Refine object operations and multi-object delete sections

Updated the formatting and structure of the object operations and multi-object delete sections in the README.

.dockerignore

@@ -0,0 +1,4 @@
+*.md
+.gocache/
+blobs/
+data/

.env.example

@@ -0,0 +1,8 @@
+LOG_LEVEL=debug
+LOG_FORMAT=text
+DATA_PATH=data/
+PORT=2600
+AUDIT_LOG=true
+ADDRESS=0.0.0.0
+GC_INTERVAL=10
+GC_ENABLED=true

.gitignore

@@ -1,5 +1,8 @@
 .env
+*.db
 .vscode/
 blobs/
-*.db
+data/
 .idea/
+.gocache/
+.gomodcache/

Dockerfile

@@ -0,0 +1,16 @@
+FROM golang:1.25-alpine AS build
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -o /app/fs .
+
+FROM scratch AS runner
+
+COPY --from=build /app/fs /app/fs
+
+WORKDIR /app
+CMD ["/app/fs"]

LICENSE.md

@@ -0,0 +1,8 @@
+Copyright 2025 ferdzo
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

README.md

@@ -1,3 +1,41 @@
 # fs
 
-An experimental Object Storage written in Go that should be compatible with S3
+An experimental Object Storage written in Go that should be partially compatible with S3
+
+## Features
+
+Bucket operations:
+- `PUT /{bucket}`
+- `HEAD /{bucket}`
+- `DELETE /{bucket}`
+- `GET /` (list buckets)
+- 
+Object operations:
+- `PUT /{bucket}/{key}`
+- `GET /{bucket}/{key}`
+- `HEAD /{bucket}/{key}`
+- `DELETE /{bucket}/{key}`
+- `GET /{bucket}?list-type=2&prefix=...` (ListObjectsV2-style)
+
+Multipart upload:
+- `POST /{bucket}/{key}?uploads` (initiate)
+- `PUT /{bucket}/{key}?uploadId=...&partNumber=N` (upload part)
+- `GET /{bucket}/{key}?uploadId=...` (list parts)
+- `POST /{bucket}/{key}?uploadId=...` (complete)
+- `DELETE /{bucket}/{key}?uploadId=...` (abort)
+
+Multi-object delete:
+- `POST /{bucket}?delete` with S3-style XML body
+
+AWS SigV4 streaming payload decoding for uploads (`aws-chunked` request bodies)
+
+## Limitations
+
+- No authentication/authorization yet.
+- Not full S3 API coverage.
+- No versioning or lifecycle policies.
+- Error and edge-case behavior is still being refined for client compatibility.
+
+## License
+
+MIT License

