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/*
 * Copyright 2014 Objectos, Fábrica de Software LTDA.
 *
 * 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 br.com.objectos.way.ui;

import static com.google.common.collect.Lists.newArrayList;

import java.io.IOException;
import java.util.List;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonGenerator;

import com.google.common.base.Throwables;

/**
 * @author [email protected] (Marcio Endo)
 */
public class ToJsonHelper {

  private final JsonGenerator jgen;

  private final List fields = newArrayList();

  private JsonField current;

  ToJsonHelper(JsonGenerator jgen) {
    this.jgen = jgen;
  }

  public ToJsonHelper add(String fieldName, boolean value) {
    this.current = new BooleanField(fieldName, value);
    return addCurrentField();
  }
  public ToJsonHelper add(String fieldName, double value) {
    this.current = new DoubleField(fieldName, value);
    return addCurrentField();
  }
  public ToJsonHelper add(String fieldName, float value) {
    this.current = new FloatField(fieldName, value);
    return addCurrentField();
  }
  public ToJsonHelper add(String fieldName, int value) {
    this.current = new IntegerField(fieldName, value);
    return addCurrentField();
  }
  public ToJsonHelper add(String fieldName, long value) {
    this.current = new LongField(fieldName, value);
    return addCurrentField();
  }

  public ToJsonHelper add(String fieldName, Object value) {
    this.current = new ObjectField(fieldName, value);
    return addCurrentField();
  }

  public ToJsonHelper add(String fieldName, String value) {
    this.current = new StringField(fieldName, value);
    return addCurrentField();
  }

  public void write() {
    try {
      tryToWrite();
    } catch (JsonGenerationException e) {
      throw Throwables.propagate(e);
    } catch (IOException e) {
      throw Throwables.propagate(e);
    }
  }

  private void tryToWrite() throws JsonGenerationException, IOException {
    jgen.writeStartObject();

    for (JsonField field : fields) {
      field.write();
    }

    jgen.writeEndObject();
  }

  private ToJsonHelper addCurrentField() {
    this.fields.add(current);
    return this;
  }

  private class BooleanField extends JsonField {

    private final boolean value;

    public BooleanField(String fieldName, boolean value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeBooleanField(fieldName, value);
    }

  }

  private class DoubleField extends JsonField {

    private final double value;

    public DoubleField(String fieldName, double value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeNumberField(fieldName, value);
    }

  }

  private class FloatField extends JsonField {

    private final float value;

    public FloatField(String fieldName, float value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeNumberField(fieldName, value);
    }

  }

  private class IntegerField extends JsonField {

    private final int value;

    public IntegerField(String fieldName, int value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeNumberField(fieldName, value);
    }

  }

  private class LongField extends JsonField {

    private final long value;

    public LongField(String fieldName, long value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeNumberField(fieldName, value);
    }

  }

  private class ObjectField extends JsonField {

    private final Object value;

    public ObjectField(String fieldName, Object value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeObjectField(fieldName, value);
    }

  }

  private class StringField extends JsonField {

    private final String value;

    public StringField(String fieldName, String value) {
      super(fieldName);
      this.value = value;
    }

    @Override
    void write() throws JsonGenerationException, IOException {
      jgen.writeStringField(fieldName, value);
    }

  }

  private abstract class JsonField {

    final String fieldName;

    public JsonField(String fieldName) {
      this.fieldName = fieldName;
    }

    abstract void write() throws JsonGenerationException, IOException;

  }

}