// vim:ts=4:sts=4:sw=4:noet:tw=72

package ircd

import (
	"crypto/rand"
	"crypto/tls"
	"fmt"
	"net"
	"os"
	"strings"
	"time"

	"code.dnix.de/an/conf"
	"code.dnix.de/an/irc"
	"code.dnix.de/an/xlog"
)

const (
	CHANLIMIT  = 1024
	CHANNELLEN = 200
	TOPICLEN   = 1024
)

var myinfo string = "%s %s/%s * *"

var isupport string = "CASEMAPPING=rfc1459 CHANTYPES=# NICKLEN=32 MODES=1 PREFIX=(ohv)@%+"

type Server struct {
	localq  chan *irc.Message
	remoteq chan *irc.Message

	addq chan Client
	delq chan Client

	host     string
	info     string
	software string
	version  string
	created  string
	motd     string

	cluster *ClusterConnector

	opers map[string]string

	clients map[string]Client
	clModes map[string]string

	chUsers  map[string]map[string]string
	chTopics map[string]string
	chModes  map[string]map[string]bool

	config     *conf.ConfigFile
	configPath string

	packetsTransferred float64
	connectionsCount   float64

	authCallback func(name, pass string) bool
}

func NewServer(configPath, software, version string) *Server {
	sv := &Server{software: software, version: version,
		created: time.Now().String()}

	sv.localq = make(chan *irc.Message, 65536)
	sv.remoteq = make(chan *irc.Message, 65536)

	sv.addq = make(chan Client, 128)
	sv.delq = make(chan Client, 128)

	sv.opers = make(map[string]string)

	sv.clients = make(map[string]Client)
	sv.clModes = make(map[string]string)

	sv.chUsers = make(map[string]map[string]string)
	sv.chTopics = make(map[string]string)
	sv.chModes = make(map[string]map[string]bool)

	sv.configPath = configPath
	sv.loadConfig()

	loglevel, _ := sv.config.GetInt("system", "loglevel")
	xlog.Init(loglevel)

	sv.host, _ = sv.config.GetString("server", "host")
	sv.info, _ = sv.config.GetString("server", "info")
	sv.motd, _ = sv.config.GetString("server", "motd")

	urls, _ := sv.config.GetString("cluster", "urls")
	sv.cluster = NewClusterConnector(urls, false)

	nicks, _ := sv.config.GetString("control", "a")
	for _, nick := range strings.Split(nicks, ",") {
		sv.opers[nick] = "a"
	}
	nicks, _ = sv.config.GetString("control", "o")
	for _, nick := range strings.Split(nicks, ",") {
		sv.opers[nick] = "o"
	}

	sv.packetsTransferred = 0
	sv.connectionsCount = 0

	return sv
}

func (sv *Server) SetAuthCallback(authCB func(name, pass string) bool) {
	sv.authCallback = authCB
}

func (sv *Server) Run() {
	xlog.Info("%s/%s", sv.software, sv.version)
	go monitoringRun(sv)
	laddr, err := sv.config.GetString("net", "listen")
	if err == nil {
		go sv.listen(laddr)
	}
	tls := true
	pem, err := sv.config.GetString("tls", "pem")
	if err != nil {
		tls = false
	}
	key, err := sv.config.GetString("tls", "key")
	if err != nil {
		tls = false
	}
	laddr, err = sv.config.GetString("net", "listen_tls")
	if err == nil && tls {
		go sv.listenTls(laddr, pem, key)
	}
	for {
		err = sv.dispatcher()
		if err != nil {
			xlog.Error("Dispatcher in panic: %s", err.Error())
		}
	}
}

func (sv *Server) Dispatch(msg *irc.Message) {
	sv.localq <- msg
}

func (sv *Server) AddClient(cl Client) {
	sv.addq <- cl
}

func (sv *Server) DelClient(cl Client) {
	sv.delq <- cl
}

func (sv *Server) listen(laddr string) {
	listen, err := net.Listen("tcp", laddr)
	if err != nil {
		xlog.Fatal(err.Error())
		os.Exit(-1)
	}
	for {
		time.Sleep(10 * time.Millisecond)
		conn, err := listen.Accept()
		if err != nil {
			xlog.Error(err.Error())
		} else {
			NewRemoteClient(sv, conn)
			sv.connectionsCount++
		}
	}
}

func (sv *Server) listenTls(laddr, pem, key string) {
	cert, err := tls.LoadX509KeyPair(pem, key)
	if err != nil {
		xlog.Fatal(err.Error())
	}
	cfg := tls.Config{Certificates: []tls.Certificate{cert}}
	cfg.Rand = rand.Reader
	listen, err := tls.Listen("tcp", laddr, &cfg)
	if err != nil {
		xlog.Fatal(err.Error())
	}
	for {
		time.Sleep(10 * time.Millisecond)
		conn, err := listen.Accept()
		if err != nil {
			xlog.Error(err.Error())
		} else {
			NewRemoteClient(sv, conn)
			sv.connectionsCount++
		}
	}
}

