package test_helpers

import (
	"bytes"
	"crypto/md5"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"
	"testing"
	"time"

	"github.com/rfjakob/gocryptfs/internal/ctlsock"
	"github.com/rfjakob/gocryptfs/internal/nametransform"
)

// TmpDir will be created inside this directory, set in init() to
// $TMPDIR/gocryptfs-test-parent .
var testParentDir = ""

// GocryptfsBinary is the assumed path to the gocryptfs build.
const GocryptfsBinary = "../../gocryptfs"

// UnmountScript is the fusermount/umount compatibility wrapper script
const UnmountScript = "../fuse-unmount.bash"

// X255 contains 255 uppercase "X". This can be used as a maximum-length filename.
var X255 string

// TmpDir is a unique temporary directory. "go test" runs package tests in parallel. We create a
// unique TmpDir in init() so the tests do not interfere.
var TmpDir string

// DefaultPlainDir is TmpDir + "/default-plain"
var DefaultPlainDir string

// DefaultCipherDir is TmpDir + "/default-cipher"
var DefaultCipherDir string

type mountInfo struct {
	// PID of the running gocryptfs process. Set by Mount().
	pid int
	// List of open FDs of the running gocrypts process. Set by Mount().
	fds []string
}

// Indexed by mountpoint
var MountInfo map[string]mountInfo

// SwitchTMPDIR changes TMPDIR and hence the directory the test are performed in.
// This is used when you want to perform tests on a special filesystem. The
// xattr tests cannot run on tmpfs and use /var/tmp instead of /tmp.
func SwitchTMPDIR(newDir string) {
	os.Setenv("TMPDIR", newDir)
	doInit()
}

func init() {
	doInit()
}

func doInit() {
	X255 = string(bytes.Repeat([]byte("X"), 255))
	MountInfo = make(map[string]mountInfo)

	testParentDir := os.TempDir() + "/gocryptfs-test-parent"
	os.MkdirAll(testParentDir, 0700)
	var err error
	TmpDir, err = ioutil.TempDir(testParentDir, "")
	if err != nil {
		panic(err)
	}
	DefaultPlainDir = TmpDir + "/default-plain"
	DefaultCipherDir = TmpDir + "/default-cipher"
}

// ResetTmpDir deletes TmpDir, create new dir tree:
//
// TmpDir
// |-- DefaultPlainDir
// *-- DefaultCipherDir
//     *-- gocryptfs.diriv
func ResetTmpDir(createDirIV bool) {
	// Try to unmount and delete everything
	entries, err := ioutil.ReadDir(TmpDir)
	if err == nil {
		for _, e := range entries {
			d := filepath.Join(TmpDir, e.Name())
			err = os.Remove(d)
			if err != nil {
				pe := err.(*os.PathError)
				if pe.Err == syscall.EBUSY {
					if testing.Verbose() {
						fmt.Printf("Remove failed: %v. Maybe still mounted?\n", pe)
					}
					err = UnmountErr(d)
					if err != nil {
						panic(err)
					}
				} else if pe.Err != syscall.ENOTEMPTY {
					panic("Unhandled error: " + pe.Err.Error())
				}
				err = os.RemoveAll(d)
				if err != nil {
					panic(err)
				}
			}
		}
	}
	err = os.Mkdir(DefaultPlainDir, 0700)
	if err != nil {
		panic(err)
	}
	err = os.Mkdir(DefaultCipherDir, 0700)
	if err != nil {
		panic(err)
	}
	if createDirIV {
		err = nametransform.WriteDirIV(-1, DefaultCipherDir)
		if err != nil {
			panic(err)
		}
	}
}

