package main

import (
	"bytes"
	"fmt"
	"io"
	"libnmdc"
	"net"
	"strings"
	"time"
)

type Server struct {
	eventChan        chan Event
	running          bool
	name             string
	client           *Client
	channel          Channel // Single blessed channel
	upstreamLauncher libnmdc.HubConnectionOptions
	upstream         *libnmdc.HubConnection
	motd             string
}

func NewServer(name string, upstream libnmdc.HubAddress) *Server {
	self := libnmdc.NewUserInfo("")
	self.ClientTag = APP_DESCRIPTION

	return &Server{eventChan: make(chan Event),
		name:   name,
		client: nil,
		motd:   "Connected to " + name,
		upstreamLauncher: libnmdc.HubConnectionOptions{
			Address: upstream,
			Self:    *self,
		},
		channel: Channel{
			clientMap: make(map[string]*Client),
			modeMap:   make(map[string]*ClientMode),
		},
	}
}

func (s *Server) RunClient(conn net.Conn) {

	s.client = &Client{
		connection: conn,
		connected:  true,
		server:     s, // FIXME circular reference!
	}

	// Send the connection handshake
	s.client.sendGlobalMessage(s.motd)

	// Can't connect to the upstream server yet, until we've recieved a nick.

	for {
		buf := make([]byte, CLIENT_READ_BUFFSIZE)
		s.client.connection.SetReadDeadline(time.Now().Add(time.Second * CLIENT_READ_TIMEOUT_SEC))
		ln, err := s.client.connection.Read(buf)
		if err != nil {
			if err == io.EOF {
				s.client.disconnect()
				return // FIXME cleanup
			}
			continue
		}

		rawLines := buf[:ln]
		rawLines = bytes.Replace(rawLines, []byte("\r\n"), []byte("\n"), -1)
		rawLines = bytes.Replace(rawLines, []byte("\r"), []byte("\n"), -1)
		lines := bytes.Split(rawLines, []byte("\n"))
		for _, line := range lines {
			if len(line) > 0 {

				// Client sent a command
				fields := strings.Fields(string(line))
				if len(fields) < 1 {
					return
				}

				if strings.HasPrefix(fields[0], ":") {
					fields = fields[1:]
				}

				s.handleCommand(strings.ToUpper(fields[0]), fields[1:])
			}
		}
	}

}

func (s *Server) ProtocolReadLoop_NMDC(closeChan chan struct{}) {

	// Initiate connection
	s.upstream = s.upstreamLauncher.Connect()

	// Read loop
	for {
		select {
		case <-closeChan:
			// Need some way of deliberately shutting down a libnmdc connection...
			return

		case hubEvent := <-s.upstream.OnEvent:
			switch hubEvent.EventType {
			case libnmdc.EVENT_USER_JOINED:
				s.client.reply(rplJoin, hubEvent.Nick, BLESSED_CHANNEL)

			case libnmdc.EVENT_USER_PART:
				s.client.reply(rplPart, hubEvent.Nick, BLESSED_CHANNEL, "Disconnected")

			case libnmdc.EVENT_USER_UPDATED_INFO:
				// description change - no relevance for IRC users

			case libnmdc.EVENT_CONNECTION_STATE_CHANGED:
				s.client.sendGlobalMessage("Upstream: " + hubEvent.StateChange.Format())

			case libnmdc.EVENT_HUBNAME_CHANGED:
				s.client.reply(rplTopic, BLESSED_CHANNEL, hubEvent.Nick)
				// c.reply(rplNoTopic, BLESSED_CHANNEL)

			case libnmdc.EVENT_PRIVATE:
				s.client.reply(rplMsg, s.client.nick, hubEvent.Nick, hubEvent.Message)

			case libnmdc.EVENT_PUBLIC:
				s.client.reply(rplMsg, s.client.nick, BLESSED_CHANNEL, hubEvent.Message)

			case libnmdc.EVENT_SYSTEM_MESSAGE_FROM_CONN, libnmdc.EVENT_SYSTEM_MESSAGE_FROM_HUB:
				s.client.sendGlobalMessage(hubEvent.Message)