func (sv *Server) dispatcher() (err error) {
	defer func() {
		if r := recover(); r != nil {
			var ok bool
			err, ok = r.(error)
			if !ok {
				err = fmt.Errorf("pkg: %v", r)
			}
		}
	}()
	for {
		select {
		case msg := <-sv.localq:
			sv.recvMsg(msg)
			sv.packetsTransferred++
		case msg := <-sv.remoteq:
			if sv.localOrigin(msg) {
				continue
			}
			sv.recvMsg(msg)
			sv.packetsTransferred++
		case cl := <-sv.addq:
			sv.addClient(cl)
		case cl := <-sv.delq:
			sv.delClient(cl)
		default:
			time.Sleep(100 * time.Microsecond)
		}
	}
	return
}

func (sv *Server) loadConfig() {
	cfg, err := conf.ReadConfigFile(sv.configPath)
	if err != nil {
		xlog.Fatal("Can't read config file (%s)", err.Error())
		os.Exit(-1)
	}
	sv.config = cfg
}

func (sv *Server) addClient(cl Client) {
	clid := strings.ToLower(cl.Name())
	if _, exists := sv.clients[clid]; exists {
		cl.Receive(irc.M(sv.host, ERR_NICKNAMEINUSE, cl.Name(), "Nickname is already in use"))
		go func() {
			time.Sleep(5 * time.Second)
			cl.Register(false)
		}()
		xlog.Info("Client registration failed: '%s' (client exists)", clid)
		return
	}
	if !sv.authCallback(cl.Name(), cl.Password()) {
		cl.Receive(irc.M(sv.host, ERR_PASSWDMISMATCH, "", "Password incorrect"))
		go func() {
			time.Sleep(5 * time.Second)
			cl.Register(false)
		}()
		xlog.Info("Client registration failed: '%s' (wrong password)", clid)
		return
	}
	sv.clients[clid] = cl
	sv.sendLogon(cl.Name())
	cl.Register(true)
	sv.cluster.Subscribe(clid, sv.remoteq)
	xlog.Info("Client registered: '%s'", clid)
	xlog.Info("Server has %d client(s)", len(sv.clients))
}

func (sv *Server) delClient(cl Client) {
	clid := strings.ToLower(cl.Name())
	sv.cluster.Unsubscribe(clid)
	cl.Destroy()
	for chid, _ := range sv.chUsers {
		if _, exists := sv.chUsers[chid][clid]; exists {
			sv.channelRemoveUser(chid, clid)
			sv.sendMsg(irc.M(cl.Name(), "PART", chid, "quit"))
		}
	}
	delete(sv.clients, clid)
	xlog.Info("Client deleted: '%s'", clid)
	xlog.Info("Server has %d client(s)", len(sv.clients))
}

func (sv *Server) recvMsg(msg *irc.Message) {
	cmd := msg.Cmd
	clid := strings.ToLower(msg.Pre)
	hook, exists := svCommandHooks[cmd]
	if !exists {
		sv.sendReply(msg.Pre, ERR_UNKNOWNCOMMAND, cmd, "Unknown command")
		return
	}
	nm := hook.NeedMode
	if nm != "" {
		if m, isoper := sv.opers[clid]; !isoper {
			sv.sendReply(msg.Pre, ERR_NOPRIVILEGES, cmd, "Permission denied: You're not a server operator")
			return
		} else {
			if strings.Index(nm, m) == -1 {
				sv.sendReply(msg.Pre, ERR_NOPRIVILEGES, cmd, "Permission denied: You're not a server admin")
				return
			}
		}
	}
	argc := len(msg.Args)
	if argc < hook.MinArgs {
		sv.sendReply(msg.Pre, ERR_NEEDMOREPARAMS, cmd, "Not enough parameters")
		return
	}
	if hook.NeedTrail && msg.Trail == "" {
		sv.sendReply(msg.Pre, ERR_NEEDMOREPARAMS, cmd, "Not enough parameters")
		return
	}
	hook.HookFn(sv, msg)
}

func (sv *Server) sendMsg(msg *irc.Message) {
	sv.deliverMsg(msg)
	sv.forwardMsg(msg)
}

