package libnmdc

import (
	"crypto/tls"
	"fmt"
	"net"
	"regexp"
	"sync"
	"time"
)

type HubConnection struct {
	// Supplied parameters
	Hco *HubConnectionOptions

	// Current remote status
	HubName string
	State   ConnectionState

	usersMut sync.RWMutex
	users    map[string]UserInfo
	userSIDs map[string]string

	proto Protocol

	// Event callback
	processEvent func(HubEvent)

	// Private state
	conn             net.Conn // this is an interface
	connValid        bool
	autoReconnect    bool
	lastDataRecieved time.Time
}

// Thread-safe user accessor.
func (this *HubConnection) Users(cb func(*map[string]UserInfo) error) error {
	this.usersMut.Lock()
	defer this.usersMut.Unlock()

	return cb(&this.users)
}

func (this *HubConnection) SayPublic(message string) {
	this.proto.SayPublic(message)
}

func (this *HubConnection) SayPrivate(recipient string, message string) {
	this.proto.SayPrivate(recipient, message)
}

func (this *HubConnection) UserExists(nick string) bool {
	this.usersMut.RLock()
	defer this.usersMut.RUnlock()

	_, already_existed := this.users[nick]
	return already_existed
}

func (this *HubConnection) UserCount() int {
	this.usersMut.RLock()
	defer this.usersMut.RUnlock()

	return len(this.users)
}

func (this *HubConnection) userJoined_NameOnly(nick string) {
	if !this.UserExists(nick) {

		this.usersMut.Lock()
		this.users[nick] = *NewUserInfo(nick)
		this.usersMut.Unlock() // Don't lock over a processEvent boundary

		this.processEvent(HubEvent{EventType: EVENT_USER_JOINED, Nick: nick})
	}
}

func (this *HubConnection) userJoined_Full(uinf *UserInfo) {
	// n.b. also called when we get a replacement MyINFO for someone
	this.usersMut.Lock()
	_, userExisted := this.users[uinf.Nick] // don't use UserExists as it would deadlock the mutex
	this.users[uinf.Nick] = *uinf
	this.usersMut.Unlock() // Don't lock over a processEvent boundary

	if !userExisted {
		this.processEvent(HubEvent{EventType: EVENT_USER_JOINED, Nick: uinf.Nick})
	} else {
		this.processEvent(HubEvent{EventType: EVENT_USER_UPDATED_INFO, Nick: uinf.Nick})
	}
}

// SayRaw sends raw bytes over the TCP socket. Callers should add the protocol
// terminating character themselves (e.g. `|` for NMDC).
// Note that protocol messages are transmitted on the caller thread, not from
// any internal libnmdc thread.
func (this *HubConnection) SayRaw(protocolCommand string) error {
	if !this.connValid {
		return ErrNotConnected
	}

	_, err := this.conn.Write([]byte(protocolCommand))
	return err
}

func (this *HubConnection) SayKeepalive() error {
	if !this.connValid {
		return ErrNotConnected
	}

	return this.SayRaw(this.proto.ProtoMessageSeparator())
}

func (this *HubConnection) Disconnect() {
	this.autoReconnect = false
	if this.conn != nil {
		this.conn.Close()
	}
	// A CONNECTIONSTATE_DISCONNECTED message will be emitted by the worker.
}

func (this *HubConnection) worker() {
	var fullBuffer string
	var err error = nil
	var nbytes int = 0

	for {

		// If we're not connected, attempt reconnect
		if this.conn == nil {

			fullBuffer = "" // clear

			if this.Hco.Address.IsSecure() {
				this.conn, err = tls.Dial("tcp", this.Hco.Address.GetHostOnly(), &tls.Config{
					InsecureSkipVerify: this.Hco.SkipVerifyTLS,
				})
			} else {
				this.conn, err = net.Dial("tcp", this.Hco.Address.GetHostOnly())
			}

			if err != nil {
				this.State = CONNECTIONSTATE_DISCONNECTED
				this.connValid = false
				this.proto = nil

			} else {
				this.State = CONNECTIONSTATE_CONNECTING
				this.connValid = true
				this.processEvent(HubEvent{EventType: EVENT_CONNECTION_STATE_CHANGED, StateChange: CONNECTIONSTATE_CONNECTING})
				this.proto = this.Hco.Address.GetProtocol().Create(this)

			}
		}

		// Read from socket into our local buffer (blocking)
		if this.connValid {

			readBuff := make([]byte, 1024)
			this.conn.SetReadDeadline(time.Now().Add(SEND_KEEPALIVE_EVERY))

			nbytes, err = this.conn.Read(readBuff)

			if checkIsNetTimeout(err) {
				// No data before read deadline
				err = nil

				if this.proto == nil {
					// Autodetect: switch to ADC
					this.proto = NewAdcProtocol(this)
				} else {
					// Normal
					// Send KA packet
					err = this.SayKeepalive()
				}
			}

			if nbytes > 0 {
				this.lastDataRecieved = time.Now()
				fullBuffer += string(readBuff[0:nbytes])
			}
		}

		if this.proto != nil {
			rxSeparator := regexp.QuoteMeta(this.proto.ProtoMessageSeparator())
			rxProtocolMessage := regexp.MustCompile(`(?ms)\A[^` + rxSeparator + `]*` + rxSeparator)

			// Attempt to parse a message block
			for len(fullBuffer) > 0 {

				// FIXME nmdc
				for len(fullBuffer) > 0 && fullBuffer[0] == '|' {
					fullBuffer = fullBuffer[1:]
				}

				protocolMessage := rxProtocolMessage.FindString(fullBuffer)
				if len(protocolMessage) > 0 {
					this.proto.ProcessCommand(protocolMessage[:len(protocolMessage)-1])
					fullBuffer = fullBuffer[len(protocolMessage):]
				} else {
					break
				}
			}

			if err == nil && time.Now().Sub(this.lastDataRecieved) > RECONNECT_IF_NO_DATA_RECIEVED_IN {
				err = fmt.Errorf("No packets recieved since %s, connection presumed lost", this.lastDataRecieved.Format(time.RFC3339))
			}
		}

		// Maybe we disconnected
		// Perform this check *last*, to ensure we've had a final shot at
		//  clearing out any queued messages
		if err != nil {
			this.State = CONNECTIONSTATE_DISCONNECTED
			this.conn = nil
			this.connValid = false
			this.proto = nil
			this.processEvent(HubEvent{EventType: EVENT_CONNECTION_STATE_CHANGED, StateChange: CONNECTIONSTATE_DISCONNECTED, Message: err.Error()})

			if this.autoReconnect {
				time.Sleep(AUTO_RECONNECT_AFTER) // Wait before reconnect
				continue
			} else {
				return // leave the worker for good
			}
		}

	}

}