package birc

import (
	"bytes"
	"crypto/tls"
	"fmt"
	"hash/crc32"
	"io"
	"io/ioutil"
	"net"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/42wim/matterbridge/bridge"
	"github.com/42wim/matterbridge/bridge/config"
	"github.com/42wim/matterbridge/bridge/helper"
	"github.com/dfordsoft/golib/ic"
	"github.com/lrstanley/girc"
	"github.com/paulrosania/go-charset/charset"
	"github.com/saintfish/chardet"

	// We need to import the 'data' package as an implicit dependency.
	// See: https://godoc.org/github.com/paulrosania/go-charset/charset
	_ "github.com/paulrosania/go-charset/data"
)

type Birc struct {
	i                                         *girc.Client
	Nick                                      string
	names                                     map[string][]string
	connected                                 chan error
	Local                                     chan config.Message // local queue for flood control
	FirstConnection, authDone                 bool
	MessageDelay, MessageQueue, MessageLength int

	*bridge.Config
}

func New(cfg *bridge.Config) bridge.Bridger {
	b := &Birc{}
	b.Config = cfg
	b.Nick = b.GetString("Nick")
	b.names = make(map[string][]string)
	b.connected = make(chan error)
	if b.GetInt("MessageDelay") == 0 {
		b.MessageDelay = 1300
	} else {
		b.MessageDelay = b.GetInt("MessageDelay")
	}
	if b.GetInt("MessageQueue") == 0 {
		b.MessageQueue = 30
	} else {
		b.MessageQueue = b.GetInt("MessageQueue")
	}
	if b.GetInt("MessageLength") == 0 {
		b.MessageLength = 400
	} else {
		b.MessageLength = b.GetInt("MessageLength")
	}
	b.FirstConnection = true
	return b
}

func (b *Birc) Command(msg *config.Message) string {
	if msg.Text == "!users" {
		b.i.Handlers.Add(girc.RPL_NAMREPLY, b.storeNames)
		b.i.Handlers.Add(girc.RPL_ENDOFNAMES, b.endNames)
		b.i.Cmd.SendRaw("NAMES " + msg.Channel)
	}
	return ""
}

func (b *Birc) Connect() error {
	b.Local = make(chan config.Message, b.MessageQueue+10)
	b.Log.Infof("Connecting %s", b.GetString("Server"))
	server, portstr, err := net.SplitHostPort(b.GetString("Server"))
	if err != nil {
		return err
	}
	port, err := strconv.Atoi(portstr)
	if err != nil {
		return err
	}
	// fix strict user handling of girc
	user := b.GetString("Nick")
	for !girc.IsValidUser(user) {
		if len(user) == 1 {
			user = "matterbridge"
			break
		}
		user = user[1:]
	}

	i := girc.New(girc.Config{
		Server:     server,
		ServerPass: b.GetString("Password"),
		Port:       port,
		Nick:       b.GetString("Nick"),
		User:       user,
		Name:       b.GetString("Nick"),
		SSL:        b.GetBool("UseTLS"),
		TLSConfig:  &tls.Config{InsecureSkipVerify: b.GetBool("SkipTLSVerify"), ServerName: server},
		PingDelay:  time.Minute,
	})

	if b.GetBool("UseSASL") {
		i.Config.SASL = &girc.SASLPlain{
			User: b.GetString("NickServNick"),
			Pass: b.GetString("NickServPassword"),
		}
	}

	i.Handlers.Add(girc.RPL_WELCOME, b.handleNewConnection)
	i.Handlers.Add(girc.RPL_ENDOFMOTD, b.handleOtherAuth)
	i.Handlers.Add(girc.ALL_EVENTS, b.handleOther)

	go func() {
		for {
			if err := i.Connect(); err != nil {
				b.Log.Errorf("disconnect: error: %s", err)
				if b.FirstConnection {
					b.connected <- err
					return
				}
			} else {
				b.Log.Info("disconnect: client requested quit")
			}
			b.Log.Info("reconnecting in 30 seconds...")
			time.Sleep(30 * time.Second)
			i.Handlers.Clear(girc.RPL_WELCOME)
			i.Handlers.Add(girc.RPL_WELCOME, func(client *girc.Client, event girc.Event) {
				b.Remote <- config.Message{Username: "system", Text: "rejoin", Channel: "", Account: b.Account, Event: config.EventRejoinChannels}
				// set our correct nick on reconnect if necessary
				b.Nick = event.Source.Name
			})
		}
	}()
	b.i = i
	err = <-b.connected
	if err != nil {
		return fmt.Errorf("connection failed %s", err)
	}
	b.Log.Info("Connection succeeded")
	b.FirstConnection = false
	if b.GetInt("DebugLevel") == 0 {
		i.Handlers.Clear(girc.ALL_EVENTS)
	}
	go b.doSend()
	return nil
}

