package notify

import (
	"b612.me/starcrypto"
	"fmt"
	"net"
	"sync/atomic"
	"time"
)

type clientConnTransportDetachState struct {
	Generation uint64
	Reason     string
	Err        string
	At         time.Time
}

const (
	clientConnTransportDetachKindReadError        = "read_error"
	clientConnTransportDetachKindHeartbeatTimeout = "heartbeat_timeout"
	clientConnTransportDetachKindOther            = "other"
)

type ClientConn struct {
	alive          atomic.Value
	status         Status
	logicalView    atomic.Pointer[LogicalConn]
	logicalState   atomic.Pointer[logicalConnState]
	runtimeState   atomic.Pointer[logicalConnRuntimeState]
	transportState atomic.Pointer[clientConnTransportState]
	sessionRuntime atomic.Pointer[clientConnSessionRuntime]
	attachment     atomic.Pointer[clientConnAttachmentState]
	identityBound  atomic.Bool
	ClientID       string
	ClientAddr     net.Addr
	server         Server
}

type Status struct {
	Alive  bool
	Reason string
	Err    error
}

func (c *ClientConn) readTUMessage() {
	if logical := c.LogicalConn(); logical != nil {
		logical.readTUMessage()
		return
	}
	rt := c.clientConnSessionRuntimeSnapshot()
	if rt == nil {
		return
	}
	c.readTUMessageLoop(rt)
}

func (c *ClientConn) readTUMessageLoop(rt *clientConnSessionRuntime) {
	if logical := c.LogicalConn(); logical != nil {
		logical.readTUMessageLoop(rt)
		return
	}
	if rt == nil {
		return
	}
	stopCtx := rt.transportStopCtx
	if stopCtx == nil {
		stopCtx = rt.stopCtx
	}
	if stopCtx == nil {
		return
	}
	conn := rt.tuConn
	generation := rt.transportGeneration
	defer closeClientConnSessionRuntimeTransportDone(rt)
	buf := streamReadBuffer()
	for {
		select {
		case <-sessionStopChan(stopCtx):
			if c.shouldCloseClientConnTransportOnStop(conn) {
				_ = conn.Close()
			}
			return
		default:
		}
		num, data, err := c.readFromTUTransportConnWithBuffer(conn, buf)
		if !c.handleTUTransportReadResultWithSession(stopCtx, conn, generation, num, data, err) {
			return
		}
	}
}

// Deprecated: rsaDecode exists only for the legacy MSG_KEY_CHANGE flow.
func (c *ClientConn) rsaDecode(message Message) {
	privKey, err := starcrypto.DecodeRsaPrivateKey(c.clientConnHandshakeRsaKeySnapshot(), "")
	if err != nil {
		fmt.Println(err)
		message.Reply([]byte("failed"))
		return
	}
	data, err := starcrypto.RSADecrypt(privKey, message.Value)
	if err != nil {
		fmt.Println(err)
		message.Reply([]byte("failed"))
		return
	}
	message.Reply([]byte("success"))
	c.setClientConnSecretKey(data)
}

func (c *ClientConn) sayGoodByeForTU() error {
	if c == nil || c.server == nil {
		return errTransportDetached
	}
	_, err := c.server.SendWaitLogical(c.LogicalConn(), "bye", nil, time.Second*3)
	if err == nil {
		return nil
	}
	_, err = c.server.sendWait(c, TransferMsg{
		ID:    10010,
		Key:   "bye",
		Value: nil,
		Type:  MSG_SYS_WAIT,
	}, time.Second*3)
	return err
}

func (c *ClientConn) GetSecretKey() []byte {
	return c.clientConnSecretKeySnapshot()
}

// Deprecated: SetSecretKey injects a raw per-connection transport key directly.
func (c *ClientConn) SetSecretKey(key []byte) {
	c.setClientConnSecretKey(key)
}

func (c *ClientConn) GetMsgEn() func([]byte, []byte) []byte {
	return c.clientConnMsgEnSnapshot()
}

