// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.

package filestore

import (
	"context"
	"encoding/hex"
	"errors"
	"io"
	"os"
	"path/filepath"
	"time"

	"github.com/spacemonkeygo/monkit/v3"
	"github.com/zeebo/errs"
	"go.uber.org/zap"

	"storj.io/common/leak"
	"storj.io/common/memory"
	"storj.io/common/storj"
	"storj.io/storj/storagenode/blobstore"
)

var (
	// Error is the default filestore error class.
	Error = errs.Class("filestore error")
	// ErrIsDir is the error returned when we encounter a directory named like a blob file
	// while traversing a blob namespace.
	ErrIsDir = Error.New("file is a directory")

	mon = monkit.Package()
	// for backwards compatibility.
	monStorage = monkit.ScopeNamed("storj.io/storj/storage/filestore")

	_ blobstore.Blobs = (*blobStore)(nil)
)

func monFileInTrash(namespace []byte) *monkit.Meter {
	return monStorage.Meter("open_file_in_trash", monkit.NewSeriesTag("namespace", hex.EncodeToString(namespace))) //mon:locked
}

// Config is configuration for the blob store.
type Config struct {
	WriteBufferSize memory.Size `help:"in-memory buffer for uploads" default:"128KiB"`
}

// DefaultConfig is the default value for Config.
var DefaultConfig = Config{
	WriteBufferSize: 128 * memory.KiB,
}

// blobStore implements a blob store.
type blobStore struct {
	log    *zap.Logger
	dir    *Dir
	config Config

	track leak.Ref
}

// New creates a new disk blob store in the specified directory.
func New(log *zap.Logger, dir *Dir, config Config) blobstore.Blobs {
	return &blobStore{dir: dir, log: log, config: config, track: leak.Root(1)}
}

// NewAt creates a new disk blob store in the specified directory.
func NewAt(log *zap.Logger, path string, config Config) (blobstore.Blobs, error) {
	dir, err := NewDir(log, path)
	if err != nil {
		return nil, Error.Wrap(err)
	}
	return &blobStore{dir: dir, log: log, config: config, track: leak.Root(1)}, nil
}

// Close closes the store.
func (store *blobStore) Close() error { return store.track.Close() }

// Open loads blob with the specified hash.
func (store *blobStore) Open(ctx context.Context, ref blobstore.BlobRef) (_ blobstore.BlobReader, err error) {
	defer mon.Task()(&ctx)(&err)
	file, formatVer, err := store.dir.Open(ctx, ref)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, err
		}
		return nil, Error.Wrap(err)
	}
	return newBlobReader(store.track.Child("blobReader", 1), file, formatVer), nil
}

// OpenWithStorageFormat loads the already-located blob, avoiding the potential need to check multiple
// storage formats to find the blob.
func (store *blobStore) OpenWithStorageFormat(ctx context.Context, blobRef blobstore.BlobRef, formatVer blobstore.FormatVersion) (_ blobstore.BlobReader, err error) {
	defer mon.Task()(&ctx)(&err)
	file, err := store.dir.OpenWithStorageFormat(ctx, blobRef, formatVer)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, err
		}
		return nil, Error.Wrap(err)
	}
	return newBlobReader(store.track.Child("blobReader", 1), file, formatVer), nil
}

// Stat looks up disk metadata on the blob file.
func (store *blobStore) Stat(ctx context.Context, ref blobstore.BlobRef) (_ blobstore.BlobInfo, err error) {
	defer mon.Task()(&ctx)(&err)
	info, err := store.dir.Stat(ctx, ref)
	return info, Error.Wrap(err)
}

// StatWithStorageFormat looks up disk metadata on the blob file with the given storage format version.
func (store *blobStore) StatWithStorageFormat(ctx context.Context, ref blobstore.BlobRef, formatVer blobstore.FormatVersion) (_ blobstore.BlobInfo, err error) {
	defer mon.Task()(&ctx)(&err)
	info, err := store.dir.StatWithStorageFormat(ctx, ref, formatVer)
	return info, Error.Wrap(err)
}

// Delete deletes blobs with the specified ref.
//
// It doesn't return an error if the blob isn't found for any reason or it cannot
// be deleted at this moment and it's delayed.
func (store *blobStore) Delete(ctx context.Context, ref blobstore.BlobRef) (err error) {
	defer mon.Task()(&ctx)(&err)
	err = store.dir.Delete(ctx, ref)
	return Error.Wrap(err)
}