api/api.go

@@ -1 +1,856 @@
 package api
+
+import (
+	"bufio"
+	"context"
+	"encoding/base64"
+	"encoding/xml"
+	"errors"
+	"fmt"
+	"fs/logging"
+	"fs/metadata"
+	"fs/models"
+	"fs/service"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+)
+
+type Handler struct {
+	router    *chi.Mux
+	svc       *service.ObjectService
+	logger    *slog.Logger
+	logConfig logging.Config
+}
+
+func NewHandler(svc *service.ObjectService, logger *slog.Logger, logConfig logging.Config) *Handler {
+	r := chi.NewRouter()
+	r.Use(middleware.Recoverer)
+	if logger == nil {
+		logger = slog.Default()
+	}
+
+	h := &Handler{
+		router:    r,
+		svc:       svc,
+		logger:    logger,
+		logConfig: logConfig,
+	}
+	return h
+}
+
+func (h *Handler) setupRoutes() {
+	h.router.Use(logging.HTTPMiddleware(h.logger, h.logConfig))
+
+	h.router.Get("/", h.handleGetBuckets)
+
+	h.router.Get("/{bucket}/", h.handleGetBucket)
+	h.router.Get("/{bucket}", h.handleGetBucket)
+	h.router.Put("/{bucket}", h.handlePutBucket)
+	h.router.Put("/{bucket}/", h.handlePutBucket)
+	h.router.Post("/{bucket}", h.handlePostBucket)
+	h.router.Post("/{bucket}/", h.handlePostBucket)
+	h.router.Delete("/{bucket}", h.handleDeleteBucket)
+	h.router.Delete("/{bucket}/", h.handleDeleteBucket)
+	h.router.Head("/{bucket}", h.handleHeadBucket)
+	h.router.Head("/{bucket}/", h.handleHeadBucket)
+
+	h.router.Get("/{bucket}/*", h.handleGetObject)
+	h.router.Put("/{bucket}/*", h.handlePutObject)
+	h.router.Post("/{bucket}/*", h.handlePostObject)
+	h.router.Head("/{bucket}/*", h.handleHeadObject)
+	h.router.Delete("/{bucket}/*", h.handleDeleteObject)
+}
+
+func (h *Handler) handleWelcome(w http.ResponseWriter) {
+	w.WriteHeader(http.StatusOK)
+	_, err := w.Write([]byte("Welcome to the Object Storage API!"))
+	if err != nil {
+		return
+	}
+}
+
+func (h *Handler) handleGetObject(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	key := chi.URLParam(r, "*")
+
+	if key == "" {
+		writeS3Error(w, r, s3ErrInvalidObjectKey, r.URL.Path)
+		return
+	}
+
+	if uploadID := r.URL.Query().Get("uploadId"); uploadID != "" {
+		h.handleListMultipartParts(w, r, bucket, key, uploadID)
+		return
+	}
+
+	stream, manifest, err := h.svc.GetObject(bucket, key)
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	defer stream.Close()
+
+	rangeHeader := strings.TrimSpace(r.Header.Get("Range"))
+	if rangeHeader != "" {
+		start, end, err := parseSingleByteRange(rangeHeader, manifest.Size)
+		if err != nil {
+			w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", manifest.Size))
+			writeS3Error(w, r, s3ErrInvalidRange, r.URL.Path)
+			return
+		}
+
+		if start > 0 {
+			if _, err := io.CopyN(io.Discard, stream, start); err != nil {
+				writeMappedS3Error(w, r, err)
+				return
+			}
+		}
+
+		length := end - start + 1
+		w.Header().Set("Content-Type", manifest.ContentType)
+		w.Header().Set("Content-Length", strconv.FormatInt(length, 10))
+		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", start, end, manifest.Size))
+		w.Header().Set("ETag", `"`+manifest.ETag+`"`)
+		w.Header().Set("Last-Modified", time.Unix(manifest.CreatedAt, 0).UTC().Format(http.TimeFormat))
+		w.Header().Set("Accept-Ranges", "bytes")
+		w.WriteHeader(http.StatusPartialContent)
+		_, _ = io.CopyN(w, stream, length)
+		return
+	}
+
+	w.Header().Set("Content-Type", manifest.ContentType)
+	w.Header().Set("Content-Length", strconv.FormatInt(manifest.Size, 10))
+	w.Header().Set("ETag", `"`+manifest.ETag+`"`)
+	w.Header().Set("Last-Modified", time.Unix(manifest.CreatedAt, 0).UTC().Format(http.TimeFormat))
+	w.Header().Set("Accept-Ranges", "bytes")
+	w.WriteHeader(http.StatusOK)
+	_, err = io.Copy(w, stream)
+
+}
+
+func (h *Handler) handlePostObject(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	key := chi.URLParam(r, "*")
+	if key == "" {
+		writeS3Error(w, r, s3ErrInvalidObjectKey, r.URL.Path)
+		return
+	}
+	defer r.Body.Close()
+
+	if _, ok := r.URL.Query()["uploads"]; ok {
+		upload, err := h.svc.CreateMultipartUpload(bucket, key)
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+		response := models.InitiateMultipartUploadResult{
+			Xmlns:    "http://s3.amazonaws.com/doc/2006-03-01/",
+			Bucket:   upload.Bucket,
+			Key:      upload.Key,
+			UploadID: upload.UploadID,
+		}
+		payload, err := xml.MarshalIndent(response, "", "    ")
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+		w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte(xml.Header))
+		_, _ = w.Write(payload)
+		return
+	}
+
+	if uploadID := r.URL.Query().Get("uploadId"); uploadID != "" {
+		var req models.CompleteMultipartUploadRequest
+		if err := xml.NewDecoder(r.Body).Decode(&req); err != nil {
+			writeS3Error(w, r, s3ErrMalformedXML, r.URL.Path)
+			return
+		}
+
+		manifest, err := h.svc.CompleteMultipartUpload(bucket, key, uploadID, req.Parts)
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+
+		response := models.CompleteMultipartUploadResult{
+			Xmlns:    "http://s3.amazonaws.com/doc/2006-03-01/",
+			Bucket:   bucket,
+			Key:      key,
+			ETag:     `"` + manifest.ETag + `"`,
+			Location: r.URL.Path,
+		}
+		payload, err := xml.MarshalIndent(response, "", "    ")
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte(xml.Header))
+		_, _ = w.Write(payload)
+		return
+	}
+
+	writeS3Error(w, r, s3ErrNotImplemented, r.URL.Path)
+}
+
+func (h *Handler) handlePutObject(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	key := chi.URLParam(r, "*")
+	if key == "" {
+		writeS3Error(w, r, s3ErrInvalidObjectKey, r.URL.Path)
+		return
+	}
+	defer r.Body.Close()
+
+	uploadID := r.URL.Query().Get("uploadId")
+	partNumberRaw := r.URL.Query().Get("partNumber")
+	if uploadID != "" || partNumberRaw != "" {
+		if uploadID == "" || partNumberRaw == "" {
+			writeS3Error(w, r, s3ErrInvalidPart, r.URL.Path)
+			return
+		}
+
+		partNumber, err := strconv.Atoi(partNumberRaw)
+		if err != nil {
+			writeS3Error(w, r, s3ErrInvalidPart, r.URL.Path)
+			return
+		}
+		if partNumber < 1 || partNumber > 10000 {
+			writeS3Error(w, r, s3ErrInvalidPart, r.URL.Path)
+			return
+		}
+
+		bodyReader := io.Reader(r.Body)
+		var decodeStream io.ReadCloser
+		if shouldDecodeAWSChunkedPayload(r) {
+			decodeStream = newAWSChunkedDecodingReader(r.Body)
+			defer decodeStream.Close()
+			bodyReader = decodeStream
+		}
+
+		etag, err := h.svc.UploadPart(bucket, key, uploadID, partNumber, bodyReader)
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+		w.Header().Set("ETag", `"`+etag+`"`)
+		w.Header().Set("Content-Length", "0")
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	contentType := r.Header.Get("Content-Type")
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+
+	bodyReader := io.Reader(r.Body)
+	var decodeStream io.ReadCloser
+	if shouldDecodeAWSChunkedPayload(r) {
+		decodeStream = newAWSChunkedDecodingReader(r.Body)
+		defer decodeStream.Close()
+		bodyReader = decodeStream
+	}
+
+	manifest, err := h.svc.PutObject(bucket, key, contentType, bodyReader)
+
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	w.Header().Set("ETag", `"`+manifest.ETag+`"`)
+	w.Header().Set("Content-Length", "0")
+
+	w.WriteHeader(http.StatusOK)
+}
+
+func (h *Handler) handleListMultipartParts(w http.ResponseWriter, r *http.Request, bucket, key, uploadID string) {
+	parts, err := h.svc.ListMultipartParts(bucket, key, uploadID)
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	response := models.ListPartsResult{
+		Xmlns:    "http://s3.amazonaws.com/doc/2006-03-01/",
+		Bucket:   bucket,
+		Key:      key,
+		UploadID: uploadID,
+		Parts:    make([]models.PartItem, 0, len(parts)),
+	}
+	for _, part := range parts {
+		response.Parts = append(response.Parts, models.PartItem{
+			PartNumber:   part.PartNumber,
+			LastModified: time.Unix(part.CreatedAt, 0).UTC().Format("2006-01-02T15:04:05.000Z"),
+			ETag:         `"` + part.ETag + `"`,
+			Size:         part.Size,
+		})
+	}
+
+	payload, err := xml.MarshalIndent(response, "", "    ")
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte(xml.Header))
+	_, _ = w.Write(payload)
+}
+
+func shouldDecodeAWSChunkedPayload(r *http.Request) bool {
+	contentEncoding := strings.ToLower(r.Header.Get("Content-Encoding"))
+	if strings.Contains(contentEncoding, "aws-chunked") {
+		return true
+	}
+	signingMode := strings.ToLower(r.Header.Get("x-amz-content-sha256"))
+	return strings.HasPrefix(signingMode, "streaming-aws4-hmac-sha256-payload")
+}
+
+func newAWSChunkedDecodingReader(src io.Reader) io.ReadCloser {
+	pr, pw := io.Pipe()
+	go func() {
+		if err := decodeAWSChunkedPayload(src, pw); err != nil {
+			_ = pw.CloseWithError(err)
+			return
+		}
+		_ = pw.Close()
+	}()
+	return pr
+}
+
+func decodeAWSChunkedPayload(src io.Reader, dst io.Writer) error {
+	reader := bufio.NewReader(src)
+	for {
+		headerLine, err := reader.ReadString('\n')
+		if err != nil {
+			return err
+		}
+		headerLine = strings.TrimRight(headerLine, "\r\n")
+		chunkSizeToken := headerLine
+		if idx := strings.IndexByte(chunkSizeToken, ';'); idx >= 0 {
+			chunkSizeToken = chunkSizeToken[:idx]
+		}
+		chunkSizeToken = strings.TrimSpace(chunkSizeToken)
+		chunkSize, err := strconv.ParseInt(chunkSizeToken, 16, 64)
+		if err != nil {
+			return fmt.Errorf("invalid aws-chunked header %q: %w", headerLine, err)
+		}
+		if chunkSize < 0 {
+			return fmt.Errorf("invalid aws-chunked size: %d", chunkSize)
+		}
+		if chunkSize > 0 {
+			if _, err := io.CopyN(dst, reader, chunkSize); err != nil {
+				return err
+			}
+		}
+
+		crlf := make([]byte, 2)
+		if _, err := io.ReadFull(reader, crlf); err != nil {
+			return err
+		}
+		if crlf[0] != '\r' || crlf[1] != '\n' {
+			return errors.New("invalid aws-chunked payload terminator")
+		}
+
+		if chunkSize == 0 {
+			for {
+				line, err := reader.ReadString('\n')
+				if err != nil {
+					return err
+				}
+				if line == "\r\n" || line == "\n" {
+					return nil
+				}
+			}
+		}
+	}
+}
+
+func (h *Handler) handleHeadObject(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	key := chi.URLParam(r, "*")
+	if key == "" {
+		writeS3Error(w, r, s3ErrInvalidObjectKey, r.URL.Path)
+		return
+	}
+
+	manifest, err := h.svc.HeadObject(bucket, key)
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	etag := manifest.ETag
+	size := strconv.FormatInt(manifest.Size, 10)
+
+	w.Header().Set("ETag", `"`+etag+`"`)
+	w.Header().Set("Content-Length", size)
+	w.Header().Set("Last-Modified", time.Unix(manifest.CreatedAt, 0).UTC().Format(http.TimeFormat))
+	w.WriteHeader(http.StatusOK)
+}
+
+func (h *Handler) handlePutBucket(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	if err := h.svc.CreateBucket(bucket); err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	w.WriteHeader(http.StatusCreated)
+}
+
+func (h *Handler) handleDeleteBucket(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	if err := h.svc.DeleteBucket(bucket); err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (h *Handler) handlePostBucket(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	if _, ok := r.URL.Query()["delete"]; !ok {
+		writeS3Error(w, r, s3ErrNotImplemented, r.URL.Path)
+		return
+	}
+	defer r.Body.Close()
+
+	bodyReader := io.Reader(r.Body)
+	var decodeStream io.ReadCloser
+	if shouldDecodeAWSChunkedPayload(r) {
+		decodeStream = newAWSChunkedDecodingReader(r.Body)
+		defer decodeStream.Close()
+		bodyReader = decodeStream
+	}
+
+	var req models.DeleteObjectsRequest
+	if err := xml.NewDecoder(bodyReader).Decode(&req); err != nil {
+		writeS3Error(w, r, s3ErrMalformedXML, r.URL.Path)
+		return
+	}
+
+	keys := make([]string, 0, len(req.Objects))
+	response := models.DeleteObjectsResult{
+		Xmlns: "http://s3.amazonaws.com/doc/2006-03-01/",
+	}
+	for _, obj := range req.Objects {
+		if obj.Key == "" {
+			response.Errors = append(response.Errors, models.DeleteError{
+				Key:     obj.Key,
+				Code:    s3ErrInvalidObjectKey.Code,
+				Message: s3ErrInvalidObjectKey.Message,
+			})
+			continue
+		}
+		keys = append(keys, obj.Key)
+	}
+
+	deleted, err := h.svc.DeleteObjects(bucket, keys)
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	if !req.Quiet {
+		response.Deleted = make([]models.DeletedEntry, 0, len(deleted))
+		for _, key := range deleted {
+			response.Deleted = append(response.Deleted, models.DeletedEntry{Key: key})
+		}
+	}
+
+	payload, err := xml.MarshalIndent(response, "", "    ")
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte(xml.Header))
+	_, _ = w.Write(payload)
+}
+
+func (h *Handler) handleDeleteObject(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	key := chi.URLParam(r, "*")
+	if key == "" {
+		writeS3Error(w, r, s3ErrInvalidObjectKey, r.URL.Path)
+		return
+	}
+	if uploadId := r.URL.Query().Get("uploadId"); uploadId != "" {
+		err := h.svc.AbortMultipartUpload(bucket, key, uploadId)
+		if err != nil {
+			writeMappedS3Error(w, r, err)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return
+	}
+	err := h.svc.DeleteObject(bucket, key)
+	if err != nil {
+		if errors.Is(err, metadata.ErrObjectNotFound) {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (h *Handler) handleHeadBucket(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+	if err := h.svc.HeadBucket(bucket); err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
+func (h *Handler) handleGetBuckets(w http.ResponseWriter, r *http.Request) {
+	buckets, err := h.svc.ListBuckets()
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	response := models.ListAllMyBucketsResult{
+		Xmlns: "http://s3.amazonaws.com/doc/2006-03-01/",
+		Owner: models.BucketsOwner{
+			ID:          "local",
+			DisplayName: "local",
+		},
+		Buckets: models.BucketsElement{
+			Items: make([]models.BucketItem, 0, len(buckets)),
+		},
+	}
+
+	for _, bucket := range buckets {
+		manifest, err := h.svc.GetBucketManifest(bucket)
+		if err != nil {
+			h.logger.Warn("bucket_manifest_read_failed", "bucket", bucket, "error", err)
+			continue
+		}
+		response.Buckets.Items = append(response.Buckets.Items, models.BucketItem{
+			Name:         bucket,
+			CreationDate: manifest.CreatedAt.UTC().Format("2006-01-02T15:04:05.000Z"),
+		})
+	}
+
+	payload, err := xml.MarshalIndent(response, "", "    ")
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte(xml.Header))
+	_, _ = w.Write(payload)
+}
+
+func (h *Handler) handleGetBucket(w http.ResponseWriter, r *http.Request) {
+	bucket := chi.URLParam(r, "bucket")
+
+	if r.URL.Query().Get("list-type") == "2" {
+		h.handleListObjectsV2(w, r, bucket)
+		return
+	}
+	if r.URL.Query().Has("location") {
+		xmlResponse := `<?xml version="1.0" encoding="UTF-8"?>
+						<LocationConstraint xmlns="http://s3.amazonaws.com/doc/2006-03-01/">us-east-1</LocationConstraint>`
+
+		w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+		w.Header().Set("Content-Length", strconv.Itoa(len(xmlResponse)))
+		w.WriteHeader(http.StatusOK)
+		_, err := w.Write([]byte(xmlResponse))
+		if err != nil {
+			return
+		}
+		return
+	}
+	writeS3Error(w, r, s3ErrNotImplemented, r.URL.Path)
+
+}
+
+func (h *Handler) handleListObjectsV2(w http.ResponseWriter, r *http.Request, bucket string) {
+	prefix := r.URL.Query().Get("prefix")
+	delimiter := r.URL.Query().Get("delimiter")
+	startAfter := r.URL.Query().Get("start-after")
+	encodingType := strings.ToLower(strings.TrimSpace(r.URL.Query().Get("encoding-type")))
+	if encodingType != "" && encodingType != "url" {
+		writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+		return
+	}
+
+	maxKeys := 1000
+	if rawMaxKeys := strings.TrimSpace(r.URL.Query().Get("max-keys")); rawMaxKeys != "" {
+		parsed, err := strconv.Atoi(rawMaxKeys)
+		if err != nil || parsed < 0 {
+			writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+			return
+		}
+		if parsed > 1000 {
+			parsed = 1000
+		}
+		maxKeys = parsed
+	}
+
+	continuationToken := strings.TrimSpace(r.URL.Query().Get("continuation-token"))
+	continuationMarker := ""
+	if continuationToken != "" {
+		decoded, err := base64.StdEncoding.DecodeString(continuationToken)
+		if err != nil || len(decoded) == 0 {
+			writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+			return
+		}
+		continuationMarker = string(decoded)
+	}
+
+	objects, err := h.svc.ListObjects(bucket, prefix)
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	entries := buildListV2Entries(objects, prefix, delimiter)
+	startIdx := 0
+	if continuationMarker != "" {
+		found := false
+		for i, entry := range entries {
+			if entry.Marker == continuationMarker {
+				startIdx = i + 1
+				found = true
+				break
+			}
+		}
+		if !found {
+			writeS3Error(w, r, s3ErrInvalidArgument, r.URL.Path)
+			return
+		}
+	} else if startAfter != "" {
+		for startIdx < len(entries) && entries[startIdx].SortKey <= startAfter {
+			startIdx++
+		}
+	}
+
+	result := models.ListBucketResultV2{
+		Xmlns:             "http://s3.amazonaws.com/doc/2006-03-01/",
+		Name:              bucket,
+		Prefix:            s3EncodeIfNeeded(prefix, encodingType),
+		Delimiter:         s3EncodeIfNeeded(delimiter, encodingType),
+		MaxKeys:           maxKeys,
+		ContinuationToken: continuationToken,
+		StartAfter:        s3EncodeIfNeeded(startAfter, encodingType),
+		EncodingType:      encodingType,
+	}
+
+	endIdx := startIdx
+	for endIdx < len(entries) && result.KeyCount < maxKeys {
+		entry := entries[endIdx]
+		if entry.Object != nil {
+			result.Contents = append(result.Contents, models.Contents{
+				Key:          s3EncodeIfNeeded(entry.Object.Key, encodingType),
+				LastModified: time.Unix(entry.Object.CreatedAt, 0).UTC().Format("2006-01-02T15:04:05.000Z"),
+				ETag:         `"` + entry.Object.ETag + `"`,
+				Size:         entry.Object.Size,
+				StorageClass: "STANDARD",
+			})
+		} else {
+			result.CommonPrefixes = append(result.CommonPrefixes, models.CommonPrefixes{
+				Prefix: s3EncodeIfNeeded(entry.CommonPrefix, encodingType),
+			})
+		}
+		result.KeyCount++
+		endIdx++
+	}
+
+	result.IsTruncated = endIdx < len(entries)
+	if result.IsTruncated && result.KeyCount > 0 {
+		result.NextContinuationToken = base64.StdEncoding.EncodeToString([]byte(entries[endIdx-1].Marker))
+	}
+
+	xmlResponse, err := xml.MarshalIndent(result, "", "    ")
+	if err != nil {
+		writeMappedS3Error(w, r, err)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.Header().Set("Content-Length", strconv.Itoa(len(xml.Header)+len(xmlResponse)))
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte(xml.Header))
+	_, _ = w.Write(xmlResponse)
+
+}
+
+type listV2Entry struct {
+	Marker       string
+	SortKey      string
+	Object       *models.ObjectManifest
+	CommonPrefix string
+}
+
+func buildListV2Entries(objects []*models.ObjectManifest, prefix, delimiter string) []listV2Entry {
+	sorted := make([]*models.ObjectManifest, 0, len(objects))
+	sorted = append(sorted, objects...)
+	sort.Slice(sorted, func(i, j int) bool {
+		return sorted[i].Key < sorted[j].Key
+	})
+
+	entries := make([]listV2Entry, 0, len(sorted))
+	seenCommonPrefixes := make(map[string]struct{})
+	for _, object := range sorted {
+		if object == nil {
+			continue
+		}
+		if delimiter != "" {
+			relative := strings.TrimPrefix(object.Key, prefix)
+			if idx := strings.Index(relative, delimiter); idx >= 0 {
+				commonPrefix := prefix + relative[:idx+len(delimiter)]
+				if _, exists := seenCommonPrefixes[commonPrefix]; exists {
+					continue
+				}
+				seenCommonPrefixes[commonPrefix] = struct{}{}
+				entries = append(entries, listV2Entry{
+					Marker:       "C:" + commonPrefix,
+					SortKey:      commonPrefix,
+					CommonPrefix: commonPrefix,
+				})
+				continue
+			}
+		}
+
+		entries = append(entries, listV2Entry{
+			Marker:  "K:" + object.Key,
+			SortKey: object.Key,
+			Object:  object,
+		})
+	}
+	return entries
+}
+
+func s3EncodeIfNeeded(value, encodingType string) string {
+	if encodingType != "url" || value == "" {
+		return value
+	}
+	encoded := url.QueryEscape(value)
+	return strings.ReplaceAll(encoded, "+", "%20")
+}
+
+func parseSingleByteRange(rangeHeader string, size int64) (int64, int64, error) {
+	if size <= 0 || !strings.HasPrefix(rangeHeader, "bytes=") {
+		return 0, 0, errors.New("invalid range")
+	}
+	spec := strings.TrimSpace(strings.TrimPrefix(rangeHeader, "bytes="))
+	if spec == "" || strings.Contains(spec, ",") {
+		return 0, 0, errors.New("invalid range")
+	}
+
+	parts := strings.SplitN(spec, "-", 2)
+	if len(parts) != 2 {
+		return 0, 0, errors.New("invalid range")
+	}
+
+	if parts[0] == "" {
+		suffixLength, err := strconv.ParseInt(parts[1], 10, 64)
+		if err != nil || suffixLength <= 0 {
+			return 0, 0, errors.New("invalid range")
+		}
+		if suffixLength > size {
+			suffixLength = size
+		}
+		start := size - suffixLength
+		end := size - 1
+		return start, end, nil
+	}
+
+	start, err := strconv.ParseInt(parts[0], 10, 64)
+	if err != nil || start < 0 || start >= size {
+		return 0, 0, errors.New("invalid range")
+	}
+
+	var end int64
+	if parts[1] == "" {
+		end = size - 1
+	} else {
+		end, err = strconv.ParseInt(parts[1], 10, 64)
+		if err != nil || end < start {
+			return 0, 0, errors.New("invalid range")
+		}
+		if end >= size {
+			end = size - 1
+		}
+	}
+
+	return start, end, nil
+}
+
+func (h *Handler) Start(ctx context.Context, address string) error {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	h.logger.Info("server_starting",
+		"address", address,
+		"log_format", h.logConfig.Format,
+		"log_level", h.logConfig.LevelName,
+		"audit_log", h.logConfig.Audit,
+	)
+	h.setupRoutes()
+
+	server := http.Server{
+		Addr:    address,
+		Handler: h.router,
+	}
+	errCh := make(chan error, 1)
+
+	go func() {
+		if err := server.ListenAndServe(); err != nil {
+			if !errors.Is(err, http.ErrServerClosed) {
+				errCh <- err
+			}
+		}
+	}()
+
+	select {
+	case <-ctx.Done():
+		h.logger.Info("shutdown_context_done", "reason", ctx.Err())
+	case err := <-errCh:
+		h.logger.Error("server_listen_failed", "error", err)
+		if closeErr := h.svc.Close(); closeErr != nil {
+			h.logger.Error("service_close_failed", "error", closeErr)
+		}
+		return err
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	if err := server.Shutdown(ctx); err != nil {
+		h.logger.Error("server_shutdown_failed", "error", err)
+		return err
+	}
+	if err := h.svc.Close(); err != nil {
+		h.logger.Error("service_close_failed", "error", err)
+		return err
+	}
+
+	h.logger.Info("server_stopped")
+	return nil
+}

