gradle-master/subprojects/dependency-management/src/main/java/org/gradle/api/internal/artifacts/ivyservice/resolveengine/graph/builder/IncompatibleVariantsSelectionMessageBuilder.java
/*
 * Copyright 2019 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.graph.builder;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import org.gradle.api.attributes.Attribute;
import org.gradle.api.internal.attributes.ImmutableAttributes;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Set;

class IncompatibleVariantsSelectionMessageBuilder {
    static String buildMessage(ComponentState selected, Set<NodeState> incompatibleNodes) {
        StringBuilder sb = new StringBuilder("Multiple incompatible variants of ")
                .append(selected.getId())
                .append(" were selected:\n");
        ArrayList<NodeState> sorted = Lists.newArrayList(incompatibleNodes);
        sorted.sort(Comparator.comparing(NodeState::getNameWithVariant));
        for (NodeState node : sorted) {
            sb.append("   - Variant ").append(node.getNameWithVariant()).append(" has attributes ");
            appendAttributes(sb, node.getMetadata().getAttributes());
            sb.append("\n");
        }
        return sb.toString();
    }

    private static void appendAttributes(StringBuilder sb, ImmutableAttributes attributes) {
        ImmutableSet<Attribute<?>> keySet = attributes.keySet();
        List<Attribute<?>> sorted = Lists.newArrayList(keySet);
        sorted.sort(Comparator.comparing(Attribute::getName));
        boolean space = false;
        sb.append("{");
        for (Attribute<?> attribute : sorted) {
            if (space) {
                sb.append(", ");
            }
            sb.append(attribute.getName()).append("=").append(attributes.getAttribute(attribute));
            space = true;
        }
        sb.append("}");
    }
}
