001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.spi.connector.checksum;
020
021import org.eclipse.aether.RepositorySystemSession;
022import org.eclipse.aether.repository.RemoteRepository;
023import org.eclipse.aether.transfer.TransferResource;
024
025/**
026 * Assists repository connectors in applying checksum policies to downloaded resources.
027 *
028 * @noimplement This interface is not intended to be implemented by clients.
029 * @noextend This interface is not intended to be extended by clients.
030 */
031public interface ChecksumPolicyProvider {
032
033    /**
034     * Retrieves the checksum policy with the specified identifier for use on the given remote resource.
035     *
036     * @param session The repository system session during which the request is made, must not be {@code null}.
037     * @param repository The repository hosting the resource being transferred, must not be {@code null}.
038     * @param resource The transfer resource on which the policy will be applied, must not be {@code null}.
039     * @param policy The identifier of the policy to apply, must not be {@code null}.
040     * @return The policy to apply or {@code null} if checksums should be ignored.
041     */
042    ChecksumPolicy newChecksumPolicy(
043            RepositorySystemSession session, RemoteRepository repository, TransferResource resource, String policy);
044
045    /**
046     * Returns the least strict policy. A checksum policy is said to be less strict than another policy if it would
047     * accept a downloaded resource in all cases where the other policy would reject the resource.
048     *
049     * @param session The repository system session during which the request is made, must not be {@code null}.
050     * @param policy1 A policy to compare, must not be {@code null}.
051     * @param policy2 A policy to compare, must not be {@code null}.
052     * @return The least strict policy among the two input policies.
053     */
054    String getEffectiveChecksumPolicy(RepositorySystemSession session, String policy1, String policy2);
055}