package mtprotoedge

import (
	"context"
	"sync"
	"testing"
	"time"

	"github.com/gotd/td/bin"
	"github.com/gotd/td/mt"
	"github.com/gotd/td/proto"
	"github.com/gotd/td/tg"
)

func TestOutboundActorSerializesConcurrentSends(t *testing.T) {
	const dc = 2
	addr, pub, srv := startTestServer(t, Options{DC: dc})
	conn, auth, cipher := dialHandshake(t, addr, dc, pub)

	clientMsgID := proto.NewMessageIDGen(time.Now)
	sendEncrypted(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
	collectReplies(t, conn, cipher, auth.AuthKey, mt.MsgsAckTypeID)
	srv.Conns().SetReceivesUpdates(auth.SessionID, true)

	const sends = 64
	var wg sync.WaitGroup
	errs := make(chan error, sends)
	for i := 0; i < sends; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
			defer cancel()
			errs <- srv.Conns().PushToSession(ctx, auth.SessionID, proto.MessageFromServer, &tg.UpdatesTooLong{})
		}()
	}
	wg.Wait()
	close(errs)
	for err := range errs {
		if err != nil {
			t.Fatalf("push: %v", err)
		}
	}

	var prevMsgID int64
	var prevSeqNo int32 = -1
	for i := 0; i < sends; i++ {
		data, id, _ := readServerMessage(t, conn, cipher, auth.AuthKey)
		if id != tg.UpdatesTooLongTypeID {
			t.Fatalf("message %d type = %#x, want updatesTooLong", i, id)
		}
		if i > 0 && data.MessageID <= prevMsgID {
			t.Fatalf("message %d msg_id = %d after %d, want strictly increasing", i, data.MessageID, prevMsgID)
		}
		if data.SeqNo%2 != 1 {
			t.Fatalf("message %d seq_no = %d, want odd content-related seq_no", i, data.SeqNo)
		}
		if i > 0 && data.SeqNo <= prevSeqNo {
			t.Fatalf("message %d seq_no = %d after %d, want increasing", i, data.SeqNo, prevSeqNo)
		}
		prevMsgID = data.MessageID
		prevSeqNo = data.SeqNo
	}
}

func TestOutboundResendAndAckState(t *testing.T) {
	const dc = 2
	addr, pub, srv := startTestServer(t, Options{DC: dc})
	conn, auth, cipher := dialHandshake(t, addr, dc, pub)

	clientMsgID := proto.NewMessageIDGen(time.Now)
	sendEncrypted(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
	collectReplies(t, conn, cipher, auth.AuthKey, mt.MsgsAckTypeID)
	srv.Conns().SetReceivesUpdates(auth.SessionID, true)

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	if err := srv.Conns().PushToSession(ctx, auth.SessionID, proto.MessageFromServer, &tg.UpdatesTooLong{}); err != nil {
		cancel()
		t.Fatalf("push: %v", err)
	}
	cancel()

	original, id, _ := readServerMessage(t, conn, cipher, auth.AuthKey)
	if id != tg.UpdatesTooLongTypeID {
		t.Fatalf("pushed type = %#x, want updatesTooLong", id)
	}

	resendReqID := clientMsgID.New(proto.MessageFromClient)
	sendEncryptedWithSeq(t, conn, cipher, auth, resendReqID, 3, &mt.MsgResendReq{MsgIDs: []int64{original.MessageID}})
	resent, resentType, _ := readServerMessage(t, conn, cipher, auth.AuthKey)
	if resentType != tg.UpdatesTooLongTypeID {
		t.Fatalf("resent type = %#x, want updatesTooLong", resentType)
	}
	if resent.MessageID != original.MessageID || resent.SeqNo != original.SeqNo {
		t.Fatalf("resent frame = (msg_id=%d seq=%d), want original (msg_id=%d seq=%d)",
			resent.MessageID, resent.SeqNo, original.MessageID, original.SeqNo)
	}
	_, stateType, stateBuf := readServerMessage(t, conn, cipher, auth.AuthKey)
	if stateType != mt.MsgsStateInfoTypeID {
		t.Fatalf("state type = %#x, want msgs_state_info", stateType)
	}
	assertStateInfo(t, stateBuf, resendReqID, []byte{msgStateReceived})
	_, ackType, _ := readServerMessage(t, conn, cipher, auth.AuthKey)
	if ackType != mt.MsgsAckTypeID {
		t.Fatalf("ack type = %#x, want msgs_ack", ackType)
	}

	sendEncryptedWithSeq(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), 4, &mt.MsgsAck{MsgIDs: []int64{original.MessageID}})
	ackedResendReqID := clientMsgID.New(proto.MessageFromClient)
	sendEncryptedWithSeq(t, conn, cipher, auth, ackedResendReqID, 5, &mt.MsgResendReq{MsgIDs: []int64{original.MessageID}})
	_, ackedStateType, ackedStateBuf := readServerMessage(t, conn, cipher, auth.AuthKey)
	if ackedStateType != mt.MsgsStateInfoTypeID {
		t.Fatalf("after ack type = %#x, want msgs_state_info without resend", ackedStateType)
	}
	assertStateInfo(t, ackedStateBuf, ackedResendReqID, []byte{msgStateReceived})
}

func assertStateInfo(t *testing.T, b *bin.Buffer, reqMsgID int64, want []byte) {
	t.Helper()
	var info mt.MsgsStateInfo
	if err := info.Decode(b); err != nil {
		t.Fatalf("decode msgs_state_info: %v", err)
	}
	if info.ReqMsgID != reqMsgID {
		t.Fatalf("msgs_state_info.req_msg_id = %d, want %d", info.ReqMsgID, reqMsgID)
	}
	if string(info.Info) != string(want) {
		t.Fatalf("msgs_state_info.info = %v, want %v", []byte(info.Info), want)
	}
}