package org.apache.fulcrum.json.gson;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.
   */
  
  import java.io.IOException;
  import java.text.DateFormat;
  import java.text.ParseException;
  import java.util.Date;
  
  import com.google.gson.Gson;
  import com.google.gson.JsonSyntaxException;
  import com.google.gson.TypeAdapter;
  import com.google.gson.TypeAdapterFactory;
  import com.google.gson.reflect.TypeToken;
  import com.google.gson.stream.JsonReader;
  import com.google.gson.stream.JsonToken;
  import com.google.gson.stream.JsonWriter;
  
  /**
   * Adapter for Date. Although this class appears stateless, it is not.
   * DateFormat captures its time zone and locale when it is created, which gives
   * this class state. DateFormat isn't thread safe either, so this class has
   * to synchronize its read and write methods.
   */
  public final class DateTypeAdapter extends TypeAdapter<Date> {
    public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
      @Override
      @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
      public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
        return typeToken.getRawType() == Date.class ? (TypeAdapter<T>) new DateTypeAdapter() : null;
      }
    };
    
    // default 
    private DateFormat customDateFormat = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT);;
    
    public void setCustomDateFormat(DateFormat df) {
        this.customDateFormat = df;
    }
    
    public DateFormat getCustomDateFormat() {
        return customDateFormat;
    }
  
  
    @Override public Date read(JsonReader in) throws IOException {
      if (in.peek() == JsonToken.NULL) {
        in.nextNull();
        return null;
      }
      return deserializeToDate(in.nextString());
    }
  
    private synchronized Date deserializeToDate(String json) {
      try {
        return customDateFormat.parse(json);
      } catch (ParseException e) {
        throw new JsonSyntaxException(json, e);
      }
    }
  
    @Override public synchronized void write(JsonWriter out, Date value) throws IOException {
      if (value == null) {
        out.nullValue();
        return;
      }
      String dateFormatAsString = customDateFormat.format(value);
      out.value(dateFormatAsString);
    }
  
  }