/**
 * boilerpipe
 *
 * Copyright (c) 2009, 2014 Christian Kohlschütter
 *
 * The author licenses this file to You 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.kohlschutter.boilerpipe.filters.simple;

import java.util.Iterator;
import java.util.List;

import com.kohlschutter.boilerpipe.BoilerpipeFilter;
import com.kohlschutter.boilerpipe.BoilerpipeProcessingException;
import com.kohlschutter.boilerpipe.document.TextBlock;
import com.kohlschutter.boilerpipe.document.TextDocument;
import com.kohlschutter.boilerpipe.labels.DefaultLabels;

/**
 * Removes {@link TextBlock}s which have explicitly been marked as "not content".
 */
public final class BoilerplateBlockFilter implements BoilerpipeFilter {
  public static final BoilerplateBlockFilter INSTANCE = new BoilerplateBlockFilter(null);
  public static final BoilerplateBlockFilter INSTANCE_KEEP_TITLE = new BoilerplateBlockFilter(
      DefaultLabels.TITLE);
  private final String labelToKeep;

  /**
   * Returns the singleton instance for BoilerplateBlockFilter.
   */
  public static BoilerplateBlockFilter getInstance() {
    return INSTANCE;
  }

  public BoilerplateBlockFilter(final String labelToKeep) {
    this.labelToKeep = labelToKeep;
  }

  public boolean process(TextDocument doc) throws BoilerpipeProcessingException {
    List<TextBlock> textBlocks = doc.getTextBlocks();
    boolean hasChanges = false;

    for (Iterator<TextBlock> it = textBlocks.iterator(); it.hasNext();) {
      TextBlock tb = it.next();
      if (!tb.isContent() && (labelToKeep == null || !tb.hasLabel(DefaultLabels.TITLE))) {
        it.remove();
        hasChanges = true;
      }
    }

    return hasChanges;
  }

}
