package liquibase.ext.spatial.sqlgenerator;
   
   import java.util.Arrays;
   import java.util.Iterator;
   
   import liquibase.database.Database;
   import liquibase.database.core.PostgresDatabase;
   import liquibase.ext.spatial.statement.CreateSpatialIndexStatement;
   import liquibase.sql.Sql;
  import liquibase.sql.UnparsedSql;
  import liquibase.sqlgenerator.SqlGeneratorChain;
  import liquibase.structure.core.Index;
  
  /**
   * <code>CreateSpatialIndexGeneratorMySQL</code> generates the SQL for creating a spatial index in
   * MySQL.
   */
  public class CreateSpatialIndexGeneratorPostgreSQL extends AbstractCreateSpatialIndexGenerator {
     @Override
     public boolean supports(final CreateSpatialIndexStatement statement, final Database database) {
        return database instanceof PostgresDatabase;
     }
  
     @Override
     public Sql[] generateSql(final CreateSpatialIndexStatement statement, final Database database,
           final SqlGeneratorChain sqlGeneratorChain) {
        final StringBuilder sql = new StringBuilder();
        sql.append("CREATE INDEX ");
        sql.append(database.escapeObjectName(statement.getIndexName(), Index.class));
        sql.append(" ON ");
        sql.append(database.escapeTableName(statement.getTableCatalogName(),
              statement.getTableSchemaName(), statement.getTableName()));
        sql.append(" USING GIST ").append("(");
        final Iterator<String> iterator = Arrays.asList(statement.getColumns()).iterator();
        while (iterator.hasNext()) {
           final String column = iterator.next();
           sql.append(database.escapeColumnName(statement.getTableCatalogName(),
                 statement.getTableSchemaName(), statement.getTableName(), column));
           if (iterator.hasNext()) {
              sql.append(", ");
           }
        }
        sql.append(")");
        final Sql createIndex = new UnparsedSql(sql.toString(), getAffectedIndex(statement));
        return new Sql[] { createIndex };
     }
  }