package notify

import (
	"b612.me/stario"
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net"
	"testing"
	"time"
)

func TestClientConnReadTUMessagePreservesServerStopReason(t *testing.T) {
	server := NewServer().(*ServerCommon)
	left, right := net.Pipe()
	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()

	client, _, _ := newRegisteredServerClientForTest(t, server, "client-stop", left, stopCtx, stopFn)

	done := make(chan struct{})
	go func() {
		client.readTUMessage()
		close(done)
	}()

	server.stopClientSession(client, "recv stop signal from server", nil)
	_ = right.Close()

	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("readTUMessage should exit after server stop")
	}

	if status := client.Status(); status.Alive || status.Reason != "recv stop signal from server" || status.Err != nil {
		t.Fatalf("unexpected status after server stop: %+v", status)
	}
	if got := server.GetLogicalConn(client.ClientID); got != nil {
		t.Fatalf("logical should be removed after server stop, got %+v", got)
	}
}

func TestClientConnReadTUMessageReadErrorStopsAndRemovesClient(t *testing.T) {
	server := NewServer().(*ServerCommon)
	left, right := net.Pipe()
	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()

	client, _, _ := newRegisteredServerClientForTest(t, server, "client-read-error", left, stopCtx, stopFn)

	done := make(chan struct{})
	go func() {
		client.readTUMessage()
		close(done)
	}()

	_ = right.Close()

	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("readTUMessage should exit after read error")
	}

	status := client.Status()
	if status.Alive || status.Reason != "read error" || status.Err == nil {
		t.Fatalf("unexpected status after read error: %+v", status)
	}
	if got := server.GetLogicalConn(client.ClientID); got != nil {
		t.Fatalf("logical should be removed after read error, got %+v", got)
	}
}

func TestClientConnMarkSessionStoppedUsesRuntimeStopFn(t *testing.T) {
	client := &ClientConn{}
	client.markSessionStarted()

	runtimeCtx, runtimeCancel := context.WithCancel(context.Background())
	defer runtimeCancel()
	client.setClientConnSessionRuntime(&clientConnSessionRuntime{
		stopCtx: runtimeCtx,
		stopFn:  runtimeCancel,
	})

	client.markSessionStopped("runtime stop", nil)

	select {
	case <-runtimeCtx.Done():
	case <-time.After(time.Second):
		t.Fatal("runtime stop context should be canceled by markSessionStopped")
	}
}

func TestClientConnDetachServerOwnedSessionClearsRuntimeTransport(t *testing.T) {
	client := &ClientConn{}
	left, right := net.Pipe()
	defer right.Close()

	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()
	client.startClientConnSession(left, stopCtx, stopFn)

	client.detachServerOwnedSession()

	if got := client.clientConnTransportSnapshot(); got != nil {
		t.Fatalf("runtime transport should be cleared after detach, got %v", got)
	}
	if got := client.clientConnStopContextSnapshot(); got != stopCtx {
		t.Fatalf("runtime stop context should be preserved after detach, got %v want %v", got, stopCtx)
	}
}

func TestClientConnReadFromTUTransportUsesRuntimeConn(t *testing.T) {
	client := &ClientConn{}
	runtimeLeft, runtimeRight := net.Pipe()
	defer runtimeLeft.Close()
	defer runtimeRight.Close()

	runtimeCtx, runtimeCancel := context.WithCancel(context.Background())
	defer runtimeCancel()
	client.setClientConnSessionRuntime(&clientConnSessionRuntime{
		tuConn:  runtimeLeft,
		stopCtx: runtimeCtx,
		stopFn:  runtimeCancel,
	})

	payload := []byte("runtime-tu-conn")
	writeDone := make(chan error, 1)
	go func() {
		_, err := runtimeRight.Write(payload)
		writeDone <- err
	}()

	num, data, err := client.readFromTUTransport()
	if err != nil {
		t.Fatalf("readFromTUTransport failed: %v", err)
	}
	if got, want := string(data[:num]), string(payload); got != want {
		t.Fatalf("payload mismatch: got %q want %q", got, want)
	}
	select {
	case err := <-writeDone:
		if err != nil {
			t.Fatalf("runtime writer failed: %v", err)
		}
	case <-time.After(time.Second):
		t.Fatal("runtime writer did not finish")
	}
}

func TestStartClientConnSessionInitializesDefaultRuntime(t *testing.T) {
	client := &ClientConn{}
	left, right := net.Pipe()
	defer left.Close()
	defer right.Close()

	stopCtx, stopFn := client.startClientConnSession(left, nil, nil)
	defer stopFn()