// InitFS calls "gocryptfs -init" on a new directory in TmpDir, passing
// "extraArgs" in addition to useful defaults.
//
// The returned cipherdir has NO trailing slash.
func InitFS(t *testing.T, extraArgs ...string) string {
	dir, err := ioutil.TempDir(TmpDir, "")
	if err != nil {
		if t != nil {
			t.Fatal(err)
		} else {
			log.Panic(err)
		}
	}
	args := []string{"-q", "-init", "-extpass", "echo test", "-scryptn=10"}
	args = append(args, extraArgs...)
	args = append(args, dir)

	cmd := exec.Command(GocryptfsBinary, args...)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	err = cmd.Run()
	if err != nil {
		if t != nil {
			t.Fatalf("InitFS with args %v failed: %v", args, err)
		} else {
			log.Panic(err)
		}
	}

	return dir
}

// Mount CIPHERDIR "c" on PLAINDIR "p"
// Creates "p" if it does not exist.
func Mount(c string, p string, showOutput bool, extraArgs ...string) error {
	args := []string{"-q", "-wpanic", "-nosyslog", "-fg", fmt.Sprintf("-notifypid=%d", os.Getpid())}
	args = append(args, extraArgs...)
	//args = append(args, "-fusedebug")
	//args = append(args, "-d")
	args = append(args, c, p)

	if _, err := os.Stat(p); err != nil {
		err = os.Mkdir(p, 0777)
		if err != nil {
			return err
		}
	}

	cmd := exec.Command(GocryptfsBinary, args...)
	if showOutput {
		// The Go test logic waits for our stdout to close, and when we share
		// it with the subprocess, it will wait for it to close it as well.
		// Use an intermediate pipe so the tests do not hang when unmouting
		// fails.
		pr, pw, err := os.Pipe()
		if err != nil {
			return err
		}
		// We can close the fd after cmd.Run() has executed
		defer pw.Close()
		cmd.Stderr = pw
		cmd.Stdout = pw
		go func() {
			io.Copy(os.Stdout, pr)
			pr.Close()
		}()
	}

	// Two things can happen:
	// 1) The mount fails and the process exits
	// 2) The mount succeeds and the process sends us USR1
	chanExit := make(chan error, 1)
	chanUsr1 := make(chan os.Signal, 1)
	signal.Notify(chanUsr1, syscall.SIGUSR1)

	// Start the process and save the PID
	err := cmd.Start()
	if err != nil {
		return err
	}
	pid := cmd.Process.Pid

	// Wait for exit or usr1
	go func() {
		chanExit <- cmd.Wait()
	}()
	select {
	case err := <-chanExit:
		return err
	case <-chanUsr1:
		// noop
	case <-time.After(1 * time.Second):
		log.Panicf("Timeout waiting for process %d", pid)
	}

	// Save PID and open FDs
	MountInfo[p] = mountInfo{pid, ListFds(pid)}
	return nil
}

// MountOrExit calls Mount() and exits on failure.
func MountOrExit(c string, p string, extraArgs ...string) {
	err := Mount(c, p, true, extraArgs...)
	if err != nil {
		fmt.Printf("mount failed: %v\n", err)
		os.Exit(1)
	}
}

// MountOrFatal calls Mount() and calls t.Fatal() on failure.
func MountOrFatal(t *testing.T, c string, p string, extraArgs ...string) {
	err := Mount(c, p, true, extraArgs...)
	if err != nil {
		t.Fatal(fmt.Errorf("mount failed: %v", err))
	}
}

// UnmountPanic tries to umount "dir" and panics on error.
func UnmountPanic(dir string) {
	err := UnmountErr(dir)
	if err != nil {
		fmt.Printf("UnmountPanic: %v. Running lsof %s\n", err, dir)
		cmd := exec.Command("lsof", dir)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		cmd.Run()
		panic("UnmountPanic: unmount failed: " + err.Error())
	}
}