func (b *Birc) Disconnect() error {
	b.i.Close()
	close(b.Local)
	return nil
}

func (b *Birc) JoinChannel(channel config.ChannelInfo) error {
	// need to check if we have nickserv auth done before joining channels
	for {
		if b.authDone {
			break
		}
		time.Sleep(time.Second)
	}
	if channel.Options.Key != "" {
		b.Log.Debugf("using key %s for channel %s", channel.Options.Key, channel.Name)
		b.i.Cmd.JoinKey(channel.Name, channel.Options.Key)
	} else {
		b.i.Cmd.Join(channel.Name)
	}
	return nil
}

func (b *Birc) Send(msg config.Message) (string, error) {
	// ignore delete messages
	if msg.Event == config.EventMsgDelete {
		return "", nil
	}

	b.Log.Debugf("=> Receiving %#v", msg)

	// we can be in between reconnects #385
	if !b.i.IsConnected() {
		b.Log.Error("Not connected to server, dropping message")
	}

	// Execute a command
	if strings.HasPrefix(msg.Text, "!") {
		b.Command(&msg)
	}

	// convert to specified charset
	if b.GetString("Charset") != "" {
		switch b.GetString("Charset") {
		case "gbk", "gb18030", "gb2312", "big5", "euc-kr", "euc-jp", "shift-jis", "iso-2022-jp":
			msg.Text = ic.ConvertString("utf-8", b.GetString("Charset"), msg.Text)
		default:
			buf := new(bytes.Buffer)
			w, err := charset.NewWriter(b.GetString("Charset"), buf)
			if err != nil {
				b.Log.Errorf("charset from utf-8 conversion failed: %s", err)
				return "", err
			}
			fmt.Fprint(w, msg.Text)
			w.Close()
			msg.Text = buf.String()
		}
	}

	// Handle files
	if msg.Extra != nil {
		for _, rmsg := range helper.HandleExtra(&msg, b.General) {
			b.Local <- rmsg
		}
		if len(msg.Extra["file"]) > 0 {
			for _, f := range msg.Extra["file"] {
				fi := f.(config.FileInfo)
				if fi.Comment != "" {
					msg.Text += fi.Comment + ": "
				}
				if fi.URL != "" {
					msg.Text = fi.URL
					if fi.Comment != "" {
						msg.Text = fi.Comment + ": " + fi.URL
					}
				}
				b.Local <- config.Message{Text: msg.Text, Username: msg.Username, Channel: msg.Channel, Event: msg.Event}
			}
			return "", nil
		}
	}

	var msgLines []string
	if b.GetBool("MessageSplit") {
		msgLines = helper.GetSubLines(msg.Text, b.MessageLength)
	} else {
		msgLines = helper.GetSubLines(msg.Text, 0)
	}
	for i := range msgLines {
		if len(b.Local) >= b.MessageQueue {
			b.Log.Debugf("flooding, dropping message (queue at %d)", len(b.Local))
			return "", nil
		}

		b.Local <- config.Message{
			Text:     msgLines[i],
			Username: msg.Username,
			Channel:  msg.Channel,
			Event:    msg.Event,
		}
	}
	return "", nil
}

func (b *Birc) doSend() {
	rate := time.Millisecond * time.Duration(b.MessageDelay)
	throttle := time.NewTicker(rate)
	for msg := range b.Local {
		<-throttle.C
		username := msg.Username
		if b.GetBool("Colornicks") {
			checksum := crc32.ChecksumIEEE([]byte(msg.Username))
			colorCode := checksum%14 + 2 // quick fix - prevent white or black color codes
			username = fmt.Sprintf("\x03%02d%s\x0F", colorCode, msg.Username)
		}
		if msg.Event == config.EventUserAction {
			b.i.Cmd.Action(msg.Channel, username+msg.Text)
		} else {
			b.Log.Debugf("Sending to channel %s", msg.Channel)
			b.i.Cmd.Message(msg.Channel, username+msg.Text)
		}
	}
}

