/*
    * 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.HashMap;
  import java.util.LinkedHashSet;
  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 for Maven-specific dependency graph management.
   *
   * <h2>Overview</h2>
   * <p>
   * This implementation works in conjunction with Maven ModelBuilder to handle dependency
   * management across the dependency graph. While ModelBuilder manages dependencies within
   * a single POM context (inheritance, imports), this class applies lineage-based modifications
   * based on previously recorded dependency management rules sourced from ancestors while
   * building the dependency graph. Root-sourced management rules are special, in that they are
   * always applied, while rules collected during traversal are carefully applied to proper
   * descendants only, to not override work done by ModelBuilder already.
   * </p>
   *
   * <h2>Managed Properties</h2>
   * <ul>
   * <li><strong>Version &amp; Scope:</strong> Handled by ModelBuilder for own dependency management
   *     (think "effective POM"). This implementation ensures these are not applied to the same
   *     node that provided the rules, to not override ModelBuilder's work.</li>
   * <li><strong>Optional:</strong> Not handled by ModelBuilder; managed here.</li>
   * <li><strong>System Paths:</strong> Aligned across the entire graph, ensuring the same
   *     system path is used by the same dependency.</li>
   * <li><strong>Exclusions:</strong> Always applied as additional information (not effective
   *     or applied in the same POM).</li>
   * </ul>
   *
   * <h2>Depth-Based Rule Application</h2>
   * <p>
   * This implementation achieves proper rule application by tracking "depth" for each collected
   * rule and ignoring rules coming from the same depth as the processed dependency node.
   * </p>
   * <ul>
   * <li><strong>Depth 0:</strong> Factory instance created during session initialization and
   *     parameterized. Collection begins with "derive" operation using root context.</li>
   * <li><strong>Depth 1:</strong> Special case for "version", "scope" and "optional" properties.
   *     At this level, "apply onto itself" ensures root-defined rules are applied to first-level
   *     siblings (which, if managed by ModelBuilder, will be the same, making this a no-op).</li>
   * <li><strong>Depth > 1:</strong> "Apply onto itself" is not in effect; only "apply below" is used.</li>
   * </ul>
   *
   * <h2>Rule Precedence</h2>
   * <p>
   * Rules are keyed by dependency management entry coordinates (GACE: Group, Artifact, Classifier,
   * Extension - see {@link Key}) and are recorded only if a rule for the same key did not exist
   * previously. This implements the "nearer (to root) management wins" rule, while root management
   * overrides all.
   * </p>
   *
   * <h2>Managed Bits and Graph Transformations</h2>
   * <p>
   * When a {@link org.eclipse.aether.graph.DependencyNode} becomes "managed" by any property
   * provided from this manager, {@link org.eclipse.aether.graph.DependencyNode#getManagedBits()}
   * will carry this information for the given property. Later graph transformations will abstain
   * from modifying these properties of marked nodes (assuming the node already has the property
   * set to what it should have). Sometimes this is unwanted, especially for properties that need
   * to be inherited in the graph (values derived from parent-child context of the actual node,
   * like "scope" or "optional").
   * </p>
   *
   * <h2>Implementation Notes</h2>
   * <ul>
   * <li>This class maintains a "path" (list of parent managers) and "depth".</li>
  * <li>The field {@code managedLocalPaths} is <em>intentionally left out of hash/equals</em>.</li>
  * <li>Each dependency "derives" an instance with its own context to process second-level
  *     dependencies and so on.</li>
  * </ul>
  *
  * @since 2.0.0
  */
 public abstract class AbstractDependencyManager implements DependencyManager {
     /** The path of parent managers from root to current level. */
     protected final ArrayList<AbstractDependencyManager> path;
 
     /** The current depth in the dependency graph (0 = factory, 1 = root, 2+ = descendants). */
     protected final int depth;
 
     /** Maximum depth for rule derivation (exclusive). */
     protected final int deriveUntil;
 
     /** Minimum depth for rule application (inclusive). */
     protected final int applyFrom;
 
     /** Managed version rules keyed by dependency coordinates. */
     protected final MMap<Key, String> managedVersions;
 
     /** Managed scope rules keyed by dependency coordinates. */
     protected final MMap<Key, String> managedScopes;
 
     /** Managed optional flags keyed by dependency coordinates. */
     protected final MMap<Key, Boolean> managedOptionals;
 
     /** Managed local paths for system dependencies (intentionally excluded from equals/hashCode). */
     protected final MMap<Key, String> managedLocalPaths;
 
     /** Managed exclusions keyed by dependency coordinates. */
     protected final MMap<Key, Holder<Collection<Exclusion>>> managedExclusions;
 
