/*
    * 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.eclipse.aether.internal.impl;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.repository.RepositoryPolicy;
  import org.eclipse.aether.spi.connector.checksum.ChecksumPolicy;
  import org.eclipse.aether.spi.connector.checksum.ChecksumPolicyProvider;
  import org.eclipse.aether.transfer.TransferResource;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   */
  @Singleton
  @Named
  public final class DefaultChecksumPolicyProvider implements ChecksumPolicyProvider {
  
      private static final int ORDINAL_IGNORE = 0;
  
      private static final int ORDINAL_WARN = 1;
  
      private static final int ORDINAL_FAIL = 2;
  
      @Override
      public ChecksumPolicy newChecksumPolicy(
              RepositorySystemSession session, RemoteRepository repository, TransferResource resource, String policy) {
          requireNonNull(session, "session cannot be null");
          requireNonNull(repository, "repository cannot be null");
          requireNonNull(resource, "resource cannot be null");
          validatePolicy("policy", policy);
  
          switch (policy) {
              case RepositoryPolicy.CHECKSUM_POLICY_IGNORE:
                  return null;
              case RepositoryPolicy.CHECKSUM_POLICY_FAIL:
                  return new FailChecksumPolicy(resource);
              case RepositoryPolicy.CHECKSUM_POLICY_WARN:
                  return new WarnChecksumPolicy(resource);
              default:
                  throw new IllegalArgumentException("Unsupported policy: " + policy);
          }
      }
  
      @Override
      public String getEffectiveChecksumPolicy(RepositorySystemSession session, String policy1, String policy2) {
          requireNonNull(session, "session cannot be null");
          validatePolicy("policy1", policy1);
          validatePolicy("policy2", policy2);
  
          if (policy1.equals(policy2)) {
              return policy1;
          }
          int ordinal1 = ordinalOfPolicy(policy1);
          int ordinal2 = ordinalOfPolicy(policy2);
          if (ordinal2 < ordinal1) {
              return (ordinal2 != ORDINAL_WARN) ? policy2 : RepositoryPolicy.CHECKSUM_POLICY_WARN;
          } else {
              return (ordinal1 != ORDINAL_WARN) ? policy1 : RepositoryPolicy.CHECKSUM_POLICY_WARN;
          }
      }
  
      private static int ordinalOfPolicy(String policy) {
          switch (policy) {
              case RepositoryPolicy.CHECKSUM_POLICY_IGNORE:
                  return ORDINAL_IGNORE;
              case RepositoryPolicy.CHECKSUM_POLICY_FAIL:
                  return ORDINAL_FAIL;
              case RepositoryPolicy.CHECKSUM_POLICY_WARN:
                  return ORDINAL_WARN;
              default:
                  throw new IllegalArgumentException("Unsupported policy: " + policy);
          }
      }
  
      private static void validatePolicy(String paramName, String policy) {
          requireNonNull(policy, paramName + "cannot be null");
  
          switch (policy) {
             case RepositoryPolicy.CHECKSUM_POLICY_IGNORE:
             case RepositoryPolicy.CHECKSUM_POLICY_FAIL:
             case RepositoryPolicy.CHECKSUM_POLICY_WARN:
                 break;
             default:
                 throw new IllegalArgumentException("Unsupported policy: " + policy);
         }
     }
 }