gt:             count = changes.size();
context: /*
   * Copyright (C) 2014 The Android Open Source Project
   *
   * 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.cafemember.messenger.support.widget;
  
  import android.support.annotation.NonNull;
  import android.support.v4.animation.AnimatorCompatHelper;
  import android.support.v4.view.ViewCompat;
  import android.support.v4.view.ViewPropertyAnimatorCompat;
  import android.support.v4.view.ViewPropertyAnimatorListener;
  import org.cafemember.messenger.support.widget.RecyclerView.ViewHolder;
  import android.view.View;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * This implementation of {@link RecyclerView.ItemAnimator} provides basic
   * animations on remove, add, and move events that happen to the items in
   * a RecyclerView. RecyclerView uses a DefaultItemAnimator by default.
   *
   * @see RecyclerView#setItemAnimator(RecyclerView.ItemAnimator)
   */
  public class DefaultItemAnimator extends SimpleItemAnimator {
      private static final boolean DEBUG = false;
  
      private ArrayList<ViewHolder> mPendingRemovals = new ArrayList<>();
      private ArrayList<ViewHolder> mPendingAdditions = new ArrayList<>();
      private ArrayList<MoveInfo> mPendingMoves = new ArrayList<>();
      private ArrayList<ChangeInfo> mPendingChanges = new ArrayList<>();
  
      private ArrayList<ArrayList<ViewHolder>> mAdditionsList = new ArrayList<>();
      private ArrayList<ArrayList<MoveInfo>> mMovesList = new ArrayList<>();
      private ArrayList<ArrayList<ChangeInfo>> mChangesList = new ArrayList<>();
  
      private ArrayList<ViewHolder> mAddAnimations = new ArrayList<>();
      private ArrayList<ViewHolder> mMoveAnimations = new ArrayList<>();
      private ArrayList<ViewHolder> mRemoveAnimations = new ArrayList<>();
      private ArrayList<ViewHolder> mChangeAnimations = new ArrayList<>();
  
      private static class MoveInfo {
          public ViewHolder holder;
          public int fromX, fromY, toX, toY;
  
          private MoveInfo(ViewHolder holder, int fromX, int fromY, int toX, int toY) {
              this.holder = holder;
              this.fromX = fromX;
              this.fromY = fromY;
              this.toX = toX;
              this.toY = toY;
          }
      }
  
      private static class ChangeInfo {
          public ViewHolder oldHolder, newHolder;
          public int fromX, fromY, toX, toY;
          private ChangeInfo(ViewHolder oldHolder, ViewHolder newHolder) {
              this.oldHolder = oldHolder;
              this.newHolder = newHolder;
          }
  
          private ChangeInfo(ViewHolder oldHolder, ViewHolder newHolder,
                  int fromX, int fromY, int toX, int toY) {
              this(oldHolder, newHolder);
              this.fromX = fromX;
              this.fromY = fromY;
              this.toX = toX;
              this.toY = toY;
          }
  
          @Override
          public String toString() {
              return "ChangeInfo{" +
                      "oldHolder=" + oldHolder +
                      ", newHolder=" + newHolder +
                      ", fromX=" + fromX +
                      ", fromY=" + fromY +
                      ", toX=" + toX +
                      ", toY=" + toY +
                      '}';
          }
      }
  
