refactor(#2708): Make all methods of FileManager none static (#2709)

* refactor(#2708): Make all methods of FileManager none static

* refactor(#2708): Add unit tests for getAllFiles

* refactor(#2708): Add unit tests for getFile

* refactor(#2708): Add tests in FileManager for storeFile and deleteFile

* refactor(#2708): Make FileHasher none static and add tests

* refactor(#2708): Add unit test for checkFileContentChanged in FileManager

* refactor(#2708): Remove hash code from FileMetadata

streampipes-commons/src/main/java/org/apache/streampipes/commons/file/FileHasher.java

@@ -28,7 +28,12 @@
 
 public class FileHasher {
 
-  public static String hash(File file) throws IOException {
+  public String hash(File file) throws IOException {
+
+    if (file == null) {
+      throw new IOException("Input file is null. Please provide a valid file to calculate the hash.");
+    }
+
     try (InputStream is = Files.newInputStream(Paths.get(file.toURI()))) {
       return DigestUtils.md5Hex(is);
     }

streampipes-commons/src/test/java/org/apache/streampipes/commons/file/FileHasherTest.java

@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.apache.streampipes.commons.file;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class FileHasherTest {
+
+  private FileHasher fileHasher;
+
+  @BeforeEach
+  public void setup() {
+    this.fileHasher = new FileHasher();
+  }
+
+  @Test
+  void hash_returnsCorrectHashForFile() throws IOException {
+    var file = new File("src/test/resources/test.txt");
+    assertEquals("6df4d50a41a5d20bc4faad8a6f09aa8f", fileHasher.hash(file));
+  }
+
+  @Test
+  void hash_throwsIOExceptionForNonExistingFile() {
+    var file = new File("src/test/resources/nonExistingFile.txt");
+    assertThrows(IOException.class, () -> fileHasher.hash(file));
+  }
+
+  @Test
+  void hash_throwsIOExceptionForNullFile() {
+    assertThrows(IOException.class, () -> fileHasher.hash(null));
+  }
+}

streampipes-data-export/src/main/java/org/apache/streampipes/export/generator/ExportPackageGenerator.java

@@ -124,7 +124,7 @@ public byte[] generateExportPackage() throws IOException {
         String filename = fileResolver.findDocument(item.getResourceId()).getFilename();
         addDoc(builder, item, new FileResolver(), manifest::addFile);
         try {
-          builder.addBinary(filename, Files.readAllBytes(FileManager.getFile(filename).toPath()));
+          builder.addBinary(filename, Files.readAllBytes(new FileManager().getFile(filename).toPath()));
         } catch (IOException e) {
           e.printStackTrace();
         }

streampipes-extensions/streampipes-connect-adapters-iiot/src/main/java/org/apache/streampipes/connect/iiot/utils/FileProtocolUtils.java

@@ -56,7 +56,7 @@ public static InputStream getFileInputStream(String selectedFilename) throws Fil
    */
   private static boolean checkIfFileChanged(String selectedFilename) {
     try {
-      var hash = FileHasher.hash(getFile(selectedFilename));
+      var hash = new FileHasher().hash(getFile(selectedFilename));
       StreamPipesClient client = getStreamPipesClientInstance();
       return client.fileApi()
                    .checkFileContentChanged(selectedFilename, hash);

streampipes-model/src/main/java/org/apache/streampipes/model/file/FileMetadata.java

@@ -91,4 +91,5 @@ public String getFiletype() {
   public void setFiletype(String filetype) {
     this.filetype = filetype;
   }
+
 }

streampipes-pipeline-management/src/main/java/org/apache/streampipes/manager/file/FileManager.java

@@ -34,17 +34,38 @@
 
 public class FileManager {
 
-  public static List<FileMetadata> getAllFiles() {
+  private final IFileMetadataStorage fileMetadataStorage;
+  private final FileHandler fileHandler;
+  private final FileHasher fileHasher;
+
+  public FileManager(IFileMetadataStorage fileMetadataStorage,
+                     FileHandler fileHandler,
+                     FileHasher fileHasher) {
+    this.fileMetadataStorage = fileMetadataStorage;
+    this.fileHandler = fileHandler;
+    this.fileHasher = fileHasher;
+  }
+
+  public FileManager() {
+    this.fileMetadataStorage = StorageDispatcher
+        .INSTANCE
+        .getNoSqlStore()
+        .getFileMetadataStorage();
+    this.fileHandler = new FileHandler();
+    this.fileHasher = new FileHasher();
+  }
+
+  public List<FileMetadata> getAllFiles() {
     return getAllFiles(null);
   }
 
-  public static List<FileMetadata> getAllFiles(String filetypes) {
-    List<FileMetadata> allFiles = getFileMetadataStorage().getAllFileMetadataDescriptions();
+  public List<FileMetadata> getAllFiles(String filetypes) {
+    List<FileMetadata> allFiles = fileMetadataStorage.getAllFileMetadataDescriptions();
     return filetypes != null ? filterFiletypes(allFiles, filetypes) : allFiles;
   }
 
