package org.waveprotocol.wave.model.document.operation.impl;

import org.waveprotocol.wave.model.document.operation.AnnotationBoundaryMap;
import org.waveprotocol.wave.model.document.operation.Attributes;
import org.waveprotocol.wave.model.document.operation.BufferedDocInitialization;
import org.waveprotocol.wave.model.document.operation.EvaluatingDocInitializationCursor;
import org.waveprotocol.wave.model.document.operation.impl.OperationComponents.AnnotationBoundary;
import org.waveprotocol.wave.model.document.operation.impl.OperationComponents.Characters;
import org.waveprotocol.wave.model.document.operation.impl.OperationComponents.DocInitializationComponent;
import org.waveprotocol.wave.model.document.operation.impl.OperationComponents.ElementEnd;
import org.waveprotocol.wave.model.document.operation.impl.OperationComponents.ElementStart;

import java.util.ArrayList;

/**
 * An implementation of {@link EvaluatingDocInitializationCursor} that buffers
 * the operation and returns it as a {@link BufferedDocInitialization}.
 * 
 * See also {@link DocInitializationBuilder}, which is similar but implements a
 * standard Java builder pattern instead of EvaluatingDocInitializationCursor.
 */
public class DocInitializationBuffer implements
    EvaluatingDocInitializationCursor<BufferedDocInitialization> {
  private static final DocInitializationComponent[] EMPTY_ARRAY =
      new DocInitializationComponent[0];

  private final ArrayList<DocInitializationComponent> accu =
      new ArrayList<DocInitializationComponent>();

  /**
   * {@inheritDoc}
   * 
   * Behaviour is undefined if this buffer is used after calling this method.
   */
  @Override
  public final BufferedDocInitialization finish() {
    // TODO: This should not need a call to asInitialization().
    return DocOpUtil.asInitialization(BufferedDocOpImpl.create(accu.toArray(EMPTY_ARRAY)));
  }

  /** @see #finish() */
  // This is dangerous; we currently use it for ill-formedness-detection
  // tests, and may use it for efficiency in other places in the future.
  public final BufferedDocInitialization finishUnchecked() {
    return DocOpUtil.asInitialization(BufferedDocOpImpl.createUnchecked(accu.toArray(EMPTY_ARRAY)));
  }

  @Override
  public final void annotationBoundary(AnnotationBoundaryMap map) {
    accu.add(new AnnotationBoundary(map));
  }
  @Override
  public final void characters(String s) {
    accu.add(new Characters(s));
  }
  @Override
  public final void elementEnd() {
    accu.add(ElementEnd.INSTANCE);
  }
  @Override
  public final void elementStart(String type, Attributes attrs) {
    accu.add(new ElementStart(type, attrs));
  }
}