/*
    * 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.util.graph.manager;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.LinkedHashSet;
  import java.util.Map;
  import java.util.Objects;
  
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.collection.DependencyCollectionContext;
  import org.eclipse.aether.collection.DependencyManagement;
  import org.eclipse.aether.collection.DependencyManager;
  import org.eclipse.aether.graph.Dependency;
  import org.eclipse.aether.graph.Exclusion;
  import org.eclipse.aether.scope.ScopeManager;
  import org.eclipse.aether.scope.SystemDependencyScope;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A dependency manager support class.
   * <p>
   * This implementation is Maven specific, as it works hand-in-hand along with Maven ModelBuilder. While model builder
   * handles dependency management in the context of single POM (inheritance, imports, etc.), this implementation carries
   * in-lineage modifications based on previously recorded dependency management rules sourced from ascendants while
   * building the dependency graph. Root sourced management rules are special, in a way they are always applied, while
   * en-route collected ones are carefully applied to proper descendants only, to not override work done by model
   * builder already.
   * <p>
   * Details: Model builder handles version, scope from own dependency management (think "effective POM"). On the other
   * hand it does not handle optional for example. System paths are aligned across whole graph, making sure there is
   * same system path used by same dependency. Finally, exclusions (exclusions are additional information not effective
   * or applied in same POM) are always applied. This implementation makes sure, that version and scope are not applied
   * onto same node that actually provided the rules, to no override work that ModelBuilder did. It achieves this goal
   * by tracking "depth" for each collected rule and ignoring rules coming from same depth as processed dependency node is.
   *
   * @since 2.0.0
   */
  public abstract class AbstractDependencyManager implements DependencyManager {
  
      protected final int depth;
  
      protected final int deriveUntil;
  
      protected final int applyFrom;
  
      protected final Map<Object, Holder<String>> managedVersions;
  
      protected final Map<Object, Holder<String>> managedScopes;
  
      protected final Map<Object, Holder<Boolean>> managedOptionals;
  
      protected final Map<Object, Holder<String>> managedLocalPaths;
  
      protected final Map<Object, Collection<Holder<Collection<Exclusion>>>> managedExclusions;
  
      protected final SystemDependencyScope systemDependencyScope;
  
      private final int hashCode;
  
      protected AbstractDependencyManager(int deriveUntil, int applyFrom, ScopeManager scopeManager) {
          this(
                  0,
                  deriveUntil,
                  applyFrom,
                  Collections.emptyMap(),
                  Collections.emptyMap(),
                  Collections.emptyMap(),
                  Collections.emptyMap(),
                  Collections.emptyMap(),
                  scopeManager != null
                          ? scopeManager.getSystemDependencyScope().orElse(null)
                          : SystemDependencyScope.LEGACY);
      }
  
      @SuppressWarnings("checkstyle:ParameterNumber")
      protected AbstractDependencyManager(
              int depth,
              int deriveUntil,
             int applyFrom,
             Map<Object, Holder<String>> managedVersions,
             Map<Object, Holder<String>> managedScopes,
             Map<Object, Holder<Boolean>> managedOptionals,
             Map<Object, Holder<String>> managedLocalPaths,
             Map<Object, Collection<Holder<Collection<Exclusion>>>> managedExclusions,
             SystemDependencyScope systemDependencyScope) {
         this.depth = depth;
         this.deriveUntil = deriveUntil;
         this.applyFrom = applyFrom;
         this.managedVersions = requireNonNull(managedVersions);
         this.managedScopes = requireNonNull(managedScopes);
         this.managedOptionals = requireNonNull(managedOptionals);
         this.managedLocalPaths = requireNonNull(managedLocalPaths);
         this.managedExclusions = requireNonNull(managedExclusions);
         // nullable: if using scope manager, but there is no system scope defined
         this.systemDependencyScope = systemDependencyScope;
 
         this.hashCode = Objects.hash(
                 depth,
                 deriveUntil,
                 applyFrom,
                 managedVersions,
                 managedScopes,
                 managedOptionals,
                 managedLocalPaths,
                 managedExclusions);
     }
 
     protected abstract DependencyManager newInstance(
             Map<Object, Holder<String>> managedVersions,
             Map<Object, Holder<String>> managedScopes,
             Map<Object, Holder<Boolean>> managedOptionals,
             Map<Object, Holder<String>> managedLocalPaths,
             Map<Object, Collection<Holder<Collection<Exclusion>>>> managedExclusions);
 