// Deprecated: SetMsgEn overrides the per-connection transport codec directly.
func (c *ClientConn) SetMsgEn(fn func([]byte, []byte) []byte) {
	c.setClientConnMsgEn(fn)
}

func (c *ClientConn) GetMsgDe() func([]byte, []byte) []byte {
	return c.clientConnMsgDeSnapshot()
}

// Deprecated: SetMsgDe overrides the per-connection transport codec directly.
func (c *ClientConn) SetMsgDe(fn func([]byte, []byte) []byte) {
	c.setClientConnMsgDe(fn)
}

func (c *ClientConn) StopMonitorChan() <-chan struct{} {
	return sessionStopChan(c.clientConnStopContextSnapshot())
}

func (c *ClientConn) Status() Status {
	return c.clientConnStatusSnapshot()
}

func (c *ClientConn) Server() Server {
	if c != nil {
		if logical := c.logicalView.Load(); logical != nil {
			if server := logical.Server(); server != nil {
				return server
			}
		}
	}
	return c.server
}

func (c *ClientConn) GetRemoteAddr() net.Addr {
	return c.clientConnRemoteAddrSnapshot()
}

func (c *ClientConn) markClientConnIdentityBound() {
	if c == nil {
		return
	}
	if logical := c.logicalView.Load(); logical != nil {
		logical.markIdentityBound()
		return
	}
	state := c.ensureLogicalConnState()
	if state == nil {
		c.identityBound.Store(true)
		return
	}
	state.updatePeer(func(peer *logicalConnPeerState) {
		peer.identityBound = true
	})
	c.syncLegacyLogicalFieldsFromState(state)
}

func (c *ClientConn) clientConnIdentityBoundSnapshot() bool {
	if c == nil {
		return false
	}
	return c.clientConnLogicalPeerStateSnapshot().identityBound
}

func (c *ClientConn) markClientConnStreamTransport() {
	if c == nil {
		return
	}
	if logical := c.logicalView.Load(); logical != nil {
		logical.markStreamTransport()
		return
	}
	state := c.ensureClientConnTransportState()
	if state == nil {
		return
	}
	state.streamTransport.Store(true)
}

func (c *ClientConn) clientConnUsesStreamTransportSnapshot() bool {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return false
	}
	return state.streamTransport.Load()
}

func (c *ClientConn) shouldPreserveLogicalPeerOnTransportLoss() bool {
	if c == nil {
		return false
	}
	return c.clientConnIdentityBoundSnapshot() && c.clientConnUsesStreamTransportSnapshot()
}

func (c *ClientConn) markClientConnTransportAttached() uint64 {
	if c == nil {
		return 0
	}
	if logical := c.logicalView.Load(); logical != nil {
		return logical.markTransportAttached()
	}
	state := c.ensureClientConnTransportState()
	if state == nil {
		return 0
	}
	gen := state.transportGen.Add(1)
	state.attachCount.Add(1)
	state.lastAttachAt.Store(time.Now().UnixNano())
	return gen
}

func (c *ClientConn) clientConnTransportGenerationSnapshot() uint64 {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return 0
	}
	return state.transportGen.Load()
}

func (c *ClientConn) clientConnTransportAttachCountSnapshot() uint64 {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return 0
	}
	return state.attachCount.Load()
}

func (c *ClientConn) markClientConnTransportDetached(reason string, err error) {
	if c == nil {
		return
	}
	if logical := c.logicalView.Load(); logical != nil {
		logical.markTransportDetached(reason, err)
		return
	}
	state := c.ensureClientConnTransportState()
	if state == nil {
		return
	}
	detachState := &clientConnTransportDetachState{
		Generation: c.clientConnTransportGenerationSnapshot(),
		Reason:     reason,
		At:         time.Now(),
	}
	if err != nil {
		detachState.Err = err.Error()
	}
	state.detachCount.Add(1)
	state.transportDetach.Store(detachState)
}

func (c *ClientConn) clientConnTransportDetachCountSnapshot() uint64 {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return 0
	}
	return state.detachCount.Load()
}