api/s3_errors.go

@@ -0,0 +1,148 @@
+package api
+
+import (
+	"encoding/xml"
+	"errors"
+	"fs/metadata"
+	"fs/models"
+	"fs/service"
+	"net/http"
+)
+
+type s3APIError struct {
+	Status  int
+	Code    string
+	Message string
+}
+
+var (
+	s3ErrInvalidObjectKey = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "InvalidArgument",
+		Message: "Object key is required.",
+	}
+	s3ErrNotImplemented = s3APIError{
+		Status:  http.StatusNotImplemented,
+		Code:    "NotImplemented",
+		Message: "A header you provided implies functionality that is not implemented.",
+	}
+	s3ErrInvalidPart = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "InvalidPart",
+		Message: "One or more of the specified parts could not be found.",
+	}
+	s3ErrInvalidPartOrder = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "InvalidPartOrder",
+		Message: "The list of parts was not in ascending order.",
+	}
+	s3ErrMalformedXML = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "MalformedXML",
+		Message: "The XML you provided was not well-formed or did not validate against our published schema.",
+	}
+	s3ErrInvalidArgument = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "InvalidArgument",
+		Message: "Invalid argument.",
+	}
+	s3ErrInvalidRange = s3APIError{
+		Status:  http.StatusRequestedRangeNotSatisfiable,
+		Code:    "InvalidRange",
+		Message: "The requested range is not satisfiable.",
+	}
+	s3ErrEntityTooSmall = s3APIError{
+		Status:  http.StatusBadRequest,
+		Code:    "EntityTooSmall",
+		Message: "Your proposed upload is smaller than the minimum allowed object size.",
+	}
+	s3ErrInternal = s3APIError{
+		Status:  http.StatusInternalServerError,
+		Code:    "InternalError",
+		Message: "We encountered an internal error. Please try again.",
+	}
+)
+
+func mapToS3Error(err error) s3APIError {
+	switch {
+	case errors.Is(err, metadata.ErrInvalidBucketName):
+		return s3APIError{
+			Status:  http.StatusBadRequest,
+			Code:    "InvalidBucketName",
+			Message: "The specified bucket is not valid.",
+		}
+	case errors.Is(err, metadata.ErrBucketAlreadyExists):
+		return s3APIError{
+			Status:  http.StatusConflict,
+			Code:    "BucketAlreadyOwnedByYou",
+			Message: "Your previous request to create the named bucket succeeded and you already own it.",
+		}
+	case errors.Is(err, metadata.ErrBucketNotFound):
+		return s3APIError{
+			Status:  http.StatusNotFound,
+			Code:    "NoSuchBucket",
+			Message: "The specified bucket does not exist.",
+		}
+	case errors.Is(err, metadata.ErrBucketNotEmpty):
+		return s3APIError{
+			Status:  http.StatusConflict,
+			Code:    "BucketNotEmpty",
+			Message: "The bucket you tried to delete is not empty.",
+		}
+	case errors.Is(err, metadata.ErrObjectNotFound):
+		return s3APIError{
+			Status:  http.StatusNotFound,
+			Code:    "NoSuchKey",
+			Message: "The specified key does not exist.",
+		}
+	case errors.Is(err, metadata.ErrMultipartNotFound):
+		return s3APIError{
+			Status:  http.StatusNotFound,
+			Code:    "NoSuchUpload",
+			Message: "The specified multipart upload does not exist.",
+		}
+	case errors.Is(err, metadata.ErrMultipartNotPending):
+		return s3APIError{
+			Status:  http.StatusBadRequest,
+			Code:    "InvalidRequest",
+			Message: "The multipart upload is not in a valid state for this operation.",
+		}
+	case errors.Is(err, service.ErrInvalidPart):
+		return s3ErrInvalidPart
+	case errors.Is(err, service.ErrInvalidPartOrder):
+		return s3ErrInvalidPartOrder
+	case errors.Is(err, service.ErrInvalidCompleteRequest):
+		return s3ErrMalformedXML
+	case errors.Is(err, service.ErrEntityTooSmall):
+		return s3ErrEntityTooSmall
+	default:
+		return s3ErrInternal
+	}
+}
+
+func writeS3Error(w http.ResponseWriter, r *http.Request, apiErr s3APIError, resource string) {
+	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.WriteHeader(apiErr.Status)
+
+	if r != nil && r.Method == http.MethodHead {
+		return
+	}
+
+	payload := models.S3ErrorResponse{
+		Code:     apiErr.Code,
+		Message:  apiErr.Message,
+		Resource: resource,
+	}
+
+	out, err := xml.MarshalIndent(payload, "", "    ")
+	if err != nil {
+		return
+	}
+
+	_, _ = w.Write([]byte(xml.Header))
+	_, _ = w.Write(out)
+}
+
+func writeMappedS3Error(w http.ResponseWriter, r *http.Request, err error) {
+	writeS3Error(w, r, mapToS3Error(err), r.URL.Path)
+}

go.mod

@@ -3,8 +3,12 @@ module fs
 go 1.25.7
 
 require (
-	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
-	github.com/klauspost/reedsolomon v1.13.2 // indirect
-	go.etcd.io/bbolt v1.4.3 // indirect
+	github.com/go-chi/chi/v5 v5.2.5
+	github.com/google/uuid v1.6.0
+	go.etcd.io/bbolt v1.4.3
+)
+
+require (
+	github.com/joho/godotenv v1.5.1 // indirect
 	golang.org/x/sys v0.41.0 // indirect
 )

go.sum

@@ -1,10 +1,20 @@
-github.com/klauspost/cpuid/v2 v2.3.0 h1:S4CRMLnYUhGeDFDqkGriYKdfoFlDnMtqTiI/sFzhA9Y=
-github.com/klauspost/cpuid/v2 v2.3.0/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
-github.com/klauspost/reedsolomon v1.13.2 h1:9qtQy2tKEVpVB8Pfq87ZljHZb60/LbeTQ1OxV8EGzdE=
-github.com/klauspost/reedsolomon v1.13.2/go.mod h1:ggJT9lc71Vu+cSOPBlxGvBN6TfAS77qB4fp8vJ05NSA=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-chi/chi/v5 v5.2.5 h1:Eg4myHZBjyvJmAFjFvWgrqDTXFyOzjj7YIm3L3mu6Ug=
+github.com/go-chi/chi/v5 v5.2.5/go.mod h1:X7Gx4mteadT3eDOMTsXzmI4/rwUpOwBHLpAfupzFJP0=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 go.etcd.io/bbolt v1.4.3 h1:dEadXpI6G79deX5prL3QRNP6JB8UxVkqo4UPnHaNXJo=
 go.etcd.io/bbolt v1.4.3/go.mod h1:tKQlpPaYCVFctUIgFKFnAlvbmB3tpy1vkTnDWohtc0E=
-golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
-golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
+golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
 golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

