Add serialization and deserialization for ObjectCollection

9 files changed, 173 insertions, 14 deletions

diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
index e0ef4f7..16d95e6 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollection.java
@@ -1,8 +1,9 @@
 package com.keuin.kbackupfabric.util.backup.incremental;
 
+import java.io.Serializable;
 import java.util.*;
 
-public class ObjectCollection {
+public class ObjectCollection implements Serializable {
     private final String name;
     private final Map<String, ObjectElement> elements;
     private final Map<String, ObjectCollection> subCollections;
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactory.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactory.java
index be9e426..ea9edd9 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactory.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactory.java
@@ -16,6 +16,7 @@ import java.util.*;
  * The identifier should use hashes that are strong enough, to prevent possible collisions.
  */
 public class ObjectCollectionFactory <T extends ObjectIdentifier> {
+
     private final FileIdentifierFactory<T> identifierFactory;
 
     public ObjectCollectionFactory(FileIdentifierFactory<T> identifierFactory) {
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializer.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializer.java
new file mode 100644
index 0000000..cc77837
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializer.java
@@ -0,0 +1,30 @@
+package com.keuin.kbackupfabric.util.backup.incremental;
+
+import java.io.*;
+import java.util.Objects;
+
+public class ObjectCollectionSerializer {
+    public static ObjectCollection fromFile(File file) throws IOException {
+        Objects.requireNonNull(file);
+        ObjectCollection collection;
+        try (FileInputStream fileInputStream = new FileInputStream(file)) {
+            try (ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream)) {
+                collection = (ObjectCollection) objectInputStream.readObject();
+            } catch (ClassNotFoundException ignored) {
+                // this should not happen
+                return null;
+            }
+        }
+        return collection;
+    }
+
+    public static void toFile(ObjectCollection collection, File file) throws IOException {
+        Objects.requireNonNull(collection);
+        Objects.requireNonNull(file);
+        try (FileOutputStream fileOutputStream = new FileOutputStream(file)) {
+            try (ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream)) {
+                objectOutputStream.writeObject(collection);
+            }
+        }
+    }
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectElement.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectElement.java
index 1232fb9..cbb886e 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectElement.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectElement.java
@@ -2,13 +2,14 @@ package com.keuin.kbackupfabric.util.backup.incremental;
 
 import com.keuin.kbackupfabric.util.backup.incremental.identifier.ObjectIdentifier;
 
+import java.io.Serializable;
 import java.util.Objects;
 
 /**
  * Representing a file in a ObjectCollection.
  * Immutable.
  */
-public class ObjectElement {
+public class ObjectElement implements Serializable {
     private final String name;
     private final ObjectIdentifier identifier;
 
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/ObjectIdentifier.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/ObjectIdentifier.java
index 6744616..aece07d 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/ObjectIdentifier.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/ObjectIdentifier.java
@@ -1,11 +1,13 @@
 package com.keuin.kbackupfabric.util.backup.incremental.identifier;
 
+import java.io.Serializable;
+
 /**
  * The identifier distinguishing files in the object collection.
  * It should be based on cryptographic hash function in order to prevent possible attacks to the backup system.
  * All identifiers should be immutable and implement their own equals method.
  * Immutable.
  */
-public interface ObjectIdentifier {
+public interface ObjectIdentifier extends Serializable {
     String getIdentification();
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
index 64716ed..9ecf2d3 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/identifier/Sha256Identifier.java
@@ -41,27 +41,28 @@ public class Sha256Identifier extends SingleHashIdentifier {
         try {
             MessageDigest digest = MessageDigest.getInstance("SHA-256");
 
-            FileInputStream inputStream = new FileInputStream(file);
-
-            // This does not work. I don't know why
+            try (FileInputStream inputStream = new FileInputStream(file)) {
+                // This does not work. I don't know why
 //            FileChannel channel = inputStream.getChannel();
 //            ByteBuffer buffer = ByteBuffer.allocate(128);
 //            int readLength;
 //            while ((readLength = channel.read(buffer)) > 0)
 //                digest.update(buffer);
 
-            // This also works, without warnings
-            byte[] readBuffer = new byte[1024 * 1024];
-            int readLength;
-            while ((readLength = inputStream.read(readBuffer)) > 0)
-                digest.update(readBuffer,0, readLength);
+                // This also works, without warnings
+                byte[] readBuffer = new byte[1024 * 1024];
+                int readLength;
+                while ((readLength = inputStream.read(readBuffer)) > 0)
+                    digest.update(readBuffer, 0, readLength);
 
-            // The below lines also works, but the IDE will complain about the while loop
+                // The below lines also works, but the IDE will complain about the while loop
 //            DigestInputStream digestInputStream = new DigestInputStream(inputStream, digest);
 //            while(digestInputStream.read() > 0)
 //                ;
 
