package state

import (
	"sync"
	"time"

	"github.com/mk6i/retro-aim-server/wire"
)

// SessSendStatus is the result of sending a message to a user.
type SessSendStatus int

const (
	// SessSendOK indicates message was sent to recipient
	SessSendOK SessSendStatus = iota
	// SessSendClosed indicates send did not complete because session is closed
	SessSendClosed
	// SessQueueFull indicates send failed due to full queue -- client is likely
	// dead
	SessQueueFull
)

// Session represents a user's current session. Unless stated otherwise, all
// methods may be safely accessed by multiple goroutines.
type Session struct {
	awayMessage    string
	chatRoomCookie string
	closed         bool
	idle           bool
	idleTime       time.Time
	invisible      bool
	msgCh          chan wire.SNACMessage
	mutex          sync.RWMutex
	nowFn          func() time.Time
	signonComplete bool
	screenName     string
	signonTime     time.Time
	stopCh         chan struct{}
	warning        uint16
	caps           [][16]byte
}

// NewSession returns a new instance of Session. By default, the user may have
// up to 1000 pending messages before blocking.
func NewSession() *Session {
	return &Session{
		msgCh:      make(chan wire.SNACMessage, 1000),
		nowFn:      time.Now,
		stopCh:     make(chan struct{}),
		signonTime: time.Now(),
		caps:       make([][16]byte, 0),
	}
}

// IncrementWarning increments the user's warning level. To decrease, pass a
// negative increment value.
func (s *Session) IncrementWarning(incr uint16) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.warning += incr
}

// SetInvisible toggles the user's invisibility status.
func (s *Session) SetInvisible(invisible bool) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.invisible = invisible
}

// Invisible returns true if the user is idle.
func (s *Session) Invisible() bool {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.invisible
}

// SetScreenName sets the user's screen name.
func (s *Session) SetScreenName(screenName string) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.screenName = screenName
}

// ScreenName returns the user's screen name.
func (s *Session) ScreenName() string {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.screenName
}

// SetSignonTime sets the user's sign-ontime.
func (s *Session) SetSignonTime(t time.Time) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.signonTime = t
}

// SetIdle sets the user's idle state.
func (s *Session) SetIdle(dur time.Duration) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.idle = true
	// set the time the user became idle
	s.idleTime = s.nowFn().Add(-dur)
}

// UnsetIdle removes the user's idle state.
func (s *Session) UnsetIdle() {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.idle = false
}

// SetAwayMessage sets the user's away message.
func (s *Session) SetAwayMessage(awayMessage string) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.awayMessage = awayMessage
}

// AwayMessage returns the user's away message.
func (s *Session) AwayMessage() string {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.awayMessage
}

// SetChatRoomCookie sets the chatRoomCookie for the chat room the user is currently in.
func (s *Session) SetChatRoomCookie(cookie string) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.chatRoomCookie = cookie
}

// ChatRoomCookie gets the chatRoomCookie for the chat room the user is currently in.
func (s *Session) ChatRoomCookie() string {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.chatRoomCookie
}

// SignonComplete indicates whether the client has completed the sign-on sequence.
func (s *Session) SignonComplete() bool {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.signonComplete
}

// SetSignonComplete indicates that the client has completed the sign-on sequence.
func (s *Session) SetSignonComplete() {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.signonComplete = true
}

// TLVUserInfo returns a TLV list containing session information required by
// multiple SNAC message types that convey user information.
func (s *Session) TLVUserInfo() wire.TLVUserInfo {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return wire.TLVUserInfo{
		ScreenName:   s.screenName,
		WarningLevel: s.warning,
		TLVBlock: wire.TLVBlock{
			TLVList: s.userInfo(),
		},
	}
}

func (s *Session) userInfo() wire.TLVList {
	tlvs := wire.TLVList{}

	// sign-in timestamp
	tlvs.Append(wire.NewTLV(wire.OServiceUserInfoSignonTOD, uint32(s.signonTime.Unix())))

	// away message status
	if s.awayMessage != "" {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoUserFlags, wire.OServiceUserFlagOSCARFree|wire.OServiceUserFlagUnavailable))
	} else {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoUserFlags, wire.OServiceUserFlagOSCARFree))
	}

	// reflects invisibility toggle status back to toggling client
	if s.invisible {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoStatus, wire.OServiceUserStatusInvisible))
	} else {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoStatus, uint32(0)))
	}

	// idle status
	if s.idle {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoIdleTime, uint16(s.nowFn().Sub(s.idleTime).Minutes())))
	}

	// capabilities (buddy icon, chat, etc...)
	if len(s.caps) > 0 {
		tlvs.Append(wire.NewTLV(wire.OServiceUserInfoOscarCaps, s.caps))
	}

	return tlvs
}

// SetCaps sets capability UUIDs that represent the features the client
// supports. If set, capability metadata appears in the user info TLV list.
func (s *Session) SetCaps(caps [][16]byte) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	s.caps = caps
}

// Caps retrieves user capabilities.
func (s *Session) Caps() [][16]byte {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	return s.caps
}

func (s *Session) Warning() uint16 {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	var w uint16
	w = s.warning
	return w
}

// ReceiveMessage returns a channel of messages relayed via this session. It
// may only be read by one consumer. The channel never closes; call this method
// in a select block along with Closed in order to detect session closure.
func (s *Session) ReceiveMessage() chan wire.SNACMessage {
	return s.msgCh
}

// RelayMessage receives a SNAC message from a user and passes it on
// asynchronously to the consumer of this session's messages. It returns
// SessSendStatus to indicate whether the message was successfully sent or
// not. This method is non-blocking.
func (s *Session) RelayMessage(msg wire.SNACMessage) SessSendStatus {
	s.mutex.RLock()
	defer s.mutex.RUnlock()
	if s.closed {
		return SessSendClosed
	}
	select {
	case s.msgCh <- msg:
		return SessSendOK
	case <-s.stopCh:
		return SessSendClosed
	default:
		return SessQueueFull
	}
}

// Close shuts down the session's ability to relay messages. Once invoked,
// RelayMessage returns SessQueueFull and Closed returns a closed channel.
// It is not possible to re-open message relaying once closed. It is safe to
// call from multiple go routines.
func (s *Session) Close() {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	if s.closed {
		return
	}
	close(s.stopCh)
	s.closed = true
}

// Closed blocks until the session is closed.
func (s *Session) Closed() <-chan struct{} {
	return s.stopCh
}