package main

import (
	"fmt"
	"log"
	"net"
	"os"
	"regexp"
	"strings"
	"sync"
	"time"

	"github.com/aler9/gortsplib"
	"gopkg.in/alecthomas/kingpin.v2"
)

var Version string = "v0.0.0"

const (
	_READ_TIMEOUT  = 5 * time.Second
	_WRITE_TIMEOUT = 5 * time.Second
)

type trackFlow int

const (
	_TRACK_FLOW_RTP trackFlow = iota
	_TRACK_FLOW_RTCP
)

type track struct {
	rtpPort  int
	rtcpPort int
}

type streamProtocol int

const (
	_STREAM_PROTOCOL_UDP streamProtocol = iota
	_STREAM_PROTOCOL_TCP
)

func (s streamProtocol) String() string {
	if s == _STREAM_PROTOCOL_UDP {
		return "udp"
	}
	return "tcp"
}

type program struct {
	protocols   map[streamProtocol]struct{}
	rtspPort    int
	rtpPort     int
	rtcpPort    int
	publishUser string
	publishPass string
	preScript   string
	postScript  string
	mutex       sync.RWMutex
	rtspl       *serverTcpListener
	rtpl        *serverUdpListener
	rtcpl       *serverUdpListener
	clients     map[*serverClient]struct{}
	publishers  map[string]*serverClient
}

func newProgram() (*program, error) {
	kingpin.CommandLine.Help = "rtsp-simple-server " + Version + "\n\n" +
		"RTSP server."

	argVersion := kingpin.Flag("version", "print rtsp-simple-server version").Bool()
	argProtocolsStr := kingpin.Flag("protocols", "supported protocols").Default("udp,tcp").String()
	argRtspPort := kingpin.Flag("rtsp-port", "port of the RTSP TCP listener").Default("8554").Int()
	argRtpPort := kingpin.Flag("rtp-port", "port of the RTP UDP listener").Default("8000").Int()
	argRtcpPort := kingpin.Flag("rtcp-port", "port of the RTCP UDP listener").Default("8001").Int()
	argPublishUser := kingpin.Flag("publish-user", "optional username required to publish").Default("").String()
	argPublishPass := kingpin.Flag("publish-pass", "optional password required to publish").Default("").String()
	argPreScript := kingpin.Flag("pre-script", "optional script to run on client connect").Default("").String()
	argPostScript := kingpin.Flag("post-script", "optional script to run on client disconnect").Default("").String()

	kingpin.Parse()

	version := *argVersion
	protocolsStr := *argProtocolsStr
	rtspPort := *argRtspPort
	rtpPort := *argRtpPort
	rtcpPort := *argRtcpPort
	publishUser := *argPublishUser
	publishPass := *argPublishPass
	preScript := *argPreScript
	postScript := *argPostScript

	if version == true {
		fmt.Println("rtsp-simple-server " + Version)
		os.Exit(0)
	}

	if rtspPort == 0 {
		return nil, fmt.Errorf("rtsp port not provided")
	}

	if rtpPort == 0 {
		return nil, fmt.Errorf("rtp port not provided")
	}

	if rtcpPort == 0 {
		return nil, fmt.Errorf("rtcp port not provided")
	}

	if (rtpPort % 2) != 0 {
		return nil, fmt.Errorf("rtp port must be even")
	}

	if rtcpPort != (rtpPort + 1) {
		return nil, fmt.Errorf("rtcp port must be rtp port plus 1")
	}

	protocols := make(map[streamProtocol]struct{})
	for _, proto := range strings.Split(protocolsStr, ",") {
		switch proto {
		case "udp":
			protocols[_STREAM_PROTOCOL_UDP] = struct{}{}

		case "tcp":
			protocols[_STREAM_PROTOCOL_TCP] = struct{}{}

		default:
			return nil, fmt.Errorf("unsupported protocol: %s", proto)
		}
	}
	if len(protocols) == 0 {
		return nil, fmt.Errorf("no protocols provided")
	}

	if publishUser != "" {
		if !regexp.MustCompile("^[a-zA-Z0-9]+$").MatchString(publishUser) {
			return nil, fmt.Errorf("publish username must be alphanumeric")
		}
	}

	if publishPass != "" {
		if !regexp.MustCompile("^[a-zA-Z0-9]+$").MatchString(publishPass) {
			return nil, fmt.Errorf("publish password must be alphanumeric")
		}
	}

	if publishUser != "" && publishPass == "" || publishUser == "" && publishPass != "" {
		return nil, fmt.Errorf("publish username and password must be both filled")
	}

	log.Printf("rtsp-simple-server %s", Version)

	p := &program{
		protocols:   protocols,
		rtspPort:    rtspPort,
		rtpPort:     rtpPort,
		rtcpPort:    rtcpPort,
		publishUser: publishUser,
		publishPass: publishPass,
		preScript:   preScript,
		postScript:  postScript,
		clients:     make(map[*serverClient]struct{}),
		publishers:  make(map[string]*serverClient),
	}

	var err error

	p.rtpl, err = newServerUdpListener(p, rtpPort, _TRACK_FLOW_RTP)
	if err != nil {
		return nil, err
	}

	p.rtcpl, err = newServerUdpListener(p, rtcpPort, _TRACK_FLOW_RTCP)
	if err != nil {
		return nil, err
	}

	p.rtspl, err = newServerTcpListener(p)
	if err != nil {
		return nil, err
	}

	return p, nil
}

func (p *program) run() {
	go p.rtpl.run()
	go p.rtcpl.run()
	go p.rtspl.run()

	infty := make(chan struct{})
	<-infty
}

func (p *program) forwardTrack(path string, id int, flow trackFlow, frame []byte) {
	for c := range p.clients {
		if c.path == path && c.state == _CLIENT_STATE_PLAY {
			if c.streamProtocol == _STREAM_PROTOCOL_UDP {
				if flow == _TRACK_FLOW_RTP {
					p.rtpl.chanWrite <- &udpWrite{
						addr: &net.UDPAddr{
							IP:   c.ip,
							Port: c.streamTracks[id].rtpPort,
						},
						buf: frame,
					}
				} else {
					p.rtcpl.chanWrite <- &udpWrite{
						addr: &net.UDPAddr{
							IP:   c.ip,
							Port: c.streamTracks[id].rtcpPort,
						},
						buf: frame,
					}
				}

			} else {
				c.chanWrite <- &gortsplib.InterleavedFrame{
					Channel: trackToInterleavedChannel(id, flow),
					Content: frame,
				}
			}
		}
	}
}

func main() {
	p, err := newProgram()
	if err != nil {
		log.Fatal("ERR: ", err)
	}

	p.run()
}