package tgsig

import (
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"dev.narayana.im/narayana/telegabber/calls/signaling"
	"gotgcalls/ntgcalls"

	"github.com/zelenin/go-tdlib/client"
)

// concurrent-safe variant of fakeNtg; vanilla fakeNtg appends to slices
// without locking, unusable under -race
type raceNtg struct {
	mu         sync.Mutex
	onSignal   ntgcalls.SignalCallback
	onConnCh   ntgcalls.ConnectionChangeCallback
	stopCount  atomic.Int64
	signalSent atomic.Int64
}

func (f *raceNtg) OnSignal(cb ntgcalls.SignalCallback) {
	f.mu.Lock()
	f.onSignal = cb
	f.mu.Unlock()
}
func (f *raceNtg) OnConnectionChange(cb ntgcalls.ConnectionChangeCallback) {
	f.mu.Lock()
	f.onConnCh = cb
	f.mu.Unlock()
}
func (f *raceNtg) CreateP2PCall(int64) error              { return nil }
func (f *raceNtg) SkipExchange(int64, []byte, bool) error { return nil }
func (f *raceNtg) ConnectP2P(int64, []ntgcalls.RTCServer, []string, bool) error {
	return nil
}
func (f *raceNtg) SendSignalingData(int64, []byte) error {
	f.signalSent.Add(1)
	return nil
}
func (f *raceNtg) Stop(int64) error {
	f.stopCount.Add(1)
	return nil
}

// simulates ntgcalls' C++ thread reaching into Go
func (f *raceNtg) fire(chatID int64, data []byte) {
	f.mu.Lock()
	cb := f.onSignal
	f.mu.Unlock()
	if cb != nil {
		cb(chatID, data)
	}
}

// concurrent-safe variant of fakeTdlib
type raceTdlib struct {
	created    atomic.Int64
	accepted   atomic.Int64
	discarded  atomic.Int64
	signalSent atomic.Int64
	nextCallID atomic.Int32
}

func (f *raceTdlib) CreateCall(*client.CreateCallRequest) (*client.CallId, error) {
	f.created.Add(1)
	id := f.nextCallID.Add(1)
	return &client.CallId{Id: id}, nil
}
func (f *raceTdlib) AcceptCall(*client.AcceptCallRequest) (*client.Ok, error) {
	f.accepted.Add(1)
	return &client.Ok{}, nil
}
func (f *raceTdlib) DiscardCall(*client.DiscardCallRequest) (*client.Ok, error) {
	f.discarded.Add(1)
	return &client.Ok{}, nil
}
func (f *raceTdlib) SendCallSignalingData(*client.SendCallSignalingDataRequest) (*client.Ok, error) {
	f.signalSent.Add(1)
	return &client.Ok{}, nil
}

// many dispatchers in parallel with Adapter.Close; -race must not flag
// the ntg/tdlib touch sites, post-Close dispatches must be skipped, and
// every withCallContext must release its RLock or Close blocks forever
func TestAdapter_NoRaceUnderConcurrentDispatchAndClose(t *testing.T) {
	tdlib := &raceTdlib{}
	ntg := &raceNtg{}
	mgr := NewManager(nil)
	a := New(tdlib, ntg, nil, "jid@gw", mgr)

	// pre-register a side so dispatchers find something
	userID := int64(42)
	callee := a.NewCallee(7, userID, false)
	cb := &callee.callBase

	bridgeSide := &recCaller{}
	calleeSide := &recCallee{}
	br := signaling.New(signaling.Config{
		Caller: bridgeSide, Callee: calleeSide, Timers: noopTimers{},
	})
	cb.Bind(br)
	br.Start()
	br.Ringing()

	var wg sync.WaitGroup
	stop := make(chan struct{})

	// Spammer 1: OnSignal callback (simulates ntgcalls C++ thread).
	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			select {
			case <-stop:
				return
			default:
			}
			ntg.fire(userID, []byte("data"))
		}
	}()

	// spammer 2: OnNewSignalingData (tdlib updateHandler)
	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			select {
			case <-stop:
				return
			default:
			}
			mgr.OnNewSignalingData("jid@gw", &client.UpdateNewCallSignalingData{
				CallId: 7,
				Data:   []byte("data"),
			})
		}
	}()

	// spammer 3: callBase.Terminate (bridge tear-down attempts)
	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			select {
			case <-stop:
				return
			default:
			}
			cb.Terminate(signaling.ReasonHangup)
		}
	}()

	// let spammers warm up
	time.Sleep(20 * time.Millisecond)

	// close concurrently with the spammers
	closeDone := make(chan struct{})
	go func() {
		a.Close()
		close(closeDone)
	}()

	select {
	case <-closeDone:
	case <-time.After(2 * time.Second):
		t.Fatal("Close blocked > 2s - a withCallContext somewhere is not releasing its RLock")
	}

	// snapshot counters at the moment Close returned
	postCloseSignals := tdlib.signalSent.Load()
	postCloseDiscards := tdlib.discarded.Load()
	postCloseNtgSignals := ntg.signalSent.Load()
	postCloseStops := ntg.stopCount.Load()

	// let spammers run a bit more - counters must stay flat
	time.Sleep(50 * time.Millisecond)
	close(stop)
	wg.Wait()

	if tdlib.signalSent.Load() != postCloseSignals {
		t.Errorf("tdlib.signalSent advanced after Close: %d -> %d",
			postCloseSignals, tdlib.signalSent.Load())
	}
	if tdlib.discarded.Load() != postCloseDiscards {
		t.Errorf("tdlib.discarded advanced after Close: %d -> %d",
			postCloseDiscards, tdlib.discarded.Load())
	}
	if ntg.signalSent.Load() != postCloseNtgSignals {
		t.Errorf("ntg.signalSent advanced after Close: %d -> %d",
			postCloseNtgSignals, ntg.signalSent.Load())
	}
	if ntg.stopCount.Load() != postCloseStops {
		t.Errorf("ntg.stopCount advanced after Close: %d -> %d",
			postCloseStops, ntg.stopCount.Load())
	}
}

// Close twice must not panic or race
func TestAdapter_CloseIsIdempotent(t *testing.T) {
	tdlib := &raceTdlib{}
	ntg := &raceNtg{}
	a := New(tdlib, ntg, nil, "jid@gw", NewManager(nil))

	var wg sync.WaitGroup
	for i := 0; i < 5; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			a.Close()
		}()
	}
	wg.Wait()
}