1 files changed, 95 insertions, 0 deletions
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();
+    }
+
+}