	if !client.Status().Alive {
		t.Fatalf("client should start alive: %+v", client.Status())
	}
	if stopCtx == nil || stopFn == nil {
		t.Fatal("startClientConnSession should initialize default stop context")
	}
	if got := client.clientConnTransportSnapshot(); got != left {
		t.Fatal("runtime transport snapshot should match passed conn")
	}
	if got := client.clientConnStopContextSnapshot(); got != stopCtx {
		t.Fatal("runtime stop context snapshot should match returned context")
	}
	if got := client.clientConnStopFuncSnapshot(); got == nil {
		t.Fatal("runtime stop func snapshot should be initialized")
	}
	if got := client.GetRemoteAddr(); got == nil || got.String() != left.RemoteAddr().String() {
		t.Fatalf("client remote addr mismatch: got %v want %v", got, left.RemoteAddr())
	}
}

func TestLogicalConnSessionTransportLifecycleUsesLogicalRuntimeOwner(t *testing.T) {
	client := &ClientConn{ClientID: "logical-runtime"}
	logical := client.LogicalConn()
	if logical == nil {
		t.Fatal("LogicalConn should exist")
	}

	firstLeft, firstRight := net.Pipe()
	defer firstRight.Close()
	stopCtx, stopFn := logical.startSession(firstLeft, nil, nil)
	defer stopFn()

	if stopCtx == nil {
		t.Fatal("logical startSession should initialize stop context")
	}
	if got := logical.transportSnapshot(); got != firstLeft {
		t.Fatalf("logical transport snapshot mismatch: got %v want %v", got, firstLeft)
	}
	if !logical.transportAttachedSnapshot() {
		t.Fatal("logical transport should be attached after startSession")
	}

	firstGeneration := logical.transportGenerationSnapshot()
	if firstGeneration == 0 {
		t.Fatal("logical transport generation should advance for stream runtime")
	}

	secondLeft, secondRight := net.Pipe()
	defer secondRight.Close()
	if err := logical.attachSessionTransport(secondLeft); err != nil {
		t.Fatalf("logical attachSessionTransport failed: %v", err)
	}

	if got := logical.transportSnapshot(); got != secondLeft {
		t.Fatalf("logical transport snapshot after attach mismatch: got %v want %v", got, secondLeft)
	}
	if !logical.transportAttachedSnapshot() {
		t.Fatal("logical transport should stay attached after attachSessionTransport")
	}
	if got := logical.transportGenerationSnapshot(); got <= firstGeneration {
		t.Fatalf("logical transport generation should advance after attach: got %d want > %d", got, firstGeneration)
	}

	detachedConn, err := logical.detachTransportForTransfer()
	if err != nil {
		t.Fatalf("logical detachTransportForTransfer failed: %v", err)
	}
	if detachedConn != secondLeft {
		t.Fatalf("detached conn mismatch: got %v want %v", detachedConn, secondLeft)
	}
	if got := logical.transportSnapshot(); got != nil {
		t.Fatalf("logical transport should be cleared after detach, got %v", got)
	}
	if logical.transportAttachedSnapshot() {
		t.Fatal("logical transport should be detached after detachTransportForTransfer")
	}
	if got := logical.stopContextSnapshot(); got != stopCtx {
		t.Fatalf("logical stop context should be preserved after detach, got %v want %v", got, stopCtx)
	}
}

func TestLogicalConnOwnerStateMutationsSyncLegacyClientView(t *testing.T) {
	client := &ClientConn{ClientID: "logical-owner-state"}
	logical := client.LogicalConn()
	if logical == nil {
		t.Fatal("LogicalConn should exist")
	}

	logical.markIdentityBound()
	logical.markStreamTransport()
	attachGeneration := logical.markTransportAttached()
	logical.setClientConnLastHeartbeatUnix(12345)
	logical.markTransportDetached("read error", errors.New("boom"))

	if !client.clientConnIdentityBoundSnapshot() {
		t.Fatal("legacy client identity-bound snapshot should follow logical state")
	}
	if !client.clientConnUsesStreamTransportSnapshot() {
		t.Fatal("legacy client stream-transport snapshot should follow logical state")
	}
	if got := client.clientConnTransportGenerationSnapshot(); got != attachGeneration {
		t.Fatalf("legacy client transport generation = %d, want %d", got, attachGeneration)
	}
	if got := client.clientConnLastHeartbeatUnixSnapshot(); got != 12345 {
		t.Fatalf("legacy client last heartbeat = %d, want %d", got, 12345)
	}
	detach := client.clientConnTransportDetachSnapshot()
	if detach == nil {
		t.Fatal("legacy client detach snapshot should follow logical state")
	}
	if detach.Reason != "read error" || detach.Err != "boom" || detach.Generation != attachGeneration {
		t.Fatalf("legacy client detach snapshot mismatch: %+v", detach)
	}

	logical.clearTransportDetachState()
	if got := client.clientConnTransportDetachSnapshot(); got != nil {
		t.Fatalf("legacy client detach snapshot should clear with logical state, got %+v", got)
	}
}

func TestLogicalDetachTransportForTransferKeepsHandoffConnAlive(t *testing.T) {
	server := NewServer().(*ServerCommon)
	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()

	left, right := net.Pipe()
	defer right.Close()

