1 files changed, 188 insertions, 0 deletions
diff --git a/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java b/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java
new file mode 100644
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--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java
@@ -0,0 +1,188 @@
+package com.keuin.kbackupfabric.backup.incremental.manager;
+
+import com.keuin.kbackupfabric.backup.incremental.ObjectCollection;
+import com.keuin.kbackupfabric.backup.incremental.ObjectElement;
+import com.keuin.kbackupfabric.backup.incremental.identifier.ObjectIdentifier;
+import com.keuin.kbackupfabric.backup.incremental.identifier.StorageObjectLoader;
+import com.keuin.kbackupfabric.util.PrintUtil;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.*;
+
+import static org.apache.commons.io.FileUtils.forceDelete;
+
+public class IncrementalBackupStorageManager {
+
+    private final Path backupStorageBase;
+    private final Map<ObjectIdentifier, File> map = new HashMap<>();
+    private boolean loaded = false;
+
+    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 {
+        if (!backupStorageBase.toFile().isDirectory()) {
+            if (!backupStorageBase.toFile().mkdirs())
+                throw new IOException("Backup storage base directory does not exist, and failed to create it.");
+        }
+        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;
+
+        // touch directory
+        if (!collectionBasePath.exists()) {
+            int retryCounter = 0;
+            boolean success = false;
+            while (retryCounter++ < 5) {
+                if (collectionBasePath.mkdirs()) {
+                    success = true;
+                    break;
+                }
+            }
+            if (!success) {
+                throw new IOException("Failed to create directory " + collectionBasePath.getAbsolutePath());
+            }
+        }
+
+        // copy sub files
+        for (Map.Entry<String, ObjectElement> entry : collection.getElementMap().entrySet()) {
+            File copySource = new File(backupStorageBase.toFile(), entry.getValue().getIdentifier().getIdentification());
+            File copyTarget = new File(collectionBasePath.getAbsolutePath(), entry.getKey());
+
+            if (!baseContainsObject(entry.getValue())) {
+                throw new IOException(String.format("File %s does not exist in the base.", copySource.getName()));
+            }
+            if (copyTarget.exists()) {
+                boolean successDeleting = false;
+                for (int i = 0; i < 5; ++i) {
+                    try {
+                        forceDelete(copyTarget);
+                        successDeleting = true;
+                        break;
+                    } catch (FileNotFoundException ignored) {
+                        break;
+                    } catch (IOException e) {
+                        PrintUtil.error(String.format("Failed to delete file %s, retry.", copyTarget.getName()));
+                    }
+                }
+                if (!successDeleting) {
+                    String msg = String.format("Failed to delete file %s.", copyTarget.getName());
+                    PrintUtil.error(msg);
+                    throw new IOException(msg);
+                }
+            }
+
+            Files.copy(copySource.toPath(), copyTarget.toPath());
+            ++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;
+    }
+
+    public int cleanUnusedObjects(Iterable<ObjectCollection> collectionIterable) {
+        // construct object list in memory
+        Set<String> objects = new HashSet<>();
+//        backupStorageBase
+
+        for (ObjectCollection collection : collectionIterable) {
+            for (ObjectElement ele : collection.getElementMap().values()) {
+
+            }
+        }
+        throw new RuntimeException("not impl");
+    }
+
+    /**
+     * Check all objects, return unused ones.
+     *
+     * @return the unused ones.
+     */
+    private Map<ObjectIdentifier, File> markUnusedObjects() {
+        throw new RuntimeException("not impl");
+    }
+
+    /**
+     * 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();
+    }
+
+    private void lazyLoadStorage() throws IOException {
+        if (!loaded) {
+            loadStorage();
+            loaded = true;
+        }
+    }
+
+    private synchronized void loadStorage() throws IOException {
+        map.clear();
+        Files.walk(backupStorageBase, 1).forEach(path -> {
+            File file = path.toFile();
+            ObjectIdentifier identifier = StorageObjectLoader.asIdentifier(file);
+            if (identifier == null) {
+                map.clear();
+                throw new IllegalStateException(String.format(
+                        "Bad storage object %s: cannot recognize identifier.", file.getName()
+                ));
+            }
+            map.put(identifier, file);
+        });
+    }
+
+}