package badger

import (
	"io/ioutil"
	"math"
	"math/rand"
	"os"
	"runtime"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"gx/ipfs/QmU4emVTYFKnoJ5yK3pPEN9joyEx6U7y892PDx26ZtNxQd/badger/y"
)

func val(large bool) []byte {
	var buf []byte
	if large {
		buf = make([]byte, 8192)
	} else {
		buf = make([]byte, 16)
	}
	rand.Read(buf)
	return buf
}

func numKeys(db *DB) int {
	var count int
	err := db.View(func(txn *Txn) error {
		itr := txn.NewIterator(DefaultIteratorOptions)
		defer itr.Close()

		for itr.Rewind(); itr.Valid(); itr.Next() {
			count++
		}
		return nil
	})
	y.Check(err)
	return count
}

func numKeysManaged(db *DB, readTs uint64) int {
	txn := db.NewTransactionAt(readTs, false)
	defer txn.Discard()

	itr := txn.NewIterator(DefaultIteratorOptions)
	defer itr.Close()

	var count int
	for itr.Rewind(); itr.Valid(); itr.Next() {
		count++
	}
	return count
}

func TestDropAllManaged(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.managedTxns = true
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)

	N := uint64(10000)
	populate := func(db *DB, start uint64) {
		var wg sync.WaitGroup
		for i := start; i < start+N; i++ {
			wg.Add(1)
			txn := db.NewTransactionAt(math.MaxUint64, true)
			require.NoError(t, txn.Set([]byte(key("key", int(i))), val(true)))
			require.NoError(t, txn.CommitAt(uint64(i), func(err error) {
				require.NoError(t, err)
				wg.Done()
			}))
		}
		wg.Wait()
	}

	populate(db, N)
	require.Equal(t, int(N), numKeysManaged(db, math.MaxUint64))

	require.NoError(t, db.DropAll())
	require.NoError(t, db.DropAll()) // Just call it twice, for fun.
	require.Equal(t, 0, numKeysManaged(db, math.MaxUint64))

	// Check that we can still write to mdb, and using lower timestamps.
	populate(db, 1)
	require.Equal(t, int(N), numKeysManaged(db, math.MaxUint64))
	db.Close()

	// Ensure that value log is correctly replayed, that we are preserving badgerHead.
	opts.managedTxns = true
	db2, err := Open(opts)
	require.NoError(t, err)
	require.Equal(t, int(N), numKeysManaged(db2, math.MaxUint64))
	db2.Close()
}

func TestDropAll(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)

	N := uint64(10000)
	populate := func(db *DB) {
		writer := db.NewWriteBatch()
		for i := uint64(0); i < N; i++ {
			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
		}
		require.NoError(t, writer.Flush())
	}

	populate(db)
	require.Equal(t, int(N), numKeys(db))

	require.NoError(t, db.DropAll())
	require.Equal(t, 0, numKeys(db))

	// Check that we can still write to mdb, and using lower timestamps.
	populate(db)
	require.Equal(t, int(N), numKeys(db))
	db.Close()

	// Ensure that value log is correctly replayed.
	db2, err := Open(opts)
	require.NoError(t, err)
	require.Equal(t, int(N), numKeys(db2))
	db2.Close()
}

func TestDropAllTwice(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)

	N := uint64(10000)
	populate := func(db *DB) {
		writer := db.NewWriteBatch()
		for i := uint64(0); i < N; i++ {
			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
		}
		require.NoError(t, writer.Flush())
	}

	populate(db)
	require.Equal(t, int(N), numKeys(db))

	require.NoError(t, db.DropAll())
	require.Equal(t, 0, numKeys(db))

	// Call DropAll again.
	require.NoError(t, db.DropAll())
}

func TestDropAllWithPendingTxn(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)

	N := uint64(10000)
	populate := func(db *DB) {
		writer := db.NewWriteBatch()
		for i := uint64(0); i < N; i++ {
			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
		}
		require.NoError(t, writer.Flush())
	}

	populate(db)
	require.Equal(t, int(N), numKeys(db))

	txn := db.NewTransaction(true)