	client := &ClientConn{
		ClientID: "client-handoff",
		server:   server,
	}
	client.startClientConnSessionTransport(left, stopCtx, stopFn)

	logical := client.LogicalConn()
	detachedConn, err := logical.detachTransportForTransfer()
	if err != nil {
		t.Fatalf("logical detachTransportForTransfer failed: %v", err)
	}
	defer detachedConn.Close()

	payload := []byte("handoff-payload")
	readDone := make(chan error, 1)
	go func() {
		buf := make([]byte, len(payload))
		_ = right.SetReadDeadline(time.Now().Add(time.Second))
		if _, err := io.ReadFull(right, buf); err != nil {
			readDone <- err
			return
		}
		if !bytes.Equal(buf, payload) {
			readDone <- fmt.Errorf("payload mismatch: got %q want %q", string(buf), string(payload))
			return
		}
		readDone <- nil
	}()

	_ = detachedConn.SetWriteDeadline(time.Now().Add(time.Second))
	if _, err := detachedConn.Write(payload); err != nil {
		t.Fatalf("detached handoff conn write failed: %v", err)
	}

	select {
	case err := <-readDone:
		if err != nil {
			t.Fatalf("handoff conn read failed: %v", err)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("timed out waiting for handoff conn read")
	}
}

func TestClientConnTransportBindingSnapshotUsesRuntimeBinding(t *testing.T) {
	client := &ClientConn{}
	left, right := net.Pipe()
	defer left.Close()
	defer right.Close()

	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()
	client.setClientConnSessionRuntime(&clientConnSessionRuntime{
		transport: newTransportBinding(left, nil),
		tuConn:    left,
		stopCtx:   stopCtx,
		stopFn:    stopFn,
	})

	binding := client.clientConnTransportBindingSnapshot()
	if binding == nil {
		t.Fatal("runtime transport binding should exist")
	}
	if got := binding.connSnapshot(); got != left {
		t.Fatal("runtime transport binding conn should match runtime conn")
	}
	if got := binding.queueSnapshot(); got != nil {
		t.Fatalf("server-side peer binding queue should remain nil, got %v", got)
	}
}

func TestClientConnDetachServerOwnedSessionCancelsTransportOnly(t *testing.T) {
	client := &ClientConn{}
	left, right := net.Pipe()
	defer left.Close()
	defer right.Close()

	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()
	client.startClientConnSession(left, stopCtx, stopFn)

	transportStopCtx := client.clientConnTransportStopContextSnapshot()
	client.detachServerOwnedSession()

	if transportStopCtx == nil {
		t.Fatal("transport stop context should exist")
	}
	select {
	case <-transportStopCtx.Done():
	case <-time.After(time.Second):
		t.Fatal("transport stop context should be canceled after detach")
	}
	select {
	case <-client.clientConnStopContextSnapshot().Done():
		t.Fatal("logical stop context should remain active after pure detach")
	default:
	}
	if client.clientConnTransportAttachedSnapshot() {
		t.Fatal("client conn transport should be marked detached after pure detach")
	}
}

func TestAttachClientConnSessionTransportRebindsRuntimeAndStartsReadLoop(t *testing.T) {
	server := NewServer().(*ServerCommon)
	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()
	queue := stario.NewQueueCtx(stopCtx, 4, 1024)
	server.setServerSessionRuntime(&serverSessionRuntime{
		stopCtx: stopCtx,
		stopFn:  stopFn,
		queue:   queue,
	})

	oldLeft, oldRight := net.Pipe()
	defer oldRight.Close()
	client := &ClientConn{
		ClientID: "client-reattach",
		server:   server,
	}
	client.startClientConnSession(oldLeft, stopCtx, stopFn)

	newLeft, newRight := net.Pipe()
	defer newRight.Close()
	if err := client.attachClientConnSessionTransport(newLeft); err != nil {
		t.Fatalf("attachClientConnSessionTransport failed: %v", err)
	}

	rt := client.clientConnSessionRuntimeSnapshot()
	if rt == nil {
		t.Fatal("client conn runtime should exist after attach")
	}
	if rt.tuConn != newLeft || !rt.transportAttached {
		t.Fatalf("attached client conn runtime mismatch: %+v", rt)
	}

	wire := queue.BuildMessage([]byte("reattached"))
	if _, err := newRight.Write(wire); err != nil {
		t.Fatalf("new transport write failed: %v", err)
	}

	select {
	case msg := <-queue.RestoreChan():
		source := assertServerInboundQueueSource(t, msg.Conn, client)
		if got, want := source.TransportGeneration, client.clientConnTransportGenerationSnapshot(); got != want {
			t.Fatalf("queue transport generation mismatch: got %d want %d", got, want)
		}
		if got, want := string(msg.Msg), "reattached"; got != want {
			t.Fatalf("queue payload mismatch: got %q want %q", got, want)
		}
	case <-time.After(time.Second):
		t.Fatal("reattached server-owned transport did not push framed message")
	}
}