package com.nhaarman.listviewanimations.itemmanipulation;
import android.util.Pair;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A class to insert items only when there are no active items.
* A pending index-item pair can have two states: active and pending. When inserting new items, the {@link com.nhaarman.listviewanimations.itemmanipulation.AnimateAdditionAdapter.Insertable#add
* (int, Object)} method will be called directly if there are no active index-item pairs.
* Otherwise, pairs will be queued until the active list is empty.
*/
public class InsertQueue<T> {
private final AnimateAdditionAdapter.Insertable<T> mInsertable;
private final Set<AtomicInteger> mActiveIndexes = new HashSet<AtomicInteger>();
private final List<Pair<Integer, T>> mPendingItemsToInsert = new ArrayList<Pair<Integer, T>>();
public InsertQueue(final AnimateAdditionAdapter.Insertable<T> insertable) {
mInsertable = insertable;
}
/**
* Insert an item into the queue at given index. Will directly call {@link com.nhaarman.listviewanimations.itemmanipulation.AnimateAdditionAdapter.Insertable#add(int,
* Object)} if there are no active index-item pairs. Otherwise, the pair will be queued.
* @param index the index at which the item should be inserted.
* @param item the item to insert.
*/
public void insert(final int index, final T item) {
if (mActiveIndexes.isEmpty() && mPendingItemsToInsert.isEmpty()) {
mActiveIndexes.add(new AtomicInteger(index));
//noinspection unchecked
mInsertable.add(index, item);
} else {
mPendingItemsToInsert.add(new Pair<Integer, T>(index, item));
}
}
@SuppressWarnings("UnusedDeclaration")
public void insert(final Pair<Integer, T>... indexItemPair) {
insert(Arrays.asList(indexItemPair));
}
public void insert(final List<Pair<Integer, T>> indexItemPairs) {
if (mActiveIndexes.isEmpty() && mPendingItemsToInsert.isEmpty()) {
for (Pair<Integer, T> pair : indexItemPairs) {
for (AtomicInteger existing : mActiveIndexes) {
if (existing.intValue() >= pair.first) {
existing.incrementAndGet();
}
}
mActiveIndexes.add(new AtomicInteger(pair.first));
mInsertable.add(pair.first, pair.second);
}
} else {
mPendingItemsToInsert.addAll(indexItemPairs);
}
}
/**
* Clears the active states and inserts any pending pairs if applicable.
*/
public void clearActive() {
mActiveIndexes.clear();
insertPending();
}
/**
* Clear the active state for given index. Will insert any pending pairs if this call leads to a state where there are no active pairs.
* @param index the index to remove.
*/
public void removeActiveIndex(final int index) {
boolean found = false;
for (Iterator<AtomicInteger> iterator = mActiveIndexes.iterator(); iterator.hasNext() && !found; ) {
if (iterator.next().get() == index) {
iterator.remove();
found = true;
}
}
if (mActiveIndexes.isEmpty()) {
insertPending();
}
}
/**
* Inserts pending items into the Insertable, and adds them to the active positions (correctly managing position shifting). Clears the pending items.
*/
private void insertPending() {
for (Pair<Integer, T> pi : mPendingItemsToInsert) {
for (AtomicInteger existing : mActiveIndexes) {
if (existing.intValue() >= pi.first) {
existing.incrementAndGet();
}
}
mActiveIndexes.add(new AtomicInteger(pi.first));
mInsertable.add(pi.first, pi.second);
}
mPendingItemsToInsert.clear();
}
/**
* Returns a collection of currently active indexes.
*/
public Collection<Integer> getActiveIndexes() {
HashSet<Integer> result = new HashSet<Integer>();
for (AtomicInteger i : mActiveIndexes) {
result.add(i.get());
}
return result;
}
/**
* Returns a {@code List} of {@code Pair}s with the index and items that are pending to be inserted, in the order they were requested.
*/
public List<Pair<Integer, T>> getPendingItemsToInsert() {
return mPendingItemsToInsert;
}
}