// Copyright 2015 The rkt Authors
//
// 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.

package lock

import (
	"io/ioutil"
	"os"
	"path/filepath"
	"testing"
)

func TestExclusiveKeyLock(t *testing.T) {
	dir, err := ioutil.TempDir("", "")
	if err != nil {
		t.Fatalf("error creating tmpdir: %v", err)
	}
	defer os.RemoveAll(dir)

	l1, err := ExclusiveKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating key lock: %v", err)
	}

	_, err = TryExclusiveKeyLock(dir, "key01")
	if err == nil {
		t.Fatalf("expected err trying exclusive key lock")
	}

	l1.Close()
}

func TestCleanKeyLocks(t *testing.T) {
	dir, err := ioutil.TempDir("", "")
	if err != nil {
		t.Fatalf("error creating tmpdir: %v", err)
	}
	defer os.RemoveAll(dir)

	l1, err := ExclusiveKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	err = CleanKeyLocks(dir)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	filesnum, err := countFiles(dir)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if filesnum != 1 {
		t.Fatalf("expected 1 file in lock dir. found %d files", filesnum)
	}

	l2, err := SharedKeyLock(dir, "key02")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	l1.Close()
	l2.Close()

	err = CleanKeyLocks(dir)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	filesnum, err = countFiles(dir)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if filesnum != 0 {
		t.Fatalf("expected empty lock dir. found %d files", filesnum)
	}
}

func TestFileChangedLock(t *testing.T) {
	dir, err := ioutil.TempDir("", "")
	if err != nil {
		t.Fatalf("error creating tmpdir: %v", err)
	}
	defer os.RemoveAll(dir)

	l1, err := ExclusiveKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	l2, err := NewKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	// Simulate that l1 owner removes the actual key1 lock file
	err = os.Remove(filepath.Join(dir, "key01"))
	if err != nil {
		t.Fatalf("error creating NewLock: %v", err)
	}
	l1.Close()

	// Now l2 owner takes a lock, using the fd of the removed file
	err = l2.lock(keyLockShared, 0)
	if err == nil {
		t.Fatalf("expected error")
	}
	l2.Close()

	// Do the same with a new file created after removal
	dir, err = ioutil.TempDir("", "")
	if err != nil {
		t.Fatalf("error creating tmpdir: %v", err)
	}
	defer os.RemoveAll(dir)

	l1, err = ExclusiveKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	l2, err = NewKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	// Simulate that l1 owner removes the actual key1 lock file
	err = os.Remove(filepath.Join(dir, "key01"))
	if err != nil {
		t.Fatalf("error creating NewLock: %v", err)
	}
	l1.Close()

	// Simulate that another user comes and takes a lock, this will create
	// a new lock  file as it was removed.
	l3, err := ExclusiveKeyLock(dir, "key01")
	l3.Close()

	// Now l2 owner takes a lock, using the fd of the old file
	err = l2.lock(keyLockShared, 0)
	if err == nil {
		t.Fatalf("expected error")
	}

	// Do the same but with a retry so if should work.
	dir, err = ioutil.TempDir("", "")
	if err != nil {
		t.Fatalf("error creating tmpdir: %v", err)
	}
	defer os.RemoveAll(dir)

	l1, err = ExclusiveKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	l2, err = NewKeyLock(dir, "key01")
	if err != nil {
		t.Fatalf("error creating keyLock: %v", err)
	}

	// Simulate that l1 owner removes the actual key1 lock file
	err = os.Remove(filepath.Join(dir, "key01"))
	if err != nil {
		t.Fatalf("error creating NewLock: %v", err)
	}
	l1.Close()

	// Simulate that another user comes and takes a lock, this will create
	// a new lock  file as it was removed.
	l3, err = ExclusiveKeyLock(dir, "key01")
	l3.Close()

	// Now l2 owner takes a lock, using the fd of the old file
	err = l2.lock(keyLockShared, 1)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

func countFiles(dir string) (int, error) {
	f, err := os.Open(dir)
	if err != nil {
		return -1, err
	}
	defer f.Close()
	files, err := f.Readdir(0)
	if err != nil {
		return -1, err
	}
	return len(files), nil
}