org.apache.whirr.cli.Main.java Source code

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Here is the source code for org.apache.whirr.cli.Main.java

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/**
 * 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.whirr.cli;

import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import org.apache.whirr.command.Command;
import org.apache.whirr.service.ClusterActionHandler;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.SortedSet;

import static com.google.common.collect.Lists.newArrayList;

/**
 * The entry point for the Whirr CLI.
 */
public class Main {

    private Map<String, Command> commandMap = Maps.newLinkedHashMap();
    private int maxLen = 0;

    Main(Command... commands) throws IOException {
        this(newArrayList(commands));
    }

    Main(Iterable<Command> commands) throws IOException {
        for (Command command : commands) {
            commandMap.put(command.getName(), command);
            maxLen = Math.max(maxLen, command.getName().length());
        }
    }

    int run(InputStream in, PrintStream out, PrintStream err, List<String> list) throws Exception {
        if (list.isEmpty()) {
            printUsage(out);
            return -1;
        }
        Command command = commandMap.get(list.get(0));
        if (command == null) {
            err.printf("Unrecognized command '%s'\n", list.get(0));
            err.println();
            printUsage(err);
            return -1;
        }
        return command.run(in, out, err, list.subList(1, list.size()));
    }

    private void printUsage(PrintStream stream) {
        stream.println("Usage: whirr COMMAND [ARGS]");
        stream.println("where COMMAND may be one of:");
        stream.println();
        for (Command command : commandMap.values()) {
            stream.printf("%" + maxLen + "s  %s\n", command.getName(), command.getDescription());
        }
        stream.println();
        stream.println("Available roles for instances:");
        for (String roleName : getSortedRoleNames()) {
            stream.println("  " + roleName);
        }
    }

    private static SortedSet<String> getSortedRoleNames() {
        ServiceLoader<ClusterActionHandler> loader = ServiceLoader.load(ClusterActionHandler.class);

        SortedSet<String> roles = Sets.newTreeSet();
        for (ClusterActionHandler handler : loader) {
            roles.add(handler.getRole());
        }
        return roles;
    }

    public static void main(String... args) throws Exception {
        ServiceLoader<Command> loader = ServiceLoader.load(Command.class);
        Main main = new Main(loader);

        int rc = main.run(System.in, System.out, System.err, Arrays.asList(args));
        System.exit(rc);
    }
}