func (b *Birc) endNames(client *girc.Client, event girc.Event) {
	channel := event.Params[1]
	sort.Strings(b.names[channel])
	maxNamesPerPost := (300 / b.nicksPerRow()) * b.nicksPerRow()
	for len(b.names[channel]) > maxNamesPerPost {
		b.Remote <- config.Message{Username: b.Nick, Text: b.formatnicks(b.names[channel][0:maxNamesPerPost]),
			Channel: channel, Account: b.Account}
		b.names[channel] = b.names[channel][maxNamesPerPost:]
	}
	b.Remote <- config.Message{Username: b.Nick, Text: b.formatnicks(b.names[channel]),
		Channel: channel, Account: b.Account}
	b.names[channel] = nil
	b.i.Handlers.Clear(girc.RPL_NAMREPLY)
	b.i.Handlers.Clear(girc.RPL_ENDOFNAMES)
}

func (b *Birc) handleNewConnection(client *girc.Client, event girc.Event) {
	b.Log.Debug("Registering callbacks")
	i := b.i
	b.Nick = event.Params[0]

	i.Handlers.Add("PRIVMSG", b.handlePrivMsg)
	i.Handlers.Add("CTCP_ACTION", b.handlePrivMsg)
	i.Handlers.Add(girc.RPL_TOPICWHOTIME, b.handleTopicWhoTime)
	i.Handlers.Add(girc.NOTICE, b.handleNotice)
	i.Handlers.Add("JOIN", b.handleJoinPart)
	i.Handlers.Add("PART", b.handleJoinPart)
	i.Handlers.Add("QUIT", b.handleJoinPart)
	i.Handlers.Add("KICK", b.handleJoinPart)
}

func (b *Birc) handleJoinPart(client *girc.Client, event girc.Event) {
	if len(event.Params) == 0 {
		b.Log.Debugf("handleJoinPart: empty Params? %#v", event)
		return
	}
	channel := strings.ToLower(event.Params[0])
	if event.Command == "KICK" && event.Params[1] == b.Nick {
		b.Log.Infof("Got kicked from %s by %s", channel, event.Source.Name)
		time.Sleep(time.Duration(b.GetInt("RejoinDelay")) * time.Second)
		b.Remote <- config.Message{Username: "system", Text: "rejoin", Channel: channel, Account: b.Account, Event: config.EventRejoinChannels}
		return
	}
	if event.Command == "QUIT" {
		if event.Source.Name == b.Nick && strings.Contains(event.Trailing, "Ping timeout") {
			b.Log.Infof("%s reconnecting ..", b.Account)
			b.Remote <- config.Message{Username: "system", Text: "reconnect", Channel: channel, Account: b.Account, Event: config.EventFailure}
			return
		}
	}
	if event.Source.Name != b.Nick {
		if b.GetBool("nosendjoinpart") {
			return
		}
		b.Log.Debugf("<= Sending JOIN_LEAVE event from %s to gateway", b.Account)
		msg := config.Message{Username: "system", Text: event.Source.Name + " " + strings.ToLower(event.Command) + "s", Channel: channel, Account: b.Account, Event: config.EventJoinLeave}
		b.Log.Debugf("<= Message is %#v", msg)
		b.Remote <- msg
		return
	}
	b.Log.Debugf("handle %#v", event)
}

func (b *Birc) handleNotice(client *girc.Client, event girc.Event) {
	if strings.Contains(event.String(), "This nickname is registered") && event.Source.Name == b.GetString("NickServNick") {
		b.handleNickServ()
	} else {
		b.handlePrivMsg(client, event)
	}
}

func (b *Birc) handleOther(client *girc.Client, event girc.Event) {
	if b.GetInt("DebugLevel") == 1 {
		if event.Command != "CLIENT_STATE_UPDATED" &&
			event.Command != "CLIENT_GENERAL_UPDATED" {
			b.Log.Debugf("%#v", event.String())
		}
		return
	}
	switch event.Command {
	case "372", "375", "376", "250", "251", "252", "253", "254", "255", "265", "266", "002", "003", "004", "005":
		return
	}
	b.Log.Debugf("%#v", event.String())
}

func (b *Birc) handleOtherAuth(client *girc.Client, event girc.Event) {
	b.handleNickServ()
	// we are now fully connected
	b.connected <- nil
}

func (b *Birc) skipPrivMsg(event girc.Event) bool {
	// Our nick can be changed
	b.Nick = b.i.GetNick()