// DeleteWithStorageFormat deletes blobs with the specified ref and storage format version.
func (store *blobStore) DeleteWithStorageFormat(ctx context.Context, ref blobstore.BlobRef, formatVer blobstore.FormatVersion) (err error) {
	defer mon.Task()(&ctx)(&err)
	err = store.dir.DeleteWithStorageFormat(ctx, ref, formatVer)
	return Error.Wrap(err)
}

// DeleteNamespace deletes blobs folder of specific satellite, used after successful GE only.
func (store *blobStore) DeleteNamespace(ctx context.Context, ref []byte) (err error) {
	defer mon.Task()(&ctx)(&err)
	err = store.dir.DeleteNamespace(ctx, ref)
	return Error.Wrap(err)
}

// DeleteTrashNamespace deletes trash folder of specific satellite.
func (store *blobStore) DeleteTrashNamespace(ctx context.Context, namespace []byte) (err error) {
	defer mon.Task()(&ctx)(&err)
	err = store.dir.DeleteTrashNamespace(ctx, namespace)
	return Error.Wrap(err)
}

// Trash moves the ref to a trash directory.
func (store *blobStore) Trash(ctx context.Context, ref blobstore.BlobRef) (err error) {
	defer mon.Task()(&ctx)(&err)
	return Error.Wrap(store.dir.Trash(ctx, ref))
}

// RestoreTrash moves every piece in the trash back into the regular location.
func (store *blobStore) RestoreTrash(ctx context.Context, namespace []byte) (keysRestored [][]byte, err error) {
	defer mon.Task()(&ctx)(&err)
	keysRestored, err = store.dir.RestoreTrash(ctx, namespace)
	return keysRestored, Error.Wrap(err)
}

// TryRestoreTrashPiece attempts to restore a piece from the trash if it exists.
// It returns nil if the piece was restored, or an error if the piece was not
// in the trash or could not be restored.
func (store *blobStore) TryRestoreTrashPiece(ctx context.Context, ref blobstore.BlobRef) (err error) {
	defer mon.Task()(&ctx)(&err)
	return Error.Wrap(store.dir.TryRestoreTrashPiece(ctx, ref))
}

// EmptyTrash removes all files in trash that have been there longer than trashExpiryDur.
func (store *blobStore) EmptyTrash(ctx context.Context, namespace []byte, trashedBefore time.Time) (bytesEmptied int64, keys [][]byte, err error) {
	defer mon.Task()(&ctx)(&err)
	bytesEmptied, keys, err = store.dir.EmptyTrash(ctx, namespace, trashedBefore)
	return bytesEmptied, keys, Error.Wrap(err)
}

// GarbageCollect tries to delete any files that haven't yet been deleted.
func (store *blobStore) GarbageCollect(ctx context.Context) (err error) {
	defer mon.Task()(&ctx)(&err)
	err = store.dir.GarbageCollect(ctx)
	return Error.Wrap(err)
}

// Create creates a new blob that can be written.
// Optionally takes a size argument for performance improvements, -1 is unknown size.
func (store *blobStore) Create(ctx context.Context, ref blobstore.BlobRef, size int64) (_ blobstore.BlobWriter, err error) {
	defer mon.Task()(&ctx)(&err)
	file, err := store.dir.CreateTemporaryFile(ctx, size)
	if err != nil {
		return nil, Error.Wrap(err)
	}
	return newBlobWriter(store.track.Child("blobWriter", 1), ref, store, MaxFormatVersionSupported, file, store.config.WriteBufferSize.Int()), nil
}

// SpaceUsedForBlobs adds up the space used in all namespaces for blob storage.
func (store *blobStore) SpaceUsedForBlobs(ctx context.Context) (space int64, err error) {
	defer mon.Task()(&ctx)(&err)

	var totalSpaceUsed int64
	namespaces, err := store.ListNamespaces(ctx)
	if err != nil {
		return 0, Error.New("failed to enumerate namespaces: %v", err)
	}
	for _, namespace := range namespaces {
		used, err := store.SpaceUsedForBlobsInNamespace(ctx, namespace)
		if err != nil {
			return 0, Error.New("failed to sum space used: %v", err)
		}
		totalSpaceUsed += used
	}
	return totalSpaceUsed, nil
}

