package command

import (
	"context"
	"errors"
	"fmt"
	"io"
	"strings"
	"testing"
	"time"

	"github.com/seaweedfs/seaweedfs/weed/filer"
	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
	"github.com/seaweedfs/seaweedfs/weed/pb/remote_pb"
	"github.com/seaweedfs/seaweedfs/weed/remote_storage"
	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
	"github.com/seaweedfs/seaweedfs/weed/util"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/proto"
)

// TestVersionedFilePathRewrittenForRemote verifies that the fix for
// https://github.com/seaweedfs/seaweedfs/discussions/8481#discussioncomment-16209342
// works correctly: internal .versions/v_{id} paths are rewritten to the
// original S3 object key before syncing to the remote.
func TestVersionedFilePathRewrittenForRemote(t *testing.T) {
	bucketsDir := "/buckets"
	bucketName := "devicetransaction"
	bucket := util.FullPath(bucketsDir).Child(bucketName)

	objectPath := "9e149757-2363-11f1-bfa6-11c8ff31b539/transactionlog-2026-03-19-16-30-00.xml"
	versionId := "6761c63812bd9b64704acf08a3ba5800"
	versionFileName := "v_" + versionId

	// The filer event for the version file creation
	versionedParentPath := string(bucket) + "/" + objectPath + s3_constants.VersionsFolder

	// The CREATE event that remote_gateway receives
	event := &filer_pb.SubscribeMetadataResponse{
		Directory: versionedParentPath,
		EventNotification: &filer_pb.EventNotification{
			NewParentPath: versionedParentPath,
			NewEntry: &filer_pb.Entry{
				Name:    versionFileName,
				Content: []byte("test content"),
			},
		},
	}

	// Verify preconditions
	if !filer_pb.IsCreate(event) {
		t.Fatal("expected create event")
	}
	if isMultipartUploadFile(event.EventNotification.NewParentPath, event.EventNotification.NewEntry.Name) {
		t.Fatal("should not be detected as multipart upload")
	}
	if !filer.HasData(event.EventNotification.NewEntry) {
		t.Fatal("version file should have data")
	}
	if !shouldSendToRemote(event.EventNotification.NewEntry) {
		t.Fatal("version file should be eligible for remote sync")
	}

	// Apply the versioned path rewriting (as remote_gateway now does)
	parentPath, entryName := event.EventNotification.NewParentPath, event.EventNotification.NewEntry.Name
	if newParent, newName, ok := rewriteVersionedSourcePath(parentPath, entryName); ok {
		parentPath, entryName = newParent, newName
	}

	// Compute the remote destination with the rewritten path
	remoteStorageMountLocation := &remote_pb.RemoteStorageLocation{
		Name:   "central",
		Bucket: bucketName,
		Path:   "/",
	}
	sourcePath := util.NewFullPath(parentPath, entryName)
	dest := toRemoteStorageLocation(bucket, sourcePath, remoteStorageMountLocation)

	// Verify the destination does NOT contain internal .versions structure
	if strings.Contains(dest.Path, s3_constants.VersionsFolder) {
		t.Errorf("remote destination path still contains .versions: %s", dest.Path)
	}

	expectedPath := "/" + objectPath
	if dest.Path != expectedPath {
		t.Errorf("remote destination path = %q, want %q", dest.Path, expectedPath)
	}
}

// TestVersionsDirectoryFilteredByHasData verifies that the .versions
// directory creation event is correctly filtered out (no data), so only
// the version file event needs path rewriting.
func TestVersionsDirectoryFilteredByHasData(t *testing.T) {
	bucket := "/buckets/devicetransaction"
	objectPath := "9e149757-2363-11f1-bfa6-11c8ff31b539/transactionlog-2026-03-19-16-30-00.xml"

	dirEvent := &filer_pb.SubscribeMetadataResponse{
		Directory: bucket + "/9e149757-2363-11f1-bfa6-11c8ff31b539",
		EventNotification: &filer_pb.EventNotification{
			NewParentPath: bucket + "/9e149757-2363-11f1-bfa6-11c8ff31b539",
			NewEntry: &filer_pb.Entry{
				Name:        objectPath[strings.LastIndex(objectPath, "/")+1:] + s3_constants.VersionsFolder,
				IsDirectory: true,
			},
		},
	}

	if filer.HasData(dirEvent.EventNotification.NewEntry) {
		t.Error(".versions directory should not have data")
	}
}

func TestIsVersionedPath(t *testing.T) {
	tests := []struct {
		label    string
		dir      string
		name     string
		isDir    bool
		expected bool
	}{
		// Version file inside .versions directory (file, v_ prefix)
		{
			label:    "version file in .versions dir",
			dir:      "/buckets/mybucket/path/to/file.xml" + s3_constants.VersionsFolder,
			name:     "v_6761c63812bd9b64704acf08a3ba5800",
			isDir:    false,
			expected: true,
		},
		// Regular file (not versioned)
		{
			label:    "regular file",
			dir:      "/buckets/mybucket/path/to",
			name:     "file.xml",
			isDir:    false,
			expected: false,
		},
		// .versions directory entry itself
		{
			label:    ".versions directory entry",
			dir:      "/buckets/mybucket/path/to",
			name:     "file.xml" + s3_constants.VersionsFolder,
			isDir:    true,
			expected: true,
		},
		// Non-version file inside .versions dir (no v_ prefix) — not internal
		{
			label:    "non-version file in .versions dir",
			dir:      "/buckets/mybucket/file.xml" + s3_constants.VersionsFolder,
			name:     "some_other_file",
			isDir:    false,
			expected: false,
		},
		// User-created directory whose name ends with .versions — not
		// treated as versioned when isDir=false (file inside it)
		{
			label:    "file in user dir ending with .versions but no v_ prefix",
			dir:      "/buckets/mybucket/my" + s3_constants.VersionsFolder,
			name:     "data.txt",
			isDir:    false,
			expected: false,
		},
		// Regular directory (not .versions)
		{
			label:    "regular directory",
			dir:      "/buckets/mybucket/path/to",
			name:     "subdir",
			isDir:    true,
			expected: false,
		},
		// Entry whose name ends with .versions but is a file, not a dir
		{
			label:    "file named like .versions dir",
			dir:      "/buckets/mybucket/path/to",
			name:     "file.xml" + s3_constants.VersionsFolder,
			isDir:    false,
			expected: false,
		},
		// Non-bucket mount: .versions dir should not match
		{
			label:    ".versions dir outside /buckets/",
			dir:      "/mnt/remote/path/to",
			name:     "file.xml" + s3_constants.VersionsFolder,
			isDir:    true,
			expected: false,
		},
		// Non-bucket mount: v_ file should not match
		{
			label:    "v_ file outside /buckets/",
			dir:      "/data/archive/file.xml" + s3_constants.VersionsFolder,
			name:     "v_abc123",
			isDir:    false,
			expected: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.label, func(t *testing.T) {
			got := isVersionedPath(tt.dir, tt.name, tt.isDir)
			if got != tt.expected {
				t.Errorf("isVersionedPath(%q, %q, %v) = %v, want %v",
					tt.dir, tt.name, tt.isDir, got, tt.expected)
			}
		})
	}
}

