// Copyright (C) 2017 Luke Shumaker <lukeshu@sbcglobal.net>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
// 02110-1301 USA

package nslcd_systemd_test

import (
	"context"
	"fmt"
	"io/ioutil"
	"net"
	"os"
	"runtime"
	"strings"
	"sync"
	"syscall"
	"testing"
	"time"

	"git.lukeshu.com/go/libnslcd/nslcd_proto"
	"git.lukeshu.com/go/libnslcd/nslcd_server"
	"git.lukeshu.com/go/libnslcd/nslcd_systemd"
	"golang.org/x/sys/unix"
)

func init() {
	if fdIsDevNull(3) == nil {
		return
	}

	devnull, err := os.OpenFile("/dev/null", os.O_RDWR, 0666)
	if err != nil {
		panic(err)
	}
	if devnull.Fd() == 3 {
		return
	}

	fmt.Fprintln(os.Stderr, "Could not open /dev/null on FD 3; calling dup2 and re-exec()ing")
	// shell out to do the FD manipulation--If we made it here,
	// there's a good chance that FD3 was managed by the go
	// runtime, and would be changed before we execve(2).
	panic(syscall.Exec("/bin/sh", append([]string{"sh", "-c", "exec -- \"$@\" 3<>/dev/null"}, os.Args...), os.Environ()))
}

type testContext struct {
	*testing.T
	tmpdir string
	status chan<- string
}

func testDriver(
	t *testContext,
	backend nslcd_systemd.Backend,
	limits nslcd_server.Limits,
	notifyHandler func(dat []byte, oob []byte) error,
	client func(sockname string)) {

	t.status <- "setting up"

	errfatal := func(err error) {
		if err != nil {
			t.Fatal(err)
		}
	}

	evExitSupervisor := make(chan error)
	evExitServer := make(chan uint8)

	// supervisor //////////////////////////////////////////////////////////
	notify_sock, err := sdNotifyListen(t.tmpdir + "/notify.sock")
	errfatal(err)
	go func() {
		evExitSupervisor <- sdNotifyHandle(notify_sock, notifyHandler)
	}()

	// server //////////////////////////////////////////////////////////////
	errfatal(sdActivatedStream(t.tmpdir + "/nslcd.sock"))
	go func() {
		evExitServer <- nslcd_systemd.Main(backend, limits, context.Background())
	}()

	// client/driver ///////////////////////////////////////////////////////
	t.status <- "running client"
	client(t.tmpdir + "/nslcd.sock")

	// exit ////////////////////////////////////////////////////////////////

	// A limitation of Unix sockets is that some may get dropped
	// if they arrive close together.  So give it some (a half
	// second is probably generous by a couple orders of
	// magnitude) time between the client sending any signals and
	// us sending SIGTERM, so that we are sure it gets both.
	time.Sleep(time.Second / 2)

	t.status <- "waiting for server exit"
	errfatal(unix.Kill(unix.Getpid(), unix.SIGTERM))
	status := <-evExitServer
	if status != 0 {
		t.Fatalf("Main() exited with %d", status)
	}

	t.status <- "waiting for supervisor exit"
	errfatal(notify_sock.SetReadDeadline(time.Now()))
	err = <-evExitSupervisor
	if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
		err = nil
	}
	errfatal(err)
	errfatal(notify_sock.Close())
}

func testClientHang(t *testContext, backend nslcd_systemd.Backend, toclose bool) {
}

type NonLockingBackend struct {
	nslcd_server.NilBackend
}

func (o *NonLockingBackend) Init() error   { return nil }
func (o *NonLockingBackend) Reload() error { return nil }
func (o *NonLockingBackend) Close()        {}

func (o *NonLockingBackend) Passwd_All(ctx context.Context, req nslcd_proto.Request_Passwd_All) <-chan nslcd_proto.Passwd {
	ret := make(chan nslcd_proto.Passwd)
	go func() {
		defer close(ret)

		for i := 0; i < 500; i++ {
			ret <- nslcd_proto.Passwd{
				Name:    fmt.Sprintf("user%d", i),
				PwHash:  "x",
				UID:     int32(1000 + i),
				GID:     1000,
				GECOS:   fmt.Sprintf("User %d", i),
				HomeDir: fmt.Sprintf("/home/user%d", i),
				Shell:   "/bin/sh",
			}
		}
	}()
	return ret
}

type LockingBackend struct {
	NonLockingBackend
	lock sync.RWMutex
}

func (o *LockingBackend) Reload() error {
	o.lock.Lock()
	defer o.lock.Unlock()
	return o.NonLockingBackend.Reload()
}

func (o *LockingBackend) Close() {
	o.lock.Lock()
	defer o.lock.Unlock()
	o.NonLockingBackend.Close()
}

func (o *LockingBackend) Passwd_All(ctx context.Context, req nslcd_proto.Request_Passwd_All) <-chan nslcd_proto.Passwd {
	o.lock.RLock()
	ret := make(chan nslcd_proto.Passwd)
	go func() {
		defer o.lock.RUnlock()
		defer close(ret)