func (sv *Server) deliverMsg(msg *irc.Message) {
	if strings.HasPrefix(msg.Args[0], "#") {
		chid := strings.ToLower(msg.Args[0])
		if _, exists := sv.chUsers[chid]; !exists {
			sv.sendReply(msg.Pre, ERR_NOSUCHNICK, msg.Args[0], "No such nick/channel")
			return
		}
		for clid, _ := range sv.chUsers[chid] {
			if strings.ToLower(msg.Pre) == clid && msg.Cmd == "PRIVMSG" {
				continue
			}
			if cl, exists := sv.clients[clid]; exists {
				cl.Receive(msg)
			}
		}
	} else {
		clid := strings.ToLower(msg.Args[0])
		if _, exists := sv.clients[clid]; !exists {
			sv.sendReply(msg.Pre, ERR_NOSUCHNICK, msg.Args[0], "No such nick/channel")
			return
		}
		cl := sv.clients[clid]
		cl.Receive(msg)
	}
}

func (sv *Server) forwardMsg(msg *irc.Message) {
	if sv.localOrigin(msg) {
		sv.cluster.Publish(msg)
	}
}

func (sv *Server) sendReply(nick, cmd, args, trail string) {
	clid := strings.ToLower(nick)
	if _, exists := sv.clients[clid]; !exists {
		return
	}
	cl := sv.clients[clid]
	if args != "" {
		args = nick + " " + args
	} else {
		args = nick
	}
	cl.Receive(irc.M(sv.host, cmd, args, trail))
}

func (sv *Server) localOrigin(msg *irc.Message) bool {
	_, localClient := sv.clients[strings.ToLower(msg.Pre)]
	localServer := (msg.Pre == sv.host)
	return localClient || localServer
}

func (sv *Server) sendLogon(nick string) {
	sv.sendReply(nick, RPL_WELCOME, "", "Willkommen!")
	sv.sendReply(nick, RPL_YOURHOST, "",
		fmt.Sprintf("Your host is %s, running on %s/%s",
			sv.host, sv.software, sv.version))
	sv.sendReply(nick, RPL_CREATED, "",
		fmt.Sprintf("This server was created %s", sv.created))
	sv.sendReply(nick, RPL_MYINFO, "",
		fmt.Sprintf(myinfo, sv.host, sv.software, sv.version))
	sv.sendReply(nick, RPL_ISUPPORT, "",
		isupport+" are supported by this server")
	sv.sendReply(nick, RPL_MOTDSTART, "",
		fmt.Sprintf("- %s Message of the day -", sv.host))
	for _, line := range strings.Split(sv.motd, "\n") {
		sv.sendReply(nick, RPL_MOTD, "", fmt.Sprintf("- %s", line))
	}
	sv.sendReply(nick, RPL_ENDOFMOTD, "", "End of MOTD command")
	if m, isoper := sv.opers[strings.ToLower(nick)]; isoper {
		switch m {
		case "a":
			sv.sendReply(nick, RPL_YOUREOPER, "", "You are now a server admin")
		case "o":
			sv.sendReply(nick, RPL_YOUREOPER, "", "You are now a server operator")
		}
	}
}

func (sv *Server) channelNames(nick, ch string) {
	chid := strings.ToLower(ch)
	if _, exists := sv.chUsers[chid]; !exists {
		return
	}
	names := ""
	for clid, _ := range sv.chUsers[chid] {
		name := sv.clients[clid].Name()
		if names != "" {
			names += " "
		}
		modeFlags := "ohv"
		modeChars := "@%+"
		for i, mf := range modeFlags {
			if _, exists := sv.chModes[chid][string(mf)+" "+clid]; exists {
				name = string(modeChars[i]) + name
				break
			}
		}
		names = names + name
	}
	chunks := len(strings.Split(names, " "))/8 + 1
	nameList := strings.SplitN(names, " ", chunks)
	for _, nameSlice := range nameList {
		sv.sendReply(nick, RPL_NAMEREPLY, "= "+ch, nameSlice)
	}
	sv.sendReply(nick, RPL_ENDOFNAMES, ch, "End of /NAMES list")
}

func (sv *Server) channelCheckMode(chid, mode string) bool {
	if _, exists := sv.chModes[chid]; !exists {
		return false
	}
	if _, exists := sv.chModes[chid][mode]; !exists {
		return false
	}
	return true
}

func (sv *Server) channelCheckPerm(chid, clid, modes string) bool {
	for _, m := range modes {
		if sv.channelCheckMode(chid, string(m)+" "+clid) {
			return true
		}
	}
	return false
}

func (sv *Server) channelRemoveUser(chid, clid string) {
	if _, exists := sv.chUsers[chid]; !exists {
		return
	}
	delete(sv.chUsers[chid], clid)
	delete(sv.chModes[chid], "o "+clid)
	delete(sv.chModes[chid], "h "+clid)
	delete(sv.chModes[chid], "v "+clid)
	if len(sv.chUsers[chid]) == 0 {
		sv.cluster.Unsubscribe(chid)
		delete(sv.chUsers, chid)
		delete(sv.chTopics, chid)
		delete(sv.chModes, chid)
	}
}