// TestDeleteMarkerDetectedBeforeHasDataFilter verifies that a delete marker
// (zero-content version entry with ExtDeleteMarkerKey="true") is detected
// and can be propagated as a deletion, rather than being silently dropped
// by the HasData() check.
func TestDeleteMarkerDetectedBeforeHasDataFilter(t *testing.T) {
	bucketsDir := "/buckets"
	bucketName := "devicetransaction"
	bucket := util.FullPath(bucketsDir).Child(bucketName)

	objectPath := "docs/report.pdf"
	versionId := "aabb112233445566"
	versionFileName := "v_" + versionId
	versionedParentPath := string(bucket) + "/" + objectPath + s3_constants.VersionsFolder

	// A delete marker CREATE event: has ExtDeleteMarkerKey but no content
	deleteMarkerEntry := &filer_pb.Entry{
		Name: versionFileName,
		Extended: map[string][]byte{
			s3_constants.ExtDeleteMarkerKey: []byte("true"),
			s3_constants.ExtVersionIdKey:    []byte(versionId),
		},
		// Content and Chunks are nil → HasData() returns false
	}

	// Preconditions
	if filer.HasData(deleteMarkerEntry) {
		t.Fatal("delete marker should have no data")
	}
	if !isDeleteMarker(deleteMarkerEntry) {
		t.Fatal("should be detected as a delete marker")
	}

	// The versioned path should be rewritable to the original key
	newParent, newName, ok := rewriteVersionedSourcePath(versionedParentPath, deleteMarkerEntry.Name)
	if !ok {
		t.Fatal("delete marker path should be rewritable")
	}

	// Verify the rewritten path points to the original object
	remoteStorageMountLocation := &remote_pb.RemoteStorageLocation{
		Name:   "central",
		Bucket: bucketName,
		Path:   "/",
	}
	dest := toRemoteStorageLocation(bucket, util.NewFullPath(newParent, newName), remoteStorageMountLocation)

	expectedPath := "/" + objectPath
	if dest.Path != expectedPath {
		t.Errorf("delete marker destination = %q, want %q", dest.Path, expectedPath)
	}
	if strings.Contains(dest.Path, s3_constants.VersionsFolder) {
		t.Errorf("delete marker destination should not contain .versions: %s", dest.Path)
	}
}

func TestRewriteVersionedSourcePath(t *testing.T) {
	tests := []struct {
		name        string
		dir         string
		entryName   string
		wantDir     string
		wantName    string
		wantChanged bool
	}{
		{
			name:        "version file in .versions dir",
			dir:         "/buckets/bucket/path/to/file.xml" + s3_constants.VersionsFolder,
			entryName:   "v_6761c63812bd9b64704acf08a3ba5800",
			wantDir:     "/buckets/bucket/path/to",
			wantName:    "file.xml",
			wantChanged: true,
		},
		{
			name:        "regular file",
			dir:         "/buckets/bucket/path/to",
			entryName:   "file.xml",
			wantDir:     "/buckets/bucket/path/to",
			wantName:    "file.xml",
			wantChanged: false,
		},
		{
			name:        "version file at bucket root",
			dir:         "/buckets/bucket/report.pdf" + s3_constants.VersionsFolder,
			entryName:   "v_abc123",
			wantDir:     "/buckets/bucket",
			wantName:    "report.pdf",
			wantChanged: true,
		},
		{
			name:        "non-bucket path not rewritten",
			dir:         "/file.xml" + s3_constants.VersionsFolder,
			entryName:   "v_abc123",
			wantDir:     "/file.xml" + s3_constants.VersionsFolder,
			wantName:    "v_abc123",
			wantChanged: false,
		},
		{
			name:        "non-bucket mount not rewritten",
			dir:         "/mnt/remote/file.xml" + s3_constants.VersionsFolder,
			entryName:   "v_abc123",
			wantDir:     "/mnt/remote/file.xml" + s3_constants.VersionsFolder,
			wantName:    "v_abc123",
			wantChanged: false,
		},
		{
			name:        "non-version file in .versions dir",
			dir:         "/buckets/bucket/file.xml" + s3_constants.VersionsFolder,
			entryName:   "some_other_file",
			wantDir:     "/buckets/bucket/file.xml" + s3_constants.VersionsFolder,
			wantName:    "some_other_file",
			wantChanged: false,
		},
		{
			name:        "dir not ending in .versions",
			dir:         "/buckets/bucket/path/to",
			entryName:   "v_abc123",
			wantDir:     "/buckets/bucket/path/to",
			wantName:    "v_abc123",
			wantChanged: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			gotDir, gotName, gotChanged := rewriteVersionedSourcePath(tt.dir, tt.entryName)
			if gotDir != tt.wantDir || gotName != tt.wantName || gotChanged != tt.wantChanged {
				t.Errorf("rewriteVersionedSourcePath(%q, %q) = (%q, %q, %v), want (%q, %q, %v)",
					tt.dir, tt.entryName, gotDir, gotName, gotChanged, tt.wantDir, tt.wantName, tt.wantChanged)
			}
		})
	}
}

func chunkedEntry(name string, remote *filer_pb.RemoteEntry, etags ...string) *filer_pb.Entry {
	entry := &filer_pb.Entry{Name: name, Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}, RemoteEntry: remote}
	for i, etag := range etags {
		entry.Chunks = append(entry.Chunks, &filer_pb.FileChunk{FileId: fmt.Sprintf("3,%02x", i), Offset: int64(i) * 1024, Size: 1024, ETag: etag})
	}
	return entry
}

func TestIsMetadataOnlyUpdate(t *testing.T) {
	const dir = "/buckets/media"
	replicated := &filer_pb.RemoteEntry{StorageName: "b2", RemoteETag: "abc", RemoteSize: 2048, RemoteMtime: 1786096669}

