New OPDS.XML DTD and Catalog loading changes

git-svn-id: https://only.mawhrin.net/repos/FBReaderJ/trunk@1619 6a642e6f-84f6-412e-ac94-c4a38d5a04b0

TODO.network

@@ -10,8 +10,7 @@ DONE сделать SeekBar (как в ветке alex) в пункте Navigate
 
 DONE каталог должен иметь не 2 состояния (загружен/не загружен), а загружен полностью/не полностью/не загружен:
      в случае загрузки "не полностью" при повторном открытии продолжать загрузку с точки, где прервались (для тех каталогов, что поделены на куски по 20 книг)
-     ** по-умолчанию сделать отбрасывание элементов недогруженных страниц
+DONE по-умолчанию сделать отбрасывание элементов недогруженных страниц (плюс свойство OPDSLink'ов hasStableIdentifiers)
-        (плюс свойство OPDSLink'ов, подтверждающее стабильность идентификаторов)
 *  3 иконки в верхнем-правом углу для книжек
 
 DONE регистрация новых пользователей -- в диалоге authentication

data/network/catalog.dtd

@@ -0,0 +1,56 @@
+<!ELEMENT catalog (site,title,summary?,link+,advancedSearch?,relationAliases?,feeds?,authentication?,urlRewritingRules?,icon)>
+<!ATTLIST catalog 
+	type (opds) #REQUIRED
+	hasStableIdentifiers (true|false) "false"
+>
+
+<!ELEMENT site (#PCDATA)>
+<!ELEMENT title (#PCDATA)>
+<!ELEMENT summary (#PCDATA)>
+<!ELEMENT icon (#PCDATA)>
+
+<!ELEMENT link (#PCDATA)>
+<!ATTLIST link 
+	rel (main|search|signIn|signOut|signUp|refillAccount|recoverPassword) #REQUIRED
+	type CDATA #REQUIRED
+>
+
+<!ELEMENT relationAliases (alias+)>
+<!ELEMENT alias EMPTY>
+<!ATTLIST alias
+	alias CDATA #REQUIRED
+	name CDATA #REQUIRED
+	type CDATA ""
+>
+
+<!ELEMENT advancedSearch (field+)>
+<!ATTLIST advancedSearch
+	style (separateWords|quoted) #REQUIRED
+>
+
+<!ELEMENT field (#PCDATA)>
+<!ATTLIST field
+	name (author|titleOrSeries|tag|annotation) #REQUIRED
+>
+
+<!ELEMENT feeds (condition+)>
+
+<!ELEMENT condition (#PCDATA)>
+<!ATTLIST condition
+	show (never|signedIn) #REQUIRED
+>
+
+<!ELEMENT authentication EMPTY>
+<!ATTLIST authentication
+	type (basic|litres) #REQUIRED
+>
+
+<!ELEMENT urlRewritingRules (rule+)>
+
+<!ELEMENT rule EMPTY>
+<!ATTLIST rule
+	type (addUrlParameter) #REQUIRED
+	apply (always|external|internal) "always"
+	name CDATA #REQUIRED
+	value CDATA #REQUIRED
+>

data/network/feedbooks.com.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE catalog SYSTEM "catalog.dtd">
-<catalog type="opds">
+<catalog type="opds" hasStableIdentifiers="true">
 	<site>feedbooks.com</site>
 	<title>Feedbooks OPDS Catalog</title>
 	<summary>Feedbooks: Food for the mind. A place to discover and publish e-books.</summary>

data/network/litres.ru.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE catalog SYSTEM "catalog.dtd">
-<catalog type="opds">
+<catalog type="opds" hasStableIdentifiers="true">
 	<site>litres.ru</site>
 	<title>Каталог LitRes</title>
 	<summary>Продажа электронных книг.</summary>

src/org/geometerplus/android/fbreader/network/AddCustomCatalogItemTree.java

@@ -21,6 +21,7 @@ package org.geometerplus.android.fbreader.network;
 
 import org.geometerplus.zlibrary.core.resources.ZLResource;
 
+import org.geometerplus.fbreader.network.NetworkLibraryItem;
 import org.geometerplus.fbreader.network.NetworkTree;
 
