/*
 * 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.apache.maven.shared.dependency.graph.internal;

import org.eclipse.aether.collection.DependencyCollectionContext;
import org.eclipse.aether.collection.DependencySelector;
import org.eclipse.aether.graph.Dependency;

/**
 * A dependency selector that excludes dependencies of an specific Scope which occur beyond level one of the dependency
 * graph.
 *
 * @see Dependency#getScope()
 * @author Gabriel Belingueres
 * @since 3.1.0
 */
public class DirectScopeDependencySelector implements DependencySelector {

    private final String scope;

    private final int depth;

    public DirectScopeDependencySelector(String scope) {
        this(scope, 0);
    }

    private DirectScopeDependencySelector(String scope, int depth) {
        if (scope == null) {
            throw new IllegalArgumentException("scope is null!");
        }
        this.scope = scope;
        this.depth = depth;
    }

    /**
     * Decides whether the specified dependency should be included in the dependency graph.
     *
     * @param dependency The dependency to check, must not be {@code null}.
     * @return {@code false} if the dependency should be excluded from the children of the current node, {@code true}
     *         otherwise.
     */
    @Override
    public boolean selectDependency(Dependency dependency) {
        return depth < 2 || !scope.equals(dependency.getScope());
    }

    /**
     * Derives a dependency selector for the specified collection context. When calculating the child selector,
     * implementors are strongly advised to simply return the current instance if nothing changed to help save memory.
     *
     * @param context The dependency collection context, must not be {@code null}.
     * @return The dependency selector for the target node, must not be {@code null}.
     */
    @Override
    public DependencySelector deriveChildSelector(DependencyCollectionContext context) {
        if (depth >= 2) {
            return this;
        }

        return new DirectScopeDependencySelector(scope, depth + 1);
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + depth;
        result = prime * result + ((scope == null) ? 0 : scope.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        DirectScopeDependencySelector other = (DirectScopeDependencySelector) obj;
        if (depth != other.depth) {
            return false;
        }
        if (scope == null) {
            if (other.scope != null) {
                return false;
            }
        } else if (!scope.equals(other.scope)) {
            return false;
        }
        return true;
    }
}