	tests := []struct {
		name     string
		dir      string
		oldEntry *filer_pb.Entry
		newEntry *filer_pb.Entry
		want     bool
	}{
		{
			name:     "same chunks",
			dir:      dir,
			oldEntry: chunkedEntry("output.pdf", replicated, "e1", "e2"),
			newEntry: chunkedEntry("output.pdf", replicated, "e1", "e2"),
			want:     true,
		},
		{
			name:     "same chunks, no RemoteEntry",
			dir:      dir,
			oldEntry: chunkedEntry("output.pdf", nil, "e1", "e2"),
			newEntry: chunkedEntry("output.pdf", nil, "e1", "e2"),
			want:     true,
		},
		{
			name:     "rewritten chunks",
			dir:      dir,
			oldEntry: chunkedEntry("output.pdf", replicated, "e1", "e2"),
			newEntry: chunkedEntry("output.pdf", replicated, "e1", "e3"),
			want:     false,
		},
		{
			name:     "first write into an empty entry",
			dir:      dir,
			oldEntry: chunkedEntry("output.pdf", nil),
			newEntry: chunkedEntry("output.pdf", nil, "e1"),
			want:     false,
		},
		{
			name:     "rename",
			dir:      dir,
			oldEntry: chunkedEntry("output.pdf", replicated, "e1"),
			newEntry: chunkedEntry("renamed.pdf", replicated, "e1"),
			want:     false,
		},
		{
			name:     "move to another directory",
			dir:      "/buckets/media/inbox",
			oldEntry: chunkedEntry("output.pdf", replicated, "e1"),
			newEntry: chunkedEntry("output.pdf", replicated, "e1"),
			want:     false,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			message := &filer_pb.EventNotification{NewParentPath: dir, OldEntry: tt.oldEntry, NewEntry: tt.newEntry}
			if got := isMetadataOnlyUpdate(tt.dir, message); got != tt.want {
				t.Errorf("isMetadataOnlyUpdate = %v, want %v", got, tt.want)
			}
		})
	}
}

// stubFilerClient serves one entry; nil means not found. A non-nil err fails
// every lookup instead.
type stubFilerClient struct {
	filer_pb.SeaweedFilerClient
	entry     *filer_pb.Entry
	err       error
	updateErr error
	lookups   int
	updates   int
}

func (c *stubFilerClient) LookupDirectoryEntry(context.Context, *filer_pb.LookupDirectoryEntryRequest, ...grpc.CallOption) (*filer_pb.LookupDirectoryEntryResponse, error) {
	c.lookups++
	if c.err != nil {
		return nil, c.err
	}
	return &filer_pb.LookupDirectoryEntryResponse{Entry: c.entry}, nil
}

func (c *stubFilerClient) UpdateEntry(context.Context, *filer_pb.UpdateEntryRequest, ...grpc.CallOption) (*filer_pb.UpdateEntryResponse, error) {
	c.updates++
	if c.updateErr != nil {
		return &filer_pb.UpdateEntryResponse{}, c.updateErr
	}
	return &filer_pb.UpdateEntryResponse{}, nil
}

func (c *stubFilerClient) WithFilerClient(_ bool, fn func(filer_pb.SeaweedFilerClient) error) error {
	return fn(c)
}

func (c *stubFilerClient) AdjustedUrl(location *filer_pb.Location) string { return location.Url }

func (c *stubFilerClient) GetDataCenter() string { return "" }

// TestLiveRemoteEntry tells apart the two update events that carry no
// RemoteEntry: a file never replicated (#11139), which must be uploaded, and a
// chmod logged before the sync finished uploading the preceding write, which
// must not be uploaded again.
func TestLiveRemoteEntry(t *testing.T) {
	const dir = "/buckets/media"
	stamped := &filer_pb.RemoteEntry{StorageName: "b2", RemoteETag: "abc", RemoteSize: 2048, RemoteMtime: 1786096669}

	t.Run("event carries the RemoteEntry, no lookup", func(t *testing.T) {
		filerClient := &stubFilerClient{}
		got, err := liveRemoteEntry(filerClient, dir, chunkedEntry("output.pdf", stamped, "e1"))
		if err != nil {
			t.Fatal(err)
		}
		if got != stamped {
			t.Errorf("got %+v, want the event's own RemoteEntry", got)
		}
		if filerClient.lookups != 0 {
			t.Errorf("looked up the filer %d times with the answer already in hand", filerClient.lookups)
		}
	})

	t.Run("never replicated", func(t *testing.T) {
		event := chunkedEntry("output.pdf", nil, "e1")
		if !shouldSendToRemote(event) {
			t.Fatal("an entry with no RemoteEntry should be eligible for sending")
		}
		filerClient := &stubFilerClient{entry: chunkedEntry("output.pdf", nil, "e1")}
		got, err := liveRemoteEntry(filerClient, dir, event)
		if err != nil {
			t.Fatal(err)
		}
		if got != nil {
			t.Errorf("got %+v, want nil so the update takes the write path", got)
		}
	})

	t.Run("stamped after the event was logged", func(t *testing.T) {
		filerClient := &stubFilerClient{entry: chunkedEntry("output.pdf", stamped, "e1")}
		got, err := liveRemoteEntry(filerClient, dir, chunkedEntry("output.pdf", nil, "e1"))
		if err != nil {
			t.Fatal(err)
		}
		if got != stamped {
			t.Errorf("got %+v, want the filer's current RemoteEntry so the update stays on the metadata path", got)
		}
		if filerClient.lookups != 1 {
			t.Errorf("looked up the filer %d times, want 1", filerClient.lookups)
		}
	})

	t.Run("deleted since", func(t *testing.T) {
		_, err := liveRemoteEntry(&stubFilerClient{}, dir, chunkedEntry("output.pdf", nil, "e1"))
		if !errors.Is(err, filer_pb.ErrNotFound) {
			t.Errorf("err = %v, want filer_pb.ErrNotFound so the update is skipped rather than uploaded from a deleted entry", err)
		}
	})
}

func chunk(fileId, etag string) *filer_pb.FileChunk {
	return &filer_pb.FileChunk{FileId: fileId, Size: 1024, ETag: etag}
}

func entryWith(name string, remote *filer_pb.RemoteEntry, chunks ...*filer_pb.FileChunk) *filer_pb.Entry {
	return &filer_pb.Entry{Name: name, Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}, RemoteEntry: remote, Chunks: chunks}
}

// TestIsSuperseded decides what a failed upload means for its event (#11148).
// A replay from an earlier offset re-emits creates for entries the filer has
// since deleted or rewritten; their chunks are gone, so the upload can never
// succeed, and failing the event pins the offset before it forever. Those are
// skipped. A failure to upload an entry the filer still holds as described is
// a real failure and must keep failing the event so the subscription retries.
//
// Every write stores its chunks under new file ids, so the entry is compared
// by chunk identity, the way the filer itself decides which chunks an update
// leaves for deletion. Content fingerprints would miss a delete-and-recreate
// of identical bytes and fail the event forever on its dead chunks.
func TestIsSuperseded(t *testing.T) {
	const dir = "/buckets/ingest"
	event := entryWith("tmpjt9req69__Alan_Doe_Resume-1.pdf", nil, chunk("3,01", "e1"), chunk("3,02", "e2"))
	stamped := &filer_pb.RemoteEntry{StorageName: "b2", RemoteMtime: 1786096669}