logging/logging.go

@@ -0,0 +1,150 @@
+package logging
+
+import (
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5/middleware"
+)
+
+type Config struct {
+	Level     slog.Level
+	LevelName string
+	Format    string
+	Audit     bool
+	AddSource bool
+	DebugMode bool
+}
+
+func ConfigFromEnv() Config {
+	levelName := strings.ToLower(strings.TrimSpace(os.Getenv("LOG_LEVEL")))
+	format := strings.ToLower(strings.TrimSpace(os.Getenv("LOG_FORMAT")))
+	return ConfigFromValues(levelName, format, envBool("AUDIT_LOG", true))
+}
+
+func ConfigFromValues(levelName, format string, audit bool) Config {
+	levelName = strings.ToLower(strings.TrimSpace(levelName))
+	if levelName == "" {
+		levelName = "info"
+	}
+	level := parseLevel(levelName)
+	levelName = strings.ToUpper(level.String())
+
+	format = strings.ToLower(strings.TrimSpace(format))
+	if format == "" {
+		format = "text"
+	}
+	if format != "json" && format != "text" {
+		format = "text"
+	}
+
+	debugMode := level <= slog.LevelDebug
+	return Config{
+		Level:     level,
+		LevelName: levelName,
+		Format:    format,
+		Audit:     audit,
+		AddSource: debugMode,
+		DebugMode: debugMode,
+	}
+}
+
+func NewLogger(cfg Config) *slog.Logger {
+	opts := &slog.HandlerOptions{
+		Level:     cfg.Level,
+		AddSource: cfg.AddSource,
+	}
+	opts.ReplaceAttr = func(_ []string, attr slog.Attr) slog.Attr {
+		if attr.Key == slog.SourceKey {
+			if src, ok := attr.Value.Any().(*slog.Source); ok && src != nil {
+				attr.Key = "src"
+				attr.Value = slog.StringValue(filepath.Base(src.File) + ":" + strconv.Itoa(src.Line))
+			}
+		}
+		return attr
+	}
+
+	var handler slog.Handler
+	if cfg.Format == "json" {
+		handler = slog.NewJSONHandler(os.Stdout, opts)
+	} else {
+		handler = slog.NewTextHandler(os.Stdout, opts)
+	}
+
+	logger := slog.New(handler)
+	slog.SetDefault(logger)
+	return logger
+}
+
+func HTTPMiddleware(logger *slog.Logger, cfg Config) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			start := time.Now()
+			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+
+			next.ServeHTTP(ww, r)
+
+			if !cfg.Audit && !cfg.DebugMode {
+				return
+			}
+
+			elapsed := time.Since(start)
+			status := ww.Status()
+			if status == 0 {
+				status = http.StatusOK
+			}
+			attrs := []any{
+				"method", r.Method,
+				"path", r.URL.Path,
+				"status", status,
+				"bytes", ww.BytesWritten(),
+				"duration_ms", float64(elapsed.Nanoseconds()) / 1_000_000.0,
+				"remote_addr", r.RemoteAddr,
+			}
+
+			if cfg.DebugMode {
+				attrs = append(attrs,
+					"query", r.URL.RawQuery,
+					"user_agent", r.UserAgent(),
+					"content_length", r.ContentLength,
+					"content_type", r.Header.Get("Content-Type"),
+					"x_amz_sha256", r.Header.Get("x-amz-content-sha256"),
+				)
+				logger.Debug("http_request", attrs...)
+				return
+			}
+
+			logger.Info("http_request", attrs...)
+		})
+	}
+}
+
+func envBool(key string, defaultValue bool) bool {
+	raw := os.Getenv(key)
+	if raw == "" {
+		return defaultValue
+	}
+	value, err := strconv.ParseBool(raw)
+	if err != nil {
+		return defaultValue
+	}
+	return value
+}
+
+func parseLevel(levelName string) slog.Level {
+	switch levelName {
+	case "debug":
+		return slog.LevelDebug
+	case "warn", "warning":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}

main.go

@@ -1,54 +1,62 @@
 package main
 
 import (
-	"fmt"
+	"context"
+	"fs/api"
+	"fs/logging"
 	"fs/metadata"
 	"fs/service"
-	"io"
+	"fs/storage"
+	"fs/utils"
 	"os"
+	"os/signal"
+	"path/filepath"
+	"strconv"
+	"syscall"
 )
 
 func main() {
-	fmt.Println("Hello, World!")
-	imageStream, err := os.Open("fer.jpg")
-	if err != nil {
-		fmt.Printf("Error opening image stream: %v\n", err)
-		return
-	}
-	defer imageStream.Close()
+	config := utils.NewConfig()
+	logConfig := logging.ConfigFromValues(config.LogLevel, config.LogFormat, config.AuditLog)
+	logger := logging.NewLogger(logConfig)
+	logger.Info("boot",
+		"log_level", logConfig.LevelName,
+		"log_format", logConfig.Format,
+		"audit_log", logConfig.Audit,
+		"data_path", config.DataPath,
+	)
 
-	metadataHandler, err := metadata.NewMetadataHandler("metadata.db")
-	if err != nil {
-		fmt.Printf("Error initializing metadata handler: %v\n", err)
+	if err := os.MkdirAll(config.DataPath, 0o755); err != nil {
+		logger.Error("failed_to_prepare_data_path", "path", config.DataPath, "error", err)
 		return
 	}
 
-	objectService := service.NewObjectService(metadataHandler)
+	dbPath := filepath.Join(config.DataPath, "metadata.db")
+	metadataHandler, err := metadata.NewMetadataHandler(dbPath)
+	if err != nil {
+		logger.Error("failed_to_initialize_metadata_handler", "error", err)
+		return
+	}
+	blobHandler, err := storage.NewBlobStore(config.DataPath, config.ChunkSize)
+	if err != nil {
+		_ = metadataHandler.Close()
+		logger.Error("failed_to_initialize_blob_store", "error", err)
+		return
+	}
 
-	manifest, err := objectService.PutObject("test-bucket-ferdzo/fer.jpg", "image/jpeg", imageStream)
-	if err != nil {
-		fmt.Printf("Error ingesting stream: %v\n", err)
-		return
-	}
-	fmt.Printf("Manifest: %+v\n", manifest)
+	objectService := service.NewObjectService(metadataHandler, blobHandler)
+	handler := api.NewHandler(objectService, logger, logConfig)
+	addr := config.Address + ":" + strconv.Itoa(config.Port)
 
-	objectData, manifest2, err := objectService.GetObject("test-bucket-ferdzo", "fer.jpg")
-	if err != nil {
-		fmt.Printf("Error retrieving object: %v\n", err)
-		return
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+	if config.GcEnabled {
+		go objectService.RunGC(ctx, config.GcInterval)
 	}
-	fmt.Printf("Retrieved manifest: %+v\n", manifest2)
-	recoveredFile, err := os.Create("recovered_" + manifest2.Key)
-	if err != nil {
-		fmt.Printf("Error creating file: %v\n", err)
-		return
-	}
-	defer recoveredFile.Close()
 
-	bytesWritten, err := io.Copy(recoveredFile, objectData)
-	if err != nil {
-		fmt.Printf("Error streaming to recovered file: %v\n", err)
+	if err = handler.Start(ctx, addr); err != nil {
+		logger.Error("server_stopped_with_error", "error", err)
 		return
 	}
-	fmt.Printf("Successfully streamed %d bytes to disk!\n", bytesWritten)
+
 }

metadata/metadata.go

@@ -2,37 +2,221 @@ package metadata
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"fs/models"
+	"regexp"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
 
 	"go.etcd.io/bbolt"
 )
 
-const ManifestBucketName = "object_manifests"
-
 type MetadataHandler struct {
 	db *bbolt.DB
 }
 
+var systemIndex = []byte("__SYSTEM_BUCKETS__")
+var multipartUploadIndex = []byte("__MULTIPART_UPLOADS__")
+var multipartUploadPartsIndex = []byte("__MULTIPART_UPLOAD_PARTS__")
+
+var validBucketName = regexp.MustCompile(`^[a-z0-9.-]{3,63}$`)
+
+var (
+	ErrInvalidBucketName   = errors.New("invalid bucket name")
+	ErrBucketAlreadyExists = errors.New("bucket already exists")
+	ErrBucketNotFound      = errors.New("bucket not found")
+	ErrBucketNotEmpty      = errors.New("bucket not empty")
+	ErrObjectNotFound      = errors.New("object not found")
+	ErrMultipartNotFound   = errors.New("multipart upload not found")
+	ErrMultipartNotPending = errors.New("multipart upload is not pending")
+)
+
 func NewMetadataHandler(dbPath string) (*MetadataHandler, error) {
-	db, err := bbolt.Open(dbPath, 0600, nil)
+	db, err := bbolt.Open(dbPath, 0600, &bbolt.Options{Timeout: 2 * time.Second})
 	if err != nil {
 		return nil, err
 	}
-	return &MetadataHandler{db: db}, nil
+	h := &MetadataHandler{db: db}
+
+	err = h.db.Update(func(tx *bbolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists(systemIndex)
+		return err
+	})
+	if err != nil {
+		_ = db.Close()
+		return nil, err
+	}
+	err = h.db.Update(func(tx *bbolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists(multipartUploadIndex)
+		return err
+	})
+	if err != nil {
+		_ = db.Close()
+		return nil, err
+	}
+	err = h.db.Update(func(tx *bbolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists(multipartUploadPartsIndex)
+		return err
+	})
+	if err != nil {
+		_ = db.Close()
+		return nil, err
+	}
+
+	return h, nil
 }
 
