package au.gov.amsa.ais.message;
   
   import au.gov.amsa.ais.AisExtractor;
   import au.gov.amsa.ais.AisExtractorFactory;
   import au.gov.amsa.ais.AisParseException;
   import au.gov.amsa.ais.Util;
   
   import static au.gov.amsa.ais.AisMessageType.POSITION_GPS;
   
  /**
   * Decoder for AIS message type 27 (AIS Satelitte).
   *
   * @author dcuenot
   *
   */
  public class AisPositionGPS implements AisPosition {
  
      private static final Integer COG_NOT_AVAILABLE = 511;
      private static final Integer SOG_NOT_AVAILABLE = 63;
      private static final Integer LONGITUDE_NOT_AVAILABLE = 181 * 600; // 108600;
      private static final Integer LATITUDE_NOT_AVAILABLE = 91 * 600; // 54600;
      private final AisExtractor extractor;
      private final String source;
      private final int messageId;
      private final int mmsi;
      private final Double longitude;
      private final Double latitude;
  
      public AisPositionGPS(String message, String source, int padBits) {
          this(Util.getAisExtractorFactory(), message, source, padBits);
      }
      
      public AisPositionGPS(String message, int padBits) {
          this(message, null, padBits);
      }
  
      public AisPositionGPS(AisExtractorFactory factory, String message, String source, int padBits) {
          this.source = source;
          this.extractor = factory.create(message, 96, padBits);
          messageId = extractor.getMessageId();
          Util.checkMessageId(messageId, POSITION_GPS);
          mmsi = extractor.getValue(8, 38);
          longitude = extractLongitude(extractor);
          latitude = extractLatitude(extractor);
      }
  
  
      static Double extractCourseOverGround(AisExtractor extractor) {
          try {
              int val = extractor.getValue(85, 94);
              if (val == COG_NOT_AVAILABLE || val >= 360)
                  return null;
              else
                  return val * 1.0;
          } catch (AisParseException e) {
              return null;
          }
      }
  
      static Double extractSpeedOverGround(AisExtractor extractor) {
          try {
              int val = extractor.getValue(79, 85);
              if (val == SOG_NOT_AVAILABLE)
                  return null;
              else
                  return val * 1.0;
          } catch (AisParseException e) {
              return null;
          }
      }
  
      static Double extractLongitude(AisExtractor extractor) {
          try {
              int val = extractor.getSignedValue(44, 62);
              if (val == LONGITUDE_NOT_AVAILABLE) {
                  return null;
              } else {
                  Util.checkLong(val / 600.0);
                  return val / 600.0;
              }
          } catch (AisParseException e) {
              return null;
          }
      }
  
      static Double extractLatitude(AisExtractor extractor) {
  
          try {
              int val = extractor.getSignedValue(62, 79);
              if (val == LATITUDE_NOT_AVAILABLE) {
                  return null;
              } else {
                  Util.checkLat(val / 600.0);
                  return val / 600.0;
              }
          } catch (AisParseException e) {
              return null;
          }
      }
 
     @Override
     public int getMessageId() {
         return messageId;
     }
 
     @Override
     public int getRepeatIndicator() {
         return extractor.getValue(6, 8);
     }
 
     @Override
     public int getMmsi() {
         return mmsi;
     }
 
     public NavigationalStatus getNavigationalStatus() { return NavigationalStatus.values()[extractor.getValue(40, 44)]; }
 
     @Override
     public Double getSpeedOverGroundKnots() {
         return extractSpeedOverGround(extractor);
     }
 
     @Override
     public boolean isHighAccuracyPosition() {
         return Util.areEqual(extractor.getValue(38, 39), 1);
     }
 
     @Override
     public Double getLongitude() {
         return longitude;
     }
 
     @Override
     public Double getLatitude() {
         return latitude;
     }
 
     @Override
     public Double getCourseOverGround() {
         return extractCourseOverGround(extractor);
     }
 
     @Override
     public Integer getTrueHeading() {
         return null;
     }
 
     @Override
     public int getTimeSecondsOnly() {
         return 0;
     }
 
     public int getSpare() {
         return extractor.getValue(95, 96);
     }
 
     @Override
     public boolean isUsingRAIM() {
         return Util.areEqual(extractor.getValue(39, 40), 1);
     }
 
     @Override
     public String getSource() {
         return source;
     }
 
     @Override
     public String toString() {
         StringBuilder builder = new StringBuilder();
         builder.append("AisPositionGPS [source=");
         builder.append(source);
         builder.append(", messageId=");
         builder.append(messageId);
         builder.append(", repeatIndicator=");
         builder.append(getRepeatIndicator());
         builder.append(", mmsi=");
         builder.append(mmsi);
         builder.append(", navigationalStatus=");
         builder.append(getNavigationalStatus());
         builder.append(", speedOverGroundKnots=");
         builder.append(getSpeedOverGroundKnots());
         builder.append(", isHighAccuracyPosition=");
         builder.append(isHighAccuracyPosition());
         builder.append(", longitude=");
         builder.append(longitude);
         builder.append(", latitude=");
         builder.append(latitude);
         builder.append(", courseOverGround=");
         builder.append(getCourseOverGround());
         builder.append(", trueHeading=");
         builder.append(getTrueHeading());
         builder.append(", timeSecondsOnly=");
         builder.append(getTimeSecondsOnly());
         builder.append(", spare=");
         builder.append(getSpare());
         builder.append(", isUsingRAIM=");
         builder.append(isUsingRAIM());
         builder.append("]");
         return builder.toString();
     }
 
 }