		for i := 0; i < 500; i++ {
			ret <- nslcd_proto.Passwd{
				Name:    fmt.Sprintf("user%d", i),
				PwHash:  "x",
				UID:     int32(1000 + i),
				GID:     1000,
				GECOS:   fmt.Sprintf("User %d", i),
				HomeDir: fmt.Sprintf("/home/user%d", i),
				Shell:   "/bin/sh",
			}
		}
	}()
	return ret
}

func TestClientHang(t *testing.T) {
	testcases := []struct {
		name    string
		backend nslcd_systemd.Backend
		toclose bool
	}{
		{"NoLocks-ClientOpen", &NonLockingBackend{}, false},
		{"NoLocks-ClientClose", &NonLockingBackend{}, true},
		{"Locking-ClientOpen", &LockingBackend{}, false},
		{"Locking-ClientClose", &LockingBackend{}, true},
	}
	for _, testcase := range testcases {
		func() {
			tmpdir, err := ioutil.TempDir("", "go-test-libnslcd-client-hang.")
			if err != nil {
				t.Fatal(err)
			}
			defer os.RemoveAll(tmpdir)
			defer sdActivatedReset()
			t.Run(testcase.name, func(t *testing.T) {
				testWithTimeout(t, 2*time.Second, func(t *testing.T, s chan<- string) {
					ctx := &testContext{T: t, tmpdir: tmpdir, status: s}

					backend := testcase.backend

					limits := nslcd_server.Limits{
						Timeout: 1 * time.Second,
					}

					evReload := make(chan bool)

					notifyHandler := func() func(dat []byte, oob []byte) error {
						reloading := false
						return func(dat []byte, oob []byte) error {
							for _, line := range strings.Split(string(dat), "\n") {
								switch line {
								case "RELOADING=1":
									reloading = true
								case "READY=1":
									if reloading {
										evReload <- true
									}
									reloading = false
								}
							}
							return nil
						}
					}()

					client := func(sockname string) {
						errfatal := func(err error) {
							if err != nil {
								t.Fatal(err)
							}
						}

						ctx.status <- "talking with server"
						conn, err := net.Dial("unix", sockname)
						errfatal(err)
						errfatal(nslcd_proto.Write(conn, nslcd_proto.NSLCD_VERSION))
						errfatal(nslcd_proto.Write(conn, nslcd_proto.NSLCD_ACTION_PASSWD_ALL))
						// Wait for NSLCD_RESULT_*, to make sure the server has made
						// it in to backend code.
						var n int32
						errfatal(nslcd_proto.Read(conn, &n))
						if n != nslcd_proto.NSLCD_VERSION {
							ctx.Fatal("server version wrong")
						}
						errfatal(nslcd_proto.Read(conn, &n))
						if n != nslcd_proto.NSLCD_ACTION_PASSWD_ALL {
							ctx.Fatal("server action wrong")
						}
						errfatal(nslcd_proto.Read(conn, &n))
						if n != nslcd_proto.NSLCD_RESULT_BEGIN && n != nslcd_proto.NSLCD_RESULT_END {
							ctx.Fatal("server result malformed")
						}
						if testcase.toclose {
							errfatal(conn.Close())
						}

						ctx.status <- "waiting for server reload"
						errfatal(unix.Kill(unix.Getpid(), unix.SIGHUP))
						<-evReload
					}

					testDriver(ctx, backend, limits, notifyHandler, client)
				})
			})
		}()
	}
}

func TestLargeRequest(t *testing.T) {
	tmpdir, err := ioutil.TempDir("", "go-test-libnslcd-large-request.")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpdir)
	defer sdActivatedReset()
	t.Run("large-request", func(t *testing.T) {
		testWithTimeout(t, 2*time.Second, func(t *testing.T, s chan<- string) {
			KiB := 1024
			GiB := 1024 * 1024 * 1024

			ctx := &testContext{T: t, tmpdir: tmpdir, status: s}

			backend := &LockingBackend{}

			limits := nslcd_server.Limits{
				Timeout:        1 * time.Second,
				RequestMaxSize: int64(1 * KiB),
			}

			notifyHandler := func(dat []byte, oob []byte) error { return nil }

			client := func(sockname string) {
				errfatal := func(err error) {
					if err != nil {
						t.Fatal(err)
					}
				}

				conn, err := net.Dial("unix", sockname)
				errfatal(err)
				errfatal(nslcd_proto.Write(conn, nslcd_proto.NSLCD_VERSION))
				errfatal(nslcd_proto.Write(conn, nslcd_proto.NSLCD_ACTION_PASSWD_BYNAME))
				errfatal(nslcd_proto.Write(conn, int32(1*GiB)))
			}

			testDriver(ctx, backend, limits, notifyHandler, client)

			var memstats runtime.MemStats
			runtime.ReadMemStats(&memstats)
			if memstats.HeapSys > uint64(1*GiB) {
				t.Fatalf("Used more than 1 GiB heap: %s B", humanizeU64(memstats.HeapSys))
			}
		})
	})
}