/*
 * 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.settings.building;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * Signals one ore more errors during settings building. The settings builder tries to collect as many problems as
 * possible before eventually failing to provide callers with rich error information. Use {@link #getProblems()} to
 * query the details of the failure.
 *
 * @author Benjamin Bentmann
 */
public class SettingsBuildingException extends Exception {

    private final List<SettingsProblem> problems;

    /**
     * Creates a new exception with the specified problems.
     *
     * @param problems The problems that causes this exception, may be {@code null}.
     */
    public SettingsBuildingException(List<SettingsProblem> problems) {
        super(toMessage(problems));

        this.problems = new ArrayList<>();
        if (problems != null) {
            this.problems.addAll(problems);
        }
    }

    /**
     * Gets the problems that caused this exception.
     *
     * @return The problems that caused this exception, never {@code null}.
     */
    public List<SettingsProblem> getProblems() {
        return problems;
    }

    private static String toMessage(List<SettingsProblem> problems) {
        StringWriter buffer = new StringWriter(1024);

        PrintWriter writer = new PrintWriter(buffer);

        writer.print(problems.size());
        writer.print((problems.size() == 1) ? " problem was " : " problems were ");
        writer.print("encountered while building the effective settings");
        writer.println();

        for (SettingsProblem problem : problems) {
            writer.print("[");
            writer.print(problem.getSeverity());
            writer.print("] ");
            writer.print(problem.getMessage());
            writer.print(" @ ");
            writer.println(problem.getLocation());
        }

        return buffer.toString();
    }
}