-func (h *MetadataHandler) PutManifest(manifest *models.ObjectManifest) error {
+func (h *MetadataHandler) Close() error {
+	return h.db.Close()
+}
+
+func (h *MetadataHandler) CreateBucket(bucketName string) error {
+	if !validBucketName.MatchString(bucketName) {
+		return fmt.Errorf("%w: %s", ErrInvalidBucketName, bucketName)
+	}
+
 	err := h.db.Update(func(tx *bbolt.Tx) error {
-		metadataBucket, err := tx.CreateBucketIfNotExists([]byte(ManifestBucketName))
+		indexBucket, err := tx.CreateBucketIfNotExists([]byte(systemIndex))
 		if err != nil {
 			return err
 		}
-		key := fmt.Sprintf("%s/%s", manifest.Bucket, manifest.Key)
+		if indexBucket.Get([]byte(bucketName)) != nil {
+			return fmt.Errorf("%w: %s", ErrBucketAlreadyExists, bucketName)
+		}
+
+		_, err = tx.CreateBucketIfNotExists([]byte(bucketName))
+		if err != nil {
+			return err
+		}
+		manifest := models.BucketManifest{
+			Name:      bucketName,
+			CreatedAt: time.Now(),
+		}
+		data, _ := json.Marshal(manifest)
+
+		return indexBucket.Put([]byte(bucketName), data)
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (h *MetadataHandler) DeleteBucket(bucketName string) error {
+	if !validBucketName.MatchString(bucketName) {
+		return fmt.Errorf("%w: %s", ErrInvalidBucketName, bucketName)
+	}
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		indexBucket, err := tx.CreateBucketIfNotExists([]byte(systemIndex))
+		if err != nil {
+			return err
+		}
+		if indexBucket.Get([]byte(bucketName)) == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucketName)
+		}
+		metadataBucket := tx.Bucket([]byte(bucketName))
+		if metadataBucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucketName)
+		}
+		if k, _ := metadataBucket.Cursor().First(); k != nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotEmpty, bucketName)
+		}
+
+		multipartUploadsBucket, err := getMultipartUploadBucket(tx)
+		if err != nil {
+			return err
+		}
+		cursor := multipartUploadsBucket.Cursor()
+		for _, payload := cursor.First(); payload != nil; _, payload = cursor.Next() {
+			upload := models.MultipartUpload{}
+			if err := json.Unmarshal(payload, &upload); err != nil {
+				return err
+			}
+			if upload.Bucket == bucketName && upload.State == "pending" {
+				return fmt.Errorf("%w: %s", ErrBucketNotEmpty, bucketName)
+			}
+		}
+
+		if err := tx.DeleteBucket([]byte(bucketName)); err != nil && !errors.Is(err, bbolt.ErrBucketNotFound) {
+			return fmt.Errorf("error deleting metadata bucket %s: %w", bucketName, err)
+		}
+		if err := indexBucket.Delete([]byte(bucketName)); err != nil {
+			return fmt.Errorf("error deleting bucket %s from system index: %w", bucketName, err)
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (h *MetadataHandler) ListBuckets() ([]string, error) {
+	buckets := []string{}
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		systemIndexBucket := tx.Bucket([]byte(systemIndex))
+		if systemIndexBucket == nil {
+			return errors.New("system index not found")
+		}
+		c := systemIndexBucket.Cursor()
+		for k, _ := c.First(); k != nil; k, _ = c.Next() {
+			buckets = append(buckets, string(k))
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return buckets, nil
+}
+
+func (h *MetadataHandler) GetBucketManifest(bucketName string) (*models.BucketManifest, error) {
+	var manifest *models.BucketManifest
+
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		systemIndexBucket := tx.Bucket([]byte(systemIndex))
+		if systemIndexBucket == nil {
+			return errors.New("system index not found")
+		}
+		data := systemIndexBucket.Get([]byte(bucketName))
+		if data == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucketName)
+		}
+		err := json.Unmarshal(data, &manifest)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return manifest, nil
+}
+
+func (h *MetadataHandler) PutManifest(manifest *models.ObjectManifest) error {
+	bucket := manifest.Bucket
+	key := manifest.Key
+
+	if _, err := h.GetBucketManifest(bucket); err != nil {
+		return err
+	}
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
 		data, err := json.Marshal(manifest)
 		if err != nil {
 			return err
 		}
+		metadataBucket := tx.Bucket([]byte(bucket))
+		if metadataBucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
+		}
 		return metadataBucket.Put([]byte(key), data)
 	})
 	if err != nil {
@@ -44,16 +228,15 @@ func (h *MetadataHandler) PutManifest(manifest *models.ObjectManifest) error {
 func (h *MetadataHandler) GetManifest(bucket, key string) (*models.ObjectManifest, error) {
 	var manifest *models.ObjectManifest
 
-	h.db.View(func(tx *bbolt.Tx) error {
-		metadataBucket := tx.Bucket([]byte(ManifestBucketName))
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		metadataBucket := tx.Bucket([]byte(bucket))
 		if metadataBucket == nil {
-			return fmt.Errorf("bucket %s not found", ManifestBucketName)
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
 		}
-		key := fmt.Sprintf("%s/%s", bucket, key)
 		data := metadataBucket.Get([]byte(key))
 		if data == nil {
 
-			return fmt.Errorf("manifest not found for bucket %s and key %s", bucket, key)
+			return fmt.Errorf("%w: %s/%s", ErrObjectNotFound, bucket, key)
 		}
 		err := json.Unmarshal(data, &manifest)
 		if err != nil {
@@ -61,6 +244,455 @@ func (h *MetadataHandler) GetManifest(bucket, key string) (*models.ObjectManifes
 		}
 		return nil
 	})
+	if err != nil {
+		return nil, err
+	}
 
 	return manifest, nil
 }
+
+func (h *MetadataHandler) ListObjects(bucket, prefix string) ([]*models.ObjectManifest, error) {
+
+	var objects []*models.ObjectManifest
+
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		systemIndexBucket := tx.Bucket([]byte(systemIndex))
+		if systemIndexBucket == nil {
+			return errors.New("system index not found")
+		}
+		if systemIndexBucket.Get([]byte(bucket)) == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
+		}
+		_bucket := tx.Bucket([]byte(bucket))
+		if _bucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
+		}
+		err := _bucket.ForEach(func(k, v []byte) error {
+			if prefix != "" && !strings.HasPrefix(string(k), prefix) {
+				return nil
+			}
+			object := models.ObjectManifest{}
+			err := json.Unmarshal(v, &object)
+			if err != nil {
+				return err
+			}
+			objects = append(objects, &object)
+			return nil
+		})
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return objects, nil
+}
+
+func (h *MetadataHandler) DeleteManifest(bucket, key string) error {
+	if _, err := h.GetManifest(bucket, key); err != nil {
+		return err
+	}
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		metadataBucket := tx.Bucket([]byte(bucket))
+		if metadataBucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
+		}
+		return metadataBucket.Delete([]byte(key))
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+
+}
+
+func (h *MetadataHandler) DeleteManifests(bucket string, keys []string) ([]string, error) {
+	deleted := make([]string, 0, len(keys))
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		metadataBucket := tx.Bucket([]byte(bucket))
+		if metadataBucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, bucket)
+		}
+
+		for _, key := range keys {
+			if key == "" {
+				continue
+			}
+			if metadataBucket.Get([]byte(key)) != nil {
+				if err := metadataBucket.Delete([]byte(key)); err != nil {
+					return err
+				}
+			}
+			deleted = append(deleted, key)
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return deleted, nil
+}
+
+func (h *MetadataHandler) CreateMultipartUpload(bucket, key string) (*models.MultipartUpload, error) {
+	var upload *models.MultipartUpload
+
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		systemIndexBucket := tx.Bucket([]byte(systemIndex))
+		if systemIndexBucket == nil {
+			return errors.New("system index not found")
+		}
+		if systemIndexBucket.Get([]byte(bucket)) != nil {
+			return nil
+		}
+		return ErrBucketNotFound
+	})
+	if err != nil {
+		return nil, err
+	}
+	uploadId := uuid.New().String()
+	createdAt := time.Now().UTC().Format(time.RFC3339)
+	upload = &models.MultipartUpload{
+		Bucket:    bucket,
+		Key:       key,
+		UploadID:  uploadId,
+		CreatedAt: createdAt,
+		State:     "pending",
+	}
+
+	err = h.db.Update(func(tx *bbolt.Tx) error {
+		multipartUploadBucket := tx.Bucket([]byte(multipartUploadIndex))
+		if multipartUploadBucket == nil {
+			return errors.New("multipart upload index not found")
+		}
+		payload, err := json.Marshal(upload)
+		if err != nil {
+			return err
+		}
+		err = multipartUploadBucket.Put([]byte(uploadId), payload)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return upload, nil
+}
+
+func getMultipartUploadBucket(tx *bbolt.Tx) (*bbolt.Bucket, error) {
+	multipartUploadBucket := tx.Bucket(multipartUploadIndex)
+	if multipartUploadBucket == nil {
+		return nil, errors.New("multipart upload index not found")
+	}
+	return multipartUploadBucket, nil
+}
+
+func getMultipartPartsBucket(tx *bbolt.Tx) (*bbolt.Bucket, error) {
+	multipartPartsBucket := tx.Bucket(multipartUploadPartsIndex)
+	if multipartPartsBucket == nil {
+		return nil, errors.New("multipart upload parts index not found")
+	}
+	return multipartPartsBucket, nil
+}
+
+func getMultipartUploadFromBucket(multipartUploadBucket *bbolt.Bucket, uploadID string) (*models.MultipartUpload, error) {
+	payload := multipartUploadBucket.Get([]byte(uploadID))
+	if payload == nil {
+		return nil, fmt.Errorf("%w: %s", ErrMultipartNotFound, uploadID)
+	}
+	upload := models.MultipartUpload{}
+	if err := json.Unmarshal(payload, &upload); err != nil {
+		return nil, err
+	}
+	return &upload, nil
+}
+
+func getMultipartUploadFromTx(tx *bbolt.Tx, uploadID string) (*models.MultipartUpload, *bbolt.Bucket, error) {
+	multipartUploadBucket, err := getMultipartUploadBucket(tx)
+	if err != nil {
+		return nil, nil, err
+	}
+	upload, err := getMultipartUploadFromBucket(multipartUploadBucket, uploadID)
+	if err != nil {
+		return nil, nil, err
+	}
+	return upload, multipartUploadBucket, nil
+}
+
+func putMultipartUpload(multipartUploadBucket *bbolt.Bucket, uploadID string, upload *models.MultipartUpload) error {
+	payload, err := json.Marshal(upload)
+	if err != nil {
+		return err
+	}
+	return multipartUploadBucket.Put([]byte(uploadID), payload)
+}
+
+func deleteMultipartPartsByUploadID(tx *bbolt.Tx, uploadID string) error {
+	multipartPartsBucket, err := getMultipartPartsBucket(tx)
+	if err != nil {
+		return err
+	}
+
+	prefix := uploadID + ":"
+	cursor := multipartPartsBucket.Cursor()
+	keysToDelete := make([][]byte, 0)
+	for k, _ := cursor.Seek([]byte(prefix)); k != nil && strings.HasPrefix(string(k), prefix); k, _ = cursor.Next() {
+		keyCopy := make([]byte, len(k))
+		copy(keyCopy, k)
+		keysToDelete = append(keysToDelete, keyCopy)
+	}
+	for _, key := range keysToDelete {
+		if err := multipartPartsBucket.Delete(key); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (h *MetadataHandler) GetMultipartUpload(uploadID string) (*models.MultipartUpload, error) {
+	var upload *models.MultipartUpload
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		var err error
+		upload, _, err = getMultipartUploadFromTx(tx, uploadID)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return upload, nil
+}
+func (h *MetadataHandler) PutMultipartPart(uploadID string, part models.UploadedPart) error {
+	if part.PartNumber < 1 || part.PartNumber > 10000 {
+		return fmt.Errorf("invalid part number: %d", part.PartNumber)
+	}
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		upload, _, err := getMultipartUploadFromTx(tx, uploadID)
+		if err != nil {
+			return err
+		}
+		if upload.State != "pending" {
+			return fmt.Errorf("%w: %s", ErrMultipartNotPending, uploadID)
+		}
+
+		multipartPartsBucket, err := getMultipartPartsBucket(tx)
+		if err != nil {
+			return err
+		}
+
+		key := fmt.Sprintf("%s:%05d", uploadID, part.PartNumber)
+		payload, err := json.Marshal(part)
+		if err != nil {
+			return err
+		}
+		return multipartPartsBucket.Put([]byte(key), payload)
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+func (h *MetadataHandler) ListMultipartParts(uploadID string) ([]models.UploadedPart, error) {
+	parts := make([]models.UploadedPart, 0)
+
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		if _, _, err := getMultipartUploadFromTx(tx, uploadID); err != nil {
+			return err
+		}
+
+		multipartPartsBucket, err := getMultipartPartsBucket(tx)
+		if err != nil {
+			return err
+		}
+		prefix := uploadID + ":"
+		cursor := multipartPartsBucket.Cursor()
+		for k, v := cursor.Seek([]byte(prefix)); k != nil && strings.HasPrefix(string(k), prefix); k, v = cursor.Next() {
+			part := models.UploadedPart{}
+			if err := json.Unmarshal(v, &part); err != nil {
+				return err
+			}
+			parts = append(parts, part)
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Slice(parts, func(i, j int) bool {
+		return parts[i].PartNumber < parts[j].PartNumber
+	})
+	return parts, nil
+}
+func (h *MetadataHandler) CompleteMultipartUpload(uploadID string, final *models.ObjectManifest) error {
+	if final == nil {
+		return errors.New("final object manifest is required")
+	}
+
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		upload, multipartUploadBucket, err := getMultipartUploadFromTx(tx, uploadID)
+		if err != nil {
+			return err
+		}
+		if upload.State != "pending" {
+			return fmt.Errorf("%w: %s", ErrMultipartNotPending, uploadID)
+		}
+
+		metadataBucket := tx.Bucket([]byte(upload.Bucket))
+		if metadataBucket == nil {
+			return fmt.Errorf("%w: %s", ErrBucketNotFound, upload.Bucket)
+		}
+		final.Bucket = upload.Bucket
+		final.Key = upload.Key
+		finalPayload, err := json.Marshal(final)
+		if err != nil {
+			return err
+		}
+		if err := metadataBucket.Put([]byte(upload.Key), finalPayload); err != nil {
+			return err
+		}
+
+		upload.State = "completed"
+		if err := putMultipartUpload(multipartUploadBucket, uploadID, upload); err != nil {
+			return err
+		}
+
+		if err := deleteMultipartPartsByUploadID(tx, uploadID); err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+func (h *MetadataHandler) AbortMultipartUpload(uploadID string) error {
+	err := h.db.Update(func(tx *bbolt.Tx) error {
+		upload, multipartUploadBucket, err := getMultipartUploadFromTx(tx, uploadID)
+		if err != nil {
+			return err
+		}
+		if upload.State == "completed" {
+			return fmt.Errorf("%w: %s", ErrMultipartNotPending, uploadID)
+		}
+		upload.State = "aborted"
+		if err := putMultipartUpload(multipartUploadBucket, uploadID, upload); err != nil {
+			return err
+		}
+
+		if err := deleteMultipartPartsByUploadID(tx, uploadID); err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (h *MetadataHandler) GetReferencedChunkSet() (map[string]struct{}, error) {
+	chunkSet := make(map[string]struct{})
+	pendingUploadSet := make(map[string]struct{})
+
+	err := h.db.View(func(tx *bbolt.Tx) error {
+		systemIndexBucket := tx.Bucket([]byte(systemIndex))
+		if systemIndexBucket == nil {
+			return errors.New("system index not found")
+		}
+		c := systemIndexBucket.Cursor()
+		for k, _ := c.First(); k != nil; k, _ = c.Next() {
+			metadataBucket := tx.Bucket(k)
+			if metadataBucket == nil {
+				continue
+			}
+			err := metadataBucket.ForEach(func(k, v []byte) error {
+				object := models.ObjectManifest{}
+				err := json.Unmarshal(v, &object)
+				if err != nil {
+					return err
+				}
+				for _, chunkID := range object.Chunks {
+					chunkSet[chunkID] = struct{}{}
+				}
+				return nil
+			})
+			if err != nil {
+				return err
+			}
+		}
+
+		uploadsBucket := tx.Bucket(multipartUploadIndex)
+		if uploadsBucket == nil {
+			return errors.New("multipart upload index not found")
+		}
+		if err := uploadsBucket.ForEach(func(k, v []byte) error {
+			upload := models.MultipartUpload{}
+			if err := json.Unmarshal(v, &upload); err != nil {
+				return err
+			}
+			if upload.State == "pending" {
+				pendingUploadSet[string(k)] = struct{}{}
+			}
+			return nil
+		}); err != nil {
+			return err
+		}
+
+		partsBucket := tx.Bucket(multipartUploadPartsIndex)
+		if partsBucket == nil {
+			return errors.New("multipart upload parts index not found")
+		}
+		if err := partsBucket.ForEach(func(k, v []byte) error {
+			uploadID, _, ok := strings.Cut(string(k), ":")
+			if !ok {
+				return nil
+			}
+			if _, pending := pendingUploadSet[uploadID]; !pending {
+				return nil
+			}
+
+			part := models.UploadedPart{}
+			if err := json.Unmarshal(v, &part); err != nil {
+				return err
+			}
+			for _, chunkID := range part.Chunks {
+				chunkSet[chunkID] = struct{}{}
+			}
+			return nil
+		}); err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return chunkSet, nil
+}
+
+func (h *MetadataHandler) GetReferencedChunks() ([]string, error) {
+	chunkSet, err := h.GetReferencedChunkSet()
+	if err != nil {
+		return nil, err
+	}
+
+	chunks := make([]string, 0, len(chunkSet))
+	for chunkID := range chunkSet {
+		chunks = append(chunks, chunkID)
+	}
+	return chunks, nil
+
+}

