Initial commit: Open sourcing all of the Maple Open Technologies code.

cloud/maplefile-backend/internal/service/file/get.go

@@ -0,0 +1,98 @@
+// monorepo/cloud/backend/internal/maplefile/service/file/get.go
+package file
+
+import (
+	"context"
+
+	"go.uber.org/zap"
+
+	"github.com/gocql/gocql"
+	"codeberg.org/mapleopentech/monorepo/cloud/maplefile-backend/config"
+	"codeberg.org/mapleopentech/monorepo/cloud/maplefile-backend/config/constants"
+	dom_collection "codeberg.org/mapleopentech/monorepo/cloud/maplefile-backend/internal/domain/collection"
+	uc_filemetadata "codeberg.org/mapleopentech/monorepo/cloud/maplefile-backend/internal/usecase/filemetadata"
+	"codeberg.org/mapleopentech/monorepo/cloud/maplefile-backend/pkg/httperror"
+)
+
+type GetFileService interface {
+	Execute(ctx context.Context, fileID gocql.UUID) (*FileResponseDTO, error)
+}
+
+type getFileServiceImpl struct {
+	config             *config.Configuration
+	logger             *zap.Logger
+	collectionRepo     dom_collection.CollectionRepository
+	getMetadataUseCase uc_filemetadata.GetFileMetadataUseCase
+}
+
+func NewGetFileService(
+	config *config.Configuration,
+	logger *zap.Logger,
+	collectionRepo dom_collection.CollectionRepository,
+	getMetadataUseCase uc_filemetadata.GetFileMetadataUseCase,
+) GetFileService {
+	logger = logger.Named("GetFileService")
+	return &getFileServiceImpl{
+		config:             config,
+		logger:             logger,
+		collectionRepo:     collectionRepo,
+		getMetadataUseCase: getMetadataUseCase,
+	}
+}
+
+func (svc *getFileServiceImpl) Execute(ctx context.Context, fileID gocql.UUID) (*FileResponseDTO, error) {
+	//
+	// STEP 1: Validation
+	//
+	if fileID.String() == "" {
+		svc.logger.Warn("Empty file ID provided")
+		return nil, httperror.NewForBadRequestWithSingleField("file_id", "File ID is required")
+	}
+
+	//
+	// STEP 2: Get user ID from context
+	//
+	userID, ok := ctx.Value(constants.SessionUserID).(gocql.UUID)
+	if !ok {
+		svc.logger.Error("Failed getting user ID from context")
+		return nil, httperror.NewForInternalServerErrorWithSingleField("message", "Authentication context error")
+	}
+
+	//
+	// STEP 3: Get file metadata
+	//
+	file, err := svc.getMetadataUseCase.Execute(fileID)
+	if err != nil {
+		svc.logger.Error("Failed to get file metadata",
+			zap.Any("error", err),
+			zap.Any("file_id", fileID))
+		return nil, err
+	}
+
+	//
+	// STEP 4: Check if user has access to the file's collection
+	//
+	hasAccess, err := svc.collectionRepo.CheckAccess(ctx, file.CollectionID, userID, dom_collection.CollectionPermissionReadOnly)
+	if err != nil {
+		svc.logger.Error("Failed to check collection access",
+			zap.Any("error", err),
+			zap.Any("collection_id", file.CollectionID),
+			zap.Any("user_id", userID))
+		return nil, err
+	}
+
+	if !hasAccess {
+		svc.logger.Warn("Unauthorized file access attempt",
+			zap.Any("user_id", userID),
+			zap.Any("file_id", fileID),
+			zap.Any("collection_id", file.CollectionID))
+		return nil, httperror.NewForForbiddenWithSingleField("message", "You don't have permission to access this file")
+	}
+
+	//
+	// STEP 5: Map domain model to response DTO
+	//
+	response := mapFileToDTO(file)
+
+	return response, nil
+}