package grpcapi

import (
	"context"
	"crypto/tls"
	"errors"
	"net"
	"net/http"
	"testing"
	"time"

	"galaxy/gateway/internal/app"
	"galaxy/gateway/internal/config"
	"galaxy/gateway/internal/session"
	gatewayv1 "galaxy/gateway/proto/galaxy/gateway/v1"
	"galaxy/gateway/proto/galaxy/gateway/v1/gatewayv1connect"

	"connectrpc.com/connect"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"golang.org/x/net/http2"
)

func TestExecuteCommandRejectsMalformedEnvelope(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	_, err := client.ExecuteCommand(context.Background(), connect.NewRequest(&gatewayv1.ExecuteCommandRequest{}))
	require.Error(t, err)
	assert.Equal(t, connect.CodeInvalidArgument, connect.CodeOf(err))
}

func TestSubscribeEventsRejectsMalformedEnvelope(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	err := subscribeEventsError(t, context.Background(), client, &gatewayv1.SubscribeEventsRequest{})
	require.Error(t, err)
	assert.Equal(t, connect.CodeInvalidArgument, connect.CodeOf(err))
}

func TestExecuteCommandRejectsUnsupportedProtocolVersion(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	_, err := client.ExecuteCommand(context.Background(), connect.NewRequest(&gatewayv1.ExecuteCommandRequest{
		ProtocolVersion: "v2",
		DeviceSessionId: "device-session-123",
		MessageType:     "fleet.move",
		TimestampMs:     123456789,
		RequestId:       "request-123",
		PayloadBytes:    []byte("payload"),
		PayloadHash:     []byte("hash"),
		Signature:       []byte("signature"),
	}))
	require.Error(t, err)
	assert.Equal(t, connect.CodeFailedPrecondition, connect.CodeOf(err))
	assert.Equal(t, `unsupported protocol_version "v2"`, connectErrorMessage(t, err))
}

func TestExecuteCommandValidEnvelopeStillReturnsUnimplemented(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{
		SessionCache: staticSessionCache{
			lookupFunc: func(context.Context, string) (session.Record, error) {
				return newActiveSessionRecord(), nil
			},
		},
		ReplayStore: staticReplayStore{},
	})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	_, err := client.ExecuteCommand(context.Background(), connect.NewRequest(newValidExecuteCommandRequest()))
	require.Error(t, err)
	assert.Equal(t, connect.CodeUnimplemented, connect.CodeOf(err))
}

func TestExecuteCommandMissingReplayStoreFailsClosed(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{
		SessionCache: staticSessionCache{
			lookupFunc: func(context.Context, string) (session.Record, error) {
				return newActiveSessionRecord(), nil
			},
		},
	})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	_, err := client.ExecuteCommand(context.Background(), connect.NewRequest(newValidExecuteCommandRequest()))
	require.Error(t, err)
	assert.Equal(t, connect.CodeUnavailable, connect.CodeOf(err))
	assert.Equal(t, "replay store is unavailable", connectErrorMessage(t, err))
}

func TestSubscribeEventsValidEnvelopeSendsBootstrapEventAndWaitsForCancellation(t *testing.T) {
	t.Parallel()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	server, runGateway := newTestGateway(t, ServerDependencies{
		SessionCache: staticSessionCache{
			lookupFunc: func(context.Context, string) (session.Record, error) {
				return newActiveSessionRecord(), nil
			},
		},
		ReplayStore: staticReplayStore{},
	})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	stream, err := client.SubscribeEvents(ctx, connect.NewRequest(newValidSubscribeEventsRequest()))
	require.NoError(t, err)
	t.Cleanup(func() { _ = stream.Close() })

	event := recvBootstrapEvent(t, stream)
	assertServerTimeBootstrapEvent(t, event, newTestResponseSignerPublicKey(), "request-123", "trace-123", testCurrentTime.UnixMilli())

	recvResult := make(chan error, 1)
	go func() {
		if stream.Receive() {
			recvResult <- errors.New("stream produced unexpected event")
			return
		}
		recvResult <- stream.Err()
	}()

	require.Never(t, func() bool {
		select {
		case <-recvResult:
			return true
		default:
			return false
		}
	}, 100*time.Millisecond, 10*time.Millisecond, "stream closed before cancellation")

	cancel()

	var recvErr error
	require.Eventually(t, func() bool {
		select {
		case recvErr = <-recvResult:
			return true
		default:
			return false
		}
	}, time.Second, 10*time.Millisecond, "stream did not stop after client cancellation")
	require.Error(t, recvErr)
	assert.Equal(t, connect.CodeCanceled, connect.CodeOf(recvErr))
}

func TestSubscribeEventsMissingReplayStoreFailsClosed(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{
		SessionCache: staticSessionCache{
			lookupFunc: func(context.Context, string) (session.Record, error) {
				return newActiveSessionRecord(), nil
			},
		},
	})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	err := subscribeEventsError(t, context.Background(), client, newValidSubscribeEventsRequest())
	require.Error(t, err)
	assert.Equal(t, connect.CodeUnavailable, connect.CodeOf(err))
	assert.Equal(t, "replay store is unavailable", connectErrorMessage(t, err))
}