     @Override
     public DependencyManager deriveChildManager(DependencyCollectionContext context) {
         requireNonNull(context, "context cannot be null");
         if (!isDerived()) {
             return this;
         }
 
         Map<Object, Holder<String>> managedVersions = this.managedVersions;
         Map<Object, Holder<String>> managedScopes = this.managedScopes;
         Map<Object, Holder<Boolean>> managedOptionals = this.managedOptionals;
         Map<Object, Holder<String>> managedLocalPaths = this.managedLocalPaths;
         Map<Object, Collection<Holder<Collection<Exclusion>>>> managedExclusions = this.managedExclusions;
 
         for (Dependency managedDependency : context.getManagedDependencies()) {
             Artifact artifact = managedDependency.getArtifact();
             Object key = new Key(artifact);
 
             String version = artifact.getVersion();
             if (!version.isEmpty() && !managedVersions.containsKey(key)) {
                 if (managedVersions == this.managedVersions) {
                     managedVersions = new HashMap<>(this.managedVersions);
                 }
                 managedVersions.put(key, new Holder<>(depth, version));
             }
 
             String scope = managedDependency.getScope();
             if (!scope.isEmpty() && !managedScopes.containsKey(key)) {
                 if (managedScopes == this.managedScopes) {
                     managedScopes = new HashMap<>(this.managedScopes);
                 }
                 managedScopes.put(key, new Holder<>(depth, scope));
             }
 
             Boolean optional = managedDependency.getOptional();
             if (optional != null && !managedOptionals.containsKey(key)) {
                 if (managedOptionals == this.managedOptionals) {
                     managedOptionals = new HashMap<>(this.managedOptionals);
                 }
                 managedOptionals.put(key, new Holder<>(depth, optional));
             }
 
             String localPath = systemDependencyScope == null
                     ? null
                     : systemDependencyScope.getSystemPath(managedDependency.getArtifact());
             if (localPath != null && !managedLocalPaths.containsKey(key)) {
                 if (managedLocalPaths == this.managedLocalPaths) {
                     managedLocalPaths = new HashMap<>(this.managedLocalPaths);
                 }
                 managedLocalPaths.put(key, new Holder<>(depth, localPath));
             }
 
             Collection<Exclusion> exclusions = managedDependency.getExclusions();
             if (!exclusions.isEmpty()) {
                 if (managedExclusions == this.managedExclusions) {
                     managedExclusions = new HashMap<>(this.managedExclusions);
                 }
                 Collection<Holder<Collection<Exclusion>>> managed =
                         managedExclusions.computeIfAbsent(key, k -> new ArrayList<>());
                 managed.add(new Holder<>(depth, exclusions));
             }
         }
 
         return newInstance(managedVersions, managedScopes, managedOptionals, managedLocalPaths, managedExclusions);
     }
 
     @Override
     public DependencyManagement manageDependency(Dependency dependency) {
         requireNonNull(dependency, "dependency cannot be null");
         DependencyManagement management = null;
         Object key = new Key(dependency.getArtifact());
 
         if (isApplied()) {
             Holder<String> version = managedVersions.get(key);
             // is managed locally by model builder
             // apply only rules coming from "higher" levels
             if (version != null && isApplicable(version)) {
                 management = new DependencyManagement();
                 management.setVersion(version.getValue());
             }
 
             Holder<String> scope = managedScopes.get(key);
             // is managed locally by model builder
             // apply only rules coming from "higher" levels
             if (scope != null && isApplicable(scope)) {
                 if (management == null) {
                     management = new DependencyManagement();
                 }
                 management.setScope(scope.getValue());
 
                 if (systemDependencyScope != null
                         && !systemDependencyScope.is(scope.getValue())
                         && systemDependencyScope.getSystemPath(dependency.getArtifact()) != null) {
                     Map<String, String> properties =
                             new HashMap<>(dependency.getArtifact().getProperties());
                     systemDependencyScope.setSystemPath(properties, null);
                     management.setProperties(properties);
                 }
             }
 