      @Override
      public void runPendingAnimations() {
          boolean removalsPending = !mPendingRemovals.isEmpty();
          boolean movesPending = !mPendingMoves.isEmpty();
          boolean changesPending = !mPendingChanges.isEmpty();
          boolean additionsPending = !mPendingAdditions.isEmpty();
          if (!removalsPending && !movesPending && !additionsPending && !changesPending) {
              // nothing to animate
              return;
          }
          // First, remove stuff
          for (ViewHolder holder : mPendingRemovals) {
              animateRemoveImpl(holder);
          }
          mPendingRemovals.clear();
          // Next, move stuff
          if (movesPending) {
              final ArrayList<MoveInfo> moves = new ArrayList<>();
              moves.addAll(mPendingMoves);
              mMovesList.add(moves);
              mPendingMoves.clear();
              Runnable mover = new Runnable() {
                  @Override
                  public void run() {
                      for (MoveInfo moveInfo : moves) {
                          animateMoveImpl(moveInfo.holder, moveInfo.fromX, moveInfo.fromY,
                                  moveInfo.toX, moveInfo.toY);
                      }
                      moves.clear();
                      mMovesList.remove(moves);
                  }
              };
              if (removalsPending) {
                  View view = moves.get(0).holder.itemView;
                  ViewCompat.postOnAnimationDelayed(view, mover, getRemoveDuration());
              } else {
                  mover.run();
              }
          }
          // Next, change stuff, to run in parallel with move animations
          if (changesPending) {
              final ArrayList<ChangeInfo> changes = new ArrayList<>();
              changes.addAll(mPendingChanges);
              mChangesList.add(changes);
              mPendingChanges.clear();
              Runnable changer = new Runnable() {
                  @Override
                  public void run() {
                      for (ChangeInfo change : changes) {
                          animateChangeImpl(change);
                      }
                      changes.clear();
                      mChangesList.remove(changes);
                  }
              };
              if (removalsPending) {
                  ViewHolder holder = changes.get(0).oldHolder;
                  ViewCompat.postOnAnimationDelayed(holder.itemView, changer, getRemoveDuration());
              } else {
                  changer.run();
              }
          }
          // Next, add stuff
          if (additionsPending) {
              final ArrayList<ViewHolder> additions = new ArrayList<>();
              additions.addAll(mPendingAdditions);
              mAdditionsList.add(additions);
              mPendingAdditions.clear();
              Runnable adder = new Runnable() {
                  public void run() {
                      for (ViewHolder holder : additions) {
                          animateAddImpl(holder);
                      }
                      additions.clear();
                      mAdditionsList.remove(additions);
                  }
              };
              if (removalsPending || movesPending || changesPending) {
                  long removeDuration = removalsPending ? getRemoveDuration() : 0;
                  long moveDuration = movesPending ? getMoveDuration() : 0;
                  long changeDuration = changesPending ? getChangeDuration() : 0;
                  long totalDelay = removeDuration + Math.max(moveDuration, changeDuration);
                  View view = additions.get(0).itemView;
                  ViewCompat.postOnAnimationDelayed(view, adder, totalDelay);
              } else {
                  adder.run();
              }
          }
      }
  
      @Override
      public boolean animateRemove(final ViewHolder holder) {
          resetAnimation(holder);
          mPendingRemovals.add(holder);
          return true;
      }
  
      private void animateRemoveImpl(final ViewHolder holder) {
          final View view = holder.itemView;
          final ViewPropertyAnimatorCompat animation = ViewCompat.animate(view);
          mRemoveAnimations.add(holder);
          animation.setDuration(getRemoveDuration())
                  .alpha(0).setListener(new VpaListenerAdapter() {
              @Override
              public void onAnimationStart(View view) {
                  dispatchRemoveStarting(holder);
              }
  
              @Override
              public void onAnimationEnd(View view) {
                  animation.setListener(null);
                  ViewCompat.setAlpha(view, 1);
                  dispatchRemoveFinished(holder);
                  mRemoveAnimations.remove(holder);
                  dispatchFinishedWhenDone();
              }
          }).start();
      }
  
      @Override
      public boolean animateAdd(final ViewHolder holder) {
          resetAnimation(holder);
          ViewCompat.setAlpha(holder.itemView, 0);
          mPendingAdditions.add(holder);
          return true;
      }
  
      private void animateAddImpl(final ViewHolder holder) {
          final View view = holder.itemView;
          final ViewPropertyAnimatorCompat animation = ViewCompat.animate(view);
          mAddAnimations.add(holder);
          animation.alpha(1).setDuration(getAddDuration()).
                  setListener(new VpaListenerAdapter() {
                      @Override
                      public void onAnimationStart(View view) {
                          dispatchAddStarting(holder);
                      }
                      @Override
                      public void onAnimationCancel(View view) {
                          ViewCompat.setAlpha(view, 1);
                      }
  
                      @Override
                      public void onAnimationEnd(View view) {
                          animation.setListener(null);
                          dispatchAddFinished(holder);
                          mAddAnimations.remove(holder);
                          dispatchFinishedWhenDone();
                      }
                  }).start();
      }
  
      @Override
      public boolean animateMove(final ViewHolder holder, int fromX, int fromY,
              int toX, int toY) {
          final View view = holder.itemView;
          fromX += ViewCompat.getTranslationX(holder.itemView);
          fromY += ViewCompat.getTranslationY(holder.itemView);
          resetAnimation(holder);
          int deltaX = toX - fromX;
          int deltaY = toY - fromY;
          if (deltaX == 0 && deltaY == 0) {
              dispatchMoveFinished(holder);
              return false;
          }
          if (deltaX != 0) {
              ViewCompat.setTranslationX(view, -deltaX);
          }
          if (deltaY != 0) {
              ViewCompat.setTranslationY(view, -deltaY);
          }
          mPendingMoves.add(new MoveInfo(holder, fromX, fromY, toX, toY));
          return true;
      }
  
