/*
 * Copyright 2018 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.initialization.exception;

import org.gradle.execution.MultipleBuildFailures;
import org.gradle.internal.service.scopes.Scopes;
import org.gradle.internal.service.scopes.ServiceScope;

import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.List;

@ServiceScope(Scopes.BuildTree.class)
public interface ExceptionAnalyser {
    /**
     * Transforms the given build failure to add context where relevant and to remove unnecessary noise.
     *
     * <p>Note that the argument may be mutated as part of the transformation, for example its causes or stack trace may be changed.</p>
     */
    RuntimeException transform(Throwable failure);

    /**
     * Transforms and combines the given failures into a single build failure.
     *
     * @return null if the list of exceptions is empty.
     */
    default @Nullable
    RuntimeException transform(List<Throwable> failures) {
        if (failures.isEmpty()) {
            return null;
        }
        List<Throwable> unpacked = new ArrayList<>(failures.size());
        for (Throwable failure : failures) {
            if (failure instanceof MultipleBuildFailures) {
                unpacked.addAll(((MultipleBuildFailures) failure).getCauses());
            } else {
                unpacked.add(failure);
            }
        }
        if (unpacked.size() == 1) {
            return transform(unpacked.get(0));
        } else {
            return transform(new MultipleBuildFailures(unpacked));
        }
    }
}