			}
		}
	}
}

func (s *Server) handleCommand(command string, args []string) {

	switch command {
	case "PING":
		s.client.reply(rplPong)

	case "INFO":
		s.client.reply(rplInfo, APP_DESCRIPTION)

	case "VERSION":
		s.client.reply(rplVersion, VERSION)

	case "PASS":
		// RFC2812 registration
		// Stash the password for later
		if len(args) < 1 {
			s.client.reply(errMoreArgs)
			return
		}
		s.upstreamLauncher.NickPassword = args[0]

	case "NICK":
		if len(args) < 1 {
			s.client.reply(errMoreArgs)
			return
		}

		if s.upstreamLauncher.Self.Nick == "" {
			// allow set, as part of the login phase
			s.upstreamLauncher.Self.Nick = args[0]
		} else {
			s.client.reply(rplKill, "Can't change nicks on this server", "")
			s.client.disconnect()
		}

	case "USER":
		// This command sets altname, realname, ... none of which we use
		// It's the final step in a PASS/NICK/USER login handshake.

		if s.client.registered == true {
			s.client.reply(rplKill, "You're already registered.", "")
			s.client.disconnect()
			return
		}

		if s.client.nick == "" {
			s.client.reply(rplKill, "Your nickname is already being used", "")
			s.client.disconnect()
			return
		}

		s.client.reply(rplWelcome)
		s.client.registered = true

		// Spawn upstream connection
		go s.ProtocolReadLoop_NMDC(nil) // FIXME need shutdown synchronisation

		// Tell the user that they themselves joined the chat channel
		s.client.reply(rplJoin, s.client.nick, BLESSED_CHANNEL)

	case "JOIN":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		if len(args) < 1 {
			s.client.reply(errMoreArgs)
			return
		}

		switch args[0] {
		case BLESSED_CHANNEL:
			// That's fine, but they're already there
		case "0":
			// Intend to quit all channels, but we don't allow that
		default:
			s.client.reply(rplKill, "There is only '"+BLESSED_CHANNEL+"'.", "")
			s.client.disconnect()
		}

	case "PART":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		// you can check out any time you like, but you can never leave
		// we'll need to transmit s.client.reply(rplPart, c.nick, channel.name, reason) messages on behalf of other nmdc users, though

	case "PRIVMSG":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		if len(args) < 2 {
			s.client.reply(errMoreArgs)
			return
		}

		message := strings.Join(args[1:], " ")

		// IRC is case-insensitive case-preserving. We can respect that for the
		//  channel name, but not really for user nicks

		if strings.ToLower(args[0]) == BLESSED_CHANNEL {
			s.upstream.SayPublic(message)

		} else if _, clientExists := s.upstream.Users[args[0]]; clientExists {
			s.upstream.SayPrivate(args[0], message)

		} else {
			s.client.reply(errNoSuchNick, args[0])

		}

	case "QUIT":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		s.client.disconnect()

	case "TOPIC":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		if len(args) < 1 {
			s.client.reply(errMoreArgs)
			return
		}

		exists := strings.ToLower(args[0]) == BLESSED_CHANNEL
		if exists == false {
			s.client.reply(errNoSuchNick, args[0])
			return
		}

		// Valid topic get
		if len(args) == 1 {
			s.client.reply(rplTopic, BLESSED_CHANNEL, s.upstream.HubName)
			return
		}

		// Disallow topic set
		s.client.reply(errNoPriv)
		return

	case "LIST":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		listItem := fmt.Sprintf("%s %d :%s", BLESSED_CHANNEL, len(s.channel.clientMap), s.upstream.HubName)
		s.client.reply(rplList, listItem)
		s.client.reply(rplListEnd)

	case "OPER":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		if len(args) < 2 {
			s.client.reply(errMoreArgs)
			return
		}

		// Can't use this command.
		s.client.reply(errPassword)

	case "KILL":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		s.client.reply(errNoPriv)
		return

	case "KICK":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		s.client.reply(errNoPriv)
		return

	case "MODE":
		if s.client.registered == false {
			s.client.reply(errNotReg)
			return
		}

		if len(args) < 1 {
			s.client.reply(errMoreArgs)
			return
		}

		if strings.ToLower(args[0]) != BLESSED_CHANNEL {
			s.client.reply(errNoSuchNick, args[0])
			return
		}

		if len(args) == 1 {
			// No more args, they just want the mode
			s.client.reply(rplChannelModeIs, args[0], BLESSED_CHANNEL_MODE, "")
		} else {
			// Setting modes is disallowed
			s.client.reply(errNoPriv)
		}

		return

	default:
		s.client.reply(errUnknownCommand, command)
	}
}