      private void animateMoveImpl(final ViewHolder holder, int fromX, int fromY, int toX, int toY) {
          final View view = holder.itemView;
          final int deltaX = toX - fromX;
          final int deltaY = toY - fromY;
          if (deltaX != 0) {
              ViewCompat.animate(view).translationX(0);
          }
          if (deltaY != 0) {
              ViewCompat.animate(view).translationY(0);
          }
          // TODO: make EndActions end listeners instead, since end actions aren't called when
          // vpas are canceled (and can't end them. why?)
          // need listener functionality in VPACompat for this. Ick.
          final ViewPropertyAnimatorCompat animation = ViewCompat.animate(view);
          mMoveAnimations.add(holder);
          animation.setDuration(getMoveDuration()).setListener(new VpaListenerAdapter() {
              @Override
              public void onAnimationStart(View view) {
                  dispatchMoveStarting(holder);
              }
              @Override
              public void onAnimationCancel(View view) {
                  if (deltaX != 0) {
                      ViewCompat.setTranslationX(view, 0);
                  }
                  if (deltaY != 0) {
                      ViewCompat.setTranslationY(view, 0);
                  }
              }
              @Override
              public void onAnimationEnd(View view) {
                  animation.setListener(null);
                  dispatchMoveFinished(holder);
                  mMoveAnimations.remove(holder);
                  dispatchFinishedWhenDone();
              }
          }).start();
      }
  
      @Override
      public boolean animateChange(ViewHolder oldHolder, ViewHolder newHolder,
              int fromX, int fromY, int toX, int toY) {
          if (oldHolder == newHolder) {
              // Don't know how to run change animations when the same view holder is re-used.
              // run a move animation to handle position changes.
              return animateMove(oldHolder, fromX, fromY, toX, toY);
          }
          final float prevTranslationX = ViewCompat.getTranslationX(oldHolder.itemView);
          final float prevTranslationY = ViewCompat.getTranslationY(oldHolder.itemView);
          final float prevAlpha = ViewCompat.getAlpha(oldHolder.itemView);
          resetAnimation(oldHolder);
          int deltaX = (int) (toX - fromX - prevTranslationX);
          int deltaY = (int) (toY - fromY - prevTranslationY);
          // recover prev translation state after ending animation
          ViewCompat.setTranslationX(oldHolder.itemView, prevTranslationX);
          ViewCompat.setTranslationY(oldHolder.itemView, prevTranslationY);
          ViewCompat.setAlpha(oldHolder.itemView, prevAlpha);
          if (newHolder != null) {
              // carry over translation values
              resetAnimation(newHolder);
              ViewCompat.setTranslationX(newHolder.itemView, -deltaX);
              ViewCompat.setTranslationY(newHolder.itemView, -deltaY);
              ViewCompat.setAlpha(newHolder.itemView, 0);
          }
          mPendingChanges.add(new ChangeInfo(oldHolder, newHolder, fromX, fromY, toX, toY));
          return true;
      }
  
      private void animateChangeImpl(final ChangeInfo changeInfo) {
          final ViewHolder holder = changeInfo.oldHolder;
          final View view = holder == null ? null : holder.itemView;
          final ViewHolder newHolder = changeInfo.newHolder;
          final View newView = newHolder != null ? newHolder.itemView : null;
          if (view != null) {
              final ViewPropertyAnimatorCompat oldViewAnim = ViewCompat.animate(view).setDuration(
                      getChangeDuration());
              mChangeAnimations.add(changeInfo.oldHolder);
              oldViewAnim.translationX(changeInfo.toX - changeInfo.fromX);
              oldViewAnim.translationY(changeInfo.toY - changeInfo.fromY);
              oldViewAnim.alpha(0).setListener(new VpaListenerAdapter() {
                  @Override
                  public void onAnimationStart(View view) {
                      dispatchChangeStarting(changeInfo.oldHolder, true);
                  }
  
                  @Override
                  public void onAnimationEnd(View view) {
                      oldViewAnim.setListener(null);
                      ViewCompat.setAlpha(view, 1);
                      ViewCompat.setTranslationX(view, 0);
                      ViewCompat.setTranslationY(view, 0);
                      dispatchChangeFinished(changeInfo.oldHolder, true);
                      mChangeAnimations.remove(changeInfo.oldHolder);
                      dispatchFinishedWhenDone();
                  }
              }).start();
          }
          if (newView != null) {
              final ViewPropertyAnimatorCompat newViewAnimation = ViewCompat.animate(newView);
              mChangeAnimations.add(changeInfo.newHolder);
              newViewAnimation.translationX(0).translationY(0).setDuration(getChangeDuration()).
                      alpha(1).setListener(new VpaListenerAdapter() {
                  @Override
                  public void onAnimationStart(View view) {
                      dispatchChangeStarting(changeInfo.newHolder, false);
                  }
                  @Override
                  public void onAnimationEnd(View view) {
                      newViewAnimation.setListener(null);
                      ViewCompat.setAlpha(newView, 1);
                      ViewCompat.setTranslationX(newView, 0);
                      ViewCompat.setTranslationY(newView, 0);
                      dispatchChangeFinished(changeInfo.newHolder, false);
                      mChangeAnimations.remove(changeInfo.newHolder);
                      dispatchFinishedWhenDone();
                  }
              }).start();
          }
      }
  