// UnmountErr tries to unmount "dir", retrying 10 times, and returns the
// resulting error.
func UnmountErr(dir string) (err error) {
	var fdsNow []string
	pid := MountInfo[dir].pid
	fds := MountInfo[dir].fds
	if pid <= 0 {
		fmt.Printf("UnmountErr: %q was not found in MountInfo, cannot check for FD leaks\n", dir)
	}

	max := 10
	// When a new filesystem is mounted, Gnome tries to read files like
	// .xdg-volume-info, autorun.inf, .Trash.
	// If we try to unmount before Gnome is done, the unmount fails with
	// "Device or resource busy", causing spurious test failures.
	// Retry a few times to hide that problem.
	for i := 1; i <= max; i++ {
		if pid > 0 {
			fdsNow = ListFds(pid)
		}
		cmd := exec.Command(UnmountScript, "-u", dir)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		err = cmd.Run()
		if err == nil {
			if pid > 0 && len(fdsNow) > len(fds) {
				fmt.Printf("FD leak? Details:\nold=%v \nnew=%v\n", fds, fdsNow)
			}
			return nil
		}
		code := ExtractCmdExitCode(err)
		fmt.Printf("UnmountErr: got exit code %d, retrying (%d/%d)\n", code, i, max)
		time.Sleep(100 * time.Millisecond)
	}
	return err
}

// Md5fn returns an md5 string for file "filename"
func Md5fn(filename string) string {
	buf, err := ioutil.ReadFile(filename)
	if err != nil {
		fmt.Printf("ReadFile: %v\n", err)
		return ""
	}
	return Md5hex(buf)
}

// Md5hex returns an md5 string for "buf"
func Md5hex(buf []byte) string {
	rawHash := md5.Sum(buf)
	hash := hex.EncodeToString(rawHash[:])
	return hash
}

// VerifySize checks that the file size equals "want". This checks:
// 1) Size reported by Stat()
// 2) Number of bytes returned when reading the whole file
func VerifySize(t *testing.T, path string, want int) {
	buf, err := ioutil.ReadFile(path)
	if err != nil {
		t.Errorf("ReadFile failed: %v", err)
	} else if len(buf) != want {
		t.Errorf("wrong read size: got=%d want=%d", len(buf), want)
	}

	fi, err := os.Stat(path)
	if err != nil {
		t.Errorf("Stat failed: %v", err)
	} else if fi.Size() != int64(want) {
		t.Errorf("wrong stat file size, got=%d want=%d", fi.Size(), want)
	}
}

// TestMkdirRmdir creates and deletes a directory
func TestMkdirRmdir(t *testing.T, plainDir string) {
	dir := plainDir + "/dir1"
	err := os.Mkdir(dir, 0777)
	if err != nil {
		t.Error(err)
		return
	}
	err = syscall.Rmdir(dir)
	if err != nil {
		t.Error(err)
		return
	}
	// Create a directory and put a file in it
	// Trying to rmdir it should fail with ENOTEMPTY
	err = os.Mkdir(dir, 0777)
	if err != nil {
		t.Error(err)
		return
	}
	f, err := os.Create(dir + "/file")
	if err != nil {
		t.Error(err)
		return
	}
	f.Close()
	err = syscall.Rmdir(dir)
	errno := err.(syscall.Errno)
	if errno != syscall.ENOTEMPTY {
		t.Errorf("Should have gotten ENOTEMPTY, got %v", errno)
	}
	err = syscall.Unlink(dir + "/file")
	if err != nil {
		t.Error(err)
		return
	}
	err = syscall.Rmdir(dir)
	if err != nil {
		t.Error(err)
		return
	}
	// We should also be able to remove a directory we do not have permissions to
	// read or write
	err = os.Mkdir(dir, 0000)
	if err != nil {
		t.Error(err)
		return
	}
	err = syscall.Rmdir(dir)
	if err != nil {
		// Make sure the directory can cleaned up by the next test run
		os.Chmod(dir, 0700)
		t.Error(err)
		return
	}
}

// TestRename creates and renames a file
func TestRename(t *testing.T, plainDir string) {
	file1 := plainDir + "/rename1"
	file2 := plainDir + "/rename2"
	err := ioutil.WriteFile(file1, []byte("content"), 0777)
	if err != nil {
		t.Error(err)
		return
	}
	err = syscall.Rename(file1, file2)
	if err != nil {
		t.Error(err)
		return
	}
	syscall.Unlink(file2)
}