 
@@ -39,4 +40,9 @@ public class AddCustomCatalogItemTree extends NetworkTree {
 	public String getSummary() {
 		return null;
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
 }

src/org/geometerplus/android/fbreader/network/ItemsLoadingHandler.java

@@ -19,12 +19,16 @@
 
 package org.geometerplus.android.fbreader.network;
 
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Set;
 
 import android.os.Message;
 import android.os.Handler;
 
+import org.geometerplus.fbreader.network.INetworkLink;
 import org.geometerplus.fbreader.network.NetworkLibraryItem;
 
 
@@ -34,15 +38,31 @@ abstract class ItemsLoadingHandler extends Handler {
 	private static final int WHAT_FINISHED = 1;
 
 	private final LinkedList<NetworkLibraryItem> myItems = new LinkedList<NetworkLibraryItem>();
+	private final HashMap<INetworkLink, LinkedList<NetworkLibraryItem>> myUncommitedItems = new HashMap<INetworkLink, LinkedList<NetworkLibraryItem>>();
 	private final Object myItemsMonitor = new Object();
 
 	private volatile boolean myFinishProcessed;
 	private final Object myFinishMonitor = new Object();
 
 
-	public final void addItem(NetworkLibraryItem item) {
+	public final void addItem(INetworkLink link, NetworkLibraryItem item) {
 		synchronized (myItemsMonitor) {
 			myItems.add(item);
+			LinkedList<NetworkLibraryItem> uncommited = myUncommitedItems.get(link);
+			if (uncommited == null) {
+				uncommited = new LinkedList<NetworkLibraryItem>();
+				myUncommitedItems.put(link, uncommited);
+			}
+			uncommited.add(item);
+		}
+	}
+
+	public final void commitItems(INetworkLink link) {
+		synchronized (myItemsMonitor) {
+			LinkedList<NetworkLibraryItem> uncommited = myUncommitedItems.get(link);
+			if (uncommited != null) {
+				uncommited.clear();
+			}
 		}
 	}
 
@@ -78,8 +98,14 @@ abstract class ItemsLoadingHandler extends Handler {
 	}
 
 	private final void doProcessFinish(String errorMessage, boolean interrupted) {
+		HashSet<NetworkLibraryItem> uncommitedItems = new HashSet<NetworkLibraryItem>();
+		synchronized (myUncommitedItems) {
+			for (LinkedList<NetworkLibraryItem> items: myUncommitedItems.values()) {
+				uncommitedItems.addAll(items);
+			}
+		}
 		synchronized (myFinishMonitor) {
-			onFinish(errorMessage, interrupted);
+			onFinish(errorMessage, interrupted, uncommitedItems);
 			myFinishProcessed = true;
 			myFinishMonitor.notifyAll(); // wake up process, that waits for finish condition (see ensureFinish() method)
 		}
@@ -100,7 +126,7 @@ abstract class ItemsLoadingHandler extends Handler {
 	// callbacks
 	public abstract void onUpdateItems(List<NetworkLibraryItem> items);
 	public abstract void afterUpdateItems();
-	public abstract void onFinish(String errorMessage, boolean interrupted);
+	public abstract void onFinish(String errorMessage, boolean interrupted, Set<NetworkLibraryItem> uncommitedItems);
 
 
 	@Override

src/org/geometerplus/android/fbreader/network/ItemsLoadingRunnable.java

@@ -22,6 +22,7 @@ package org.geometerplus.android.fbreader.network;
 import android.os.Message;
 import android.os.Handler;
 
+import org.geometerplus.fbreader.network.INetworkLink;
 import org.geometerplus.fbreader.network.NetworkOperationData;
 import org.geometerplus.fbreader.network.NetworkLibraryItem;
 
@@ -98,8 +99,8 @@ abstract class ItemsLoadingRunnable implements Runnable {
 		err = doLoading(new NetworkOperationData.OnNewItemListener() {
 			private long myUpdateTime;
 			private int myItemsNumber;
-			public void onNewItem(NetworkLibraryItem item) {
+			public void onNewItem(INetworkLink link, NetworkLibraryItem item) {
-				myHandler.addItem(item);
+				myHandler.addItem(link, item);
 				++myItemsNumber;
 				final long now = System.currentTimeMillis();
 				if (now > myUpdateTime) {
@@ -110,6 +111,9 @@ abstract class ItemsLoadingRunnable implements Runnable {
 			public boolean confirmInterrupt() {
 				return confirmInterruptLoading() || myItemsNumber >= ItemsLimit;
 			}
+			public void commitItems(INetworkLink link) {
+				myHandler.commitItems(link);
+			}
 		});
 		myHandler.sendUpdateItems();
 		myHandler.ensureItemsProcessed();

