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/*
 * Copyright 2013 Nicolas Morel
 *
 * 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.dominokit.jacksonapt.ser;

import java.util.Iterator;
import org.dominokit.jacksonapt.JsonSerializationContext;
import org.dominokit.jacksonapt.JsonSerializer;
import org.dominokit.jacksonapt.JsonSerializerParameters;
import org.dominokit.jacksonapt.stream.JsonWriter;

/**
 * Default {@link org.dominokit.jacksonapt.JsonSerializer} implementation for {@link
 * java.lang.Iterable}.
 *
 * @param  Type of the elements inside the {@link java.lang.Iterable}
 */
public class IterableJsonSerializer, T> extends JsonSerializer {

  /**
   * newInstance
   *
   * @param serializer {@link org.dominokit.jacksonapt.JsonSerializer} used to serialize the objects
   *     inside the {@link java.lang.Iterable}
   * @param   Type of the {@link Iterable}
   * @return a new instance of {@link org.dominokit.jacksonapt.ser.IterableJsonSerializer}
   */
  public static > IterableJsonSerializer newInstance(
      JsonSerializer serializer) {
    return new IterableJsonSerializer(serializer);
  }

  protected final JsonSerializer serializer;

  /**
   * Constructor for IterableJsonSerializer.
   *
   * @param serializer {@link org.dominokit.jacksonapt.JsonSerializer} used to serialize the objects
   *     inside the {@link java.lang.Iterable}.
   */
  protected IterableJsonSerializer(JsonSerializer serializer) {
    if (null == serializer) {
      throw new IllegalArgumentException("serializer cannot be null");
    }
    this.serializer = serializer;
  }

  /** {@inheritDoc} */
  @Override
  protected boolean isEmpty(I value) {
    return null == value || !value.iterator().hasNext();
  }

  /** {@inheritDoc} */
  @Override
  public void doSerialize(
      JsonWriter writer, I values, JsonSerializationContext ctx, JsonSerializerParameters params) {
    Iterator iterator = values.iterator();

    if (!iterator.hasNext()) {
      if (ctx.isWriteEmptyJsonArrays()) {
        writer.beginArray();
        writer.endArray();
      } else {
        writer.cancelName();
      }
      return;
    }

    if (ctx.isWriteSingleElemArraysUnwrapped()) {

      T first = iterator.next();

      if (iterator.hasNext()) {
        // there is more than one element, we write the array normally
        writer.beginArray();
        serializer.serialize(writer, first, ctx, params);
        while (iterator.hasNext()) {
          serializer.serialize(writer, iterator.next(), ctx, params);
        }
        writer.endArray();
      } else {
        // there is only one element, we write it directly
        serializer.serialize(writer, first, ctx, params);
      }

    } else {
      writer.beginArray();
      while (iterator.hasNext()) {
        serializer.serialize(writer, iterator.next(), ctx, params);
      }
      writer.endArray();
    }
  }
}