package main

import (
	"bytes"
	"time"

	"github.com/nonoo/kappanhang/log"
)

const maxSerialFrameLength = 80 // Max. frame length according to Hamlib.

type serialStream struct {
	common streamCommon

	serialPort serialPortStruct
	tcpsrv     serialTCPSrv

	sendSeq uint16

	readFromSerialPort struct {
		buf          bytes.Buffer
		frameStarted bool
		frameTimeout *time.Timer
	}

	deinitNeededChan   chan bool
	deinitFinishedChan chan bool
}

func (s *serialStream) send(d []byte) error {
	s.common.pkt0.sendSeqLock()
	defer s.common.pkt0.sendSeqUnlock()

	l := byte(len(d))
	p := append([]byte{0x15 + l, 0x00, 0x00, 0x00, 0x00, 0x00, byte(s.common.pkt0.sendSeq), byte(s.common.pkt0.sendSeq >> 8),
		byte(s.common.localSID >> 24), byte(s.common.localSID >> 16), byte(s.common.localSID >> 8), byte(s.common.localSID),
		byte(s.common.remoteSID >> 24), byte(s.common.remoteSID >> 16), byte(s.common.remoteSID >> 8), byte(s.common.remoteSID),
		0xc1, l, 0x00, byte(s.sendSeq >> 8), byte(s.sendSeq)}, d...)
	if err := s.common.send(p); err != nil {
		return err
	}
	s.common.pkt0.sendSeq++
	s.sendSeq++
	return nil
}

func (s *serialStream) sendOpenClose(close bool) error {
	s.common.pkt0.sendSeqLock()
	defer s.common.pkt0.sendSeqUnlock()

	var magic byte
	if close {
		magic = 0x00
	} else {
		magic = 0x05
	}

	p := []byte{0x16, 0x00, 0x00, 0x00, 0x00, 0x00, byte(s.common.pkt0.sendSeq), byte(s.common.pkt0.sendSeq >> 8),
		byte(s.common.localSID >> 24), byte(s.common.localSID >> 16), byte(s.common.localSID >> 8), byte(s.common.localSID),
		byte(s.common.remoteSID >> 24), byte(s.common.remoteSID >> 16), byte(s.common.remoteSID >> 8), byte(s.common.remoteSID),
		0xc0, 0x01, 0x00, byte(s.sendSeq >> 8), byte(s.sendSeq), magic}
	if err := s.common.send(p); err != nil {
		return err
	}
	s.common.pkt0.sendSeq++
	s.sendSeq++
	return nil
}

func (s *serialStream) handleRead(r []byte) {
	if len(r) >= 22 {
		if r[16] == 0xc1 && r[0]-0x15 == r[17] {
			r = r[21:]

			// log.Print("fromradio ", r)

			s.serialPort.write <- r
			if s.tcpsrv.toClient != nil {
				s.tcpsrv.toClient <- r
			}
		}
	}

}

func (s *serialStream) gotDataForRadio(r []byte) {
	for len(r) > 0 && !s.readFromSerialPort.frameStarted {
		if s.readFromSerialPort.buf.Len() > 1 {
			s.readFromSerialPort.buf.Reset()
		}
		if s.readFromSerialPort.buf.Len() == 0 {
			// Cut until we find the frame start byte.
			for r[0] != 0xfe {
				r = r[1:]
				if len(r) == 0 {
					return
				}
			}
			// Found the first start byte.
			s.readFromSerialPort.buf.WriteByte(r[0])
			r = r[1:]
		}
		if len(r) > 0 && s.readFromSerialPort.buf.Len() == 1 {
			if r[0] != 0xfe {
				s.readFromSerialPort.buf.Reset()
				r = r[1:]
			} else {
				// Found the second start byte.
				s.readFromSerialPort.buf.WriteByte(r[0])
				r = r[1:]
				s.readFromSerialPort.frameTimeout.Reset(100 * time.Millisecond)
				s.readFromSerialPort.frameStarted = true
			}
		}
	}

	for _, b := range r {
		s.readFromSerialPort.buf.WriteByte(b)
		if b == 0xfc || b == 0xfd || s.readFromSerialPort.buf.Len() == maxSerialFrameLength {
			// log.Print("toradio ", s.readFromSerialPort.buf.Bytes())

			if err := s.send(s.readFromSerialPort.buf.Bytes()); err != nil {
				reportError(err)
			}
			if !s.readFromSerialPort.frameTimeout.Stop() {
				<-s.readFromSerialPort.frameTimeout.C
			}
			s.readFromSerialPort.buf.Reset()
			s.readFromSerialPort.frameStarted = false
			break
		}
	}
}

func (s *serialStream) loop() {
	for {
		select {
		case r := <-s.common.readChan:
			s.handleRead(r)
		case r := <-s.serialPort.read:
			s.gotDataForRadio(r)
		case r := <-s.tcpsrv.fromClient:
			s.gotDataForRadio(r)
		case <-s.readFromSerialPort.frameTimeout.C:
			s.readFromSerialPort.buf.Reset()
			s.readFromSerialPort.frameStarted = false
		case <-s.deinitNeededChan:
			s.deinitFinishedChan <- true
			return
		}
	}
}

func (s *serialStream) start(devName string) error {
	if err := s.serialPort.init(devName); err != nil {
		return err
	}

	if err := s.common.sendPkt3(); err != nil {
		return err
	}
	if err := s.common.waitForPkt4Answer(); err != nil {
		return err
	}
	if err := s.common.sendPkt6(); err != nil {
		return err
	}
	if err := s.common.waitForPkt6Answer(); err != nil {
		return err
	}

	log.Print("stream started")

	s.common.pkt7.startPeriodicSend(&s.common, 1, false)
	s.common.pkt0.startPeriodicSend(&s.common)

	if err := s.sendOpenClose(false); err != nil {
		return err
	}

	if err := s.tcpsrv.start(); err != nil {
		return err
	}

	s.deinitNeededChan = make(chan bool)
	s.deinitFinishedChan = make(chan bool)

	s.readFromSerialPort.frameTimeout = time.NewTimer(0)
	<-s.readFromSerialPort.frameTimeout.C

	go s.loop()
	return nil
}

func (s *serialStream) init() error {
	if err := s.common.init("serial", 50002); err != nil {
		return err
	}
	return nil
}

func (s *serialStream) deinit() {
	if s.common.conn != nil {
		_ = s.sendOpenClose(true)
	}

	s.tcpsrv.stop()
	s.serialPort.deinit()

	if s.deinitNeededChan != nil {
		s.deinitNeededChan <- true
		<-s.deinitFinishedChan
	}
	s.common.deinit()
}