	tests := []struct {
		name  string
		filer *stubFilerClient
		want  bool
	}{
		{name: "deleted since", filer: &stubFilerClient{}, want: true},
		{name: "rewritten since", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"), chunk("4,07", "e3"))}, want: true},
		{name: "recreated with identical content", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("5,11", "e1"), chunk("5,12", "e2"))}, want: true},
		{name: "recreated with other content", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("6,01", "e9"))}, want: true},
		{name: "truncated since", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"))}, want: true},
		{name: "still as described", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"), chunk("3,02", "e2"))}, want: false},
		{name: "still as described, since replicated", filer: &stubFilerClient{entry: entryWith(event.Name, stamped, chunk("3,01", "e1"), chunk("3,02", "e2"))}, want: false},
		{name: "appended since, chunks still live", filer: &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"), chunk("3,02", "e2"), chunk("3,03", "e3"))}, want: false},
		{name: "filer lookup failed", filer: &stubFilerClient{err: errors.New("rpc error: code = Unavailable")}, want: false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := isSuperseded(tt.filer, dir, event); got != tt.want {
				t.Errorf("isSuperseded = %v, want %v", got, tt.want)
			}
			if tt.filer.lookups != 1 {
				t.Errorf("looked up the filer %d times, want 1", tt.filer.lookups)
			}
		})
	}

	t.Run("written since: the event described an entry without data", func(t *testing.T) {
		remoteOnly := entryWith("video.mp4", &filer_pb.RemoteEntry{StorageName: "b2", RemoteSize: 20971520, RemoteMtime: 1786096669})
		if !isSuperseded(&stubFilerClient{entry: entryWith("video.mp4", remoteOnly.RemoteEntry, chunk("3,09", "e9"))}, dir, remoteOnly) {
			t.Error("isSuperseded = false, want true: the filer wrote local data to a remote-only entry")
		}
		if isSuperseded(&stubFilerClient{entry: entryWith("video.mp4", remoteOnly.RemoteEntry)}, dir, remoteOnly) {
			t.Error("isSuperseded = true, want false: the entry is still remote-only")
		}
		empty := &filer_pb.Entry{Name: "touch.txt", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}}
		if !isSuperseded(&stubFilerClient{entry: &filer_pb.Entry{Name: "touch.txt", Content: []byte("now")}}, dir, empty) {
			t.Error("isSuperseded = false, want true: the empty file was written to")
		}
		if isSuperseded(&stubFilerClient{entry: &filer_pb.Entry{Name: "touch.txt"}}, dir, empty) {
			t.Error("isSuperseded = true, want false: the file is still empty")
		}
	})

	t.Run("inline content rewritten since", func(t *testing.T) {
		event := &filer_pb.Entry{Name: "note.txt", Content: []byte("v1")}
		if !isSuperseded(&stubFilerClient{entry: &filer_pb.Entry{Name: "note.txt", Content: []byte("v2")}}, dir, event) {
			t.Error("isSuperseded = false, want true for an entry whose inline content has changed")
		}
		if isSuperseded(&stubFilerClient{entry: &filer_pb.Entry{Name: "note.txt", Content: []byte("v1")}}, dir, event) {
			t.Error("isSuperseded = true, want false for an entry whose inline content is unchanged")
		}
	})
}

// failingRemote fails every WriteFile with err and counts the attempts.
type failingRemote struct {
	remote_storage.RemoteStorageClient
	err    error
	writes int
}

func (r *failingRemote) WriteFile(*remote_pb.RemoteStorageLocation, *filer_pb.Entry, io.Reader) (*filer_pb.RemoteEntry, error) {
	r.writes++
	return nil, r.err
}

// TestRetriedWriteFileStopsWhenSuperseded checks that a failed upload asks the
// filer at once, and stops retrying when the entry is gone: the ~13s of backoff
// util.Retry would spend on a dead chunk buys nothing. An upload of an entry the
// filer still holds keeps the retry policy it had.
func TestRetriedWriteFileStopsWhenSuperseded(t *testing.T) {
	const dir = "/buckets/ingest"
	event := entryWith("tmpjt9req69__Alan_Doe_Resume-1.pdf", nil, chunk("3,01", "e1"))
	dest := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "tier", Path: "/" + event.Name}
	// What the S3 SDK reports when the volume server no longer has the chunk:
	// "requesterror" makes IsTransientError retry it to exhaustion.
	deadChunk := errors.New("RequestError: send request failed\ncaused by: Put \"https://s3.example.com/tier/x\": http://volume:8444/3,01?readDeleted=true: 404 Not Found: not found")

	t.Run("superseded before the first attempt, no write", func(t *testing.T) {
		remote := &failingRemote{err: deadChunk}
		filerClient := &stubFilerClient{}
		start := time.Now()
		_, err := retriedWriteFile(remote, filerClient, dir, event, dest)
		if !errors.Is(err, errSuperseded) {
			t.Errorf("err = %v, want errSuperseded", err)
		}
		if remote.writes != 0 {
			t.Errorf("wrote %d times, want 0: a superseded version is not worth uploading", remote.writes)
		}
		if filerClient.lookups != 1 {
			t.Errorf("looked up the filer %d times, want 1", filerClient.lookups)
		}
		if elapsed := time.Since(start); elapsed > 500*time.Millisecond {
			t.Errorf("took %v, want no backoff", elapsed)
		}
	})

	t.Run("superseded during the attempt, one write", func(t *testing.T) {
		remote := &failingRemote{err: deadChunk}
		filerClient := &supersedingFilerClient{live: entryWith(event.Name, nil, chunk("3,01", "e1"))}
		_, err := retriedWriteFile(remote, filerClient, dir, event, dest)
		if !errors.Is(err, errSuperseded) {
			t.Errorf("err = %v, want errSuperseded", err)
		}
		if !strings.Contains(err.Error(), "404 Not Found") {
			t.Errorf("err = %v, want it to keep the write failure", err)
		}
		if remote.writes != 1 {
			t.Errorf("wrote %d times, want 1: retrying a dead chunk cannot succeed", remote.writes)
		}
		if filerClient.lookups != 2 {
			t.Errorf("looked up the filer %d times, want one before the attempt and one after it failed", filerClient.lookups)
		}
	})

	t.Run("still as described, transient failure keeps retrying", func(t *testing.T) {
		prev := util.RetryWaitTime
		util.RetryWaitTime = 1600 * time.Millisecond // two attempts: 1s, then 1.5s
		t.Cleanup(func() { util.RetryWaitTime = prev })
		remote := &failingRemote{err: deadChunk}
		filerClient := &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"))}
		_, err := retriedWriteFile(remote, filerClient, dir, event, dest)
		if errors.Is(err, errSuperseded) {
			t.Errorf("err = %v, want the write failure itself", err)
		}
		if remote.writes != 2 {
			t.Errorf("wrote %d times, want 2: a transient failure on a live entry is still retried", remote.writes)
		}
		if filerClient.lookups != 3 {
			t.Errorf("looked up the filer %d times, want one before the first attempt and one per failed attempt", filerClient.lookups)
		}
	})