	// freenode doesn't send 001 as first reply
	if event.Command == "NOTICE" {
		return true
	}
	// don't forward queries to the bot
	if event.Params[0] == b.Nick {
		return true
	}
	// don't forward message from ourself
	if event.Source.Name == b.Nick {
		return true
	}
	return false
}

func (b *Birc) handlePrivMsg(client *girc.Client, event girc.Event) {
	if b.skipPrivMsg(event) {
		return
	}
	rmsg := config.Message{Username: event.Source.Name, Channel: strings.ToLower(event.Params[0]), Account: b.Account, UserID: event.Source.Ident + "@" + event.Source.Host}
	b.Log.Debugf("== Receiving PRIVMSG: %s %s %#v", event.Source.Name, event.Trailing, event)

	// set action event
	if event.IsAction() {
		rmsg.Event = config.EventUserAction
	}

	// strip action, we made an event if it was an action
	rmsg.Text += event.StripAction()

	// strip IRC colors
	re := regexp.MustCompile(`\x03(?:\d{1,2}(?:,\d{1,2})?)?|[[:cntrl:]]`)
	rmsg.Text = re.ReplaceAllString(rmsg.Text, "")

	// start detecting the charset
	var r io.Reader
	var err error
	mycharset := b.GetString("Charset")
	if mycharset == "" {
		// detect what were sending so that we convert it to utf-8
		detector := chardet.NewTextDetector()
		result, err := detector.DetectBest([]byte(rmsg.Text))
		if err != nil {
			b.Log.Infof("detection failed for rmsg.Text: %#v", rmsg.Text)
			return
		}
		b.Log.Debugf("detected %s confidence %#v", result.Charset, result.Confidence)
		mycharset = result.Charset
		// if we're not sure, just pick ISO-8859-1
		if result.Confidence < 80 {
			mycharset = "ISO-8859-1"
		}
	}
	switch mycharset {
	case "gbk", "gb18030", "gb2312", "big5", "euc-kr", "euc-jp", "shift-jis", "iso-2022-jp":
		rmsg.Text = ic.ConvertString("utf-8", b.GetString("Charset"), rmsg.Text)
	default:
		r, err = charset.NewReader(mycharset, strings.NewReader(rmsg.Text))
		if err != nil {
			b.Log.Errorf("charset to utf-8 conversion failed: %s", err)
			return
		}
		output, _ := ioutil.ReadAll(r)
		rmsg.Text = string(output)
	}

	b.Log.Debugf("<= Sending message from %s on %s to gateway", event.Params[0], b.Account)
	b.Remote <- rmsg
}

func (b *Birc) handleTopicWhoTime(client *girc.Client, event girc.Event) {
	parts := strings.Split(event.Params[2], "!")
	t, err := strconv.ParseInt(event.Params[3], 10, 64)
	if err != nil {
		b.Log.Errorf("Invalid time stamp: %s", event.Params[3])
	}
	user := parts[0]
	if len(parts) > 1 {
		user += " [" + parts[1] + "]"
	}
	b.Log.Debugf("%s: Topic set by %s [%s]", event.Command, user, time.Unix(t, 0))
}

func (b *Birc) nicksPerRow() int {
	return 4
}

func (b *Birc) storeNames(client *girc.Client, event girc.Event) {
	channel := event.Params[2]
	b.names[channel] = append(
		b.names[channel],
		strings.Split(strings.TrimSpace(event.Trailing), " ")...)
}

func (b *Birc) formatnicks(nicks []string) string {
	return strings.Join(nicks, ", ") + " currently on IRC"
}

func (b *Birc) handleNickServ() {
	if !b.GetBool("UseSASL") && b.GetString("NickServNick") != "" && b.GetString("NickServPassword") != "" {
		b.Log.Debugf("Sending identify to nickserv %s", b.GetString("NickServNick"))
		b.i.Cmd.Message(b.GetString("NickServNick"), "IDENTIFY "+b.GetString("NickServPassword"))
	}
	if strings.EqualFold(b.GetString("NickServNick"), "Q@CServe.quakenet.org") {
		b.Log.Debugf("Authenticating %s against %s", b.GetString("NickServUsername"), b.GetString("NickServNick"))
		b.i.Cmd.Message(b.GetString("NickServNick"), "AUTH "+b.GetString("NickServUsername")+" "+b.GetString("NickServPassword"))
	}
	// give nickserv some slack
	time.Sleep(time.Second * 5)
	b.authDone = true
}