src/org/geometerplus/android/fbreader/network/NetworkCatalogActions.java

@@ -20,6 +20,7 @@
 package org.geometerplus.android.fbreader.network;
 
 import java.util.List;
+import java.util.Set;
 
 import android.app.AlertDialog;
 import android.os.Message;
@@ -274,6 +275,7 @@ class NetworkCatalogActions extends NetworkTreeActions {
 			myKey = key;
 		}
 
+		@Override
 		public void onUpdateItems(List<NetworkLibraryItem> items) {
 			for (NetworkLibraryItem item: items) {
 				myTree.ChildrenItems.add(item);
@@ -281,20 +283,26 @@ class NetworkCatalogActions extends NetworkTreeActions {
 			}
 		}
 
+		@Override
 		public void afterUpdateItems() {
 			if (NetworkView.Instance().isInitialized()) {
 				NetworkView.Instance().fireModelChanged();
 			}
 		}
 
-		public void onFinish(String errorMessage, boolean interrupted) {
+		@Override
+		public void onFinish(String errorMessage, boolean interrupted,
+				Set<NetworkLibraryItem> uncommitedItems) {
 			if (interrupted &&
 					(!myTree.Item.supportsResumeLoading() || errorMessage != null)) {
 				myTree.ChildrenItems.clear();
 				myTree.clear();
 			} else {
+				myTree.removeItems(uncommitedItems);
 				myTree.updateLoadedTime();
+				if (!interrupted) {
 					afterUpdateCatalog(errorMessage, myTree.ChildrenItems.size() == 0);
+				}
 				final NetworkLibrary library = NetworkLibrary.Instance();
 				library.invalidateVisibility();
 				library.synchronize();

src/org/geometerplus/android/fbreader/network/NetworkSearchActivity.java

@@ -20,6 +20,7 @@
 package org.geometerplus.android.fbreader.network;
 
 import java.util.List;
+import java.util.Set;
 
 import android.app.AlertDialog;
 import android.app.Activity;
@@ -62,6 +63,7 @@ public class NetworkSearchActivity extends Activity {
 			myTree = tree;
 		}
 
+		@Override
 		public void onUpdateItems(List<NetworkLibraryItem> items) {
 			SearchResult result = myTree.getSearchResult();
 			for (NetworkLibraryItem item: items) {
@@ -71,6 +73,7 @@ public class NetworkSearchActivity extends Activity {
 			}
 		}
 
+		@Override
 		public void afterUpdateItems() {
 			myTree.updateSubTrees();
 			if (NetworkView.Instance().isInitialized()) {
@@ -78,7 +81,9 @@ public class NetworkSearchActivity extends Activity {
 			}
 		}
 
-		public void onFinish(String errorMessage, boolean interrupted) {
+		@Override
+		public void onFinish(String errorMessage, boolean interrupted,
+				Set<NetworkLibraryItem> uncommitedItems) {
 			if (interrupted) {
 				myTree.setSearchResult(null);
 			} else {

src/org/geometerplus/android/fbreader/network/RefillAccountTree.java

@@ -24,6 +24,7 @@ import org.geometerplus.zlibrary.core.resources.ZLResource;
 import org.geometerplus.zlibrary.core.util.ZLBoolean3;
 
 import org.geometerplus.fbreader.network.INetworkLink;
+import org.geometerplus.fbreader.network.NetworkLibraryItem;
 import org.geometerplus.fbreader.network.NetworkTree;
 import org.geometerplus.fbreader.network.tree.NetworkCatalogTree;
 import org.geometerplus.fbreader.network.authentication.NetworkAuthenticationManager;
@@ -61,4 +62,9 @@ class RefillAccountTree extends NetworkTree {
 	protected ZLImage createCover() {
 		return Cover;
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
 }

src/org/geometerplus/android/fbreader/network/SearchItemTree.java

@@ -99,4 +99,9 @@ public class SearchItemTree extends NetworkTree {
 			throw new RuntimeException("That's impossible!!!");
 		}
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
 }

