feat: add GCSAttachmentStorage implementation

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: AchoArnold

api/pkg/repositories/gcs_attachment_storage.go

@@ -0,0 +1,84 @@
+package repositories
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"cloud.google.com/go/storage"
+	"github.com/NdoleStudio/httpsms/pkg/telemetry"
+	"github.com/palantir/stacktrace"
+)
+
+// GCSAttachmentStorage stores attachments in Google Cloud Storage
+type GCSAttachmentStorage struct {
+	logger telemetry.Logger
+	tracer telemetry.Tracer
+	client *storage.Client
+	bucket string
+}
+
+// NewGCSAttachmentStorage creates a new GCSAttachmentStorage
+func NewGCSAttachmentStorage(
+	logger telemetry.Logger,
+	tracer telemetry.Tracer,
+	client *storage.Client,
+	bucket string,
+) *GCSAttachmentStorage {
+	return &GCSAttachmentStorage{
+		logger: logger.WithService(fmt.Sprintf("%T", &GCSAttachmentStorage{})),
+		tracer: tracer,
+		client: client,
+		bucket: bucket,
+	}
+}
+
+// Upload stores attachment data at the given path in GCS
+func (s *GCSAttachmentStorage) Upload(ctx context.Context, path string, data []byte) error {
+	ctx, span := s.tracer.Start(ctx)
+	defer span.End()
+
+	writer := s.client.Bucket(s.bucket).Object(path).NewWriter(ctx)
+	if _, err := writer.Write(data); err != nil {
+		return s.tracer.WrapErrorSpan(span, stacktrace.Propagate(err, fmt.Sprintf("cannot write attachment to GCS path [%s]", path)))
+	}
+
+	if err := writer.Close(); err != nil {
+		return s.tracer.WrapErrorSpan(span, stacktrace.Propagate(err, fmt.Sprintf("cannot close GCS writer for path [%s]", path)))
+	}
+
+	s.logger.Info(fmt.Sprintf("uploaded attachment to GCS path [%s/%s] with size [%d]", s.bucket, path, len(data)))
+	return nil
+}
+
+// Download retrieves attachment data from the given path in GCS
+func (s *GCSAttachmentStorage) Download(ctx context.Context, path string) ([]byte, error) {
+	ctx, span := s.tracer.Start(ctx)
+	defer span.End()
+
+	reader, err := s.client.Bucket(s.bucket).Object(path).NewReader(ctx)
+	if err != nil {
+		return nil, s.tracer.WrapErrorSpan(span, stacktrace.Propagate(err, fmt.Sprintf("cannot open GCS reader for path [%s]", path)))
+	}
+	defer reader.Close()
+
+	data, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, s.tracer.WrapErrorSpan(span, stacktrace.Propagate(err, fmt.Sprintf("cannot read attachment from GCS path [%s]", path)))
+	}
+
+	return data, nil
+}
+
+// Delete removes an attachment at the given path in GCS
+func (s *GCSAttachmentStorage) Delete(ctx context.Context, path string) error {
+	ctx, span := s.tracer.Start(ctx)
+	defer span.End()
+
+	if err := s.client.Bucket(s.bucket).Object(path).Delete(ctx); err != nil {
+		return s.tracer.WrapErrorSpan(span, stacktrace.Propagate(err, fmt.Sprintf("cannot delete GCS object at path [%s]", path)))
+	}
+
+	s.logger.Info(fmt.Sprintf("deleted attachment from GCS path [%s/%s]", s.bucket, path))
+	return nil
+}