	t.Run("still as described, permanent failure not retried", func(t *testing.T) {
		remote := &failingRemote{err: errors.New("AccessDenied: Access Denied")}
		filerClient := &stubFilerClient{entry: entryWith(event.Name, nil, chunk("3,01", "e1"))}
		_, err := retriedWriteFile(remote, filerClient, dir, event, dest)
		if err == nil || errors.Is(err, errSuperseded) {
			t.Errorf("err = %v, want the write failure itself", err)
		}
		if remote.writes != 1 {
			t.Errorf("wrote %d times, want 1", remote.writes)
		}
	})
}

type recordingRemote struct {
	remote_storage.RemoteStorageClient
	deletes []*remote_pb.RemoteStorageLocation
	writes  []*remote_pb.RemoteStorageLocation
	written [][]byte
	// chunk ids of each written entry: which version of the file went up
	writtenChunks [][]string
	deleteErr     error
	// objects present on the remote, by path: StatFile and ReadFile answer
	// from it, everything else is ErrRemoteObjectNotFound.
	objects map[string][]byte
}

func (r *recordingRemote) WriteFile(loc *remote_pb.RemoteStorageLocation, entry *filer_pb.Entry, reader io.Reader) (*filer_pb.RemoteEntry, error) {
	r.writes = append(r.writes, loc)
	var ids []string
	for _, c := range entry.GetChunks() {
		ids = append(ids, c.GetFileIdString())
	}
	r.writtenChunks = append(r.writtenChunks, ids)
	// A chunked upload's reader walks volume servers the stub filer cannot
	// name, so it is not read; the copy path hands over the old object's
	// stream for a chunkless entry, which is drained.
	var body []byte
	if rc, ok := reader.(io.ReadCloser); ok && len(entry.GetChunks()) == 0 && r.objects != nil {
		body, _ = io.ReadAll(rc)
	}
	r.written = append(r.written, body)
	return &filer_pb.RemoteEntry{StorageName: loc.Name, RemoteETag: "etag", RemoteSize: int64(len(entry.Content)), RemoteMtime: entry.Attributes.GetMtime()}, nil
}

func (r *recordingRemote) StatFile(loc *remote_pb.RemoteStorageLocation) (*filer_pb.RemoteEntry, error) {
	body, ok := r.objects[loc.Path]
	if !ok {
		return nil, remote_storage.ErrRemoteObjectNotFound
	}
	return &filer_pb.RemoteEntry{StorageName: loc.Name, RemoteSize: int64(len(body))}, nil
}

func (r *recordingRemote) ReadFile(loc *remote_pb.RemoteStorageLocation, offset int64, size int64) ([]byte, error) {
	body, ok := r.objects[loc.Path]
	if !ok {
		return nil, remote_storage.ErrRemoteObjectNotFound
	}
	return body[offset : offset+size], nil
}

func (r *recordingRemote) DeleteFile(loc *remote_pb.RemoteStorageLocation) error {
	r.deletes = append(r.deletes, loc)
	return r.deleteErr
}

// TestRenameWithInheritedRemoteEntryWritesNewKey reproduces #11261: a rename
// arrives as an update whose NewEntry carries the RemoteEntry inherited from
// the source. shouldSendToRemote returns false for it (RemoteMtime >= Mtime),
// so the old code skipped the event and never wrote the new key, while the
// filer had already deleted the old object. A path change must always write.
func TestRenameWithInheritedRemoteEntryWritesNewKey(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "bucket", Path: "/"}

	replicated := &filer_pb.RemoteEntry{StorageName: "b2", RemoteETag: "abc", RemoteSize: 2048, RemoteMtime: 1786096669}
	oldEntry := &filer_pb.Entry{Name: "probe.bin", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}, RemoteEntry: replicated}
	newEntry := &filer_pb.Entry{
		Name:        "probe.bin",
		Content:     []byte("payload"),
		Attributes:  &filer_pb.FuseAttributes{Mtime: 1786096669},
		RemoteEntry: replicated,
	}
	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/src",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:      oldEntry,
			NewParentPath: "/buckets/b/dst",
			NewEntry:      newEntry,
		},
	}

	if shouldSendToRemote(newEntry) {
		t.Fatal("precondition: inherited RemoteEntry should make shouldSendToRemote false, the bug's trigger")
	}

	remote := &recordingRemote{}
	// the filer still holds the renamed entry as the event described it
	filerClient := &stubFilerClient{entry: newEntry}
	if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
		t.Fatal(err)
	}

	wantDelete := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "bucket", Path: "/b/src/probe.bin"}
	if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
		t.Errorf("deletes = %+v, want the old key %s deleted", remote.deletes, remote_storage.FormatLocation(wantDelete))
	}
	wantWrite := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "bucket", Path: "/b/dst/probe.bin"}
	if len(remote.writes) != 1 || !proto.Equal(remote.writes[0], wantWrite) {
		t.Errorf("writes = %+v, want the new key %s written", remote.writes, remote_storage.FormatLocation(wantWrite))
	}
}

// TestRenameRemoteOnlyEntrySkipsEmptyUpload guards the edge case from the
// review of #11261: a remote-only entry (no local chunks, content lives only
// on the remote object the filer already deleted) must not be re-uploaded,
// since NewFileReader would supply EOF and create a zero-byte object.
func TestRenameRemoteOnlyEntrySkipsEmptyUpload(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "bucket", Path: "/"}

	remoteOnly := &filer_pb.RemoteEntry{StorageName: "b2", RemoteETag: "abc", RemoteSize: 20971520, RemoteMtime: 1786096669}
	oldEntry := &filer_pb.Entry{Name: "video.mp4", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}, RemoteEntry: remoteOnly}
	newEntry := &filer_pb.Entry{
		Name:        "video.mp4",
		Attributes:  &filer_pb.FuseAttributes{Mtime: 1786096669},
		RemoteEntry: remoteOnly,
	}
	if !newEntry.IsInRemoteOnly() {
		t.Fatal("precondition: entry should be remote-only")
	}
	if filer.HasData(newEntry) {
		t.Fatal("precondition: remote-only entry should have no local data")
	}

	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/src",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:      oldEntry,
			NewParentPath: "/buckets/b/dst",
			NewEntry:      newEntry,
		},
	}

	remote := &recordingRemote{}
	filerClient := &stubFilerClient{}
	if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
		t.Fatal(err)
	}
	if len(remote.writes) != 0 {
		t.Errorf("writes = %+v, want none: a remote-only rename must not upload an empty object", remote.writes)
	}
}

