Add GetFileByID method and enhance viewer handlers for file metadata retrieval

go_cloud/internal/database/db.go

@@ -383,6 +383,34 @@ func (db *DB) CreateFile(ctx context.Context, orgID *uuid.UUID, userID *uuid.UUI
 	return &f, nil
 }
 
+// GetFileByID retrieves a file by its ID
+func (db *DB) GetFileByID(ctx context.Context, fileID uuid.UUID) (*File, error) {
+	var f File
+	var orgNull sql.NullString
+	var userNull sql.NullString
+	
+	err := db.QueryRowContext(ctx, `
+		SELECT id, org_id::text, user_id::text, name, path, type, size, last_modified, created_at
+		FROM files
+		WHERE id = $1
+	`, fileID).Scan(&f.ID, &orgNull, &userNull, &f.Name, &f.Path, &f.Type, &f.Size, &f.LastModified, &f.CreatedAt)
+	
+	if err != nil {
+		return nil, err
+	}
+	
+	if orgNull.Valid {
+		oid, _ := uuid.Parse(orgNull.String)
+		f.OrgID = &oid
+	}
+	if userNull.Valid {
+		uid, _ := uuid.Parse(userNull.String)
+		f.UserID = &uid
+	}
+	
+	return &f, nil
+}
+
 // DeleteFileByPath removes a file or folder matching path for a given org or user
 func (db *DB) DeleteFileByPath(ctx context.Context, orgID *uuid.UUID, userID *uuid.UUID, path string) error {
 	var res sql.Result