func (c *ClientConn) clearClientConnTransportDetachState() {
	if c == nil {
		return
	}
	if logical := c.logicalView.Load(); logical != nil {
		logical.clearTransportDetachState()
		return
	}
	c.setClientConnTransportDetachState(nil)
}

func (c *ClientConn) clientConnTransportDetachSnapshot() *clientConnTransportDetachState {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return nil
	}
	return cloneClientConnTransportDetachState(state.transportDetach.Load())
}

func (c *ClientConn) clientConnLogicalTransportDetachedSnapshot() bool {
	if c == nil {
		return false
	}
	if !c.clientConnIdentityBoundSnapshot() || !c.clientConnUsesStreamTransportSnapshot() {
		return false
	}
	if !c.clientConnAliveSnapshot() {
		return false
	}
	return !c.clientConnTransportAttachedSnapshot()
}

func (c *ClientConn) clientConnLastTransportAttachedAtSnapshot() time.Time {
	state := c.ensureClientConnTransportState()
	if state == nil {
		return time.Time{}
	}
	unixNano := state.lastAttachAt.Load()
	if unixNano == 0 {
		return time.Time{}
	}
	return time.Unix(0, unixNano)
}

func classifyClientConnTransportDetachReason(reason string) string {
	switch reason {
	case "":
		return ""
	case "read error":
		return clientConnTransportDetachKindReadError
	case "heartbeat timeout":
		return clientConnTransportDetachKindHeartbeatTimeout
	default:
		return clientConnTransportDetachKindOther
	}
}

func (c *ClientConn) clientConnTransportDetachKindSnapshot() string {
	if c == nil {
		return ""
	}
	detach := c.clientConnTransportDetachSnapshot()
	if detach == nil {
		return ""
	}
	return classifyClientConnTransportDetachReason(detach.Reason)
}

func (c *ClientConn) clientConnTransportDetachGenerationSnapshot() uint64 {
	if c == nil {
		return 0
	}
	detach := c.clientConnTransportDetachSnapshot()
	if detach == nil {
		return 0
	}
	if detach.Generation == 0 {
		return c.clientConnTransportGenerationSnapshot()
	}
	return detach.Generation
}

func (c *ClientConn) clientConnTransportDetachExpirySnapshot() (time.Time, bool) {
	if c == nil {
		return time.Time{}, false
	}
	detach := c.clientConnTransportDetachSnapshot()
	if detach == nil || detach.At.IsZero() {
		return time.Time{}, false
	}
	if c.server == nil {
		return time.Time{}, false
	}
	keepSec := c.server.DetachedClientKeepSec()
	if keepSec <= 0 {
		return time.Time{}, false
	}
	return detach.At.Add(time.Duration(keepSec) * time.Second), true
}

func (c *ClientConn) clientConnTransportDetachExpiredSnapshot(now time.Time) bool {
	if c == nil || !c.clientConnLogicalTransportDetachedSnapshot() {
		return false
	}
	expiry, ok := c.clientConnTransportDetachExpirySnapshot()
	if !ok {
		return false
	}
	return !now.Before(expiry)
}

func (c *ClientConn) clientConnTransportDetachRemainingSnapshot(now time.Time) time.Duration {
	if c == nil || !c.clientConnLogicalTransportDetachedSnapshot() {
		return 0
	}
	expiry, ok := c.clientConnTransportDetachExpirySnapshot()
	if !ok {
		return 0
	}
	if !now.Before(expiry) {
		return 0
	}
	return expiry.Sub(now)
}

func (c *ClientConn) clientConnReattachEligibleSnapshot(now time.Time) bool {
	if c == nil || !c.clientConnLogicalTransportDetachedSnapshot() {
		return false
	}
	if !c.clientConnAliveSnapshot() {
		return false
	}
	if c.clientConnTransportAttachedSnapshot() {
		return false
	}
	if c.clientConnTransportDetachExpiredSnapshot(now) {
		return false
	}
	return true
}