/*
 * 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.api.services;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import org.apache.maven.api.Session;
import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.Nonnull;

/**
 * Base class for requests.
 *
 * @since 4.0.0
 */
@Experimental
abstract class BaseRequest {

    private final Session session;

    protected BaseRequest(@Nonnull Session session) {
        this.session = nonNull(session, "session cannot be null");
    }

    @Nonnull
    public Session getSession() {
        return session;
    }

    public static <T> T nonNull(T obj, String message) {
        if (obj == null) {
            throw new IllegalArgumentException(message);
        }
        return obj;
    }

    protected static <T> Collection<T> unmodifiable(Collection<T> obj) {
        return obj != null && !obj.isEmpty()
                ? Collections.unmodifiableCollection(new ArrayList<>(obj))
                : Collections.emptyList();
    }
}