// Copyright (C) 2009 The Android Open Source Project
//
// 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 com.google.gerrit.server.ssh;

import com.google.gerrit.client.reviewdb.Account;
import com.google.gerrit.client.rpc.Common;

import org.apache.mina.core.service.IoAcceptor;
import org.apache.mina.core.session.IoSession;
import org.apache.sshd.common.session.AbstractSession;
import org.kohsuke.args4j.Option;

import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;

/** Show the current SSH connections. */
class AdminShowConnections extends AbstractCommand {
  @Option(name = "--numeric", aliases = {"-n"}, usage = "don't resolve names")
  private boolean numeric;

  PrintWriter p;

  @Override
  protected void run() throws Failure, UnsupportedEncodingException {
    assertIsAdministrator();
    p = toPrintWriter(out);

    final IoAcceptor acceptor = GerritSshDaemon.getIoAcceptor();
    if (acceptor == null) {
      throw new Failure(1, "fatal: sshd not running");
    }

    final List<IoSession> list =
        new ArrayList<IoSession>(acceptor.getManagedSessions().values());
    Collections.sort(list, new Comparator<IoSession>() {
      @Override
      public int compare(IoSession arg0, IoSession arg1) {
        if (arg0.getCreationTime() < arg1.getCreationTime()) {
          return -1;
        } else if (arg0.getCreationTime() > arg1.getCreationTime()) {
          return 1;
        }
        return (int) (arg0.getId() - arg1.getId());
      }
    });

    final long now = System.currentTimeMillis();
    p.print(String.format(" %8s %8s   %-15s %s\n", "Start", "Idle", "User",
        "Remote Host"));
    p.print("--------------------------------------------------------------\n");
    for (final IoSession io : list) {
      final AbstractSession s = AbstractSession.getSession(io, true);
      List<AbstractCommand> active =
          s != null ? s.getAttribute(SshUtil.ACTIVE) : null;

      final SocketAddress remoteAddress = io.getRemoteAddress();
      final long start = io.getCreationTime();
      final long idle = now - io.getLastIoTime();

      p.print(String.format(" %8s %8s  %-15.15s %.30s\n", time(now, start),
          age(idle), username(s), hostname(remoteAddress)));
      if (active != null) {
        synchronized (active) {
          for (final AbstractCommand cmd : active) {
            p.print(String.format(" [ %s ]\n", cmd.getCommandLine()));
          }
        }
      }
      p.print("\n");
    }
    p.print("--\n");

    p.flush();
  }

  private static String time(final long now, final long time) {
    if (time - now < 24 * 60 * 60 * 1000L) {
      return new SimpleDateFormat("HH:mm:ss").format(new Date(time));
    }
    return new SimpleDateFormat("MMM-dd").format(new Date(time));
  }

  private static String age(long age) {
    age /= 1000;

    final int sec = (int) (age % 60);
    age /= 60;

    final int min = (int) (age % 60);
    age /= 60;

    final int hr = (int) (age % 60);
    return String.format("%02d:%02d:%02d", hr, min, sec);
  }

  private String username(final AbstractSession s) {
    if (s == null) {
      return "";
    }
    final Account.Id id = s.getAttribute(SshUtil.CURRENT_ACCOUNT);
    if (id == null) {
      return "";
    }
    if (numeric) {
      return "a/" + id.toString();
    }
    final Account a = Common.getAccountCache().get(id);
    return a != null ? a.getSshUserName() : "";
  }

  private String hostname(final SocketAddress remoteAddress) {
    if (remoteAddress == null) {
      return "?";
    }
    String host = null;
    if (remoteAddress instanceof InetSocketAddress) {
      final InetSocketAddress sa = (InetSocketAddress) remoteAddress;
      final InetAddress in = sa.getAddress();
      if (numeric) {
        return in.getHostAddress();
      }
      if (in != null) {
        host = in.getCanonicalHostName();
      } else {
        host = sa.getHostName();
      }
    }
    if (host == null) {
      host = remoteAddress.toString();
    }
    return host;
  }
}