	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		itr := txn.NewIterator(DefaultIteratorOptions)
		defer itr.Close()

		var keys []string
		for {
			var count int
			for itr.Rewind(); itr.Valid(); itr.Next() {
				count++
				item := itr.Item()
				keys = append(keys, string(item.KeyCopy(nil)))
				_, err := item.ValueCopy(nil)
				if err != nil {
					t.Logf("Got error during value copy: %v", err)
					return
				}
			}
			t.Logf("Got number of keys: %d\n", count)
			for _, key := range keys {
				item, err := txn.Get([]byte(key))
				if err != nil {
					t.Logf("Got error during key lookup: %v", err)
					return
				}
				if _, err := item.ValueCopy(nil); err != nil {
					t.Logf("Got error during second value copy: %v", err)
					return
				}
			}
		}
	}()
	// Do not cancel txn.

	go func() {
		time.Sleep(2 * time.Second)
		require.NoError(t, db.DropAll())
	}()
	wg.Wait()
}

func TestDropReadOnly(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)
	N := uint64(1000)
	populate := func(db *DB) {
		writer := db.NewWriteBatch()
		for i := uint64(0); i < N; i++ {
			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
		}
		require.NoError(t, writer.Flush())
	}

	populate(db)
	require.Equal(t, int(N), numKeys(db))
	require.NoError(t, db.Close())

	opts.ReadOnly = true
	db2, err := Open(opts)
	// acquireDirectoryLock returns ErrWindowsNotSupported on Windows. It can be ignored safely.
	if runtime.GOOS == "windows" {
		require.Equal(t, err, ErrWindowsNotSupported)
	} else {
		require.NoError(t, err)
	}
	require.Panics(t, func() { db2.DropAll() })
}

func TestWriteAfterClose(t *testing.T) {
	dir, err := ioutil.TempDir(".", "badger-test")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.ValueLogFileSize = 5 << 20
	db, err := Open(opts)
	require.NoError(t, err)
	N := uint64(1000)
	populate := func(db *DB) {
		writer := db.NewWriteBatch()
		for i := uint64(0); i < N; i++ {
			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
		}
		require.NoError(t, writer.Flush())
	}

	populate(db)
	require.Equal(t, int(N), numKeys(db))
	require.NoError(t, db.Close())
	err = db.Update(func(txn *Txn) error {
		return txn.Set([]byte("a"), []byte("b"))
	})
	require.Equal(t, ErrBlockedWrites, err)
}

func TestDropAllRace(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger")
	require.NoError(t, err)
	defer os.RemoveAll(dir)
	opts := getTestOptions(dir)
	opts.managedTxns = true
	db, err := Open(opts)
	require.NoError(t, err)

	N := 10000
	// Start a goroutine to keep trying to write to DB while DropAll happens.
	closer := y.NewCloser(1)
	go func() {
		defer closer.Done()
		ticker := time.NewTicker(time.Millisecond)
		defer ticker.Stop()

		i := N + 1 // Writes would happen above N.
		var errors int32
		for {
			select {
			case <-ticker.C:
				i++
				txn := db.NewTransactionAt(math.MaxUint64, true)
				require.NoError(t, txn.Set([]byte(key("key", i)), val(false)))
				if err := txn.CommitAt(uint64(i), func(err error) {
					if err != nil {
						atomic.AddInt32(&errors, 1)
					}
				}); err != nil {
					atomic.AddInt32(&errors, 1)
				}
			case <-closer.HasBeenClosed():
				// The following causes a data race.
				// t.Logf("i: %d. Number of (expected) write errors: %d.\n", i, errors)
				return
			}
		}
	}()

	var wg sync.WaitGroup
	for i := 1; i <= N; i++ {
		wg.Add(1)
		txn := db.NewTransactionAt(math.MaxUint64, true)
		require.NoError(t, txn.Set([]byte(key("key", i)), val(false)))
		require.NoError(t, txn.CommitAt(uint64(i), func(err error) {
			require.NoError(t, err)
			wg.Done()
		}))
	}
	wg.Wait()

	before := numKeysManaged(db, math.MaxUint64)
	require.True(t, before > N)

	require.NoError(t, db.DropAll())
	closer.SignalAndWait()

	after := numKeysManaged(db, math.MaxUint64)
	t.Logf("Before: %d. After dropall: %d\n", before, after)
	require.True(t, after < before)
	db.Close()
}