      private void endChangeAnimation(List<ChangeInfo> infoList, ViewHolder item) {
          for (int i = infoList.size() - 1; i >= 0; i--) {
              ChangeInfo changeInfo = infoList.get(i);
              if (endChangeAnimationIfNecessary(changeInfo, item)) {
                  if (changeInfo.oldHolder == null && changeInfo.newHolder == null) {
                      infoList.remove(changeInfo);
                  }
              }
          }
      }
  
      private void endChangeAnimationIfNecessary(ChangeInfo changeInfo) {
          if (changeInfo.oldHolder != null) {
              endChangeAnimationIfNecessary(changeInfo, changeInfo.oldHolder);
          }
          if (changeInfo.newHolder != null) {
              endChangeAnimationIfNecessary(changeInfo, changeInfo.newHolder);
          }
      }
      private boolean endChangeAnimationIfNecessary(ChangeInfo changeInfo, ViewHolder item) {
          boolean oldItem = false;
          if (changeInfo.newHolder == item) {
              changeInfo.newHolder = null;
          } else if (changeInfo.oldHolder == item) {
              changeInfo.oldHolder = null;
              oldItem = true;
          } else {
              return false;
          }
          ViewCompat.setAlpha(item.itemView, 1);
          ViewCompat.setTranslationX(item.itemView, 0);
          ViewCompat.setTranslationY(item.itemView, 0);
          dispatchChangeFinished(item, oldItem);
          return true;
      }
  
      @Override
      public void endAnimation(ViewHolder item) {
          final View view = item.itemView;
          // this will trigger end callback which should set properties to their target values.
          ViewCompat.animate(view).cancel();
          // TODO if some other animations are chained to end, how do we cancel them as well?
          for (int i = mPendingMoves.size() - 1; i >= 0; i--) {
              MoveInfo moveInfo = mPendingMoves.get(i);
              if (moveInfo.holder == item) {
                  ViewCompat.setTranslationY(view, 0);
                  ViewCompat.setTranslationX(view, 0);
                  dispatchMoveFinished(item);
                  mPendingMoves.remove(i);
              }
          }
          endChangeAnimation(mPendingChanges, item);
          if (mPendingRemovals.remove(item)) {
              ViewCompat.setAlpha(view, 1);
              dispatchRemoveFinished(item);
          }
          if (mPendingAdditions.remove(item)) {
              ViewCompat.setAlpha(view, 1);
              dispatchAddFinished(item);
          }
  
          for (int i = mChangesList.size() - 1; i >= 0; i--) {
              ArrayList<ChangeInfo> changes = mChangesList.get(i);
              endChangeAnimation(changes, item);
              if (changes.isEmpty()) {
                  mChangesList.remove(i);
              }
          }
          for (int i = mMovesList.size() - 1; i >= 0; i--) {
              ArrayList<MoveInfo> moves = mMovesList.get(i);
              for (int j = moves.size() - 1; j >= 0; j--) {
                  MoveInfo moveInfo = moves.get(j);
                  if (moveInfo.holder == item) {
                      ViewCompat.setTranslationY(view, 0);
                      ViewCompat.setTranslationX(view, 0);
                      dispatchMoveFinished(item);
                      moves.remove(j);
                      if (moves.isEmpty()) {
                          mMovesList.remove(i);
                      }
                      break;
                  }
              }
          }
          for (int i = mAdditionsList.size() - 1; i >= 0; i--) {
              ArrayList<ViewHolder> additions = mAdditionsList.get(i);
              if (additions.remove(item)) {
                  ViewCompat.setAlpha(view, 1);
                  dispatchAddFinished(item);
                  if (additions.isEmpty()) {
                      mAdditionsList.remove(i);
                  }
              }
          }
  
          // animations should be ended by the cancel above.
          //noinspection PointlessBooleanExpression,ConstantConditions
          if (mRemoveAnimations.remove(item) && DEBUG) {
              throw new IllegalStateException("after animation is cancelled, item should not be in "
                      + "mRemoveAnimations list");
          }
  