// SpaceUsedForBlobsInNamespace adds up how much is used in the given namespace for blob storage.
func (store *blobStore) SpaceUsedForBlobsInNamespace(ctx context.Context, namespace []byte) (int64, error) {
	var totalUsed int64
	err := store.WalkNamespace(ctx, namespace, func(info blobstore.BlobInfo) error {
		statInfo, statErr := info.Stat(ctx)
		if statErr != nil {
			store.log.Error("failed to stat blob", zap.Binary("namespace", namespace), zap.Binary("key", info.BlobRef().Key), zap.Error(statErr))
			// keep iterating; we want a best effort total here.
			return nil
		}
		totalUsed += statInfo.Size()
		return nil
	})
	if err != nil {
		return 0, err
	}
	return totalUsed, nil
}

// TrashIsEmpty returns boolean value if trash dir is empty.
func (store *blobStore) TrashIsEmpty() (_ bool, err error) {
	f, err := os.Open(store.dir.trashdir())
	if err != nil {
		return false, err
	}
	defer func() {
		err = errs.Combine(err, f.Close())
	}()

	_, err = f.Readdirnames(1)
	if errors.Is(err, io.EOF) {
		return true, nil
	}
	return false, err
}

// SpaceUsedForTrash returns the total space used by the trash.
func (store *blobStore) SpaceUsedForTrash(ctx context.Context) (total int64, err error) {
	defer mon.Task()(&ctx)(&err)

	empty, err := store.TrashIsEmpty()
	if err != nil {
		return total, err
	}
	if empty {
		return 0, nil
	}
	err = filepath.Walk(store.dir.trashdir(), func(_ string, info os.FileInfo, walkErr error) error {
		if walkErr != nil {
			err = errs.Combine(err, walkErr)
			return filepath.SkipDir
		}

		total += info.Size()
		return nil
	})
	return total, err
}

// FreeSpace returns how much space left in underlying directory.
func (store *blobStore) FreeSpace(ctx context.Context) (int64, error) {
	info, err := store.dir.Info(ctx)
	if err != nil {
		return 0, err
	}
	return info.AvailableSpace, nil
}

// CheckWritability tests writability of the storage directory by creating and deleting a file.
func (store *blobStore) CheckWritability(ctx context.Context) error {
	f, err := os.CreateTemp(store.dir.Path(), "write-test")
	if err != nil {
		return err
	}
	if err := f.Close(); err != nil {
		return err
	}
	return os.Remove(f.Name())
}

// ListNamespaces finds all known namespace IDs in use in local storage. They are not
// guaranteed to contain any blobs.
func (store *blobStore) ListNamespaces(ctx context.Context) (ids [][]byte, err error) {
	return store.dir.ListNamespaces(ctx)
}

// WalkNamespace executes walkFunc for each locally stored blob in the given namespace. If walkFunc
// returns a non-nil error, WalkNamespace will stop iterating and return the error immediately. The
// ctx parameter is intended specifically to allow canceling iteration early.
func (store *blobStore) WalkNamespace(ctx context.Context, namespace []byte, walkFunc func(blobstore.BlobInfo) error) (err error) {
	return store.dir.WalkNamespace(ctx, namespace, walkFunc)
}

// TestCreateV0 creates a new V0 blob that can be written. This is ONLY appropriate in test situations.
func (store *blobStore) TestCreateV0(ctx context.Context, ref blobstore.BlobRef) (_ blobstore.BlobWriter, err error) {
	defer mon.Task()(&ctx)(&err)

	file, err := store.dir.CreateTemporaryFile(ctx, -1)
	if err != nil {
		return nil, Error.Wrap(err)
	}
	return newBlobWriter(store.track.Child("blobWriter", 1), ref, store, FormatV0, file, store.config.WriteBufferSize.Int()), nil
}

// CreateVerificationFile creates a file to be used for storage directory verification.
func (store *blobStore) CreateVerificationFile(ctx context.Context, id storj.NodeID) error {
	return store.dir.CreateVerificationFile(ctx, id)
}

// VerifyStorageDir verifies that the storage directory is correct by checking for the existence and validity
// of the verification file.
func (store *blobStore) VerifyStorageDir(ctx context.Context, id storj.NodeID) error {
	return store.dir.Verify(ctx, id)
}