     /** System dependency scope handler, may be null if no system scope is defined. */
     protected final SystemDependencyScope systemDependencyScope;
 
     /** Pre-computed hash code (excludes managedLocalPaths). */
     private final int hashCode;
 
     /**
      * Creates a new dependency manager with the specified derivation and application parameters.
      *
      * @param deriveUntil the maximum depth for rule derivation (exclusive), must be >= 0
      * @param applyFrom the minimum depth for rule application (inclusive), must be >= 0
      * @param scopeManager the scope manager for handling system dependencies, may be null
      * @throws IllegalArgumentException if deriveUntil or applyFrom are negative
      */
     protected AbstractDependencyManager(int deriveUntil, int applyFrom, ScopeManager scopeManager) {
         this(
                 new ArrayList<>(),
                 0,
                 deriveUntil,
                 applyFrom,
                 null,
                 null,
                 null,
                 null,
                 null,
                 scopeManager != null
                         ? scopeManager.getSystemDependencyScope().orElse(null)
                         : SystemDependencyScope.LEGACY);
     }
 
     @SuppressWarnings("checkstyle:ParameterNumber")
     protected AbstractDependencyManager(
             ArrayList<AbstractDependencyManager> path,
             int depth,
             int deriveUntil,
             int applyFrom,
             MMap<Key, String> managedVersions,
             MMap<Key, String> managedScopes,
             MMap<Key, Boolean> managedOptionals,
             MMap<Key, String> managedLocalPaths,
             MMap<Key, Holder<Collection<Exclusion>>> managedExclusions,
             SystemDependencyScope systemDependencyScope) {
         this.path = path;
         this.depth = depth;
         this.deriveUntil = deriveUntil;
         this.applyFrom = applyFrom;
         this.managedVersions = managedVersions;
         this.managedScopes = managedScopes;
         this.managedOptionals = managedOptionals;
         this.managedLocalPaths = managedLocalPaths;
         this.managedExclusions = managedExclusions;
         // nullable: if using scope manager, but there is no system scope defined
         this.systemDependencyScope = systemDependencyScope;
 
         // exclude managedLocalPaths
         this.hashCode = Objects.hash(path, depth, managedVersions, managedScopes, managedOptionals, managedExclusions);
     }
 
     protected abstract DependencyManager newInstance(
             MMap<Key, String> managedVersions,
             MMap<Key, String> managedScopes,
             MMap<Key, Boolean> managedOptionals,
             MMap<Key, String> managedLocalPaths,
             MMap<Key, Holder<Collection<Exclusion>>> managedExclusions);
 
     private boolean containsManagedVersion(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedVersions != null && ancestor.managedVersions.containsKey(key)) {
                 return true;
             }
         }
         return managedVersions != null && managedVersions.containsKey(key);
     }
 
     private String getManagedVersion(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedVersions != null && ancestor.managedVersions.containsKey(key)) {
                 return ancestor.managedVersions.get(key);
             }
         }
         if (depth == 1 && managedVersions != null && managedVersions.containsKey(key)) {
             return managedVersions.get(key);
         }
         return null;
     }
 
     private boolean containsManagedScope(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedScopes != null && ancestor.managedScopes.containsKey(key)) {
                 return true;
             }
         }
         return managedScopes != null && managedScopes.containsKey(key);
     }
 
     private String getManagedScope(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedScopes != null && ancestor.managedScopes.containsKey(key)) {
                 return ancestor.managedScopes.get(key);
             }
         }
         if (depth == 1 && managedScopes != null && managedScopes.containsKey(key)) {
             return managedScopes.get(key);
         }
         return null;
     }
 
     private boolean containsManagedOptional(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedOptionals != null && ancestor.managedOptionals.containsKey(key)) {
                 return true;
             }
         }
         return managedOptionals != null && managedOptionals.containsKey(key);
     }
 
     private Boolean getManagedOptional(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedOptionals != null && ancestor.managedOptionals.containsKey(key)) {
                 return ancestor.managedOptionals.get(key);
             }
         }
         if (depth == 1 && managedOptionals != null && managedOptionals.containsKey(key)) {
             return managedOptionals.get(key);
         }
         return null;
     }
 
     private boolean containsManagedLocalPath(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedLocalPaths != null && ancestor.managedLocalPaths.containsKey(key)) {
                 return true;
             }
         }
         return managedLocalPaths != null && managedLocalPaths.containsKey(key);
     }
 
     /**
      * Gets the managed local path for system dependencies.
      * Note: Local paths don't follow the depth=1 special rule like versions/scopes.
      *
      * @param key the dependency key
      * @return the managed local path, or null if not managed
      */
     private String getManagedLocalPath(Key key) {
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedLocalPaths != null && ancestor.managedLocalPaths.containsKey(key)) {
                 return ancestor.managedLocalPaths.get(key);
             }
         }
         if (managedLocalPaths != null && managedLocalPaths.containsKey(key)) {
             return managedLocalPaths.get(key);
         }
         return null;
     }
 