          //noinspection PointlessBooleanExpression,ConstantConditions
          if (mAddAnimations.remove(item) && DEBUG) {
              throw new IllegalStateException("after animation is cancelled, item should not be in "
                      + "mAddAnimations list");
          }
  
          //noinspection PointlessBooleanExpression,ConstantConditions
          if (mChangeAnimations.remove(item) && DEBUG) {
              throw new IllegalStateException("after animation is cancelled, item should not be in "
                      + "mChangeAnimations list");
          }
  
          //noinspection PointlessBooleanExpression,ConstantConditions
          if (mMoveAnimations.remove(item) && DEBUG) {
              throw new IllegalStateException("after animation is cancelled, item should not be in "
                      + "mMoveAnimations list");
          }
          dispatchFinishedWhenDone();
      }
  
      private void resetAnimation(ViewHolder holder) {
          AnimatorCompatHelper.clearInterpolator(holder.itemView);
          endAnimation(holder);
      }
  
      @Override
      public boolean isRunning() {
          return (!mPendingAdditions.isEmpty() ||
                  !mPendingChanges.isEmpty() ||
                  !mPendingMoves.isEmpty() ||
                  !mPendingRemovals.isEmpty() ||
                  !mMoveAnimations.isEmpty() ||
                  !mRemoveAnimations.isEmpty() ||
                  !mAddAnimations.isEmpty() ||
                  !mChangeAnimations.isEmpty() ||
                  !mMovesList.isEmpty() ||
                  !mAdditionsList.isEmpty() ||
                  !mChangesList.isEmpty());
      }
  
      /**
       * Check the state of currently pending and running animations. If there are none
       * pending/running, call {@link #dispatchAnimationsFinished()} to notify any
       * listeners.
       */
      private void dispatchFinishedWhenDone() {
          if (!isRunning()) {
              dispatchAnimationsFinished();
          }
      }
  
      @Override
      public void endAnimations() {
          int count = mPendingMoves.size();
          for (int i = count - 1; i >= 0; i--) {
              MoveInfo item = mPendingMoves.get(i);
              View view = item.holder.itemView;
              ViewCompat.setTranslationY(view, 0);
              ViewCompat.setTranslationX(view, 0);
              dispatchMoveFinished(item.holder);
              mPendingMoves.remove(i);
          }
          count = mPendingRemovals.size();
          for (int i = count - 1; i >= 0; i--) {
              ViewHolder item = mPendingRemovals.get(i);
              dispatchRemoveFinished(item);
              mPendingRemovals.remove(i);
          }
          count = mPendingAdditions.size();
          for (int i = count - 1; i >= 0; i--) {
              ViewHolder item = mPendingAdditions.get(i);
              View view = item.itemView;
              ViewCompat.setAlpha(view, 1);
              dispatchAddFinished(item);
              mPendingAdditions.remove(i);
          }
          count = mPendingChanges.size();
          for (int i = count - 1; i >= 0; i--) {
              endChangeAnimationIfNecessary(mPendingChanges.get(i));
          }
          mPendingChanges.clear();
          if (!isRunning()) {
              return;
          }
  
          int listCount = mMovesList.size();
          for (int i = listCount - 1; i >= 0; i--) {
              ArrayList<MoveInfo> moves = mMovesList.get(i);
              count = moves.size();
              for (int j = count - 1; j >= 0; j--) {
                  MoveInfo moveInfo = moves.get(j);
                  ViewHolder item = moveInfo.holder;
                  View view = item.itemView;
                  ViewCompat.setTranslationY(view, 0);
                  ViewCompat.setTranslationX(view, 0);
                  dispatchMoveFinished(moveInfo.holder);
                  moves.remove(j);
                  if (moves.isEmpty()) {
                      mMovesList.remove(moves);
                  }
              }
          }
          listCount = mAdditionsList.size();
          for (int i = listCount - 1; i >= 0; i--) {
              ArrayList<ViewHolder> additions = mAdditionsList.get(i);
              count = additions.size();
              for (int j = count - 1; j >= 0; j--) {
                  ViewHolder item = additions.get(j);
                  View view = item.itemView;
                  ViewCompat.setAlpha(view, 1);
                  dispatchAddFinished(item);
                  additions.remove(j);
                  if (additions.isEmpty()) {
                      mAdditionsList.remove(additions);
                  }
              }
          }
          listCount = mChangesList.size();
          for (int i = listCount - 1; i >= 0; i--) {
              ArrayList<ChangeInfo> changes = mChangesList.get(i);
  