// TestRenameDeleteOldKeyFailureReturnsError checks that a failed delete of the
// old key on a rename is returned so MetadataProcessor retries the event,
// instead of silently continuing and leaving both keys on the remote.
func TestRenameDeleteOldKeyFailureReturnsError(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "b2", Bucket: "bucket", Path: "/"}

	newEntry := &filer_pb.Entry{
		Name:       "probe.bin",
		Content:    []byte("payload"),
		Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669},
	}
	oldEntry := &filer_pb.Entry{Name: "probe.bin", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}}
	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/src",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:      oldEntry,
			NewParentPath: "/buckets/b/dst",
			NewEntry:      newEntry,
		},
	}

	deleteErr := errors.New("AccessDenied: Access Denied")
	remote := &recordingRemote{deleteErr: deleteErr}
	filerClient := &stubFilerClient{}
	err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp)
	if !errors.Is(err, deleteErr) {
		t.Errorf("err = %v, want the delete failure returned so the event is retried", err)
	}
	if len(remote.writes) != 0 {
		t.Errorf("writes = %+v, want none: must not write the new key when the old key delete failed", remote.writes)
	}
}

// TestRenameDeleteOldKeyNotFoundStillWrites checks that an already-deleted old
// key (the filer deletes the source object synchronously during rename) does
// not block the destination write. GCS reports a missing object as
// ErrRemoteObjectNotFound, unlike S3/Azure whose deletes are idempotent, so
// treating it as a real error would pin the sync offset and never write the
// new key.
func TestRenameDeleteOldKeyNotFoundStillWrites(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/"}

	newEntry := &filer_pb.Entry{
		Name:       "probe.bin",
		Content:    []byte("payload"),
		Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669},
	}
	oldEntry := &filer_pb.Entry{Name: "probe.bin", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}}
	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/src",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:      oldEntry,
			NewParentPath: "/buckets/b/dst",
			NewEntry:      newEntry,
		},
	}

	remote := &recordingRemote{deleteErr: remote_storage.ErrRemoteObjectNotFound}
	// the filer still holds the renamed entry as the event described it
	filerClient := &stubFilerClient{entry: newEntry}
	if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
		t.Fatalf("err = %v, want nil: an already-deleted old key must not block the write", err)
	}
	wantWrite := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/b/dst/probe.bin"}
	if len(remote.writes) != 1 || !proto.Equal(remote.writes[0], wantWrite) {
		t.Errorf("writes = %+v, want the new key %s written", remote.writes, remote_storage.FormatLocation(wantWrite))
	}
}

func TestIfEntryEqualCarriesTheEventEntry(t *testing.T) {
	entry := &filer_pb.Entry{
		Name:    "f",
		Content: []byte("inline"),
		Chunks: []*filer_pb.FileChunk{
			{FileId: "3,01a"},
			{Fid: &filer_pb.FileId{VolumeId: 4, FileKey: 0x2b, Cookie: 0x0c}},
		},
	}
	cond := ifEntryEqual(entry)
	if len(cond.Clauses) != 1 || cond.Clauses[0].Kind != filer_pb.WriteCondition_IF_ENTRY_EQUAL {
		t.Fatalf("condition = %v, want one IF_ENTRY_EQUAL clause", cond)
	}
	if got := cond.Clauses[0].ExpectedEntry; !proto.Equal(got, entry) {
		t.Fatalf("expected_entry = %v, want %v", got, entry)
	}
}

// The remote-bound entry loses (or gains) the storage class attribute while
// the event entry keeps it, so IF_ENTRY_EQUAL still sees the entry the filer
// stored — otherwise every stamp on an S3-written object reads as stale.
func TestRemoteWriteEntryLeavesEventEntryUntouched(t *testing.T) {
	entry := &filer_pb.Entry{
		Name:       "f",
		Attributes: &filer_pb.FuseAttributes{Mtime: 1},
		Extended:   map[string][]byte{s3_constants.AmzStorageClass: []byte("STANDARD")},
	}

	stripped := remoteWriteEntry(entry, "")
	if _, ok := stripped.Extended[s3_constants.AmzStorageClass]; ok {
		t.Fatalf("remote entry still carries %s", s3_constants.AmzStorageClass)
	}
	if string(entry.Extended[s3_constants.AmzStorageClass]) != "STANDARD" {
		t.Fatalf("event entry Extended mutated: %v", entry.Extended)
	}

	overridden := remoteWriteEntry(entry, "GLACIER")
	if got := string(overridden.Extended[s3_constants.AmzStorageClass]); got != "GLACIER" {
		t.Fatalf("override = %q, want GLACIER", got)
	}
	if string(entry.Extended[s3_constants.AmzStorageClass]) != "STANDARD" {
		t.Fatalf("event entry Extended mutated: %v", entry.Extended)
	}

	bare := &filer_pb.Entry{Name: "g", Attributes: &filer_pb.FuseAttributes{Mtime: 1}}
	if got := string(remoteWriteEntry(bare, "GLACIER").Extended[s3_constants.AmzStorageClass]); got != "GLACIER" {
		t.Fatalf("override on nil Extended = %q, want GLACIER", got)
	}
}

func TestIsFailedPrecondition(t *testing.T) {
	refused := status.Error(codes.FailedPrecondition, "precondition failed: /buckets/b/f")
	cases := []struct {
		name string
		err  error
		want bool
	}{
		{"nil", nil, false},
		{"status", refused, true},
		{"wrapped status", fmt.Errorf("update entry: %w", refused), true},
		{"message only", errors.New("rpc error: code = FailedPrecondition desc = precondition failed: /f"), false},
		{"other", status.Error(codes.Unavailable, "filer down"), false},
	}
	for _, c := range cases {
		if got := isFailedPrecondition(c.err); got != c.want {
			t.Errorf("%s: isFailedPrecondition = %v, want %v", c.name, got, c.want)
		}
	}
}

