

func (self *Queue) CurrentTime() float64 {
	return self.time
}

func (self *Queue) Alloc(n int) {
	self.streams = make([]*stream, n)
}

func (self *Queue) Clear() {
	self.Alloc(len(self.streams))
	self.time = 0.0
}

func (self *Queue) ReadPacket() (i int, pkt av.Packet, err error) {
	for {
		flush := self.err != nil
		var tpkt timePacket
		var ok bool
		var stream *stream
		for i, stream = range self.streams {
			if ok, tpkt = stream.Read(flush); ok {
				break
			}
		}
		if ok {
			pkt = tpkt.Packet
			self.time = tpkt.time
			return
		} else {
			if self.err == nil {
				self.err = self.Poll()
			} else {
				err = self.err
				return
			}
		}
	}
	return
}

func (self *Queue) WriteTimePacket(i int, time float64, pkt av.Packet) {
	stream := self.streams[i]
	stream.pkts = append(stream.pkts, timePacket{Packet: pkt, time: time})
}