// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// +build go1.11,linux

package grpc

import (
	"context"
	"errors"
	"fmt"
	"net"
	"os"
	"syscall"
	"testing"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/sys/unix"
	"google.golang.org/api/option"
	"google.golang.org/grpc"
)

func TestDialTCPUserTimeout(t *testing.T) {
	l, err := net.Listen("tcp", ":3000")
	if err != nil {
		t.Error(err)
		return
	}
	defer l.Close()

	go func() {
		conn, err := l.Accept()
		if err != nil {
			t.Error(err)
			return
		}
		if err := conn.Close(); err != nil {
			t.Error(err)
		}
	}()

	conn, err := dialTCPUserTimeout(context.Background(), ":3000")
	if err != nil {
		t.Fatal(err)
	}
	defer conn.Close()

	timeout, err := getTCPUserTimeout(conn)
	if err != nil {
		t.Fatal(err)
	}
	if timeout != tcpUserTimeoutMilliseconds {
		t.Fatalf("expected %v, got %v", tcpUserTimeoutMilliseconds, timeout)
	}
}

func getTCPUserTimeout(conn net.Conn) (int, error) {
	tcpconn, ok := conn.(*net.TCPConn)
	if !ok {
		return 0, fmt.Errorf("conn is not *net.TCPConn. got %T", conn)
	}
	rawConn, err := tcpconn.SyscallConn()
	if err != nil {
		return 0, err
	}
	var timeout int
	var syscalErr error
	controlErr := rawConn.Control(func(fd uintptr) {
		timeout, syscalErr = syscall.GetsockoptInt(int(fd), syscall.IPPROTO_TCP, unix.TCP_USER_TIMEOUT)
	})
	if syscalErr != nil {
		return 0, syscalErr
	}
	if controlErr != nil {
		return 0, controlErr
	}
	return timeout, nil
}

// Check that tcp timeout dialer overwrites user defined dialer.
func TestDialWithDirectPathEnabled(t *testing.T) {
	os.Setenv("GOOGLE_CLOUD_ENABLE_DIRECT_PATH", "example,other")
	defer os.Clearenv()

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)

	userDialer := grpc.WithDialer(func(addr string, timeout time.Duration) (net.Conn, error) {
		t.Error("did not expect a call to user dialer, got one")
		cancel()
		return nil, errors.New("not expected")
	})

	conn, err := Dial(ctx,
		option.WithTokenSource(oauth2.StaticTokenSource(nil)), // No creds.
		option.WithGRPCDialOption(userDialer),
		option.WithEndpoint("example.google.com:443"))
	if err != nil {
		t.Errorf("DialGRPC: error %v, want nil", err)
	}
	defer conn.Close()

	// gRPC doesn't connect before the first call.
	grpc.Invoke(ctx, "foo", nil, nil, conn)
}