     /**
      * Merges exclusions from all levels in the dependency path.
      * Unlike other managed properties, exclusions are accumulated additively
      * from root to current level throughout the entire dependency path.
      *
      * @param key the dependency key
      * @return merged collection of exclusions, or null if none exist
      */
     private Collection<Exclusion> getManagedExclusions(Key key) {
         ArrayList<Exclusion> result = new ArrayList<>();
         for (AbstractDependencyManager ancestor : path) {
             if (ancestor.managedExclusions != null && ancestor.managedExclusions.containsKey(key)) {
                 result.addAll(ancestor.managedExclusions.get(key).value);
             }
         }
         if (managedExclusions != null && managedExclusions.containsKey(key)) {
             result.addAll(managedExclusions.get(key).value);
         }
         return result.isEmpty() ? null : result;
     }
 
     @Override
     public DependencyManager deriveChildManager(DependencyCollectionContext context) {
         requireNonNull(context, "context cannot be null");
         if (!isDerived()) {
             return this;
         }
 
         MMap<Key, String> managedVersions = null;
         MMap<Key, String> managedScopes = null;
         MMap<Key, Boolean> managedOptionals = null;
         MMap<Key, String> managedLocalPaths = null;
         MMap<Key, Holder<Collection<Exclusion>>> managedExclusions = null;
 
         for (Dependency managedDependency : context.getManagedDependencies()) {
             Artifact artifact = managedDependency.getArtifact();
             Key key = new Key(artifact);
 
             String version = artifact.getVersion();
             if (!version.isEmpty() && !containsManagedVersion(key)) {
                 if (managedVersions == null) {
                     managedVersions = MMap.emptyNotDone();
                 }
                 managedVersions.put(key, version);
             }
 
             if (isInheritedDerived()) {
                 String scope = managedDependency.getScope();
                 if (!scope.isEmpty() && !containsManagedScope(key)) {
                     if (managedScopes == null) {
                         managedScopes = MMap.emptyNotDone();
                     }
                     managedScopes.put(key, scope);
                 }
 
                 Boolean optional = managedDependency.getOptional();
                 if (optional != null && !containsManagedOptional(key)) {
                     if (managedOptionals == null) {
                         managedOptionals = MMap.emptyNotDone();
                     }
                     managedOptionals.put(key, optional);
                 }
             }
 
             String localPath = systemDependencyScope == null
                     ? null
                     : systemDependencyScope.getSystemPath(managedDependency.getArtifact());
             if (localPath != null && !containsManagedLocalPath(key)) {
                 if (managedLocalPaths == null) {
                     managedLocalPaths = MMap.emptyNotDone();
                 }
                 managedLocalPaths.put(key, localPath);
             }
 
             Collection<Exclusion> exclusions = managedDependency.getExclusions();
             if (!exclusions.isEmpty()) {
                 if (managedExclusions == null) {
                     managedExclusions = MMap.emptyNotDone();
                 }
                 Holder<Collection<Exclusion>> managed = managedExclusions.get(key);
                 if (managed != null) {
                     ArrayList<Exclusion> ex = new ArrayList<>(managed.getValue());
                     ex.addAll(exclusions);
                     managed = new Holder<>(ex);
                     managedExclusions.put(key, managed);
                 } else {
                     managedExclusions.put(key, new Holder<>(exclusions));
                 }
             }
         }
 
         return newInstance(
                 managedVersions != null ? managedVersions.done() : null,
                 managedScopes != null ? managedScopes.done() : null,
                 managedOptionals != null ? managedOptionals.done() : null,
                 managedLocalPaths != null ? managedLocalPaths.done() : null,
                 managedExclusions != null ? managedExclusions.done() : null);
     }
 
     @Override
     public DependencyManagement manageDependency(Dependency dependency) {
         requireNonNull(dependency, "dependency cannot be null");
         DependencyManagement management = null;
         Key key = new Key(dependency.getArtifact());
 
         if (isApplied()) {
             String version = getManagedVersion(key);
             // is managed locally by model builder
             // apply only rules coming from "higher" levels
             if (version != null) {
                 management = new DependencyManagement();
                 management.setVersion(version);
             }
 
