package core

import (
	"bufio"
	"fmt"
	"git.timovolkmann.de/gyrogpsc/ublox"
	"github.com/sirupsen/logrus"
	"go.bug.st/serial"
	"net"
	"os"
	"time"
)

type Collector interface {
	Collect()
	Stop()
	OutChannel() chan interface{}
}

type CollectorType string

const (
	SERIAL CollectorType = "SERIAL_COLLECTOR"
	TCP    CollectorType = "TCP_COLLECTOR"
)

var tcpSingleton *tcpCollector

func NewCollector(config *Configuration, typ CollectorType) Collector {
	var coll Collector
	switch typ {
	case SERIAL:
		coll = newSerial(config)
	case TCP:
		if tcpSingleton == nil {
			tcpSingleton = newTcp(config)
		}
		coll = tcpSingleton
	default:
		panic("selected collector type not implemented")
	}
	return coll
}

type serialCollector struct {
	out    chan interface{}
	config *Configuration
}

func (s *serialCollector) OutChannel() chan interface{} {
	return s.out
}

func (s *serialCollector) Collect() {
	go func(ch chan interface{}) {
		logrus.Println("start serial collector")
		mode := &serial.Mode{
			BaudRate: 115200,
		}
		port, err := serial.Open(s.config.Collectors.SerialCollectorPort, mode)
		if err != nil {
			logrus.Warn("can't open serial port:", err)
			//if e, ok := err.(serial.PortError); ok && e.Code() == serial.PortBusy {
			for i := 3; i < 20; i = i + 2 {
				logrus.Warnf("try again in -> %vms", i*i)
				time.Sleep(time.Millisecond * time.Duration(i*i))
				port, err = serial.Open(s.config.Collectors.SerialCollectorPort, mode)
				if err == nil {
					break
				}
			}
			if err != nil {
				logrus.Errorln(err)
			}
			//}
		}

		decoder := ublox.NewDecoder(port)

		defer func() {
			if r := recover(); r != nil {
				logrus.Infoln("stopped collecting channel: serial")
			}
			logrus.Infoln("close serial port")
			port.Close()
		}()
		maxSkip := 0
	loop:
		for {
			//logrus.Trace("serial collector running")
			meas, err2 := decoder.Decode()
			if err2 != nil {
				if err2.Error() == "NMEA not implemented" {
					continue
				}
				logrus.Println("serial read err:", err2)
				break
			}
			select {
			case ch <- meas:
				maxSkip = 0
			default:
				logrus.Traceln("skip collecting serial messages")
				if maxSkip >= 10 {
					break loop
				}
				maxSkip++
			}

		}
		logrus.Println("serial collector stopped")
	}(s.out)
}

func (s *serialCollector) Stop() {
	defer func() {
		if recover() != nil {
			logrus.Debugln("channel already closed")
		}
	}()
loop:
	for {
		select {
		case <-s.out:
			logrus.Debugln("waiting")
		default:
			logrus.Debugln("breaking")
			break loop
		}
	}
	close(s.out)
	s.out = make(chan interface{}, 16)
}

func newSerial(config *Configuration) *serialCollector {
	return &serialCollector{
		out:    make(chan interface{}, 16),
		config: config,
	}
}

type tcpCollector struct {
	out    chan interface{}
	config *Configuration
}

func (t *tcpCollector) OutChannel() chan interface{} {
	return t.out
}

func (t *tcpCollector) Collect() {
	logrus.Info("starting tcp collector")
}

func (t *tcpCollector) Stop() {
	defer func() {
		if recover() != nil {
			logrus.Debugln("channel already closed")
		}
	}()
loop:
	for {
		select {
		case <-t.out:
			logrus.Debugln("waiting")
		default:
			logrus.Debugln("breaking")
			break loop
		}
	}
	close(t.out)
	t.out = make(chan interface{}, 16)
}

func newTcp(config *Configuration) *tcpCollector {
	//func newTcp(proc Processor, config *Configuration) *tcpCollector {
	logrus.Println("listen for tcp connections on port", config.Collectors.TcpCollectorPort)

	listener, err := net.Listen("tcp", config.Collectors.TcpCollectorPort)
	if err != nil {
		fmt.Println("Error listening:", err)
		//os.Exit(1)
	}
	c := &tcpCollector{
		out:    make(chan interface{}, 16),
		config: config,
	}
	go func() {
		for {
			// Listen for an incoming connection.
			conn, err := listener.Accept()
			if err != nil {
				logrus.Errorln("Error accepting: ", err.Error())
				os.Exit(1)
			}
			logrus.Infoln("new incoming tcp connection...")

			// Handle connections in a new goroutine.
			go c.connectionHandler(conn)
		}
	}()
	return c
}

// handles incoming tcp connections.
func (t *tcpCollector) connectionHandler(conn net.Conn) {
	defer func() {
		if r := recover(); r != nil {
			logrus.Infoln("stopped collecting tcp: panic")
		}
		logrus.Infoln("close connection")
		conn.Close()
	}()

	sc := bufio.NewScanner(conn)
	skipped := 0
	//loop:
	for sc.Scan() {
		// Read the incoming connection into the buffer.
		res := append([]byte{}, sc.Bytes()...)
		if err2 := sc.Err(); err2 != nil {
			logrus.Warn("lost tcp link:", err2)
			break
		}
		select {
		case t.out <- res:
			skipped = 0
		default:
			logrus.Traceln("skip collecting tcp messages")
			//if skipped >= 10 {
			//	break loop
			//}
			skipped++
		}
	}
}