// VerifyExistence checks in 3 ways that "path" exists:
// stat, open, readdir. Returns true if the path exists, false otherwise.
// Panics if the result is inconsistent.
func VerifyExistence(path string) bool {
	// Check that file can be stated
	stat := true
	_, err := os.Stat(path)
	if err != nil {
		//t.Log(err)
		stat = false
	}
	// Check that file can be opened
	open := true
	fd, err := os.Open(path)
	if err != nil {
		//t.Log(err)
		open = false
	}
	fd.Close()
	// Check that file shows up in directory listing
	readdir := false
	dir := filepath.Dir(path)
	name := filepath.Base(path)
	fi, err := ioutil.ReadDir(dir)
	if err == nil {
		for _, i := range fi {
			if i.Name() == name {
				readdir = true
			}
		}
	}
	// If the result is consistent, return it.
	if stat == open && open == readdir {
		return stat
	}
	log.Panicf("inconsistent result: stat=%v open=%v readdir=%v", stat, open, readdir)
	return false
}

// Du returns the disk usage of the file "fd" points to, in bytes.
// Same as "du --block-size=1".
func Du(t *testing.T, fd int) (nBytes int64) {
	var st syscall.Stat_t
	err := syscall.Fstat(fd, &st)
	if err != nil {
		t.Fatal(err)
	}
	// st.Blocks = number of 512-byte blocks
	return st.Blocks * 512
}

// QueryCtlSock sends a request to the control socket at "socketPath" and
// returns the response.
func QueryCtlSock(t *testing.T, socketPath string, req ctlsock.RequestStruct) (response ctlsock.ResponseStruct) {
	conn, err := net.DialTimeout("unix", socketPath, 1*time.Second)
	if err != nil {
		t.Fatal(err)
	}
	defer conn.Close()
	conn.SetDeadline(time.Now().Add(time.Second))
	msg, err := json.Marshal(req)
	if err != nil {
		t.Fatal(err)
	}
	_, err = conn.Write(msg)
	if err != nil {
		t.Fatal(err)
	}
	buf := make([]byte, ctlsock.ReadBufSize)
	n, err := conn.Read(buf)
	if err != nil {
		t.Fatal(err)
	}
	buf = buf[:n]
	json.Unmarshal(buf, &response)
	return response
}

// ExtractCmdExitCode extracts the exit code from an error value that was
// returned from exec / cmd.Run()
func ExtractCmdExitCode(err error) int {
	if err == nil {
		return 0
	}
	// OMG this is convoluted
	if err2, ok := err.(*exec.ExitError); ok {
		return err2.Sys().(syscall.WaitStatus).ExitStatus()
	}
	if err2, ok := err.(*os.PathError); ok {
		return int(err2.Err.(syscall.Errno))
	}
	log.Panicf("could not decode error %#v", err)
	return 0
}

// ListFds lists the open file descriptors for process "pid". Pass pid=0 for
// ourselves.
func ListFds(pid int) []string {
	// We need /proc to get the list of fds for other processes. Only exists
	// on Linux.
	if runtime.GOOS != "linux" && pid > 0 {
		return nil
	}
	// Both Linux and MacOS have /dev/fd
	dir := "/dev/fd"
	if pid > 0 {
		dir = fmt.Sprintf("/proc/%d/fd", pid)
	}
	f, err := os.Open(dir)
	if err != nil {
		log.Panic(err)
	}
	defer f.Close()
	names, err := f.Readdirnames(0)
	if err != nil {
		log.Panic(err)
	}
	for i, n := range names {
		// Note: Readdirnames filters "." and ".."
		target, _ := os.Readlink(dir + "/" + n)
		names[i] = n + "=" + target
	}
	return names
}