package xmppsig

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

	"github.com/pion/webrtc/v4"
	"github.com/pion/webrtc/v4/pkg/media"
)

// pion OnTrack fires inside SetRemoteDescription, but setupAudio runs
// later (from OnRemoteDescriptionApplied) - so hookTrack must install
// a permanent forwarder at PC construction and buffer until
// SetTrackHandler. This drives a real pion<->pion roundtrip with the
// handler installed after the track has already landed.
func TestHookTrack_BuffersTrackThatArrivesBeforeSetHandler(t *testing.T) {
	if testing.Short() {
		t.Skip("e2e ICE handshake")
	}

	// gateway-side PC, same shape as xmppsig.NewCaller
	pcGateway, err := webrtc.NewPeerConnection(webrtc.Configuration{})
	if err != nil {
		t.Fatalf("gateway PC: %v", err)
	}
	defer pcGateway.Close()
	if _, err := pcGateway.AddTransceiverFromKind(webrtc.RTPCodecTypeAudio, webrtc.RTPTransceiverInit{
		Direction: webrtc.RTPTransceiverDirectionSendrecv,
	}); err != nil {
		t.Fatalf("gateway AddTransceiver: %v", err)
	}

	// the forwarder under test
	var base xmppBase
	base.hookTrack(pcGateway)

	// remote pion PC with an audio track to send
	pcPeer, err := webrtc.NewPeerConnection(webrtc.Configuration{})
	if err != nil {
		t.Fatalf("peer PC: %v", err)
	}
	defer pcPeer.Close()
	peerTrack, err := webrtc.NewTrackLocalStaticSample(
		webrtc.RTPCodecCapability{MimeType: webrtc.MimeTypeOpus, ClockRate: 48000, Channels: 2},
		"audio", "peer-stream",
	)
	if err != nil {
		t.Fatalf("peer track: %v", err)
	}
	if _, err := pcPeer.AddTrack(peerTrack); err != nil {
		t.Fatalf("peer AddTrack: %v", err)
	}

	// pion offer/answer + ICE-complete handshake
	gatewayConnected := make(chan struct{})
	pcGateway.OnConnectionStateChange(func(s webrtc.PeerConnectionState) {
		if s == webrtc.PeerConnectionStateConnected {
			select {
			case <-gatewayConnected:
			default:
				close(gatewayConnected)
			}
		}
	})
	completePionHandshake(t, pcGateway, pcPeer)
	select {
	case <-gatewayConnected:
	case <-time.After(15 * time.Second):
		t.Fatalf("gateway PC never reached Connected (state=%s)", pcGateway.ConnectionState())
	}

	// real RTP so OnTrack fires (pion needs the first packet to dispatch)
	stopRTP := make(chan struct{})
	go pumpSilenceOpus(peerTrack, stopRTP)
	defer close(stopRTP)

	// wait for pion to dispatch the first packet through hookTrack
	waitUntilTrue(t, "track buffered by hookTrack", 5*time.Second, func() bool {
		base.mu.Lock()
		defer base.mu.Unlock()
		return len(base.pendingTracks) > 0
	})

	// install handler late, like setupAudio from OnRemoteDescriptionApplied
	var delivered atomic.Int64
	base.SetTrackHandler(func(t *webrtc.TrackRemote) {
		delivered.Add(1)
	})
	if delivered.Load() != 1 {
		t.Errorf("SetTrackHandler did not drain pendingTracks: delivered=%d, want 1", delivered.Load())
	}

	// subsequent track events should go direct to the handler
	base.mu.Lock()
	if len(base.pendingTracks) != 0 {
		t.Errorf("pendingTracks not cleared after drain: %d entries", len(base.pendingTracks))
	}
	base.mu.Unlock()
}

// completePionHandshake drives a pion offer/answer + trickle ICE between
// two PeerConnections, with the gateway as the answerer (matching the
// xmpp-originated incoming call shape - Dino's session-initiate carries
// the offer, the gateway sends the answer).
func completePionHandshake(t *testing.T, pcAnswerer, pcOfferer *webrtc.PeerConnection) {
	t.Helper()
	// trickle ICE: forward each side's candidates to the other
	pcOfferer.OnICECandidate(func(c *webrtc.ICECandidate) {
		if c == nil {
			return
		}
		if err := pcAnswerer.AddICECandidate(c.ToJSON()); err != nil {
			t.Logf("answerer AddICECandidate: %v", err)
		}
	})
	pcAnswerer.OnICECandidate(func(c *webrtc.ICECandidate) {
		if c == nil {
			return
		}
		if err := pcOfferer.AddICECandidate(c.ToJSON()); err != nil {
			t.Logf("offerer AddICECandidate: %v", err)
		}
	})

	offer, err := pcOfferer.CreateOffer(nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := pcOfferer.SetLocalDescription(offer); err != nil {
		t.Fatal(err)
	}
	if err := pcAnswerer.SetRemoteDescription(*pcOfferer.LocalDescription()); err != nil {
		t.Fatal(err)
	}
	answer, err := pcAnswerer.CreateAnswer(nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := pcAnswerer.SetLocalDescription(answer); err != nil {
		t.Fatal(err)
	}
	if err := pcOfferer.SetRemoteDescription(*pcAnswerer.LocalDescription()); err != nil {
		t.Fatal(err)
	}
}

// writes 20ms opus silence every 20ms until stop closes
func pumpSilenceOpus(track *webrtc.TrackLocalStaticSample, stop <-chan struct{}) {
	// minimal opus silence frame: TOC byte + 1-byte SILK
	silence := []byte{0xF8, 0xFF, 0xFE}
	tick := time.NewTicker(20 * time.Millisecond)
	defer tick.Stop()
	for {
		select {
		case <-stop:
			return
		case <-tick.C:
			_ = track.WriteSample(media.Sample{Data: silence, Duration: 20 * time.Millisecond})
		}
	}
}

// local poller; duplicates the jingle one to avoid test-file ordering deps
func waitUntilTrue(t *testing.T, what string, d time.Duration, cond func() bool) {
	t.Helper()
	deadline := time.Now().Add(d)
	for time.Now().Before(deadline) {
		if cond() {
			return
		}
		time.Sleep(20 * time.Millisecond)
	}
	t.Fatalf("waitUntilTrue(%s): timed out after %v", what, d)
}