/*
 * Copyright 2017-2020 original authors
 *
 * Licensed 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
 *
 * https://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 io.micronaut.data.connection.jdbc.advice;

import io.micronaut.core.annotation.NonNull;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Objects;
import java.util.logging.Logger;
import javax.sql.DataSource;

/**
 * JDBC {@link javax.sql.DataSource} implementation that delegates all calls
 * to a given target {@link javax.sql.DataSource}.
 *
 * <p>This class is meant to be subclassed, with subclasses overriding only
 * those methods (such as {@link #getConnection()}) that should not simply
 * delegate to the target DataSource.
 *
 * @author Juergen Hoeller
 * @author graemerocher
 * @since 1.1
 * @see #getConnection
 */
public class DelegatingDataSource implements DataSource {

    @NonNull
    private final DataSource targetDataSource;

    /**
     * Create a new DelegatingDataSource.
     * @param targetDataSource the target DataSource
     */
    public DelegatingDataSource(@NonNull DataSource targetDataSource) {
        Objects.requireNonNull(targetDataSource, "The target data source cannot be null");
        this.targetDataSource = targetDataSource;
    }

    /**
     * @return Return the target DataSource that this DataSource should delegate to.
     */
    @NonNull
    public final DataSource getTargetDataSource() {
        return this.targetDataSource;
    }

    @Override
    public Connection getConnection() throws SQLException {
        return getTargetDataSource().getConnection();
    }

    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return getTargetDataSource().getConnection(username, password);
    }

    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return getTargetDataSource().getLogWriter();
    }

    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
        getTargetDataSource().setLogWriter(out);
    }

    @Override
    public int getLoginTimeout() throws SQLException {
        return getTargetDataSource().getLoginTimeout();
    }

    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
        getTargetDataSource().setLoginTimeout(seconds);
    }


    //---------------------------------------------------------------------
    // Implementation of JDBC 4.0's Wrapper interface
    //---------------------------------------------------------------------

    @Override
    @SuppressWarnings("unchecked")
    public <T> T unwrap(Class<T> iface) throws SQLException {
        if (iface.isInstance(this)) {
            return (T) this;
        }
        return getTargetDataSource().unwrap(iface);
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return (iface.isInstance(this) || getTargetDataSource().isWrapperFor(iface));
    }


    //---------------------------------------------------------------------
    // Implementation of JDBC 4.1's getParentLogger method
    //---------------------------------------------------------------------

    @Override
    public Logger getParentLogger() {
        return Logger.getLogger(Logger.GLOBAL_LOGGER_NAME);
    }

    /**
     * Unwraps the data source obtaining the target.
     * @param dataSource The data source
     * @return The target
     */
    public static @NonNull DataSource unwrapDataSource(@NonNull DataSource dataSource) {
        while (dataSource instanceof DelegatingDataSource delegatingDataSource) {
            dataSource = delegatingDataSource.getTargetDataSource();
        }
        return dataSource;
    }
}