// supersedingFilerClient answers the first lookup with the live entry and
// every later one with "not found": the entry is deleted while the upload is
// in flight.
type supersedingFilerClient struct {
	filer_pb.SeaweedFilerClient
	live    *filer_pb.Entry
	lookups int
}

func (c *supersedingFilerClient) LookupDirectoryEntry(context.Context, *filer_pb.LookupDirectoryEntryRequest, ...grpc.CallOption) (*filer_pb.LookupDirectoryEntryResponse, error) {
	c.lookups++
	if c.lookups == 1 {
		return &filer_pb.LookupDirectoryEntryResponse{Entry: c.live}, nil
	}
	return nil, filer_pb.ErrNotFound
}

func (c *supersedingFilerClient) WithFilerClient(_ bool, fn func(filer_pb.SeaweedFilerClient) error) error {
	return fn(c)
}

func (c *supersedingFilerClient) AdjustedUrl(location *filer_pb.Location) string { return location.Url }

func (c *supersedingFilerClient) GetDataCenter() string { return "" }

// TestDeleteEventAbsentRemoteObjectIsSuccess: an entry created and deleted
// before the sync uploaded it has no remote object. GCS reports the delete as
// ErrRemoteObjectNotFound; the event has nothing left to do, so it must not
// fail (a failed event pins the sync offset and is replayed on every restart).
func TestDeleteEventAbsentRemoteObjectIsSuccess(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/"}
	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/vol",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:     &filer_pb.Entry{Name: "state.db.tmp", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}},
			DeleteChunks: true,
		},
	}
	wantDelete := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/b/vol/state.db.tmp"}

	t.Run("absent object", func(t *testing.T) {
		remote := &recordingRemote{deleteErr: remote_storage.ErrRemoteObjectNotFound}
		if err := processDeleteEvent(remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil: deleting an absent object is complete", err)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want %s", remote.deletes, remote_storage.FormatLocation(wantDelete))
		}
	})

	t.Run("other failure still fails", func(t *testing.T) {
		remote := &recordingRemote{deleteErr: errors.New("AccessDenied: Access Denied")}
		if err := processDeleteEvent(remote, mountedDir, mountLoc, resp); err == nil {
			t.Fatal("err = nil, want the delete failure")
		}
	})

	t.Run("delete marker, absent object", func(t *testing.T) {
		remote := &recordingRemote{deleteErr: remote_storage.ErrRemoteObjectNotFound}
		filerClient := &stubFilerClient{}
		markerDelete := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/b/vol/state.db"}
		message := &filer_pb.EventNotification{
			NewParentPath: "/buckets/b/vol",
			NewEntry:      &filer_pb.Entry{Name: "state.db", Attributes: &filer_pb.FuseAttributes{Mtime: 1786096669}},
		}
		if err := syncDeleteMarker(remote, filerClient, message, markerDelete); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], markerDelete) {
			t.Errorf("deletes = %+v, want %s", remote.deletes, remote_storage.FormatLocation(markerDelete))
		}
		if filerClient.updates != 1 {
			t.Errorf("stamped %d times, want 1: the marker is recorded locally so a replay is a no-op", filerClient.updates)
		}
	})
}

// TestUpdateLocalEntrySkipsDeletedEntry: the stamp that follows an upload lands
// on an entry a later event already deleted. The filer answers "not found"; the
// delete's own event follows in the log, so the stamp is skipped rather than
// failed.
func TestUpdateLocalEntrySkipsDeletedEntry(t *testing.T) {
	const dir = "/buckets/b/vol"
	remoteEntry := &filer_pb.RemoteEntry{StorageName: "gcs", RemoteSize: 7}

	t.Run("plain not found from the filer", func(t *testing.T) {
		filerClient := &stubFilerClient{updateErr: fmt.Errorf("not found %s: %w", dir+"/state.db", filer_pb.ErrNotFound)}
		if err := updateLocalEntry(filerClient, dir, entryWith("state.db", nil, chunk("3,01", "e1")), remoteEntry); err != nil {
			t.Errorf("err = %v, want nil", err)
		}
	})

	t.Run("not found over grpc", func(t *testing.T) {
		filerClient := &stubFilerClient{updateErr: status.Error(codes.Unknown, "not found "+dir+"/state.db: "+filer_pb.ErrNotFound.Error())}
		if err := updateLocalEntry(filerClient, dir, entryWith("state.db", nil, chunk("3,01", "e1")), remoteEntry); err != nil {
			t.Errorf("err = %v, want nil", err)
		}
	})

	t.Run("typed not found from the filer", func(t *testing.T) {
		filerClient := &stubFilerClient{updateErr: status.Errorf(codes.NotFound, "not found %s/state.db: %v", dir, filer_pb.ErrNotFound)}
		if err := updateLocalEntry(filerClient, dir, entryWith("state.db", nil, chunk("3,01", "e1")), remoteEntry); err != nil {
			t.Errorf("err = %v, want nil", err)
		}
	})

	t.Run("the sentinel inside the path is not a missing entry", func(t *testing.T) {
		name := filer_pb.ErrNotFound.Error()
		filerClient := &stubFilerClient{updateErr: status.Error(codes.Unknown, "not found "+dir+"/"+name+": database unavailable")}
		if err := updateLocalEntry(filerClient, dir, entryWith(name, nil, chunk("3,01", "e1")), remoteEntry); err == nil {
			t.Error("err = nil, want the store failure: the stamp must be retried, not dropped")
		}
	})

	t.Run("other failure still fails", func(t *testing.T) {
		filerClient := &stubFilerClient{updateErr: status.Error(codes.Unavailable, "filer is shutting down")}
		if err := updateLocalEntry(filerClient, dir, entryWith("state.db", nil, chunk("3,01", "e1")), remoteEntry); err == nil {
			t.Error("err = nil, want the update failure")
		}
	})
}

// TestSupersededRenameUploadsCurrentEntry: a rename A -> B queued behind a
// rewrite of B. The rename's snapshot is superseded (B's chunks changed) and
// the old key A is already deleted. The rewrite's own event uploads B unless
// shouldSendToRemote skips it on the inherited RemoteEntry (same-second
// mtimes); only then does the rename upload what the filer holds now, so the
// content goes up exactly once.
func TestSupersededRenameUploadsCurrentEntry(t *testing.T) {
	const mountedDir = "/buckets"
	mountLoc := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/"}
	eventEntry := entryWith("b.txt", nil, chunk("3,01", "e1"))
	resp := &filer_pb.SubscribeMetadataResponse{
		Directory: "/buckets/b/dir",
		EventNotification: &filer_pb.EventNotification{
			OldEntry:      entryWith("a.txt", nil, chunk("3,01", "e1")),
			NewParentPath: "/buckets/b/dir",
			NewEntry:      eventEntry,
		},
	}
	wantDelete := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/b/dir/a.txt"}
	wantWrite := &remote_pb.RemoteStorageLocation{Name: "gcs", Bucket: "bucket", Path: "/b/dir/b.txt"}

	t.Run("rewrite hidden by the inherited stamp: upload once here", func(t *testing.T) {
		// RemoteMtime inherited from a.txt equals the rewrite's mtime.
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 1024}, chunk("3,02", "e2"))
		remote := &recordingRemote{}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want the old key %s deleted", remote.deletes, remote_storage.FormatLocation(wantDelete))
		}
		if len(remote.writes) != 1 || !proto.Equal(remote.writes[0], wantWrite) {
			t.Fatalf("writes = %+v, want the new key %s written once with the current entry", remote.writes, remote_storage.FormatLocation(wantWrite))
		}
		if filerClient.updates != 1 {
			t.Errorf("stamped %d times, want 1: the current entry is stamped", filerClient.updates)
		}
	})

