package liquibase.ext.spatial.sqlgenerator;
   
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
   
   import liquibase.database.Database;
   
   import com.vividsolutions.jts.geom.Geometry;
   
  public class WktConversionUtils {
     /** The SRID regular expression. */
     public static final String SRID_REGEX = "SRID[\\s]*=[\\s]*([0-9]+)[\\s]*;";
  
     /** The WKT regular expression. */
     public static final String WKT_REGEX = "((((MULTI)?(POINT|LINESTRING|POLYGON)|GEOMETRYCOLLECTION)Z?M?)[\\s]*[(].*[)])";
  
     /** The PostGIS EWKT regular expression. */
     public static final String EWKT_REGEX = "(" + SRID_REGEX + "[\\s]*)?" + WKT_REGEX;
  
     /** The EWKT <code>Pattern</code> instance. */
     public static final Pattern EWKT_PATTERN = Pattern.compile(EWKT_REGEX, Pattern.CASE_INSENSITIVE);
  
     /** Hide the default constructor. */
     private WktConversionUtils() {
     }
  
     /**
      * If the old value is a geometry or a Well-Known Text, convert it to the appropriate new value.
      * Otherwise, this method returns the old value.
      * 
      * @param oldValue
      *           the old value.
      * @param database
      *           the database instance.
      * 
      * @return the new value.
      */
     public static Object handleColumnValue(final Object oldValue, final Database database,
           final WktInsertOrUpdateGenerator generator) {
        Object newValue = oldValue;
        if (oldValue instanceof Geometry) {
           final Geometry geometry = (Geometry) oldValue;
           final String wkt = geometry.toText();
           String sridString = null;
           if (geometry.getSRID() > 0) {
              sridString = String.valueOf(geometry.getSRID());
           }
           newValue = generator.convertToFunction(wkt, sridString, database);
        } else if (oldValue instanceof String) {
           final String value = oldValue.toString().trim();
           final Matcher matcher = EWKT_PATTERN.matcher(value);
           if (matcher.matches()) {
              final String sridString = matcher.group(2);
              final String wkt = matcher.group(3);
              final String function = generator.convertToFunction(wkt, sridString, database);
              newValue = function;
           }
        }
        return newValue;
     }
  
     /**
      * Converts the given Well-Known Text and SRID to the appropriate function call for the database.
      * 
      * @param wkt
      *           the Well-Known Text string.
      * @param srid
      *           the SRID string which may be an empty string.
      * @param database
      *           the database instance.
      * @return the string that converts the WKT to a database-specific geometry.
      */
     public static String convertToFunction(final String wkt, final String srid,
           final Database database, final WktInsertOrUpdateGenerator generator) {
        if (wkt == null || wkt.equals("")) {
           throw new IllegalArgumentException("The Well-Known Text cannot be null or empty");
        }
        if (generator == null) {
           throw new IllegalArgumentException("The generator cannot be null or empty");
        }
        final String geomFromTextFunction = generator.getGeomFromWktFunction();
        String function = geomFromTextFunction + "('" + wkt + "'";
        if (srid != null && !srid.equals("")) {
           function += ", " + srid;
        } else if (generator.isSridRequiredInFunction(database)) {
           throw new IllegalArgumentException("An SRID was not provided with '" + wkt
                 + "' but is required in call to '" + geomFromTextFunction + "'");
        }
        function += ")";
        return function;
     }
  }