package au.gov.amsa.ais;
   
   import au.gov.amsa.ais.message.AbstractAisBStaticDataReport;
   import au.gov.amsa.ais.message.AisAidToNavigation;
   import au.gov.amsa.ais.message.AisBStaticDataReportPartA;
   import au.gov.amsa.ais.message.AisBStaticDataReportPartB;
   import au.gov.amsa.ais.message.AisBaseStation;
   import au.gov.amsa.ais.message.AisMessageOther;
   import au.gov.amsa.ais.message.AisPositionA;
  import au.gov.amsa.ais.message.AisPositionB;
  import au.gov.amsa.ais.message.AisPositionBExtended;
  import au.gov.amsa.ais.message.AisPositionGPS;
  import au.gov.amsa.ais.message.AisShipStaticA;
  
  /**
   * Parses AIS messages (as they are taken from the 5th column in the NMEA
   * message).
   * 
   * @author dxm
   * 
   */
  public class AisMessageParser {
  
  	private final AisExtractorFactory factory;
  
  	/**
  	 * Constructor.
  	 */
  	public AisMessageParser() {
  		this(Util.getAisExtractorFactory());
  	}
  
  	/**
  	 * Constructor.
  	 * 
  	 * @param factory
  	 */
  	public AisMessageParser(AisExtractorFactory factory) {
  		this.factory = factory;
  	}
  
  	/**
  	 * Returns an {@link AisMessage} from the string representation of the
  	 * message as per 1371-4 IMO specification (as per the appropriate column in
  	 * the NMEA message). Sets source to null.
  	 * 
  	 * @param message
  	 * @return
  	 */
  	public AisMessage parse(String message, int padBits) {
  		return parse(message, null, padBits);
  	}
  
  	/**
  	 * Returns an {@link AisMessage} from the string representation of the
  	 * message as per 1371-4 IMO specification (as per the appropriate column in
  	 * the NMEA message).
  	 * 
  	 * @param message
  	 * @param source
  	 * @return
  	 */
  	public AisMessage parse(String message, String source, int padBits) {
  		AisExtractor extractor = factory.create(message, 0, padBits);
  		int id = extractor.getMessageId();
  		
  		if (Util.isClassAPositionReport(id)) {
  			return new AisPositionA(message, source, padBits);
  		} else if (id == 4)
  			return new AisBaseStation(message, source, padBits);
  		else if (id == 5)
  			return new AisShipStaticA(message, source, padBits);
  		else if (id == 18)
  			return new AisPositionB(message, source, padBits);
  		else if (id == 19)
  			return new AisPositionBExtended(message, source, padBits);
  		else if (id == 21)
  			return new AisAidToNavigation(message, source, padBits);
  		else if (id == AisMessageType.STATIC_DATA_REPORT.getId()) {
  			int partNumber = AbstractAisBStaticDataReport.extractPartNumber(factory, message, padBits);
  			return parseStaticDataReport(partNumber, id, message, source, padBits);
  		}
  		else if (id == 27)
  			return new AisPositionGPS(message, source, padBits);
  		else
  			return new AisMessageOther(id, source, padBits);
  	}
  	
  	AisMessage parseStaticDataReport(int partNumber, int id, String message, String source, int padBits) {
  		
          if (partNumber == AbstractAisBStaticDataReport.PART_NUMBER_A) {
              return new AisBStaticDataReportPartA(message, source, padBits);
          } else if (partNumber == AbstractAisBStaticDataReport.PART_NUMBER_B) {
              return new AisBStaticDataReportPartB(message, source, padBits);
          } else {
              throw new AisParseException("Unsupported part number [" + partNumber + "]");
          }
  	}
  }