-  public static File getFile(String filename) {
-    return new FileHandler().getFile(filename);
+  public File getFile(String filename) {
+    return fileHandler.getFile(filename);
   }
 
   /**
@@ -56,7 +77,7 @@ public static File getFile(String filename) {
    * @param fileInputStream content of file
    * @return metadata of file
    */
-  public static FileMetadata storeFile(String user,
+  public FileMetadata storeFile(String user,
                                        String filename,
                                        InputStream fileInputStream) throws IOException {
 
@@ -72,13 +93,15 @@ public static FileMetadata storeFile(String user,
   }
 
 
-  public static void deleteFile(String id) {
-    FileMetadata fileMetadata = getFileMetadataStorage().getMetadataById(id);
-    new FileHandler().deleteFile(fileMetadata.getFilename());
-    getFileMetadataStorage().deleteFileMetadata(id);
+  public void deleteFile(String id) {
+    var fileMetadata = fileMetadataStorage.getMetadataById(id);
+    if (fileMetadata != null) {
+      fileHandler.deleteFile(fileMetadata.getFilename());
+      fileMetadataStorage.deleteFileMetadata(id);
+    }
   }
 
-  private static InputStream validateFileNameAndCleanFile(String filename,
+  private InputStream validateFileNameAndCleanFile(String filename,
                                                   String filetype,
                                                   InputStream fileInputStream) {
     if (!validateFileType(filename)) {
@@ -95,42 +118,34 @@ private static InputStream validateFileNameAndCleanFile(String filename,
    * @param filetype file of type
    * @return input stream without BOM
    */
-  protected static InputStream cleanFile(InputStream fileInputStream, String filetype) {
+  protected InputStream cleanFile(InputStream fileInputStream, String filetype) {
     if (Filetypes.CSV.getFileExtensions().contains(filetype.toLowerCase())) {
       fileInputStream = new BOMInputStream(fileInputStream);
     }
 
     return fileInputStream;
   }
 
-  public static boolean checkFileContentChanged(String filename, String hash) throws IOException {
-    var fileHash = FileHasher.hash(getFile(filename));
+  public boolean checkFileContentChanged(String filename, String hash) throws IOException {
+    var fileHash = fileHasher.hash(getFile(filename));
     return !fileHash.equals(hash);
   }
 
-  public static String sanitizeFilename(String filename) {
+  public String sanitizeFilename(String filename) {
     return filename.replaceAll("[^a-zA-Z0-9.\\-]", "_");
   }
 
-  public static boolean validateFileType(String filename) {
+  public boolean validateFileType(String filename) {
     return Filetypes.getAllFileExtensions()
                     .stream()
                     .anyMatch(filename::endsWith);
   }
 
-  protected static void writeToFile(String sanitizedFilename, InputStream fileInputStream) throws IOException {
-    new FileHandler().storeFile(sanitizedFilename, fileInputStream);
-  }
-
-
-  private static IFileMetadataStorage getFileMetadataStorage() {
-    return StorageDispatcher
-        .INSTANCE
-        .getNoSqlStore()
-        .getFileMetadataStorage();
+  protected void writeToFile(String sanitizedFilename, InputStream fileInputStream) throws IOException {
+    fileHandler.storeFile(sanitizedFilename, fileInputStream);
   }
 
-  protected static FileMetadata makeAndStoreFileMetadata(String user,
+  protected FileMetadata makeAndStoreFileMetadata(String user,
                                                        String sanitizedFilename,
                                                        String filetype) {
     var fileMetadata = makeFileMetadata(user, sanitizedFilename, filetype);
@@ -139,7 +154,7 @@ protected static FileMetadata makeAndStoreFileMetadata(String user,
     return fileMetadata;
   }
 
-  private static FileMetadata makeFileMetadata(String user,
+  private FileMetadata makeFileMetadata(String user,
                                                String filename,
                                                String filetype) {
 
@@ -152,12 +167,12 @@ private static FileMetadata makeFileMetadata(String user,
     return fileMetadata;
   }
 
-  private static void storeFileMetadata(FileMetadata fileMetadata) {
-    getFileMetadataStorage().addFileMetadata(fileMetadata);
+  private void storeFileMetadata(FileMetadata fileMetadata) {
+    fileMetadataStorage.addFileMetadata(fileMetadata);
   }
 
 
-  private static List<FileMetadata> filterFiletypes(List<FileMetadata> allFiles, String filetypes) {
+  private List<FileMetadata> filterFiletypes(List<FileMetadata> allFiles, String filetypes) {
     return allFiles
         .stream()
         .filter(fileMetadata -> Arrays