/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at legal-notices/CDDLv1_0.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2013 ForgeRock AS.
 */
package com.forgerock.opendj.grizzly;

import org.glassfish.grizzly.Processor;
import org.glassfish.grizzly.filterchain.Filter;
import org.glassfish.grizzly.filterchain.FilterChain;
import org.glassfish.grizzly.filterchain.FilterChainBuilder;
import org.glassfish.grizzly.filterchain.TransportFilter;
import org.glassfish.grizzly.ssl.SSLFilter;

/**
 * Common utility methods.
 */
final class GrizzlyUtils {


    /**
     * Build a filter chain from the provided processor if possible and the
     * provided filter.
     * <p>
     * If the provided processor can't be used for building the new filter
     * chain, then a chain with only a {@code TransportFilter} is used as a base
     * chain.
     *
     * @param processor
     *            processor to build the filter chain from. If the processor is
     *            not a filter chain (for example, it can be a
     *            {@code StandaloneProcessor} then it is ignored to build the
     *            returned filter chain
     * @param filter
     *            filter to add at the end of the filter chain
     * @return a new filter chain, based on the provided processor if processor
     *         is a {@code FilterChain}, and having the provided filter as the
     *         last filter
     */
    public static FilterChain buildFilterChain(Processor processor, Filter filter) {
        if (processor instanceof FilterChain) {
            return FilterChainBuilder.stateless().addAll((FilterChain) processor).add(filter).build();
        } else {
            return FilterChainBuilder.stateless().add(new TransportFilter()).add(filter).build();
        }
    }

    /**
     * Adds a filter to filter chain registered with the given connection.
     * <p>
     * For a non-SSL filter, filter is added at the last position before the
     * LDAP filter.
     * <p>
     * For a SSL filter, filter is added before any
     * {@code ConnectionSecurityLayerFilter} which is already present in the
     * filter chain.
     *
     * @param filter
     *            filter to add
     * @param connection
     *            connection to update with the new filter chain containing the
     *            provided filter
     */
    public static void addFilterToConnection(final Filter filter, org.glassfish.grizzly.Connection<?> connection) {
        final FilterChain currentChain = (FilterChain) connection.getProcessor();
        final FilterChain newChain = addFilterToChain(filter, currentChain);
        connection.setProcessor(newChain);
    }

    /**
     * Adds a filter to a filter chain.
     * <p>
     * For a non-SSL filter, filter is added at the last position before the
     * LDAP filter.
     * <p>
     * For a SSL filter, filter is added before any
     * {@code ConnectionSecurityLayerFilter} which is already present in the
     * filter chain.
     *
     * @param filter
     *            filter to add
     * @param chain
     *            initial filter chain
     * @return a new filter chain which includes the provided filter
     */
    public static FilterChain addFilterToChain(final Filter filter, final FilterChain chain) {
        // By default, before LDAP filter which is the last one
        int indexToAddFilter = chain.size() - 1;
        if (filter instanceof SSLFilter) {
            // Before any ConnectionSecurityLayerFilters if present
            for (int i = chain.size() - 2; i >= 0; i--) {
                if (!(chain.get(i) instanceof ConnectionSecurityLayerFilter)) {
                    indexToAddFilter = i + 1;
                    break;
                }
            }
        }
        return FilterChainBuilder.stateless().addAll(chain).add(indexToAddFilter, filter).build();
    }

    // Prevent instantiation.
    private GrizzlyUtils() {
        // No implementation required.
    }

}