-            return digest.digest();
+                return digest.digest();
+            }
+
         } catch (NoSuchAlgorithmException ignored) {
             // this shouldn't happen
             return new byte[SHA256_LENGTH];
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/manager/IncrementalBackupStorageManager.java b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/manager/IncrementalBackupStorageManager.java
new file mode 100644
index 0000000..cd15499
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/incremental/manager/IncrementalBackupStorageManager.java
@@ -0,0 +1,95 @@
+package com.keuin.kbackupfabric.util.backup.incremental.manager;
+
+import com.keuin.kbackupfabric.util.backup.incremental.ObjectCollection;
+import com.keuin.kbackupfabric.util.backup.incremental.ObjectElement;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Map;
+import java.util.Objects;
+
+public class IncrementalBackupStorageManager {
+
+    private final Path backupStorageBase;
+
+    public IncrementalBackupStorageManager(Path backupStorageBase) {
+        this.backupStorageBase = backupStorageBase;
+    }
+
+    /**
+     * Add a object collection to storage base.
+     * @param collection the collection.
+     * @return objects copied to the base.
+     * @throws IOException I/O Error.
+     */
+    public int addObjectCollection(ObjectCollection collection, File collectionBasePath) throws IOException {
+        Objects.requireNonNull(collection);
+        Objects.requireNonNull(collectionBasePath);
+
+        int copyCount = 0;
+
+        // copy sub files
+        for (Map.Entry<String, ObjectElement> entry : collection.getElementMap().entrySet()) {
+            File copyDestination = new File(backupStorageBase.toFile(), entry.getValue().getIdentifier().getIdentification());
+            if (!baseContainsObject(entry.getValue())) {
+                // element does not exist. copy.
+                Files.copy(Paths.get(collectionBasePath.getAbsolutePath(), entry.getKey()), copyDestination.toPath());
+                ++copyCount;
+            }
+        }
+
+        //copy sub dirs recursively
+        for (Map.Entry<String, ObjectCollection> entry : collection.getSubCollectionMap().entrySet()) {
+            File newBase = new File(collectionBasePath, entry.getKey());
+            copyCount += addObjectCollection(entry.getValue(), newBase);
+        }
+
+        return copyCount;
+    }
+
+    /**
+     * Restore an object collection from the storage base. i.e., restore the save from backup storage.
+     * @param collection the collection to be restored.
+     * @param collectionBasePath save path of the collection.
+     * @return objects restored from the base.
+     * @throws IOException I/O Error.
+     */
+    public int restoreObjectCollection(ObjectCollection collection, File collectionBasePath) throws IOException {
+        Objects.requireNonNull(collection);
+        Objects.requireNonNull(collectionBasePath);
+
+        int copyCount = 0;
+
+        // copy sub files
+        for (Map.Entry<String, ObjectElement> entry : collection.getElementMap().entrySet()) {
+            File copySource = new File(backupStorageBase.toFile(), entry.getValue().getIdentifier().getIdentification());
+            if (!baseContainsObject(entry.getValue())) {
+                throw new IOException(String.format("File %s does not exist in the base.", copySource.getName()));
+            }
+            Files.copy(copySource.toPath(), Paths.get(collectionBasePath.getAbsolutePath(), entry.getKey()));
+            ++copyCount;
+        }
+
+        //copy sub dirs recursively
+        for (Map.Entry<String, ObjectCollection> entry : collection.getSubCollectionMap().entrySet()) {
+            File newBase = new File(collectionBasePath, entry.getKey());
+            copyCount += restoreObjectCollection(entry.getValue(), newBase);
+        }
+
+        return copyCount;
+    }
+
+    /**
+     * Check if the backup base contains given element.
+     * @param objectElement the element.
+     * @return true or false.
+     */
+    private boolean baseContainsObject(ObjectElement objectElement) {
+        // This may be extended to use more variants of hash functions and combinations of other attributes (such as file size)
+        return (new File(backupStorageBase.toFile(), objectElement.getIdentifier().getIdentification())).exists();
+    }
+
+}
diff --git a/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactoryTest.java b/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactoryTest.java
index 60a42cf..b7e0aad 100644
--- a/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactoryTest.java
+++ b/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionFactoryTest.java
@@ -72,7 +72,6 @@ public class ObjectCollectionFactoryTest {
             // check `12`
             validate(collection.getSubCollectionMap().get("1").getSubCollectionMap().get("12"), Collections.emptyList(), Collections.emptyMap());
 
-
         } catch (IOException e) {
             e.printStackTrace();
             fail();
diff --git a/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializerTest.java b/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializerTest.java
new file mode 100644
index 0000000..0edfe01
--- /dev/null
+++ b/src/test/java/com/keuin/kbackupfabric/util/backup/incremental/ObjectCollectionSerializerTest.java
@@ -0,0 +1,29 @@
+package com.keuin.kbackupfabric.util.backup.incremental;
+
+import com.keuin.kbackupfabric.util.backup.incremental.identifier.Sha256Identifier;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+
+import static org.junit.Assert.assertEquals;
+
+public class ObjectCollectionSerializerTest {
+    @Test
+    public void testSerializationConsistency() throws IOException {
+        ObjectCollectionFactory<Sha256Identifier> factory =
+                new ObjectCollectionFactory<>(Sha256Identifier.getFactory());
+        ObjectCollection collection =
+                factory.fromDirectory(new File("./testfile/ObjectCollectionFactoryTest"));
+        File file = new File("./testfile/serialized");
+        if (file.exists()) {
+            Files.delete(file.toPath());
+        }
+        ObjectCollectionSerializer.toFile(collection, file);
+        ObjectCollection collection2 = ObjectCollectionSerializer.fromFile(file);
+        Files.delete(file.toPath());
+        assertEquals(collection, collection2);
+    }
+
+}
\ No newline at end of file