package worker

import (
	"context"
	"errors"
	"net"
	"testing"
	"time"

	controlplanev1 "proxy-pool/gen/controlplane/v1"
	"proxy-pool/internal/config"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

func TestNewServerRejectsInvalidOptions(t *testing.T) {
	controlPlane := validServerControlPlane()
	service := &grpcServiceStub{}
	if _, err := NewServer(controlPlane, nil, DefaultServerOptions()); !errors.Is(err, ErrInvalidServer) {
		t.Fatalf("NewServer(nil service) error = %v, want ErrInvalidServer", err)
	}
	if _, err := NewServer(controlPlane, service, ServerOptions{ShutdownTimeout: -time.Second}); !errors.Is(err, ErrInvalidServer) {
		t.Fatalf("NewServer(negative shutdown timeout) error = %v, want ErrInvalidServer", err)
	}
	controlPlane.Enabled = false
	if _, err := NewServer(controlPlane, service, DefaultServerOptions()); !errors.Is(err, ErrInvalidServer) {
		t.Fatalf("NewServer(disabled) error = %v, want ErrInvalidServer", err)
	}
}

func TestServerServesAndStopsOnContextCancellation(t *testing.T) {
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("net.Listen(): %v", err)
	}
	controlPlane := validServerControlPlane()
	controlPlane.Listen = listener.Addr().String()
	service := &grpcServiceStub{registration: Registration{WorkerID: "worker-a", SessionID: "session-a", OwnershipEpoch: 5, HeartbeatInterval: time.Second, MaxStaleAge: 2 * time.Second}}
	server, err := NewServer(controlPlane, service, ServerOptions{ShutdownTimeout: time.Second})
	if err != nil {
		t.Fatalf("NewServer(): %v", err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	result := make(chan error, 1)
	go func() { result <- server.Serve(ctx, listener) }()

	connection, err := grpc.NewClient(listener.Addr().String(), grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		t.Fatalf("grpc.NewClient(): %v", err)
	}
	client := controlplanev1.NewWorkerControlPlaneClient(connection)
	requestCtx, requestCancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer requestCancel()
	response, err := client.RegisterWorker(requestCtx, &controlplanev1.RegisterWorkerRequest{WorkerId: "worker-a", SupportedProtocolVersion: 1})
	if err != nil || response.GetSessionId() != "session-a" {
		t.Fatalf("RegisterWorker() = %+v, %v", response, err)
	}
	if err := connection.Close(); err != nil {
		t.Fatalf("connection.Close(): %v", err)
	}
	cancel()
	select {
	case err := <-result:
		if err != nil {
			t.Fatalf("Serve() error = %v", err)
		}
	case <-time.After(3 * time.Second):
		t.Fatal("Serve() did not stop after context cancellation")
	}
}

func TestServerRegistersCheckerServiceOnTheExistingControlPlaneListener(t *testing.T) {
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("net.Listen(): %v", err)
	}
	controlPlane := validServerControlPlane()
	controlPlane.Listen = listener.Addr().String()
	checker := &checkerServiceStub{}
	server, err := NewServer(controlPlane, &grpcServiceStub{}, ServerOptions{ShutdownTimeout: time.Second, Checker: checker})
	if err != nil {
		t.Fatalf("NewServer(): %v", err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	result := make(chan error, 1)
	go func() { result <- server.Serve(ctx, listener) }()

	connection, err := grpc.NewClient(listener.Addr().String(), grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		t.Fatalf("grpc.NewClient(): %v", err)
	}
	response, err := controlplanev1.NewCheckerControlPlaneClient(connection).ReportObservations(context.Background(), &controlplanev1.ObservationBatch{
		CheckerId: "checker-a",
	})
	if err != nil || response.GetAccepted() != 1 || checker.checkerID != "checker-a" {
		t.Fatalf("ReportObservations() = (%+v, %v); checker=%q", response, err, checker.checkerID)
	}
	if err := connection.Close(); err != nil {
		t.Fatalf("connection.Close(): %v", err)
	}
	cancel()
	select {
	case err := <-result:
		if err != nil {
			t.Fatalf("Serve() error = %v", err)
		}
	case <-time.After(3 * time.Second):
		t.Fatal("Serve() did not stop after context cancellation")
	}
}

type checkerServiceStub struct {
	controlplanev1.UnimplementedCheckerControlPlaneServer
	checkerID string
}

func (stub *checkerServiceStub) ReportObservations(_ context.Context, request *controlplanev1.ObservationBatch) (*controlplanev1.ReportObservationsResponse, error) {
	stub.checkerID = request.GetCheckerId()
	return &controlplanev1.ReportObservationsResponse{Accepted: 1}, nil
}

func validServerControlPlane() config.ControlPlane {
	return config.ControlPlane{
		Enabled:              true,
		Listen:               "127.0.0.1:8443",
		ProtocolVersion:      1,
		HeartbeatInterval:    config.Duration(10 * time.Second),
		SessionTTL:           config.Duration(30 * time.Second),
		MaxStaleAge:          config.Duration(10 * time.Second),
		MaxMessageBytes:      1 << 20,
		MaxRuntimeCounters:   100,
		MaxConcurrentStreams: 10,
		TLS:                  config.ControlPlaneTLS{Mode: "disabled"},
	}
}