	t.Run("rewrite newer than the stamp: its own event uploads, not this one", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096000, RemoteSize: 1024}, chunk("3,02", "e2"))
		remote := &recordingRemote{}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.deletes) != 1 {
			t.Errorf("deletes = %+v, want the old key deleted", remote.deletes)
		}
		if len(remote.writes) != 0 {
			t.Errorf("writes = %+v, want none: the rewrite event behind this one uploads b.txt", remote.writes)
		}
	})

	t.Run("deleted meanwhile: nothing to upload", func(t *testing.T) {
		remote := &recordingRemote{}
		filerClient := &stubFilerClient{}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.writes) != 0 {
			t.Errorf("writes = %+v, want none: the delete event follows", remote.writes)
		}
	})

	t.Run("uncached meanwhile, old object present: copied to the destination, stamped, old key deleted", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7})
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/a.txt": []byte("payload")}}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.writes) != 1 || !proto.Equal(remote.writes[0], wantWrite) || string(remote.written[0]) != "payload" {
			t.Fatalf("writes = %+v (%q), want the old object's bytes written at %s", remote.writes, remote.written, remote_storage.FormatLocation(wantWrite))
		}
		if filerClient.updates != 1 {
			t.Errorf("stamped %d times, want 1: the entry now points at the destination object", filerClient.updates)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want the old key deleted after the copy", remote.deletes)
		}
	})

	t.Run("uncached after an earlier run completed the rename: destination present, old key deleted, nothing written", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7})
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/a.txt": []byte("payload"), "/b/dir/b.txt": []byte("payload")}}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil: the replayed rename is already complete", err)
		}
		if len(remote.writes) != 0 {
			t.Errorf("writes = %+v, want none", remote.writes)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want the old key deleted", remote.deletes)
		}
	})

	t.Run("uncached and neither object exists: the event fails and holds the offset", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7})
		remote := &recordingRemote{}
		filerClient := &stubFilerClient{entry: current}
		err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp)
		if err == nil || !strings.Contains(err.Error(), "neither") {
			t.Fatalf("err = %v, want the lost-content failure", err)
		}
		if len(remote.writes) != 0 || len(remote.deletes) != 0 {
			t.Errorf("writes = %+v deletes = %+v, want none", remote.writes, remote.deletes)
		}
	})

	t.Run("destination holds an object of another size: replaced from the old key", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7})
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/a.txt": []byte("payload"), "/b/dir/b.txt": []byte("something else")}}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, resp); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.writes) != 1 || string(remote.written[0]) != "payload" {
			t.Fatalf("writes = %+v (%q), want the old object copied over the destination", remote.writes, remote.written)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want the old key deleted after the copy", remote.deletes)
		}
	})

	t.Run("snapshot remote-only but rewritten since: the rewrite's bytes go up, nothing is copied", func(t *testing.T) {
		remoteOnly := &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7}
		snapshot := &filer_pb.SubscribeMetadataResponse{
			Directory: "/buckets/b/dir",
			EventNotification: &filer_pb.EventNotification{
				OldEntry:      entryWith("a.txt", remoteOnly),
				NewParentPath: "/buckets/b/dir",
				NewEntry:      entryWith("b.txt", remoteOnly),
			},
		}
		// rewritten with the inherited stamp still hiding it from shouldSendToRemote
		current := entryWith("b.txt", remoteOnly, chunk("3,09", "e9"))
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/a.txt": []byte("payload")}}
		filerClient := &stubFilerClient{entry: current}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, snapshot); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.writes) != 1 || !proto.Equal(remote.writes[0], wantWrite) {
			t.Fatalf("writes = %+v, want one upload of the rewritten b.txt", remote.writes)
		}
		if len(remote.writtenChunks[0]) != 1 || remote.writtenChunks[0][0] != "3,09" {
			t.Errorf("uploaded chunks = %v, want the rewrite's chunk 3,09, not the chunkless snapshot", remote.writtenChunks[0])
		}
		if string(remote.written[0]) == "payload" {
			t.Error("the old object's bytes were copied over a rewritten entry")
		}
		if len(remote.deletes) != 1 {
			t.Errorf("deletes = %+v, want the old key deleted", remote.deletes)
		}
	})

	t.Run("snapshot already remote-only: completed the same way", func(t *testing.T) {
		remoteOnly := &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7}
		snapshot := &filer_pb.SubscribeMetadataResponse{
			Directory: "/buckets/b/dir",
			EventNotification: &filer_pb.EventNotification{
				OldEntry:      entryWith("a.txt", remoteOnly),
				NewParentPath: "/buckets/b/dir",
				NewEntry:      entryWith("b.txt", remoteOnly),
			},
		}
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/a.txt": []byte("payload")}}
		filerClient := &stubFilerClient{entry: entryWith("b.txt", remoteOnly)}
		if err := processUpdateEvent(filerClient, filerClient, "", remote, mountedDir, mountLoc, snapshot); err != nil {
			t.Fatalf("err = %v, want nil", err)
		}
		if len(remote.writes) != 1 || string(remote.written[0]) != "payload" {
			t.Errorf("writes = %+v (%q), want the old object copied to the destination", remote.writes, remote.written)
		}
		if len(remote.deletes) != 1 {
			t.Errorf("deletes = %+v, want the old key deleted after the copy", remote.deletes)
		}
	})

	t.Run("uncached after the old key was deleted: the event fails and holds the offset", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 1024})
		remote := &recordingRemote{}
		filerClient := &stubFilerClient{entry: current}
		err := uploadCurrentEntry(filerClient, filerClient, remote, "/buckets/b/dir", "b.txt", wantDelete, wantWrite, "")
		if err == nil || !strings.Contains(err.Error(), "neither") {
			t.Errorf("err = %v, want the lost-content failure", err)
		}
		if len(remote.writes) != 0 {
			t.Errorf("writes = %+v, want none", remote.writes)
		}
	})

	t.Run("uncached with the destination already synced: complete without a write", func(t *testing.T) {
		current := entryWith("b.txt", &filer_pb.RemoteEntry{StorageName: "gcs", RemoteMtime: 1786096669, RemoteSize: 7})
		remote := &recordingRemote{objects: map[string][]byte{"/b/dir/b.txt": []byte("payload")}}
		filerClient := &stubFilerClient{entry: current}
		if err := uploadCurrentEntry(filerClient, filerClient, remote, "/buckets/b/dir", "b.txt", wantDelete, wantWrite, ""); err != nil {
			t.Fatalf("err = %v, want nil: the destination object matches the entry's stamp", err)
		}
		if len(remote.writes) != 0 {
			t.Errorf("writes = %+v, want none", remote.writes)
		}
		if len(remote.deletes) != 1 || !proto.Equal(remote.deletes[0], wantDelete) {
			t.Errorf("deletes = %+v, want the old key deleted", remote.deletes)
		}
	})
}