src/org/geometerplus/fbreader/network/NetworkLibrary.java

@@ -411,12 +411,15 @@ public class NetworkLibrary {
 		LinkedList<NetworkOperationData> dataList = new LinkedList<NetworkOperationData>();
 
 		final NetworkOperationData.OnNewItemListener synchronizedListener = new NetworkOperationData.OnNewItemListener() {
-			public synchronized void onNewItem(NetworkLibraryItem item) {
+			public synchronized void onNewItem(INetworkLink link, NetworkLibraryItem item) {
-				listener.onNewItem(item);
+				listener.onNewItem(link, item);
 			}
 			public synchronized boolean confirmInterrupt() {
 				return listener.confirmInterrupt();
 			}
+			public synchronized void commitItems(INetworkLink link) {
+				listener.commitItems(link);
+			}
 		};
 
 		synchronized (myLinks) {

src/org/geometerplus/fbreader/network/NetworkOperationData.java

@@ -25,9 +25,12 @@ import org.geometerplus.zlibrary.core.network.ZLNetworkRequest;
 public class NetworkOperationData {
 
 	public interface OnNewItemListener {
-		void onNewItem(NetworkLibraryItem item);
+		void onNewItem(INetworkLink link, NetworkLibraryItem item);
 
-		// return true to confirm interrupt reading; return false to continue reading
+		void commitItems(INetworkLink link);
+
+		// returns true to confirm interrupt reading; return false to continue reading.
+		// once true has been returned, all next calls must return true.
 		boolean confirmInterrupt();
 	}
 

src/org/geometerplus/fbreader/network/NetworkTree.java

@@ -19,6 +19,9 @@
 
 package org.geometerplus.fbreader.network;
 
+import java.util.LinkedList;
+import java.util.Set;
+
 import org.geometerplus.fbreader.tree.FBTree;
 
 import org.geometerplus.zlibrary.core.image.ZLImage;
@@ -80,4 +83,33 @@ public abstract class NetworkTree extends FBTree {
 		}
 		return null;
 	}
+
+
+	public abstract NetworkLibraryItem getHoldedItem();
+
+	public void removeItems(Set<NetworkLibraryItem> items) {
+		if (items.isEmpty() || subTrees().isEmpty()) {
+			return;
+		}
+		final LinkedList<FBTree> treesList = new LinkedList<FBTree>();
+		for (FBTree tree: subTrees()) {
+			final NetworkLibraryItem treeItem = ((NetworkTree)tree).getHoldedItem();
+			if (treeItem != null && items.contains(treeItem)) {
+				treesList.add(tree);
+				items.remove(treeItem);
+			}
+		}
+		for (FBTree tree: treesList) {
+			tree.removeSelf();
+		}
+		if (items.isEmpty()) {
+			return;
+		}
+		treesList.clear();
+		treesList.addAll(subTrees());
+		while (!treesList.isEmpty()) {
+			final NetworkTree tree = (NetworkTree) treesList.remove(treesList.size() - 1);
+			tree.removeItems(items);
+		}
+	}
 }

src/org/geometerplus/fbreader/network/authentication/litres/LitResBookshelfItem.java

@@ -64,8 +64,9 @@ public class LitResBookshelfItem extends NetworkCatalogItem {
 		mgr.collectPurchasedBooks(children);
 		Collections.sort(children, new NetworkBookItemComparator());
 		for (NetworkLibraryItem item: children) {
-			listener.onNewItem(item);
+			listener.onNewItem(Link, item);
 		}
+		listener.commitItems(Link);
 		return error;
 	}
 }

src/org/geometerplus/fbreader/network/opds/NetworkOPDSFeedReader.java

@@ -36,7 +36,7 @@ class NetworkOPDSFeedReader implements OPDSFeedReader {
 	private int myIndex;
 
 	private String myNextURL;
-	private String mySkipUntilTitle;
+	private String mySkipUntilId;
 
 	private int myItemsToLoad = -1;
 