models/models.go

@@ -1,5 +1,10 @@
 package models
 
+import (
+	"encoding/xml"
+	"time"
+)
+
 type ObjectManifest struct {
 	Bucket      string   `json:"bucket"`
 	Key         string   `json:"key"`
@@ -9,3 +14,172 @@ type ObjectManifest struct {
 	Chunks      []string `json:"chunks"`
 	CreatedAt   int64    `json:"created_at"`
 }
+type BucketManifest struct {
+	Name              string    `json:"name"`
+	CreatedAt         time.Time `json:"created_at"`
+	OwnerID           string    `json:"owner_id"`
+	OwnerDisplayName  string    `json:"owner_display_name"`
+	Region            string    `json:"region"`
+	VersioningStatus  string    `json:"versioning_status"`
+	PublicAccessBlock bool      `json:"public_access_block"`
+}
+
+type ListAllMyBucketsResult struct {
+	XMLName xml.Name       `xml:"ListAllMyBucketsResult"`
+	Xmlns   string         `xml:"xmlns,attr"`
+	Owner   BucketsOwner   `xml:"Owner"`
+	Buckets BucketsElement `xml:"Buckets"`
+}
+
+type BucketsOwner struct {
+	ID          string `xml:"ID"`
+	DisplayName string `xml:"DisplayName,omitempty"`
+}
+
+type BucketsElement struct {
+	Items []BucketItem `xml:"Bucket"`
+}
+
+type BucketItem struct {
+	Name         string `xml:"Name"`
+	CreationDate string `xml:"CreationDate"`
+}
+
+type S3ErrorResponse struct {
+	XMLName   xml.Name `xml:"Error"`
+	Code      string   `xml:"Code"`
+	Message   string   `xml:"Message"`
+	Resource  string   `xml:"Resource,omitempty"`
+	RequestID string   `xml:"RequestId,omitempty"`
+	HostID    string   `xml:"HostId,omitempty"`
+}
+
+type ListBucketResult struct {
+	XMLName xml.Name `xml:"ListBucketResult"`
+	Xmlns   string   `xml:"xmlns,attr"`
+
+	Name        string `xml:"Name"`
+	Prefix      string `xml:"Prefix"`
+	KeyCount    int    `xml:"KeyCount"`
+	MaxKeys     int    `xml:"MaxKeys"`
+	IsTruncated bool   `xml:"IsTruncated"`
+
+	Contents       []Contents       `xml:"Contents"`
+	CommonPrefixes []CommonPrefixes `xml:"CommonPrefixes,omitempty"`
+}
+
+type ListBucketResultV2 struct {
+	XMLName xml.Name `xml:"ListBucketResult"`
+	Xmlns   string   `xml:"xmlns,attr"`
+
+	Name                  string `xml:"Name"`
+	Prefix                string `xml:"Prefix"`
+	Delimiter             string `xml:"Delimiter,omitempty"`
+	MaxKeys               int    `xml:"MaxKeys"`
+	KeyCount              int    `xml:"KeyCount"`
+	IsTruncated           bool   `xml:"IsTruncated"`
+	ContinuationToken     string `xml:"ContinuationToken,omitempty"`
+	NextContinuationToken string `xml:"NextContinuationToken,omitempty"`
+	StartAfter            string `xml:"StartAfter,omitempty"`
+	EncodingType          string `xml:"EncodingType,omitempty"`
+
+	Contents       []Contents       `xml:"Contents,omitempty"`
+	CommonPrefixes []CommonPrefixes `xml:"CommonPrefixes,omitempty"`
+}
+
+type Contents struct {
+	Key          string `xml:"Key"`
+	LastModified string `xml:"LastModified"`
+	ETag         string `xml:"ETag"`
+	Size         int64  `xml:"Size"`
+	StorageClass string `xml:"StorageClass"`
+}
+
+type CommonPrefixes struct {
+	Prefix string `xml:"Prefix"`
+}
+
+type MultipartUpload struct {
+	UploadID  string `json:"upload_id" xml:"UploadId"`
+	Bucket    string `json:"bucket" xml:"Bucket"`
+	Key       string `json:"key" xml:"Key"`
+	CreatedAt string `json:"created_at" xml:"CreatedAt"`
+	State     string `json:"state" xml:"State"`
+}
+
+type InitiateMultipartUploadResult struct {
+	XMLName  xml.Name `xml:"InitiateMultipartUploadResult"`
+	Xmlns    string   `xml:"xmlns,attr"`
+	Bucket   string   `xml:"Bucket"`
+	Key      string   `xml:"Key"`
+	UploadID string   `xml:"UploadId"`
+}
+type UploadedPart struct {
+	PartNumber int      `json:"part_number" xml:"PartNumber"`
+	ETag       string   `json:"etag" xml:"ETag"`
+	Size       int64    `json:"size" xml:"Size"`
+	Chunks     []string `json:"chunks"`
+	CreatedAt  int64    `json:"created_at"`
+}
+
+type CompletedPart struct {
+	PartNumber int    `xml:"PartNumber"`
+	ETag       string `xml:"ETag"`
+}
+
+type CompleteMultipartUploadRequest struct {
+	XMLName xml.Name        `xml:"CompleteMultipartUpload"`
+	Parts   []CompletedPart `xml:"Part"`
+}
+
+type CompleteMultipartUploadResult struct {
+	XMLName  xml.Name `xml:"CompleteMultipartUploadResult"`
+	Xmlns    string   `xml:"xmlns,attr"`
+	Bucket   string   `xml:"Bucket"`
+	Key      string   `xml:"Key"`
+	ETag     string   `xml:"ETag"`
+	Location string   `xml:"Location,omitempty"`
+}
+
+type ListPartsResult struct {
+	XMLName  xml.Name   `xml:"ListPartsResult"`
+	Xmlns    string     `xml:"xmlns,attr"`
+	Bucket   string     `xml:"Bucket"`
+	Key      string     `xml:"Key"`
+	UploadID string     `xml:"UploadId"`
+	Parts    []PartItem `xml:"Part"`
+}
+
+type PartItem struct {
+	PartNumber   int    `xml:"PartNumber"`
+	LastModified string `xml:"LastModified"`
+	ETag         string `xml:"ETag"`
+	Size         int64  `xml:"Size"`
+}
+
+type DeleteObjectsRequest struct {
+	XMLName xml.Name               `xml:"Delete"`
+	Objects []DeleteObjectIdentity `xml:"Object"`
+	Quiet   bool                   `xml:"Quiet"`
+}
+
+type DeleteObjectIdentity struct {
+	Key string `xml:"Key"`
+}
+
+type DeleteObjectsResult struct {
+	XMLName xml.Name       `xml:"DeleteResult"`
+	Xmlns   string         `xml:"xmlns,attr"`
+	Deleted []DeletedEntry `xml:"Deleted,omitempty"`
+	Errors  []DeleteError  `xml:"Error,omitempty"`
+}
+
+type DeletedEntry struct {
+	Key string `xml:"Key"`
+}
+
+type DeleteError struct {
+	Key     string `xml:"Key"`
+	Code    string `xml:"Code"`
+	Message string `xml:"Message"`
+}

service/service.go

@@ -1,29 +1,43 @@
 package service
 
 import (
+	"context"
+	"crypto/md5"
+	"encoding/hex"
+	"errors"
 	"fmt"
 	"fs/metadata"
 	"fs/models"
 	"fs/storage"
 	"io"
+	"log/slog"
 	"strings"
+	"sync"
 	"time"
 )
 
 type ObjectService struct {
-	metadataHandler *metadata.MetadataHandler
+	metadata *metadata.MetadataHandler
+	blob     *storage.BlobStore
+	gcMu     sync.RWMutex
 }
 
