MetaData.java

/*******************************************************************************
 * Copyright 2013 Open mHealth
 * 
 * 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.openmhealth.reference.domain;

import org.joda.time.DateTime;
import org.openmhealth.reference.exception.OmhException;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.annotation.JsonProperty;

/**
 * <p>
 * This class represents the meta-data for a data stream. All fields are
 * optional.
 * </p>
 * 
 * <p>
 * This class is immutable.
 * </p>
 * 
 * @author John Jenkins
 */
public class MetaData implements OmhObject {
	/**
	 * The version of this classed used for serialization.
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * The JSON key for the ID.
	 */
	public static final String JSON_KEY_ID = "id";
	/**
	 * The JSON key for the timestamp.
	 */
	public static final String JSON_KEY_TIMESTAMP = "timestamp";

	/**
	 * <p>
	 * This class is responsible for building new MetaData objects.
	 * </p>
	 * 
	 * <p>
	 * This class is mutable.
	 * </p>
	 * 
	 * @author John Jenkins
	 */
	public static class Builder {
		/**
		 * The current ID for this meta-data.
		 */
		private String id = null;
		/**
		 * The current timestamp for this meta-data.
		 */
		private DateTime timestamp = null;

		/**
		 * Creates an empty builder.
		 */
		public Builder() {
			// Do nothing.
		}

		/**
		 * Returns the currently set ID.
		 * 
		 * @return The currently set ID.
		 */
		public String getId() {
			return id;
		}

		/**
		 * Returns true if an ID has been set; false, otherwise.
		 * 
		 * @return True if an ID has been set; false, otherwise.
		 */
		public boolean hasId() {
			return id != null;
		}

		/**
		 * Sets the ID.
		 * 
		 * @param id
		 *        The ID.
		 */
		public void setId(final String id) {
			this.id = id;
		}

		/**
		 * Returns the currently set timestamp.
		 * 
		 * @return The currently set timestamp.
		 */
		public DateTime getTimestamp() {
			return timestamp;
		}

		/**
		 * Returns true if a time stamp has been set; false, otherwise.
		 * 
		 * @return True if a time stamp has been set; false, otherwise.
		 */
		public boolean hasTimestamp() {
			return timestamp != null;
		}

		/**
		 * Sets the time-stamp.
		 * 
		 * @param timestamp
		 *        The time-stamp.
		 */
		public void setTimestamp(final DateTime timestamp) {
			this.timestamp = timestamp;
		}

		/**
		 * Builds the MetaData object.
		 * 
		 * @return The MetaData object.
		 */
		public MetaData build() throws OmhException {
			return new MetaData(id, timestamp);
		}
		
		/**
		 * Returns true if all of the fields are null.
		 *  
		 * @return True if all fields are null; false, otherwise.
		 */
		public boolean isNull() {
			return
				(id == null) &&
				(timestamp == null);
		}
	}

	/**
	 * The unique ID for the point.
	 */
	@JsonProperty(JSON_KEY_ID)
	@JsonInclude(Include.NON_NULL)
	private final String id;
	/**
	 * The timestamp for the point.
	 */
	@JsonProperty(JSON_KEY_TIMESTAMP)
	@JsonInclude(Include.NON_NULL)
	private final DateTime timestamp;

	/**
	 * Creates a new MetaData object.
	 * 
	 * @param id
	 *        The ID for this meta-data.
	 * 
	 * @param timestamp
	 *        The time stamp for this meta-data.
	 */
	@JsonCreator
	public MetaData(
		@JsonProperty(JSON_KEY_ID) final String id,
		@JsonProperty(JSON_KEY_TIMESTAMP) final DateTime timestamp)
		throws OmhException {

		this.id = id;
		this.timestamp = timestamp;
	}

	/**
	 * Returns the ID.
	 * 
	 * @return The ID.
	 */
	public String getId() {
		return id;
	}

	/**
	 * Returns time-stamp.
	 * 
	 * @return The time-stamp.
	 */
	public DateTime getTimestamp() {
		return timestamp;
	}
}