package liquibase.ext.spatial.sqlgenerator;
   
   import liquibase.database.Database;
   import liquibase.database.core.DerbyDatabase;
   import liquibase.database.core.H2Database;
   import liquibase.exception.UnexpectedLiquibaseException;
   import liquibase.exception.ValidationErrors;
   import liquibase.ext.spatial.preconditions.SpatialIndexExistsPrecondition;
   import liquibase.ext.spatial.statement.DropSpatialIndexStatement;
  import liquibase.snapshot.SnapshotGeneratorFactory;
  import liquibase.sql.Sql;
  import liquibase.sql.UnparsedSql;
  import liquibase.sqlgenerator.SqlGeneratorChain;
  import liquibase.sqlgenerator.core.AbstractSqlGenerator;
  import liquibase.structure.DatabaseObject;
  import liquibase.structure.core.Table;
  
  /**
   * <code>DropSpatialIndexGeneratorGeoDB</code> ...
   */
  public class DropSpatialIndexGeneratorGeoDB extends AbstractSqlGenerator<DropSpatialIndexStatement> {
  
     /**
      * @see liquibase.sqlgenerator.core.AbstractSqlGenerator#supports(liquibase.statement.SqlStatement,
      *      liquibase.database.Database)
      */
     @Override
     public boolean supports(final DropSpatialIndexStatement statement, final Database database) {
        return database instanceof DerbyDatabase || database instanceof H2Database;
     }
  
     /**
      * Ensures that the table name is populated.
      */
     @Override
     public ValidationErrors validate(final DropSpatialIndexStatement statement,
           final Database database, final SqlGeneratorChain sqlGeneratorChain) {
        final ValidationErrors validationErrors = new ValidationErrors();
        validationErrors.checkRequiredField("tableName", statement.getTableName());
        return validationErrors;
     }
  
     @Override
     public Sql[] generateSql(final DropSpatialIndexStatement statement, final Database database,
           final SqlGeneratorChain sqlGeneratorChain) {
        final String catalogName = statement.getTableCatalogName();
        String schemaName = statement.getTableSchemaName();
        if (schemaName == null) {
           schemaName = database.getDefaultSchemaName();
        }
  
        final StringBuilder sql = new StringBuilder("CALL ");
        sql.append(schemaName).append(".DropSpatialIndex(");
  
        // Add the schema name parameter.
        sql.append("'").append(database.escapeStringForDatabase(schemaName)).append("'");
        sql.append(", ");
  
        // Add the table name parameter.
        final String tableName = statement.getTableName();
        sql.append("'").append(database.escapeStringForDatabase(tableName)).append("'");
        sql.append(')');
  
        final Table hatboxTable = new Table().setName(tableName + "_HATBOX");
        hatboxTable.setSchema(catalogName, schemaName);
        final UnparsedSql spatialize = new UnparsedSql(sql.toString(), hatboxTable);
        return new Sql[] { spatialize };
     }
  
     /**
      * Generates the SQL statement to drop the spatial index if it exists.
      * 
      * @param statement
      *           the drop spatial index statement.
      * @param database
      *           the database.
      * @param list
      *           the list of SQL statements to execute.
      */
     public Sql[] generateSqlIfExists(final DropSpatialIndexStatement statement,
           final Database database) {
        final String catalogName = statement.getTableCatalogName();
        final String schemaName = statement.getTableSchemaName();
        final String tableName = statement.getTableName();
        final SpatialIndexExistsPrecondition precondition = new SpatialIndexExistsPrecondition();
        precondition.setCatalogName(catalogName);
        precondition.setSchemaName(schemaName);
        precondition.setTableName(tableName);
        final DatabaseObject example = precondition.getExample(database, tableName);
        try {
           // If a spatial index exists on the table, drop it.
           if (SnapshotGeneratorFactory.getInstance().has(example, database)) {
              return generateSql(statement, database, null);
           }
        } catch (final Exception e) {
           throw new UnexpectedLiquibaseException(e);
        }
        return new Sql[0];
     }
 }