             // system scope paths always applied to have them aligned
             // (same artifact == same path) in whole graph
             if (systemDependencyScope != null
                     && (scope != null && systemDependencyScope.is(scope.getValue())
                             || (scope == null && systemDependencyScope.is(dependency.getScope())))) {
                 Holder<String> localPath = managedLocalPaths.get(key);
                 if (localPath != null) {
                     if (management == null) {
                         management = new DependencyManagement();
                     }
                     Map<String, String> properties =
                             new HashMap<>(dependency.getArtifact().getProperties());
                     systemDependencyScope.setSystemPath(properties, localPath.getValue());
                     management.setProperties(properties);
                 }
             }
 
             // optional is not managed by model builder
             // apply only rules coming from "higher" levels
             Holder<Boolean> optional = managedOptionals.get(key);
             if (optional != null && isApplicable(optional)) {
                 if (management == null) {
                     management = new DependencyManagement();
                 }
                 management.setOptional(optional.getValue());
             }
         }
 
         // exclusions affect only downstream
         // this will not "exclude" own dependency,
         // is just added as additional information
         // ModelBuilder does not merge exclusions (only applies if dependency does not have exclusion)
         // so we merge it here even from same level
         Collection<Holder<Collection<Exclusion>>> exclusions = managedExclusions.get(key);
         if (exclusions != null) {
             if (management == null) {
                 management = new DependencyManagement();
             }
             Collection<Exclusion> result = new LinkedHashSet<>(dependency.getExclusions());
             for (Holder<Collection<Exclusion>> exclusion : exclusions) {
                 result.addAll(exclusion.getValue());
             }
             management.setExclusions(result);
         }
 
         return management;
     }
 
     /**
      * Returns {@code true} if current context should be factored in (collected/derived).
      */
     protected boolean isDerived() {
         return depth < deriveUntil;
     }
 
     /**
      * Returns {@code true} if current dependency should be managed according to so far collected/derived rules.
      */
     protected boolean isApplied() {
         return depth >= applyFrom;
     }
 
     /**
      * Returns {@code true} if rule in holder is applicable at current depth.
      */
     protected boolean isApplicable(Holder<?> holder) {
         // explanation: derive collects rules (at given depth) and then last
         // call newInstance does depth++. This means that distance 1 is still "same node".
         // Hence, rules from depth - 2 or above should be applied.
         // root is special: is always applied.
         return holder.getDepth() == 0 || depth > holder.getDepth() + 1;
     }
 
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         } else if (null == obj || !getClass().equals(obj.getClass())) {
             return false;
         }
 
         AbstractDependencyManager that = (AbstractDependencyManager) obj;
         return depth == that.depth
                 && deriveUntil == that.deriveUntil
                 && applyFrom == that.applyFrom
                 && managedVersions.equals(that.managedVersions)
                 && managedScopes.equals(that.managedScopes)
                 && managedOptionals.equals(that.managedOptionals)
                 && managedExclusions.equals(that.managedExclusions);
     }
 
     @Override
     public int hashCode() {
         return hashCode;
     }
 
     protected static class Key {
         private final Artifact artifact;
         private final int hashCode;
 
         Key(Artifact artifact) {
             this.artifact = artifact;
             this.hashCode = Objects.hash(artifact.getGroupId(), artifact.getArtifactId());
         }
 
         @Override
         public boolean equals(Object obj) {
             if (obj == this) {
                 return true;
             } else if (!(obj instanceof Key)) {
                 return false;
             }
             Key that = (Key) obj;
             return artifact.getArtifactId().equals(that.artifact.getArtifactId())
                     && artifact.getGroupId().equals(that.artifact.getGroupId())
                     && artifact.getExtension().equals(that.artifact.getExtension())
                     && artifact.getClassifier().equals(that.artifact.getClassifier());
         }
 
         @Override
         public int hashCode() {
             return hashCode;
         }
 
         @Override
         public String toString() {
             return String.valueOf(artifact);
         }
     }
 
     protected static class Holder<T> {
         private final int depth;
         private final T value;
 
         Holder(int depth, T value) {
             this.depth = depth;
             this.value = requireNonNull(value);
         }
 
         public int getDepth() {
             return depth;
         }
 
         public T getValue() {
             return value;
         }
     }
 }