/*
    * 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.scope;
  
  import java.util.Collection;
  import java.util.Objects;
  
  import org.eclipse.aether.Keys;
  import org.eclipse.aether.collection.DependencyCollectionContext;
  import org.eclipse.aether.collection.DependencySelector;
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.util.artifact.ArtifactIdUtils;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A dependency selector that excludes optional dependencies which occur beyond given level.
   * <p>
   * <em>Important note:</em> equals/hashCode must factor in starting state, as instances of this class
   * (potentially differentially configured) are used now in session, but are kept in a set.
   *
   * @see Dependency#isOptional()
   */
  public final class OptionalDependencySelector implements DependencySelector {
      public static final Object IGNORED_KEYS = Keys.of(OptionalDependencySelector.class, "ignored");
      public static final Object UNSELECTED_KEYS = Keys.of(OptionalDependencySelector.class, "unselected");
  
      /**
       * Excludes optional dependencies always (from root).
       */
      public static OptionalDependencySelector fromRoot() {
          return from(1);
      }
  
      /**
       * Excludes optional transitive dependencies of direct dependencies.
       */
      public static OptionalDependencySelector fromDirect() {
          return from(2);
      }
  
      /**
       * Excludes optional transitive dependencies from given depth (1=root, 2=direct, 3=transitives of direct ones...).
       */
      public static OptionalDependencySelector from(int applyFrom) {
          if (applyFrom < 1) {
              throw new IllegalArgumentException("applyFrom must be non-zero and positive");
          }
          return new OptionalDependencySelector(Objects.hash(applyFrom), 0, applyFrom, null, null);
      }
  
      private final int seed;
      private final int depth;
      private final int applyFrom;
      private final Collection<String> ignoredKeys;
      private final Collection<String> unselectedKeys;
  
      private OptionalDependencySelector(
              int seed, int depth, int applyFrom, Collection<String> ignoredKeys, Collection<String> unselectedKeys) {
          this.seed = seed;
          this.depth = depth;
          this.applyFrom = applyFrom;
          this.ignoredKeys = ignoredKeys; // nullable
          this.unselectedKeys = unselectedKeys; // nullable
      }
  
      @Override
      public boolean selectDependency(Dependency dependency) {
          requireNonNull(dependency, "dependency cannot be null");
          String key = null;
          if (ignoredKeys != null || unselectedKeys != null) {
              key = ArtifactIdUtils.toId(dependency.getArtifact());
          }
          if (ignoredKeys != null) {
              if (ignoredKeys.contains(key)) {
                  return true;
              }
          }
          boolean result = depth < applyFrom || !dependency.isOptional();
          if (!result && unselectedKeys != null) {
              unselectedKeys.add(key);
          }
          return result;
     }
 
     @Override
     @SuppressWarnings("unchecked")
     public DependencySelector deriveChildSelector(DependencyCollectionContext context) {
         requireNonNull(context, "context cannot be null");
         if (depth >= applyFrom) {
             return this;
         }
         return new OptionalDependencySelector(
                 seed,
                 depth + 1,
                 applyFrom,
                 (Collection<String>) context.getSession().getData().get(IGNORED_KEYS),
                 (Collection<String>) context.getSession().getData().get(UNSELECTED_KEYS));
     }
 
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         } else if (null == obj || !getClass().equals(obj.getClass())) {
             return false;
         }
 
         OptionalDependencySelector that = (OptionalDependencySelector) obj;
         return seed == that.seed && depth == that.depth && applyFrom == that.applyFrom;
     }
 
     @Override
     public int hashCode() {
         int hash = getClass().hashCode();
         hash = hash * 31 + seed;
         hash = hash * 31 + depth;
         hash = hash * 31 + applyFrom;
         return hash;
     }
 
     @Override
     public String toString() {
         return String.format("%s(applied: %s)", this.getClass().getSimpleName(), depth >= applyFrom);
     }
 }