gradle-master/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/resolveengine/ProjectDependencyForcingResolver.java
/*
 * Copyright 2016 the original author or authors.
 *
 * Licensed 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.gradle.api.internal.artifacts.ivyservice.resolveengine;

import org.gradle.api.artifacts.component.ProjectComponentIdentifier;
import org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.conflicts.DefaultConflictResolverDetails;
import org.gradle.internal.Cast;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

class ProjectDependencyForcingResolver<T extends ComponentResolutionState> implements ModuleConflictResolver<T> {
    private final ModuleConflictResolver<T> delegate;

    ProjectDependencyForcingResolver(ModuleConflictResolver<T> delegate) {
        this.delegate = delegate;
    }

    @Override
    public void select(ConflictResolverDetails<T> details) {
        // the collection will only be initialized if more than one project candidate is found
        Collection<T> projectCandidates = null;
        T foundProjectCandidate = null;
        // fine one or more project dependencies among conflicting modules
        for (T candidate : details.getCandidates()) {
            if (candidate.getComponentId() instanceof ProjectComponentIdentifier) {
                if (foundProjectCandidate == null) {
                    // found the first project dependency
                    foundProjectCandidate = candidate;
                } else {
                    // found more than one
                    if (projectCandidates == null) {
                        projectCandidates = new ArrayList<>();
                        projectCandidates.add(foundProjectCandidate);
                    }
                    projectCandidates.add(candidate);
                }
            }
        }
        // if more than one conflicting project dependencies
        // let the delegate resolver select among them
        if (projectCandidates != null) {
            ConflictResolverDetails<T> projectDetails = new DefaultConflictResolverDetails<>(Cast.<List<T>>uncheckedCast(projectCandidates));
            delegate.select(projectDetails);
            details.select(projectDetails.getSelected());
            return;
        }
        // if found only one project dependency - return it, otherwise call the next resolver
        if (foundProjectCandidate != null) {
            details.select(foundProjectCandidate);
        } else {
            delegate.select(details);
        }
    }
}