@@ -50,7 +50,7 @@ class NetworkOPDSFeedReader implements OPDSFeedReader {
 	NetworkOPDSFeedReader(String baseURL, OPDSCatalogItem.State result) {
 		myBaseURL = baseURL;
 		myData = result;
-		mySkipUntilTitle = myData.LastLoadedTitle;
+		mySkipUntilId = myData.LastLoadedId;
 		if (!(result.Link instanceof OPDSLink)) {
 			throw new IllegalArgumentException("Parameter `result` has invalid `Link` field value: result.Link must be an instance of OPDSLink class.");
 		}
@@ -91,14 +91,14 @@ class NetworkOPDSFeedReader implements OPDSFeedReader {
 	}
 
 	public void processFeedEnd() {
-		if (mySkipUntilTitle != null) {
+		if (mySkipUntilId != null) {
 			// Last loaded element was not found => resume error => DO NOT RESUME
 			// TODO: notify user about error???
 			// TODO: do reload???
 			myNextURL = null;
 		}
 		myData.ResumeURI = myNextURL;
-		myData.LastLoadedTitle = null;
+		myData.LastLoadedId = null;
 	}
 
 
@@ -142,13 +142,13 @@ class NetworkOPDSFeedReader implements OPDSFeedReader {
 			--myItemsToLoad;
 		}
 
-		if (mySkipUntilTitle != null) {
+		if (mySkipUntilId != null) {
-			if (mySkipUntilTitle.equals(entry.Title)) {
+			if (mySkipUntilId.equals(entry.Id.Uri)) {
-				mySkipUntilTitle = null;
+				mySkipUntilId = null;
 			}
 			return tryInterrupt();
 		}
-		myData.LastLoadedTitle = entry.Title;
+		myData.LastLoadedId = entry.Id.Uri;
 
 		final OPDSLink opdsLink = (OPDSLink) myData.Link;
 		if (opdsLink.getCondition(entry.Id.Uri) == OPDSLink.FeedCondition.NEVER) {
@@ -176,7 +176,7 @@ class NetworkOPDSFeedReader implements OPDSFeedReader {
 			item = readCatalogItem(entry);
 		}
 		if (item != null) {
-			myData.Listener.onNewItem(item);
+			myData.Listener.onNewItem(myData.Link, item);
 		}
 		return tryInterrupt();
 	}

src/org/geometerplus/fbreader/network/opds/OPDSCatalogItem.java

@@ -31,7 +31,7 @@ class OPDSCatalogItem extends NetworkCatalogItem {
 
 	static class State extends NetworkOperationData {
 
-		public String LastLoadedTitle;
+		public String LastLoadedId;
 
 		public State(INetworkLink link, OnNewItemListener listener) {
 			super(link, listener);

src/org/geometerplus/fbreader/network/opds/OPDSCustomLink.java

@@ -30,7 +30,7 @@ class OPDSCustomLink extends OPDSLink implements ICustomNetworkLink {
 	private SaveLinkListener myListener;
 
 	OPDSCustomLink(int id, String siteName, String title, String summary, String icon, Map<String, String> links) {
-		super(siteName, title, summary, icon, links);
+		super(siteName, title, summary, icon, links, false);
 		myId = id;
 	}
 

src/org/geometerplus/fbreader/network/opds/OPDSLink.java

@@ -45,8 +45,12 @@ class OPDSLink extends AbstractNetworkLink {
 	private LinkedList<URLRewritingRule> myUrlRewritingRules;
 	private NetworkAuthenticationManager myAuthenticationManager;
 
-	OPDSLink(String siteName, String title, String summary, String icon, Map<String, String> links) {
+	private final boolean myHasStableIdentifiers;
+
+	OPDSLink(String siteName, String title, String summary, String icon,
+			Map<String, String> links, boolean hasStableIdentifiers) {
 		super(siteName, title, summary, icon, links);
+		myHasStableIdentifiers = hasStableIdentifiers;
 	}
 
 	final void setRelationAliases(Map<RelationAlias, String> relationAliases) {
@@ -88,9 +92,23 @@ class OPDSLink extends AbstractNetworkLink {
 				if (result.Listener.confirmInterrupt()) {
 					return null;
 				}
+
 				new OPDSXMLReader(
 					new NetworkOPDSFeedReader(URL, result)
 				).read(inputStream);
+
+				if (result.Listener.confirmInterrupt()) {
+					if (!myHasStableIdentifiers && result.LastLoadedId != null) {
+						// If current catalog doesn't have stable identifiers
+						// and catalog wasn't completely loaded (i.e. LastLoadedIdentifier is not null)
+						// then reset state to load current page from the beginning 
+						result.LastLoadedId = null;
+					} else {
+						result.Listener.commitItems(OPDSLink.this);
+					}
+				} else {
+					result.Listener.commitItems(OPDSLink.this);
+				}
 				return null;
 			}
 		};

src/org/geometerplus/fbreader/network/opds/OPDSLinkReader.java

@@ -36,6 +36,7 @@ public class OPDSLinkReader extends ZLXMLReaderAdapter {
 	private String myTitle;
 	private String mySummary;
 	private String myIcon;
+	private boolean myHasStableIdentifiers;
 
 	private final HashMap<String, String> myLinks = new HashMap<String, String>();
 