-func NewObjectService(metadataHandler *metadata.MetadataHandler) *ObjectService {
-	return &ObjectService{metadataHandler: metadataHandler}
+var (
+	ErrInvalidPart            = errors.New("invalid multipart part")
+	ErrInvalidPartOrder       = errors.New("invalid multipart part order")
+	ErrInvalidCompleteRequest = errors.New("invalid complete multipart request")
+	ErrEntityTooSmall         = errors.New("multipart entity too small")
+)
+
+func NewObjectService(metadataHandler *metadata.MetadataHandler, blobHandler *storage.BlobStore) *ObjectService {
+	return &ObjectService{metadata: metadataHandler, blob: blobHandler}
 }
 
-func (s *ObjectService) PutObject(uri string, contentType string, input io.Reader) (*models.ObjectManifest, error) {
+func (s *ObjectService) PutObject(bucket, key, contentType string, input io.Reader) (*models.ObjectManifest, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
 
-	bucket := strings.Split(uri, "/")[0]
-	key := strings.Join(strings.Split(uri, "/")[1:], "/")
-
-	chunks, size, etag, err := storage.IngestStream(input)
+	chunks, size, etag, err := s.blob.IngestStream(input)
 	if err != nil {
 		return nil, err
 	}
@@ -38,8 +52,14 @@ func (s *ObjectService) PutObject(uri string, contentType string, input io.Reade
 		Chunks:      chunks,
 		CreatedAt:   timestamp,
 	}
-	fmt.Println(manifest)
-	if err = s.metadataHandler.PutManifest(manifest); err != nil {
+	slog.Debug("object_written_manifest",
+		"bucket", manifest.Bucket,
+		"key", manifest.Key,
+		"size", manifest.Size,
+		"chunk_count", len(manifest.Chunks),
+		"etag", manifest.ETag,
+	)
+	if err = s.metadata.PutManifest(manifest); err != nil {
 		return nil, err
 	}
 
@@ -47,19 +67,298 @@ func (s *ObjectService) PutObject(uri string, contentType string, input io.Reade
 }
 
 func (s *ObjectService) GetObject(bucket, key string) (io.ReadCloser, *models.ObjectManifest, error) {
-	manifest, err := s.metadataHandler.GetManifest(bucket, key)
+	s.gcMu.RLock()
+
+	manifest, err := s.metadata.GetManifest(bucket, key)
 	if err != nil {
+		s.gcMu.RUnlock()
 		return nil, nil, err
 	}
 	pr, pw := io.Pipe()
 
 	go func() {
-		defer pw.Close()
-
-		err := storage.AssembleStream(manifest.Chunks, pw)
-		if err != nil {
+		defer s.gcMu.RUnlock()
+		if err := s.blob.AssembleStream(manifest.Chunks, pw); err != nil {
+			_ = pw.CloseWithError(err)
 			return
 		}
+		_ = pw.Close()
 	}()
 	return pr, manifest, nil
 }
+
+func (s *ObjectService) HeadObject(bucket, key string) (models.ObjectManifest, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	manifest, err := s.metadata.GetManifest(bucket, key)
+	if err != nil {
+		return models.ObjectManifest{}, err
+	}
+	return *manifest, nil
+}
+
+func (s *ObjectService) DeleteObject(bucket, key string) error {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+	return s.metadata.DeleteManifest(bucket, key)
+}
+
+func (s *ObjectService) ListObjects(bucket, prefix string) ([]*models.ObjectManifest, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	return s.metadata.ListObjects(bucket, prefix)
+}
+
+func (s *ObjectService) CreateBucket(bucket string) error {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+	return s.metadata.CreateBucket(bucket)
+}
+
+func (s *ObjectService) HeadBucket(bucket string) error {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	_, err := s.metadata.GetBucketManifest(bucket)
+	return err
+}
+
+func (s *ObjectService) GetBucketManifest(bucket string) (*models.BucketManifest, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	return s.metadata.GetBucketManifest(bucket)
+}
+
+func (s *ObjectService) DeleteBucket(bucket string) error {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+	return s.metadata.DeleteBucket(bucket)
+}
+
+func (s *ObjectService) ListBuckets() ([]string, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	return s.metadata.ListBuckets()
+}
+
+func (s *ObjectService) DeleteObjects(bucket string, keys []string) ([]string, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+	return s.metadata.DeleteManifests(bucket, keys)
+}
+
+func (s *ObjectService) CreateMultipartUpload(bucket, key string) (*models.MultipartUpload, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+	return s.metadata.CreateMultipartUpload(bucket, key)
+}
+
+func (s *ObjectService) UploadPart(bucket, key, uploadId string, partNumber int, input io.Reader) (string, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	if partNumber < 1 || partNumber > 10000 {
+		return "", ErrInvalidPart
+	}
+
+	upload, err := s.metadata.GetMultipartUpload(uploadId)
+	if err != nil {
+		return "", err
+	}
+	if upload.Bucket != bucket || upload.Key != key {
+		return "", metadata.ErrMultipartNotFound
+	}
+
+	var uploadedPart models.UploadedPart
+	chunkIds, totalSize, etag, err := s.blob.IngestStream(input)
+	if err != nil {
+		return "", err
+	}
+	uploadedPart = models.UploadedPart{
+		PartNumber: partNumber,
+		ETag:       etag,
+		Size:       totalSize,
+		Chunks:     chunkIds,
+		CreatedAt:  time.Now().Unix(),
+	}
+	err = s.metadata.PutMultipartPart(uploadId, uploadedPart)
+	if err != nil {
+		return "", err
+	}
+	return etag, nil
+}
+
+func (s *ObjectService) ListMultipartParts(bucket, key, uploadID string) ([]models.UploadedPart, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	upload, err := s.metadata.GetMultipartUpload(uploadID)
+	if err != nil {
+		return nil, err
+	}
+	if upload.Bucket != bucket || upload.Key != key {
+		return nil, metadata.ErrMultipartNotFound
+	}
+	return s.metadata.ListMultipartParts(uploadID)
+}
+
+func (s *ObjectService) CompleteMultipartUpload(bucket, key, uploadID string, completed []models.CompletedPart) (*models.ObjectManifest, error) {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	if len(completed) == 0 {
+		return nil, ErrInvalidCompleteRequest
+	}
+
+	upload, err := s.metadata.GetMultipartUpload(uploadID)
+	if err != nil {
+		return nil, err
+	}
+	if upload.Bucket != bucket || upload.Key != key {
+		return nil, metadata.ErrMultipartNotFound
+	}
+
+	storedParts, err := s.metadata.ListMultipartParts(uploadID)
+	if err != nil {
+		return nil, err
+	}
+	partsByNumber := make(map[int]models.UploadedPart, len(storedParts))
+	for _, part := range storedParts {
+		partsByNumber[part.PartNumber] = part
+	}
+
+	lastPartNumber := 0
+	orderedParts := make([]models.UploadedPart, 0, len(completed))
+	chunks := make([]string, 0)
+	var totalSize int64
+
+	for i, part := range completed {
+		if part.PartNumber <= lastPartNumber {
+			return nil, ErrInvalidPartOrder
+		}
+		lastPartNumber = part.PartNumber
+
+		storedPart, ok := partsByNumber[part.PartNumber]
+		if !ok {
+			return nil, ErrInvalidPart
+		}
+		if normalizeETag(part.ETag) != normalizeETag(storedPart.ETag) {
+			return nil, ErrInvalidPart
+		}
+		if i < len(completed)-1 && storedPart.Size < 5*1024*1024 {
+			return nil, ErrEntityTooSmall
+		}
+
+		orderedParts = append(orderedParts, storedPart)
+		chunks = append(chunks, storedPart.Chunks...)
+		totalSize += storedPart.Size
+	}
+
+	finalETag := buildMultipartETag(orderedParts)
+	manifest := &models.ObjectManifest{
+		Bucket:      bucket,
+		Key:         key,
+		Size:        totalSize,
+		ContentType: "application/octet-stream",
+		ETag:        finalETag,
+		Chunks:      chunks,
+		CreatedAt:   time.Now().Unix(),
+	}
+
+	if err := s.metadata.CompleteMultipartUpload(uploadID, manifest); err != nil {
+		return nil, err
+	}
+
+	return manifest, nil
+}
+
+func (s *ObjectService) AbortMultipartUpload(bucket, key, uploadID string) error {
+	s.gcMu.RLock()
+	defer s.gcMu.RUnlock()
+
+	upload, err := s.metadata.GetMultipartUpload(uploadID)
+	if err != nil {
+		return err
+	}
+	if upload.Bucket != bucket || upload.Key != key {
+		return metadata.ErrMultipartNotFound
+	}
+	return s.metadata.AbortMultipartUpload(uploadID)
+}
+
+func normalizeETag(etag string) string {
+	return strings.Trim(etag, "\"")
+}
+
+func buildMultipartETag(parts []models.UploadedPart) string {
+	hasher := md5.New()
+	for _, part := range parts {
+		etagBytes, err := hex.DecodeString(normalizeETag(part.ETag))
+		if err == nil {
+			_, _ = hasher.Write(etagBytes)
+			continue
+		}
+		_, _ = hasher.Write([]byte(normalizeETag(part.ETag)))
+	}
+	return fmt.Sprintf("%x-%d", hasher.Sum(nil), len(parts))
+}
+
+func (s *ObjectService) Close() error {
+	return s.metadata.Close()
+}
+
+func (s *ObjectService) GarbageCollect() error {
+	s.gcMu.Lock()
+	defer s.gcMu.Unlock()
+
+	referencedChunkSet, err := s.metadata.GetReferencedChunkSet()
+	if err != nil {
+		return err
+	}
+
+	totalChunks := 0
+	deletedChunks := 0
+	deleteErrors := 0
+
+	if err := s.blob.ForEachChunk(func(chunkID string) error {
+		totalChunks++
+		if _, found := referencedChunkSet[chunkID]; found {
+			return nil
+		}
+		if err := s.blob.DeleteBlob(chunkID); err != nil {
+			deleteErrors++
+			slog.Warn("garbage_collect_delete_failed", "chunk_id", chunkID, "error", err)
+			return nil
+		}
+		deletedChunks++
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	slog.Info("garbage_collect_completed",
+		"referenced_chunks", len(referencedChunkSet),
+		"total_chunks", totalChunks,
+		"deleted_chunks", deletedChunks,
+		"delete_errors", deleteErrors,
+	)
+	return nil
+}
+
+func (s *ObjectService) RunGC(ctx context.Context, interval time.Duration) {
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			_ = s.GarbageCollect()
+		}
+	}
+}

storage/blob.go

@@ -4,24 +4,48 @@ import (
 	"crypto/md5"
 	"crypto/sha256"
 	"encoding/hex"
+	"errors"
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 )
 