             String scope = getManagedScope(key);
             // is managed locally by model builder
             // apply only rules coming from "higher" levels
             if (scope != null) {
                 if (management == null) {
                     management = new DependencyManagement();
                 }
                 management.setScope(scope);
 
                 if (systemDependencyScope != null
                         && !systemDependencyScope.is(scope)
                         && systemDependencyScope.getSystemPath(dependency.getArtifact()) != null) {
                     HashMap<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)
                             || (scope == null && systemDependencyScope.is(dependency.getScope())))) {
                 String localPath = getManagedLocalPath(key);
                 if (localPath != null) {
                     if (management == null) {
                         management = new DependencyManagement();
                     }
                     HashMap<String, String> properties =
                             new HashMap<>(dependency.getArtifact().getProperties());
                     systemDependencyScope.setSystemPath(properties, localPath);
                     management.setProperties(properties);
                 }
             }
 
             // optional is not managed by model builder
             // apply only rules coming from "higher" levels
             Boolean optional = getManagedOptional(key);
             if (optional != null) {
                 if (management == null) {
                     management = new DependencyManagement();
                 }
                 management.setOptional(optional);
             }
         }
 
         // 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<Exclusion> exclusions = getManagedExclusions(key);
         if (exclusions != null) {
             if (management == null) {
                 management = new DependencyManagement();
             }
             Collection<Exclusion> result = new LinkedHashSet<>(dependency.getExclusions());
             result.addAll(exclusions);
             management.setExclusions(result);
         }
 
         return management;
     }
 
     /**
      * Returns {@code true} if current context should be factored in (collected/derived).
      */
     protected boolean isDerived() {
         return depth < deriveUntil;
     }
 
     /**
      * Manages dependency properties including "version", "scope", "optional", "local path", and "exclusions".
      * <p>
      * Property management behavior:
      * <ul>
      * <li><strong>Version:</strong> Follows {@link #isDerived()} pattern. Management is applied only at higher
      *     levels to avoid interference with the model builder.</li>
      * <li><strong>Scope:</strong> Derived from root only due to inheritance in dependency graphs. Special handling
      *     for "system" scope to align artifact paths.</li>
      * <li><strong>Optional:</strong> Derived from root only due to inheritance in dependency graphs.</li>
      * <li><strong>Local path:</strong> Managed only when scope is or was set to "system" to ensure consistent
      *     artifact path alignment.</li>
      * <li><strong>Exclusions:</strong> Accumulated additively from root to current level throughout the entire
      *     dependency path.</li>
      * </ul>
      * <p>
      * <strong>Inheritance handling:</strong> Since "scope" and "optional" properties inherit through dependency
      * graphs (beyond model builder scope), they are derived only from the root node. The actual manager
      * implementation determines specific handling behavior.
      * <p>
      * <strong>Default behavior:</strong> Defaults to {@link #isDerived()} to maintain compatibility with
      * "classic" behavior (equivalent to {@code deriveUntil=2}). For custom transitivity management, override
      * this method or ensure inherited managed properties are handled during graph transformation.
      */
     protected boolean isInheritedDerived() {
         return isDerived();
     }
 
     /**
      * Returns {@code true} if current dependency should be managed according to so far collected/derived rules.
      */
     protected boolean isApplied() {
         return depth >= applyFrom;
     }
 
     @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;
         // exclude managedLocalPaths
         return Objects.equals(path, that.path)
                 && depth == that.depth
                 && Objects.equals(managedVersions, that.managedVersions)
                 && Objects.equals(managedScopes, that.managedScopes)
                 && Objects.equals(managedOptionals, that.managedOptionals)
                 && Objects.equals(managedExclusions, that.managedExclusions);
     }
 
     @Override
     public int hashCode() {
         return hashCode;
     }
 
     /**
      * Key class for dependency management rules based on GACE coordinates.
      * GACE = Group, Artifact, Classifier, Extension (excludes version for management purposes).
      */
     protected static class Key {
         private final Artifact artifact;
         private final int hashCode;
 
         /**
          * Creates a new key from the given artifact's GACE coordinates.
          *
          * @param artifact the artifact to create a key for
          */
         Key(Artifact artifact) {
             this.artifact = artifact;
             this.hashCode = Objects.hash(
                     artifact.getArtifactId(), artifact.getGroupId(), artifact.getExtension(), artifact.getClassifier());
         }
 
         @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);
         }
     }
 
     /**
      * Wrapper class for collection to memoize hash code.
      *
      * @param <T> the collection type
      */
     protected static class Holder<T> {
         private final T value;
         private final int hashCode;
 
         Holder(T value) {
             this.value = requireNonNull(value);
             this.hashCode = Objects.hash(value);
         }
 
         public T getValue() {
             return value;
         }
 
         @Override
         public boolean equals(Object o) {
             if (!(o instanceof Holder)) {
                 return false;
             }
             Holder<?> holder = (Holder<?>) o;
             return Objects.equals(value, holder.value);
         }
 
         @Override
         public int hashCode() {
             return hashCode;
         }
     }
 }