/*
 * 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.karaf.shell.ssh;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import javax.security.auth.Subject;

import org.apache.felix.service.command.CommandProcessor;
import org.apache.felix.service.command.CommandSession;
import org.apache.sshd.server.Command;
import org.apache.sshd.server.CommandFactory;
import org.apache.sshd.server.Environment;
import org.apache.sshd.server.ExitCallback;
import org.apache.sshd.server.SessionAware;
import org.apache.sshd.server.session.ServerSession;

public class ShellCommandFactory implements CommandFactory {

    private CommandProcessor commandProcessor;

    public void setCommandProcessor(CommandProcessor commandProcessor) {
        this.commandProcessor = commandProcessor;
    }

    public Command createCommand(String command) {
        return new ShellCommand(command);
    }

    public class ShellCommand implements Command, SessionAware {

        private String command;
        private InputStream in;
        private OutputStream out;
        private OutputStream err;
        private ExitCallback callback;
        private ServerSession session;

        public ShellCommand(String command) {
            this.command = command;
        }

        public void setInputStream(InputStream in) {
            this.in = in;
        }

        public void setOutputStream(OutputStream out) {
            this.out = out;
        }

        public void setErrorStream(OutputStream err) {
            this.err = err;
        }

        public void setExitCallback(ExitCallback callback) {
            this.callback = callback;
        }

        public void setSession(ServerSession session) {
            this.session = session;
        }

        public void start(final Environment env) throws IOException {
            try {
                final CommandSession session = commandProcessor.createSession(in, new PrintStream(out), new PrintStream(err));
                Subject subject = this.session != null ? this.session.getAttribute(KarafJaasPasswordAuthenticator.SUBJECT_ATTRIBUTE_KEY) : null;
                if (subject != null) {
                    try {
                        Subject.doAs(subject, new PrivilegedExceptionAction<Object>() {
                            public Object run() throws Exception {
                                session.execute(command);
                                return null;
                            }
                        });
                    } catch (PrivilegedActionException e) {
                        throw e.getException();
                    }
                } else {
                    session.execute(command);
                }
            } catch (Exception e) {
                throw (IOException) new IOException("Unable to start shell").initCause(e);
            } finally {
                close(in, out, err);
                callback.onExit(0);
            }
        }

        public void destroy() {
		}

    }

    private static void close(Closeable... closeables) {
        for (Closeable c : closeables) {
            try {
                c.close();
            } catch (IOException e) {
                // Ignore
            }
        }
    }
}
