/*
 * 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.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.artifact.ArtifactProperties;
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.util.artifact.JavaScopes;

import static java.util.Objects.requireNonNull;

/**
 * A dependency manager managing dependencies on all levels supporting transitive dependency management.
 * <p>
 * <b>Note:</b>Unlike the {@code ClassicDependencyManager} and the {@code TransitiveDependencyManager} this
 * implementation applies management also on the first level. This is considered the resolver's default behaviour.
 * It ignores all management overrides supported by the {@code MavenModelBuilder}.
 * </p>
 *
 * @author Christian Schulte
 * @since 1.4.0
 */
public final class DefaultDependencyManager implements DependencyManager {

    private final Map<Object, String> managedVersions;

    private final Map<Object, String> managedScopes;

    private final Map<Object, Boolean> managedOptionals;

    private final Map<Object, String> managedLocalPaths;

    private final Map<Object, Collection<Exclusion>> managedExclusions;

    private int hashCode;

    /**
     * Creates a new dependency manager without any management information.
     */
    public DefaultDependencyManager() {
        this(
                Collections.<Object, String>emptyMap(),
                Collections.<Object, String>emptyMap(),
                Collections.<Object, Boolean>emptyMap(),
                Collections.<Object, String>emptyMap(),
                Collections.<Object, Collection<Exclusion>>emptyMap());
    }

    private DefaultDependencyManager(
            final Map<Object, String> managedVersions,
            final Map<Object, String> managedScopes,
            final Map<Object, Boolean> managedOptionals,
            final Map<Object, String> managedLocalPaths,
            final Map<Object, Collection<Exclusion>> managedExclusions) {
        super();
        this.managedVersions = managedVersions;
        this.managedScopes = managedScopes;
        this.managedOptionals = managedOptionals;
        this.managedLocalPaths = managedLocalPaths;
        this.managedExclusions = managedExclusions;
    }

    public DependencyManager deriveChildManager(final DependencyCollectionContext context) {
        requireNonNull(context, "context cannot be null");
        Map<Object, String> versions = this.managedVersions;
        Map<Object, String> scopes = this.managedScopes;
        Map<Object, Boolean> optionals = this.managedOptionals;
        Map<Object, String> localPaths = this.managedLocalPaths;
        Map<Object, Collection<Exclusion>> exclusions = this.managedExclusions;

        for (Dependency managedDependency : context.getManagedDependencies()) {
            Artifact artifact = managedDependency.getArtifact();
            Object key = getKey(artifact);

            String version = artifact.getVersion();
            if (!version.isEmpty() && !versions.containsKey(key)) {
                if (versions == this.managedVersions) {
                    versions = new HashMap<>(this.managedVersions);
                }
                versions.put(key, version);
            }

            String scope = managedDependency.getScope();
            if (!scope.isEmpty() && !scopes.containsKey(key)) {
                if (scopes == this.managedScopes) {
                    scopes = new HashMap<>(this.managedScopes);
                }
                scopes.put(key, scope);
            }

            Boolean optional = managedDependency.getOptional();
            if (optional != null && !optionals.containsKey(key)) {
                if (optionals == this.managedOptionals) {
                    optionals = new HashMap<>(this.managedOptionals);
                }
                optionals.put(key, optional);
            }

            String localPath = managedDependency.getArtifact().getProperty(ArtifactProperties.LOCAL_PATH, null);
            if (localPath != null && !localPaths.containsKey(key)) {
                if (localPaths == this.managedLocalPaths) {
                    localPaths = new HashMap<>(this.managedLocalPaths);
                }
                localPaths.put(key, localPath);
            }

            if (!managedDependency.getExclusions().isEmpty()) {
                if (exclusions == this.managedExclusions) {
                    exclusions = new HashMap<>(this.managedExclusions);
                }
                Collection<Exclusion> managed = exclusions.computeIfAbsent(key, k -> new LinkedHashSet<>());
                managed.addAll(managedDependency.getExclusions());
            }
        }

        return new DefaultDependencyManager(versions, scopes, optionals, localPaths, exclusions);
    }

    public DependencyManagement manageDependency(Dependency dependency) {
        requireNonNull(dependency, "dependency cannot be null");
        DependencyManagement management = null;

        Object key = getKey(dependency.getArtifact());

        String version = managedVersions.get(key);
        if (version != null) {
            management = new DependencyManagement();
            management.setVersion(version);
        }

        String scope = managedScopes.get(key);
        if (scope != null) {
            if (management == null) {
                management = new DependencyManagement();
            }
            management.setScope(scope);

            if (!JavaScopes.SYSTEM.equals(scope)
                    && dependency.getArtifact().getProperty(ArtifactProperties.LOCAL_PATH, null) != null) {
                Map<String, String> properties =
                        new HashMap<>(dependency.getArtifact().getProperties());

                properties.remove(ArtifactProperties.LOCAL_PATH);
                management.setProperties(properties);
            }
        }

        if ((scope != null && JavaScopes.SYSTEM.equals(scope))
                || (scope == null && JavaScopes.SYSTEM.equals(dependency.getScope()))) {
            String localPath = managedLocalPaths.get(key);
            if (localPath != null) {
                if (management == null) {
                    management = new DependencyManagement();
                }

                Map<String, String> properties =
                        new HashMap<>(dependency.getArtifact().getProperties());

                properties.put(ArtifactProperties.LOCAL_PATH, localPath);
                management.setProperties(properties);
            }
        }

        Boolean optional = managedOptionals.get(key);
        if (optional != null) {
            if (management == null) {
                management = new DependencyManagement();
            }
            management.setOptional(optional);
        }

        Collection<Exclusion> exclusions = managedExclusions.get(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;
    }

    private Object getKey(Artifact a) {
        return new Key(a);
    }

    @Override
    public boolean equals(final Object obj) {
        boolean equal = obj instanceof DefaultDependencyManager;

        if (equal) {
            final DefaultDependencyManager that = (DefaultDependencyManager) obj;
            equal = Objects.equals(managedVersions, that.managedVersions)
                    && Objects.equals(managedScopes, that.managedScopes)
                    && Objects.equals(managedOptionals, that.managedOptionals)
                    && Objects.equals(managedExclusions, that.managedExclusions);
        }

        return equal;
    }

    @Override
    public int hashCode() {
        if (hashCode == 0) {
            hashCode = Objects.hash(managedVersions, managedScopes, managedOptionals, managedExclusions);
        }
        return hashCode;
    }

    static class Key {

        private final Artifact artifact;

        private final int hashCode;

        Key(final Artifact artifact) {
            this.artifact = artifact;
            this.hashCode = Objects.hash(artifact.getGroupId(), artifact.getArtifactId());
        }

        @Override
        public boolean equals(final Object obj) {
            boolean equal = obj instanceof Key;

            if (equal) {
                final Key that = (Key) obj;
                return Objects.equals(artifact.getArtifactId(), that.artifact.getArtifactId())
                        && Objects.equals(artifact.getGroupId(), that.artifact.getGroupId())
                        && Objects.equals(artifact.getExtension(), that.artifact.getExtension())
                        && Objects.equals(artifact.getClassifier(), that.artifact.getClassifier());
            }

            return false;
        }

        @Override
        public int hashCode() {
            return this.hashCode;
        }
    }
}
