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package edu.isi.nlp.serialization.jackson;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;
import edu.isi.nlp.collections.MapUtils;
import java.util.List;
import java.util.Map;

/**
 * Works around a Jackson issue in serializing maps. Jackson, frustratingly, serializes maps to JSON
 * by turning the keys into Strings, which typically don't want. To get around this:
 *
 * 
 *   Don't make the map itself a {@code JsonProperty}
 *   
Provide a {@code JsonProperty}-annotated package-private accessor which returns {@code
 *       ImmutableMapProxy.forMap(myMap)}
 *   
In your {@code JsonCreator} method, take an {@code ImmutableMapProxy} as an argument and
 *       call {@link #toImmutableMap()}
 * 
 *
 * @deprecated Prefer {@link MapEntries}
 */
@Deprecated
public final class ImmutableMapProxy {

  @JsonProperty("keys")
  private final List keys;

  @JsonProperty("values")
  private final List values;

  private ImmutableMapProxy(
      @JsonProperty("keys") final List keys, @JsonProperty("values") final List values) {
    this.keys = checkNotNull(keys);
    this.values = checkNotNull(values);
    checkArgument(keys.size() == values.size());
  }

  @Deprecated
  @SuppressWarnings("deprecation")
  public static  ImmutableMapProxy forMap(Map map) {
    final List keys = Lists.newArrayListWithCapacity(map.size());
    final List values = Lists.newArrayListWithCapacity(map.size());
    for (final Map.Entry e : map.entrySet()) {
      keys.add(e.getKey());
      values.add(e.getValue());
    }
    return new ImmutableMapProxy(keys, values);
  }

  public ImmutableMap toImmutableMap() {
    return MapUtils.copyParallelListsToMap(keys, values);
  }
}