@@ -60,7 +61,8 @@ public class OPDSLinkReader extends ZLXMLReaderAdapter {
 			myTitle,
 			mySummary,
 			myIcon,
-			myLinks
+			myLinks,
+			myHasStableIdentifiers
 		);
 
 		/*if (!mySearchType.empty()) {
@@ -102,6 +104,7 @@ public class OPDSLinkReader extends ZLXMLReaderAdapter {
 
 	public INetworkLink readDocument(ZLFile file) {
 		mySiteName = myTitle = mySummary = myIcon = /*mySearchType = */myAuthenticationType = mySSLCertificate = null;
+		myHasStableIdentifiers = false;
 		myLinks.clear();
 		mySearchFields.clear();
 		myUrlConditions.clear();
@@ -126,6 +129,7 @@ public class OPDSLinkReader extends ZLXMLReaderAdapter {
 	}
 
 
+	private static final String TAG_CATALOG = "catalog";
 	private static final String TAG_SITE = "site";
 	private static final String TAG_LINK = "link";
 	private static final String TAG_TITLE = "title";
@@ -163,7 +167,10 @@ public class OPDSLinkReader extends ZLXMLReaderAdapter {
 	@Override
 	public boolean startElementHandler(String tag, ZLStringMap attributes) {
 		tag = tag.intern();
-		if (TAG_SITE == tag) {
+		if (TAG_CATALOG == tag) {
+			 final String value = attributes.getValue("hasStableIdentifiers");
+			 myHasStableIdentifiers = value != null && value.equals("true");
+		} else if (TAG_SITE == tag) {
 			myState = READ_SITENAME;
 		} else if (TAG_TITLE == tag) {
 			myState = READ_TITLE;

src/org/geometerplus/fbreader/network/tree/NetworkAuthorTree.java

@@ -118,4 +118,9 @@ public class NetworkAuthorTree extends NetworkTree {
 
 		myBooksNumber = books.size();
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
 }

src/org/geometerplus/fbreader/network/tree/NetworkBookTree.java

@@ -67,4 +67,9 @@ public class NetworkBookTree extends NetworkTree {
 	protected ZLImage createCover() {
 		return createCover(Book);
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return Book;
+	}
 }

src/org/geometerplus/fbreader/network/tree/NetworkCatalogTree.java

@@ -156,4 +156,15 @@ public class NetworkCatalogTree extends NetworkTree {
 			tree.removeSelf();
 		}
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return Item;
+	}
+
+	@Override
+	public void removeItems(Set<NetworkLibraryItem> items) {
+		ChildrenItems.removeAll(items);
+		super.removeItems(items);
+	}
 }

src/org/geometerplus/fbreader/network/tree/NetworkSeriesTree.java

@@ -85,4 +85,17 @@ public class NetworkSeriesTree extends NetworkTree {
 		}
 		return null;
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
+
+	@Override
+	public void removeItems(Set<NetworkLibraryItem> items) {
+		super.removeItems(items);
+		if (subTrees().isEmpty()) {
+			removeSelf();
+		}
+	}
 }

src/org/geometerplus/fbreader/network/tree/RootTree.java

@@ -19,6 +19,7 @@
 
 package org.geometerplus.fbreader.network.tree;
 
+import org.geometerplus.fbreader.network.NetworkLibraryItem;
 import org.geometerplus.fbreader.network.NetworkTree;
 
 public final class RootTree extends NetworkTree {
@@ -26,4 +27,9 @@ public final class RootTree extends NetworkTree {
 	public String getName() {
 		return null;
 	}
+
+	@Override
+	public NetworkLibraryItem getHoldedItem() {
+		return null;
+	}
 }