/*

   Derby - Class org.apache.derby.client.am.ClientParameterMetaData

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

*/

package org.apache.derby.client.am;

import java.sql.ParameterMetaData;
import java.sql.SQLException;
import org.apache.derby.shared.common.reference.SQLState;

// Parameter meta data as used internally by the driver is always a column meta data instance.
// We will only create instances of this class when getParameterMetaData() is called.
// This class simply wraps a column meta data instance.
//
// Once we go to JDK 1.4 as runtime pre-req, we can extend ColumnMetaData and new up ParameterMetaData instances directly,
// and we won't have to wrap column meta data instances directly.

public class ClientParameterMetaData implements ParameterMetaData {
    private ColumnMetaData columnMetaData_;

    public ClientParameterMetaData(ColumnMetaData columnMetaData) {
        columnMetaData_ = columnMetaData;
    }

    public int getParameterCount() throws SQLException {
        return columnMetaData_.columns_;
    }

    public int getParameterType(int param) throws SQLException {
        return columnMetaData_.getColumnType(param);
    }

    public String getParameterTypeName(int param) throws SQLException {
        return columnMetaData_.getColumnTypeName(param);
    }

    public String getParameterClassName(int param) throws SQLException {
        return columnMetaData_.getColumnClassName(param);
    }

    public int getParameterMode(int param) throws SQLException {
        try
        {
            columnMetaData_.checkForValidColumnIndex(param);

            if (columnMetaData_.sqlxParmmode_[param - 1] ==
                ParameterMetaData.parameterModeUnknown) {
                return ParameterMetaData.parameterModeUnknown;

            } else if (columnMetaData_.sqlxParmmode_[param - 1] ==
                       ParameterMetaData.parameterModeIn) {
                return ParameterMetaData.parameterModeIn;

            } else if (columnMetaData_.sqlxParmmode_[param - 1] ==
                       ParameterMetaData.parameterModeOut) {
                return ParameterMetaData.parameterModeOut;

            } else {
                return ParameterMetaData.parameterModeInOut;
            }
        }
        catch ( SqlException se )
        {
            throw se.getSQLException();
        }
    }

    public int isNullable(int param) throws SQLException {
        return columnMetaData_.isNullable(param);
    }

    public boolean isSigned(int param) throws SQLException {
        return columnMetaData_.isSigned(param);
    }

    public int getPrecision(int param) throws SQLException {
        return columnMetaData_.getPrecision(param);
    }

    public int getScale(int param) throws SQLException {
        return columnMetaData_.getScale(param);
    }

    // JDBC 4.0 java.sql.Wrapper interface methods

    /**
     * Check whether this instance wraps an object that implements the interface
     * specified by {@code iface}.
     *
     * @param iface a class defining an interface
     * @return {@code true} if this instance implements {@code iface}, or
     * {@code false} otherwise
     * @throws SQLException if an error occurs while determining if this
     * instance implements {@code iface}
     */
    public boolean isWrapperFor(Class iface) throws SQLException {
        return iface.isInstance(this);
    }

    /**
     * Returns {@code this} if this class implements the specified interface.
     *
     * @param  iface a class defining an interface
     * @return an object that implements the interface
     * @throws SQLException if no object is found that implements the
     * interface
     */
    public  T unwrap(Class iface) throws SQLException {
        try {
            return iface.cast(this);
        } catch (ClassCastException cce) {
            throw new SqlException(null,
                    new ClientMessageId(SQLState.UNABLE_TO_UNWRAP),
                    iface).getSQLException();
        }
    }
}