/*
 * Copyright (c) 2018, SnakeYAML
 *
 * 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.snakeyaml.engine.v2.events;

import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import org.snakeyaml.engine.v2.common.SpecVersion;
import org.snakeyaml.engine.v2.exceptions.Mark;

/**
 * Marks the beginning of a document.
 * <p>
 * This event followed by the document's content and a {@link DocumentEndEvent}.
 * </p>
 */
public final class DocumentStartEvent extends Event {

  private final boolean explicit;
  private final Optional<SpecVersion> specVersion;
  private final Map<String, String> tags;

  public DocumentStartEvent(boolean explicit, Optional<SpecVersion> specVersion,
      Map<String, String> tags, Optional<Mark> startMark, Optional<Mark> endMark) {
    super(startMark, endMark);
    this.explicit = explicit;
    Objects.requireNonNull(specVersion);
    this.specVersion = specVersion;
    Objects.requireNonNull(tags);
    this.tags = tags;
  }

  public DocumentStartEvent(boolean explicit, Optional<SpecVersion> specVersion,
      Map<String, String> tags) {
    this(explicit, specVersion, tags, Optional.empty(), Optional.empty());
  }

  public boolean isExplicit() {
    return explicit;
  }

  /**
   * @return YAML version the document conforms to.
   */
  public Optional<SpecVersion> getSpecVersion() {
    return specVersion;
  }

  /**
   * Tag shorthands as defined by the <code>%TAG</code> directive.
   *
   * @return Mapping of 'handles' to 'prefixes' (the handles include the '!' characters).
   */
  public Map<String, String> getTags() {
    return tags;
  }

  @Override
  public ID getEventId() {
    return ID.DocumentStart;
  }

  @Override
  public String toString() {
    StringBuilder builder = new StringBuilder("+DOC");
    if (isExplicit()) {
      builder.append(" ---");
    }
    return builder.toString();
  }
}