-const chunkSize = 64 * 1024
-const blobRoot = "blobs/"
+const blobRoot = "blobs"
+const maxChunkSize = 64 * 1024 * 1024
 
-func IngestStream(stream io.Reader) ([]string, int64, string, error) {
+type BlobStore struct {
+	dataRoot  string
+	chunkSize int
+}
+
+func NewBlobStore(root string, chunkSize int) (*BlobStore, error) {
+	root = strings.TrimSpace(root)
+	if root == "" {
+		return nil, errors.New("blob root is required")
+	}
+	if chunkSize <= 0 || chunkSize > maxChunkSize {
+		return nil, fmt.Errorf("chunk size must be between 1 and %d bytes", maxChunkSize)
+	}
+
+	cleanRoot := filepath.Clean(root)
+	if err := os.MkdirAll(filepath.Join(cleanRoot, blobRoot), 0o755); err != nil {
+		return nil, err
+	}
+	return &BlobStore{chunkSize: chunkSize, dataRoot: cleanRoot}, nil
+}
+
+func (bs *BlobStore) IngestStream(stream io.Reader) ([]string, int64, string, error) {
 	fullFileHasher := md5.New()
 
-	buffer := make([]byte, chunkSize)
+	buffer := make([]byte, bs.chunkSize)
 	var totalSize int64
 	var chunkIDs []string
 
 	for {
 		bytesRead, err := io.ReadFull(stream, buffer)
-		if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
+		if err != nil && err != io.EOF && !errors.Is(err, io.ErrUnexpectedEOF) {
 			return nil, 0, "", err
 		}
 
@@ -34,13 +58,13 @@ func IngestStream(stream io.Reader) ([]string, int64, string, error) {
 			chunkHash := sha256.Sum256(chunkData)
 			chunkID := hex.EncodeToString(chunkHash[:])
 
-			err := saveBlob(chunkID, chunkData)
+			err := bs.saveBlob(chunkID, chunkData)
 			if err != nil {
 				return nil, 0, "", err
 			}
 			chunkIDs = append(chunkIDs, chunkID)
 		}
-		if err == io.EOF || err == io.ErrUnexpectedEOF {
+		if err == io.EOF || errors.Is(err, io.ErrUnexpectedEOF) {
 			break
 		}
 		if err != nil {
@@ -48,29 +72,68 @@ func IngestStream(stream io.Reader) ([]string, int64, string, error) {
 		}
 
 	}
-	
+
 	etag := hex.EncodeToString(fullFileHasher.Sum(nil))
 	return chunkIDs, totalSize, etag, nil
 }
 
-func saveBlob(chunkID string, data []byte) error {
-	dir := filepath.Join(blobRoot, chunkID[:2], chunkID[2:4])
+func (bs *BlobStore) saveBlob(chunkID string, data []byte) error {
+	if !isValidChunkID(chunkID) {
+		return fmt.Errorf("invalid chunk id: %q", chunkID)
+	}
+	dir := filepath.Join(bs.dataRoot, blobRoot, chunkID[:2], chunkID[2:4])
 	if err := os.MkdirAll(dir, 0755); err != nil {
 		return err
 	}
 
 	fullPath := filepath.Join(dir, chunkID)
-	if _, err := os.Stat(fullPath); os.IsNotExist(err) {
-		if err := os.WriteFile(fullPath, data, 0644); err != nil {
-			return err
+	if _, err := os.Stat(fullPath); err == nil {
+		return nil
+	} else if !os.IsNotExist(err) {
+		return err
+	}
+
+	tmpFile, err := os.CreateTemp(dir, chunkID+".tmp-*")
+	if err != nil {
+		return err
+	}
+	tmpPath := tmpFile.Name()
+	cleanup := true
+	defer func() {
+		if cleanup {
+			_ = os.Remove(tmpPath)
 		}
+	}()
+
+	if _, err := tmpFile.Write(data); err != nil {
+		_ = tmpFile.Close()
+		return err
+	}
+	if err := tmpFile.Sync(); err != nil {
+		_ = tmpFile.Close()
+		return err
+	}
+	if err := tmpFile.Close(); err != nil {
+		return err
+	}
+
+	if err := os.Rename(tmpPath, fullPath); err != nil {
+		if _, statErr := os.Stat(fullPath); statErr == nil {
+			return nil
+		}
+		return err
+	}
+	cleanup = false
+
+	if err := syncDir(dir); err != nil {
+		return err
 	}
 	return nil
 }
 
-func AssembleStream(chunkIDs []string, w *io.PipeWriter) error {
+func (bs *BlobStore) AssembleStream(chunkIDs []string, w *io.PipeWriter) error {
 	for _, chunkID := range chunkIDs {
-		chunkData, err := GetBlob(chunkID)
+		chunkData, err := bs.GetBlob(chunkID)
 		if err != nil {
 			return err
 		}
@@ -81,7 +144,69 @@ func AssembleStream(chunkIDs []string, w *io.PipeWriter) error {
 	return nil
 }
 
-func GetBlob(chunkID string) ([]byte, error) {
-
-	return os.ReadFile(filepath.Join(blobRoot, chunkID[:2], chunkID[2:4], chunkID))
+func (bs *BlobStore) GetBlob(chunkID string) ([]byte, error) {
+	if !isValidChunkID(chunkID) {
+		return nil, fmt.Errorf("invalid chunk id: %q", chunkID)
+	}
+	return os.ReadFile(filepath.Join(bs.dataRoot, blobRoot, chunkID[:2], chunkID[2:4], chunkID))
+}
+
+func (bs *BlobStore) DeleteBlob(chunkID string) error {
+	if !isValidChunkID(chunkID) {
+		return fmt.Errorf("invalid chunk id: %q", chunkID)
+	}
+	err := os.Remove(filepath.Join(bs.dataRoot, blobRoot, chunkID[:2], chunkID[2:4], chunkID))
+	if err != nil && os.IsNotExist(err) {
+		return nil
+	}
+	return err
+}
+
+func (bs *BlobStore) ListChunks() ([]string, error) {
+	var chunkIDs []string
+	err := bs.ForEachChunk(func(chunkID string) error {
+		chunkIDs = append(chunkIDs, chunkID)
+		return nil
+	})
+	return chunkIDs, err
+}
+
+func (bs *BlobStore) ForEachChunk(fn func(chunkID string) error) error {
+	if fn == nil {
+		return errors.New("chunk callback is required")
+	}
+	return filepath.Walk(filepath.Join(bs.dataRoot, blobRoot), func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() {
+			chunkID := info.Name()
+			if isValidChunkID(chunkID) {
+				return fn(chunkID)
+			}
+		}
+		return nil
+
+	})
+}
+
+func isValidChunkID(chunkID string) bool {
+	if len(chunkID) != sha256.Size*2 {
+		return false
+	}
+	for _, ch := range chunkID {
+		if (ch < '0' || ch > '9') && (ch < 'a' || ch > 'f') {
+			return false
+		}
+	}
+	return true
+}
+
+func syncDir(dirPath string) error {
+	dir, err := os.Open(dirPath)
+	if err != nil {
+		return err
+	}
+	defer dir.Close()
+	return dir.Sync()
 }

utils/config.go

@@ -0,0 +1,94 @@
+package utils
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/joho/godotenv"
+)
+
+type Config struct {
+	DataPath   string
+	Address    string
+	Port       int
+	ChunkSize  int
+	LogLevel   string
+	LogFormat  string
+	AuditLog   bool
+	GcInterval time.Duration
+	GcEnabled  bool
+}
+
+func NewConfig() *Config {
+	_ = godotenv.Load()
+
+	config := &Config{
+		DataPath:   sanitizeDataPath(os.Getenv("DATA_PATH")),
+		Address:    firstNonEmpty(strings.TrimSpace(os.Getenv("ADDRESS")), "0.0.0.0"),
+		Port:       envIntRange("PORT", 3000, 1, 65535),
+		ChunkSize:  envIntRange("CHUNK_SIZE", 8192000, 1, 64*1024*1024),
+		LogLevel:   strings.ToLower(firstNonEmpty(strings.TrimSpace(os.Getenv("LOG_LEVEL")), "info")),
+		LogFormat:  strings.ToLower(firstNonEmpty(strings.TrimSpace(os.Getenv("LOG_FORMAT")), strings.TrimSpace(os.Getenv("LOG_TYPE")), "text")),
+		AuditLog:   envBool("AUDIT_LOG", true),
+		GcInterval: time.Duration(envIntRange("GC_INTERVAL", 10, -1, 60)) * time.Minute,
+		GcEnabled:  envBool("GC_ENABLED", true),
+	}
+
+	if config.LogFormat != "json" && config.LogFormat != "text" {
+		config.LogFormat = "text"
+	}
+
+	return config
+
+}
+
+func envIntRange(key string, defaultValue, minValue, maxValue int) int {
+	raw := strings.TrimSpace(os.Getenv(key))
+	if raw == "" {
+		return defaultValue
+	}
+	value, err := strconv.Atoi(raw)
+	if err != nil {
+		return defaultValue
+	}
+	if value < minValue || value > maxValue {
+		return defaultValue
+	}
+	return value
+}
+
+func envBool(key string, defaultValue bool) bool {
+	raw := strings.TrimSpace(os.Getenv(key))
+	if raw == "" {
+		return defaultValue
+	}
+	value, err := strconv.ParseBool(raw)
+	if err != nil {
+		return defaultValue
+	}
+	return value
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, v := range values {
+		if v != "" {
+			return v
+		}
+	}
+	return ""
+}
+
+func sanitizeDataPath(raw string) string {
+	cleaned := strings.TrimSpace(raw)
+	if cleaned == "" {
+		cleaned = "."
+	}
+	cleaned = filepath.Clean(cleaned)
+	if abs, err := filepath.Abs(cleaned); err == nil {
+		return abs
+	}
+	return cleaned
+}

utils/utils.go

@@ -0,0 +1,54 @@
+package utils
+
+import (
+	"encoding/xml"
+	"fs/models"
+	"sort"
+	"strings"
+	"time"
+)
+
+func ConstructXMLResponseForObjectList(bucket string, objects []*models.ObjectManifest) (string, error) {
+	result := models.ListBucketResult{
+		Xmlns:       "http://s3.amazonaws.com/doc/2006-03-01/",
+		Name:        bucket,
+		Prefix:      "",
+		KeyCount:    len(objects),
+		MaxKeys:     1000,
+		IsTruncated: false,
+	}
+
+	prefixSet := make(map[string]struct{})
+
+	for _, object := range objects {
+		result.Contents = append(result.Contents, models.Contents{
+			Key:          object.Key,
+			LastModified: time.Unix(object.CreatedAt, 0).UTC().Format("2006-01-02T15:04:05.000Z"),
+			ETag:         "\"" + object.ETag + "\"",
+			Size:         object.Size,
+			StorageClass: "STANDARD",
+		})
+
+		if strings.Contains(object.Key, "/") {
+			parts := strings.SplitN(object.Key, "/", 2)
+			prefixSet[parts[0]+"/"] = struct{}{}
+		}
+	}
+
+	prefixes := make([]string, 0, len(prefixSet))
+	for prefix := range prefixSet {
+		prefixes = append(prefixes, prefix)
+	}
+	sort.Strings(prefixes)
+
+	for _, prefix := range prefixes {
+		result.CommonPrefixes = append(result.CommonPrefixes, models.CommonPrefixes{Prefix: prefix})
+	}
+
+	output, err := xml.MarshalIndent(result, "", "    ")
+	if err != nil {
+		return "", err
+	}
+
+	return xml.Header + string(output), nil
+}