func TestSubscribeEventsFailsClosedWhenResponseSignerUnavailable(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{
		ResponseSigner: unavailableResponseSigner{},
		SessionCache: staticSessionCache{
			lookupFunc: func(context.Context, string) (session.Record, error) {
				return newActiveSessionRecord(), nil
			},
		},
		ReplayStore: staticReplayStore{},
	})
	defer runGateway.stop(t)

	addr := waitForListenAddr(t, server)
	client := newEdgeClient(t, addr)

	err := subscribeEventsError(t, context.Background(), client, newValidSubscribeEventsRequest())
	require.Error(t, err)
	assert.Equal(t, connect.CodeUnavailable, connect.CodeOf(err))
	assert.Equal(t, "response signer is unavailable", connectErrorMessage(t, err))
}

func TestServerLifecycle(t *testing.T) {
	t.Parallel()

	server, runGateway := newTestGateway(t, ServerDependencies{})
	addr := waitForListenAddr(t, server)
	// Probe the listener before shutdown so we know it accepted at
	// least one TCP connection.
	probe, err := net.DialTimeout("tcp", addr, time.Second)
	require.NoError(t, err)
	require.NoError(t, probe.Close())

	runGateway.stop(t)

	// After shutdown the listener must refuse new TCP connections.
	dialCtx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
	defer cancel()
	dialer := &net.Dialer{}
	closedConn, err := dialer.DialContext(dialCtx, "tcp", addr)
	if err == nil {
		_ = closedConn.Close()
		t.Fatalf("expected dial to %s to fail after shutdown", addr)
	}
}

type runningGateway struct {
	cancel   context.CancelFunc
	resultCh chan error
}

func newTestGateway(t *testing.T, deps ServerDependencies) (*Server, runningGateway) {
	t.Helper()

	grpcCfg := config.DefaultAuthenticatedGRPCConfig()
	grpcCfg.Addr = "127.0.0.1:0"
	grpcCfg.FreshnessWindow = testFreshnessWindow

	return newTestGatewayWithGRPCConfig(t, grpcCfg, deps)
}

func newTestGatewayWithGRPCConfig(t *testing.T, grpcCfg config.AuthenticatedGRPCConfig, deps ServerDependencies) (*Server, runningGateway) {
	t.Helper()

	cfg := config.Config{
		ShutdownTimeout:   time.Second,
		AuthenticatedGRPC: grpcCfg,
	}

	if deps.Clock == nil {
		deps.Clock = fixedClock{now: testCurrentTime}
	}
	if deps.ResponseSigner == nil {
		deps.ResponseSigner = newTestResponseSigner()
	}
	if deps.Router == nil && deps.Service != nil {
		deps.Router = executeCommandAdapterRouter{service: deps.Service}
	}

	server := NewServer(cfg.AuthenticatedGRPC, deps)
	application := app.New(cfg, server)

	ctx, cancel := context.WithCancel(context.Background())
	resultCh := make(chan error, 1)
	go func() {
		resultCh <- application.Run(ctx)
	}()

	return server, runningGateway{
		cancel:   cancel,
		resultCh: resultCh,
	}
}

func (g runningGateway) stop(t *testing.T) {
	t.Helper()

	g.cancel()

	var err error
	require.Eventually(t, func() bool {
		select {
		case err = <-g.resultCh:
			return true
		default:
			return false
		}
	}, 2*time.Second, 10*time.Millisecond, "gateway did not stop after cancellation")
	require.NoError(t, err)
}

func waitForListenAddr(t *testing.T, server *Server) string {
	t.Helper()

	var addr string
	require.Eventually(t, func() bool {
		addr = server.listenAddr()
		return addr != ""
	}, time.Second, 10*time.Millisecond, "server did not start listening")
	return addr
}

// newEdgeClient returns a Connect client speaking HTTP/2 cleartext to the
// authenticated edge listener. AllowHTTP forces the client to issue plain
// HTTP/2 requests (h2c) instead of attempting TLS, which the gateway's
// in-process test bootstrap does not configure.
func newEdgeClient(t *testing.T, addr string) gatewayv1connect.EdgeGatewayClient {
	t.Helper()

	httpClient := &http.Client{
		Transport: &http2.Transport{
			AllowHTTP: true,
			DialTLSContext: func(ctx context.Context, network, target string, _ *tls.Config) (net.Conn, error) {
				return (&net.Dialer{}).DialContext(ctx, network, target)
			},
		},
	}
	return gatewayv1connect.NewEdgeGatewayClient(httpClient, "http://"+addr)
}

// connectErrorMessage extracts the *connect.Error message from err. It
// fails the test if err is not a *connect.Error so the caller's expected
// message comparison doesn't accidentally match the wrapped Go error
// string instead of the protocol-level message.
func connectErrorMessage(t require.TestingT, err error) string {
	if helper, ok := t.(interface{ Helper() }); ok {
		helper.Helper()
	}

	var connectErr *connect.Error
	if !errors.As(err, &connectErr) {
		require.FailNowf(t, "expected *connect.Error", "got %T: %v", err, err)
	}
	return connectErr.Message()
}