// 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.pgm.init;

import static com.google.gerrit.pgm.init.api.InitUtil.hostname;
import static java.nio.file.Files.exists;

import com.google.gerrit.pgm.init.api.ConsoleUI;
import com.google.gerrit.pgm.init.api.InitStep;
import com.google.gerrit.pgm.init.api.Section;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.ioutil.HostPlatform;
import com.google.gerrit.server.util.SocketUtil;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.lang.ProcessBuilder.Redirect;
import java.net.InetSocketAddress;

/** Initialize the {@code sshd} configuration section. */
@Singleton
public class InitSshd implements InitStep {
  private final ConsoleUI ui;
  private final SitePaths site;
  private final Section sshd;
  private final StaleLibraryRemover remover;

  @Inject
  InitSshd(ConsoleUI ui, SitePaths site, Section.Factory sections, StaleLibraryRemover remover) {
    this.ui = ui;
    this.site = site;
    this.sshd = sections.get("sshd", null);
    this.remover = remover;
  }

  @Override
  public void run() throws Exception {
    ui.header("SSH Daemon");

    String hostname = "*";
    int port = 29418;
    String listenAddress = sshd.get("listenAddress");
    if (isOff(listenAddress)) {
      hostname = "off";
    } else if (listenAddress != null && !listenAddress.isEmpty()) {
      final InetSocketAddress addr = SocketUtil.parse(listenAddress, port);
      hostname = SocketUtil.hostname(addr);
      port = addr.getPort();
    }

    hostname = ui.readString(hostname, "Listen on address");
    if (isOff(hostname)) {
      sshd.set("listenAddress", "off");
      return;
    }

    port = ui.readInt(port, "Listen on port");
    sshd.set("listenAddress", SocketUtil.format(hostname, port));

    generateSshHostKeys();
    remover.remove("bc(pg|pkix|prov)-.*[.]jar");
  }

  static boolean isOff(String listenHostname) {
    return "off".equalsIgnoreCase(listenHostname)
        || "none".equalsIgnoreCase(listenHostname)
        || "no".equalsIgnoreCase(listenHostname);
  }

  private void generateSshHostKeys() throws InterruptedException, IOException {
    if (!exists(site.ssh_key)
        && (!exists(site.ssh_rsa)
            || !exists(site.ssh_ed25519)
            || !exists(site.ssh_ecdsa_256)
            || !exists(site.ssh_ecdsa_384)
            || !exists(site.ssh_ecdsa_521))) {
      System.err.print("Generating SSH host key ...");
      System.err.flush();

      // Generate the SSH daemon host key using ssh-keygen.
      //
      final String comment = "gerrit-code-review@" + hostname();

      // Workaround for JDK-6518827 - zero-length argument ignored on Win32
      String emptyPassphraseArg = HostPlatform.isWin32() ? "\"\"" : "";
      if (!exists(site.ssh_rsa)) {
        System.err.print(" rsa...");
        System.err.flush();
        new ProcessBuilder(
                "ssh-keygen",
                "-q" /* quiet */,
                "-t",
                "rsa",
                "-N",
                emptyPassphraseArg,
                "-C",
                comment,
                "-f",
                site.ssh_rsa.toAbsolutePath().toString())
            .redirectError(Redirect.INHERIT)
            .redirectOutput(Redirect.INHERIT)
            .start()
            .waitFor();
      }

      if (!exists(site.ssh_ed25519)) {
        System.err.print(" ed25519...");
        System.err.flush();
        try {
          new ProcessBuilder(
                  "ssh-keygen",
                  "-q" /* quiet */,
                  "-t",
                  "ed25519",
                  "-P",
                  emptyPassphraseArg,
                  "-C",
                  comment,
                  "-f",
                  site.ssh_ed25519.toAbsolutePath().toString())
              .redirectError(Redirect.INHERIT)
              .redirectOutput(Redirect.INHERIT)
              .start()
              .waitFor();
        } catch (Exception e) {
          // continue since older hosts won't be able to generate ed25519 keys.
          System.err.print(" Failed to generate ed25519 key, continuing...");
          System.err.flush();
        }
      }

      if (!exists(site.ssh_ecdsa_256)) {
        System.err.print(" ecdsa 256...");
        System.err.flush();
        try {
          new ProcessBuilder(
                  "ssh-keygen",
                  "-q" /* quiet */,
                  "-t",
                  "ecdsa",
                  "-b",
                  "256",
                  "-P",
                  emptyPassphraseArg,
                  "-C",
                  comment,
                  "-f",
                  site.ssh_ecdsa_256.toAbsolutePath().toString())
              .redirectError(Redirect.INHERIT)
              .redirectOutput(Redirect.INHERIT)
              .start()
              .waitFor();
        } catch (Exception e) {
          // continue since older hosts won't be able to generate ecdsa keys.
          System.err.print(" Failed to generate ecdsa 256 key, continuing...");
          System.err.flush();
        }
      }

      if (!exists(site.ssh_ecdsa_384)) {
        System.err.print(" ecdsa 384...");
        System.err.flush();
        try {
          new ProcessBuilder(
                  "ssh-keygen",
                  "-q" /* quiet */,
                  "-t",
                  "ecdsa",
                  "-b",
                  "384",
                  "-P",
                  emptyPassphraseArg,
                  "-C",
                  comment,
                  "-f",
                  site.ssh_ecdsa_384.toAbsolutePath().toString())
              .redirectError(Redirect.INHERIT)
              .redirectOutput(Redirect.INHERIT)
              .start()
              .waitFor();
        } catch (Exception e) {
          // continue since older hosts won't be able to generate ecdsa keys.
          System.err.print(" Failed to generate ecdsa 384 key, continuing...");
          System.err.flush();
        }
      }

      if (!exists(site.ssh_ecdsa_521)) {
        System.err.print(" ecdsa 521...");
        System.err.flush();
        try {
          new ProcessBuilder(
                  "ssh-keygen",
                  "-q" /* quiet */,
                  "-t",
                  "ecdsa",
                  "-b",
                  "521",
                  "-P",
                  emptyPassphraseArg,
                  "-C",
                  comment,
                  "-f",
                  site.ssh_ecdsa_521.toAbsolutePath().toString())
              .redirectError(Redirect.INHERIT)
              .redirectOutput(Redirect.INHERIT)
              .start()
              .waitFor();
        } catch (Exception e) {
          // continue since older hosts won't be able to generate ecdsa keys.
          System.err.print(" Failed to generate ecdsa 521 key, continuing...");
          System.err.flush();
        }
      }
      System.err.println(" done");
    }
  }
}