src/main/java/com/google/android/libraries/feed/basicstream/internal/drivers/NoContentDriver.java

// Copyright 2018 The Feed Authors.
//
// 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 com.google.android.libraries.feed.basicstream.internal.drivers;

import static com.google.android.libraries.feed.common.Validators.checkState;

import android.support.annotation.VisibleForTesting;
import com.google.android.libraries.feed.basicstream.internal.viewholders.FeedViewHolder;
import com.google.android.libraries.feed.basicstream.internal.viewholders.NoContentViewHolder;
import com.google.android.libraries.feed.basicstream.internal.viewholders.ViewHolderType;
import com.google.android.libraries.feed.common.logging.Logger;

/** {@link FeatureDriver} for NoContent card. */
public class NoContentDriver extends LeafFeatureDriver {
  private static final String TAG = "NoContentDriver";
  /*@Nullable*/ private NoContentViewHolder noContentViewHolder;

  @Override
  public void bind(FeedViewHolder viewHolder) {
    if (isBound()) {
      Logger.wtf(TAG, "Rebinding.");
    }

    checkState(viewHolder instanceof NoContentViewHolder);
    noContentViewHolder = (NoContentViewHolder) viewHolder;
    noContentViewHolder.bind();
  }

  @Override
  public int getItemViewType() {
    return ViewHolderType.TYPE_NO_CONTENT;
  }

  @Override
  public void unbind() {
    if (noContentViewHolder == null) {
      return;
    }

    noContentViewHolder.unbind();
    noContentViewHolder = null;
  }

  @Override
  public void maybeRebind() {
    if (noContentViewHolder == null) {
      return;
    }

    // Unbinding clears the viewHolder, so storing to rebind.
    NoContentViewHolder localViewHolder = noContentViewHolder;
    unbind();
    bind(localViewHolder);
  }

  @VisibleForTesting
  boolean isBound() {
    return noContentViewHolder != null;
  }

  @Override
  public void onDestroy() {}
}