/* Licensed 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.activiti.explorer.data;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.activiti.engine.ActivitiException;
import com.vaadin.data.Container;
import com.vaadin.data.Item;
import com.vaadin.data.Property;
/**
* Inspired on the LazyQueryContainer add-on for Vaadin
* (https://github.com/tlaukkan/vaadin-lazyquerycontainer)
*
* @author Joram Barrez
*/
public class LazyLoadingContainer implements Container.Indexed, Container.Sortable{
private static final long serialVersionUID = 1L;
protected LazyLoadingQuery lazyLoadingQuery;
protected int batchSize;
protected int size = -1;
protected List<Object> containerPropertyIds = new ArrayList<Object>();
protected Map<Object, Class<?>> containerPropertyTypes = new HashMap<Object, Class<?>>();
protected Map<Object, Object> containerPropertyDefaultValues = new HashMap<Object, Object>();
protected Map<Integer, Item> itemCache = new HashMap<Integer, Item>();
public LazyLoadingContainer(LazyLoadingQuery lazyLoadingQuery, int batchSize) {
this.lazyLoadingQuery = lazyLoadingQuery;
this.batchSize = batchSize;
lazyLoadingQuery.setLazyLoadingContainer(this);
}
public LazyLoadingContainer(LazyLoadingQuery lazyLoadingQuery) {
this(lazyLoadingQuery, 15);
}
public boolean addContainerProperty(Object propertyId, Class< ? > type, Object defaultValue) throws UnsupportedOperationException {
containerPropertyIds.add(propertyId);
containerPropertyTypes.put(propertyId, type);
containerPropertyDefaultValues.put(propertyId, defaultValue);
return true;
}
public boolean removeContainerProperty(Object propertyId) throws UnsupportedOperationException {
containerPropertyIds.remove(propertyId);
containerPropertyTypes.remove(propertyId);
containerPropertyDefaultValues.remove(propertyId);
return true;
}
public Collection< ? > getContainerPropertyIds() {
return containerPropertyIds;
}
public Class< ? > getType(Object propertyId) {
return containerPropertyTypes.get(propertyId);
}
public Object getDefaultValue(Object propertyId) {
return containerPropertyDefaultValues.get(propertyId);
}
public Property getContainerProperty(Object itemId, Object propertyId) {
return getItem(itemId).getItemProperty(propertyId);
}
public boolean containsId(Object itemId) {
Integer index = (Integer) itemId;
return index >= 0 && index < size();
}
public Item getItem(Object itemId) {
if(itemId != null) {
if (!itemCache.containsKey(itemId)) {
Integer index = (Integer) itemId;
int start = index - (index%batchSize);
List<Item> batch = lazyLoadingQuery.loadItems(start, batchSize);
for (Item batchItem : batch) {
itemCache.put(start, batchItem);
start++;
}
}
return itemCache.get(itemId);
}
return null;
}
public int size() {
if (size == -1) {
size = lazyLoadingQuery.size();
}
return size;
}
public Collection< ? > getItemIds() {
// We don't need an actual list of elements,
// since we map the ids in natural integer order (0,1,2,3, etc)
// so we can just override the get() and save some memory
return new AbstractList<Integer>() {
public int size() {
return size();
}
public Integer get(int index) {
return index;
}
};
}
public Object firstItemId() {
return 0;
}
public Object lastItemId() {
return size()-1;
}
public boolean isFirstId(Object itemId) {
return ((Integer) itemId).equals(0);
}
public boolean isLastId(Object itemId) {
return ((Integer) itemId).equals(size()-1);
}
public Object nextItemId(Object itemId) {
Integer index = (Integer) itemId;
return index++;
}
public Object prevItemId(Object itemId) {
Integer index = (Integer) itemId;
return index--;
}
public int indexOfId(Object itemId) {
return (Integer) itemId;
}
public Object getIdByIndex(int index) {
return new Integer(index);
}
public Collection< ? > getSortableContainerPropertyIds() {
return containerPropertyIds;
}
public void sort(Object[] propertyIds, boolean[] ascending) {
removeAllItems();
lazyLoadingQuery.setSorting(propertyIds, ascending);
}
public boolean removeAllItems() throws UnsupportedOperationException {
itemCache.clear();
size = -1;
return true;
}
// binary search using the real id of the object, and map it to an index in the container
// id = real id (eg task id)
public int getIndexForObjectId(String id) {
Item searched = lazyLoadingQuery.loadSingleResult((String) id);
if(searched == null) {
return -1;
}
return getIndexForObjectId(searched, 0, size()-1);
}
@SuppressWarnings({"unchecked", "rawtypes"})
public int getIndexForObjectId(Item searched, int low, int high) {
if (high < low) {
return -1; // not found
}
int middle = low + (high-low)/2;
Item result = null;
if (itemCache.containsKey(middle)) {
result = itemCache.get(middle);
} else {
result = lazyLoadingQuery.loadItems(middle, 1).get(0);
itemCache.put(middle, result);
}
if (!(searched instanceof Comparable)
|| !(result instanceof Comparable)) {
throw new ActivitiException("Cannot use the getIndexForObjectId method for non-Comparables");
}
int comparison = ((Comparable) searched).compareTo((Comparable) result);
if (comparison < 0) {
return getIndexForObjectId(searched, low, middle-1);
} else if (comparison > 0) {
return getIndexForObjectId(searched, middle+1, high);
} else {
return middle;
}
}
// Unsupported Operations ----------------------------------------------------------------------
public Object addItem() throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public Object addItemAfter(Object previousItemId) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public Item addItemAfter(Object previousItemId, Object newItemId) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public Object addItemAt(int index) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public Item addItemAt(int index, Object newItemId) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public boolean removeItem(Object itemId) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
public Item addItem(Object itemId) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
}