package liquibase.sqlgenerator.ext;
   
   import liquibase.database.Database;
   import liquibase.database.core.*;
   import liquibase.exception.ValidationErrors;
   import liquibase.sql.Sql;
   import liquibase.sql.UnparsedSql;
   import liquibase.sqlgenerator.SqlGeneratorChain;
   import liquibase.statement.core.AddPrimaryKeyStatement;
  import liquibase.util.StringUtils;
  
  import static liquibase.ext.Constants.EXTENSION_PRIORITY;
  
  
  public class AddPrimaryKeyGenerator extends liquibase.sqlgenerator.core.AddPrimaryKeyGenerator {
  
      @Override
      public int getPriority() {
          return EXTENSION_PRIORITY;
      }
  
  
      public Sql[] generateSql(AddPrimaryKeyStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
          String sql;
          if (statement.getConstraintName() == null  || database instanceof MySQLDatabase || database instanceof SybaseASADatabase) {
              sql = "ALTER TABLE " + database.escapeTableName(null, statement.getTableName()) + " ADD PRIMARY KEY (" + database.escapeColumnNameList(statement.getColumnNames()) + ")";
          } else {
              sql = "ALTER TABLE " + database.escapeTableName(null, statement.getTableName()) + " ADD CONSTRAINT " + database.escapeConstraintName(statement.getConstraintName()) + " PRIMARY KEY (" + database.escapeColumnNameList(statement.getColumnNames()) + ")";
          }
  
          if (StringUtils.trimToNull(statement.getTablespace()) != null && database.supportsTablespaces()) {
              if (database instanceof MSSQLDatabase) {
                  sql += " ON "+statement.getTablespace();
              } else if (database instanceof DB2Database || database instanceof SybaseASADatabase) {
                  ; //not supported
              } else {
                  sql += " USING INDEX TABLESPACE "+statement.getTablespace();
              }
          }
  
          return new Sql[] {
                  new UnparsedSql(sql)
          };
      }
  }