/*
 * Copyright (c) 2012-2018 Red Hat, Inc.
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *   Red Hat, Inc. - initial API and implementation
 */
package org.eclipse.che.workspace.infrastructure.kubernetes.provision;

import static com.google.common.base.Strings.isNullOrEmpty;
import static java.lang.String.format;
import static java.util.Collections.singletonList;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toMap;
import static org.eclipse.che.workspace.infrastructure.kubernetes.Warnings.NOT_ABLE_TO_PROVISION_SSH_KEYS;
import static org.eclipse.che.workspace.infrastructure.kubernetes.Warnings.NOT_ABLE_TO_PROVISION_SSH_KEYS_MESSAGE;
import static org.eclipse.che.workspace.infrastructure.kubernetes.namespace.KubernetesObjectUtil.isValidConfigMapKeyName;

import com.google.common.annotations.VisibleForTesting;
import io.fabric8.kubernetes.api.model.ConfigMap;
import io.fabric8.kubernetes.api.model.ConfigMapBuilder;
import io.fabric8.kubernetes.api.model.ConfigMapVolumeSourceBuilder;
import io.fabric8.kubernetes.api.model.Container;
import io.fabric8.kubernetes.api.model.PodSpec;
import io.fabric8.kubernetes.api.model.Secret;
import io.fabric8.kubernetes.api.model.SecretBuilder;
import io.fabric8.kubernetes.api.model.SecretVolumeSourceBuilder;
import io.fabric8.kubernetes.api.model.VolumeBuilder;
import io.fabric8.kubernetes.api.model.VolumeMount;
import io.fabric8.kubernetes.api.model.VolumeMountBuilder;
import java.time.ZonedDateTime;
import java.util.ArrayList;
import java.util.Base64;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;
import javax.inject.Inject;
import javax.validation.constraints.NotNull;
import org.eclipse.che.api.core.ConflictException;
import org.eclipse.che.api.core.ServerException;
import org.eclipse.che.api.core.model.workspace.runtime.RuntimeIdentity;
import org.eclipse.che.api.ssh.server.SshManager;
import org.eclipse.che.api.ssh.server.model.impl.SshPairImpl;
import org.eclipse.che.api.ssh.shared.model.SshPair;
import org.eclipse.che.api.workspace.server.model.impl.WarningImpl;
import org.eclipse.che.api.workspace.server.spi.InfrastructureException;
import org.eclipse.che.commons.annotation.Traced;
import org.eclipse.che.commons.tracing.TracingTags;
import org.eclipse.che.workspace.infrastructure.kubernetes.Warnings;
import org.eclipse.che.workspace.infrastructure.kubernetes.environment.KubernetesEnvironment;
import org.eclipse.che.workspace.infrastructure.kubernetes.environment.KubernetesEnvironment.PodRole;
import org.eclipse.che.workspace.infrastructure.kubernetes.util.RuntimeEventsPublisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class allows mount user SSH Keys as <a
 * href="https://kubernetes.io/docs/concepts/configuration/secret">Kubernetes Secrets</a> on each
 * workspace container.<br>
 *
 * <p><strong>How it works:</strong>
 *
 * <ul>
 *   <li>all registered SSH Keys are fetched;
 *   <li>create single K8s Secret with opaque type for storing SSH keys;
 *   <li>in following secret key represents host name and value contains private SSH key;
 *   <li>each key and value in secret is represented on file system by the following structure:
 *       '/etc/ssh/private/{hostName}/ssh-privatekey', where <code>hostName</code> is a key taken
 *       from secret and <code>ssh-privatekey</code> is a file that contains SSH private key taking
 *       by the following key name;
 *   <li>for VCS keys, ConfigMap with SSH settings is created and mounted to container by path
 *       '/etc/ssh/ssh_config'.
 * </ul>
 *
 * @author Vitalii Parfonov
 * @author Vlad Zhukovskyi
 */
public class SshKeysProvisioner implements ConfigurationProvisioner<KubernetesEnvironment> {

  private static String SSH_BASE_CONFIG_PATH = "/etc/ssh/";

  private static final String SSH_PRIVATE_KEYS = "private";
  private static final String SSH_PRIVATE_KEYS_PATH = SSH_BASE_CONFIG_PATH + SSH_PRIVATE_KEYS;

  private static final String SSH_CONFIG = "ssh_config";
  private static final String SSH_CONFIG_PATH = SSH_BASE_CONFIG_PATH + SSH_CONFIG;

  private static final String SSH_CONFIG_MAP_NAME = "sshconfigmap";
  private static final String SSH_SECRET_NAME_SUFFIX = "-sshprivatekeys";

  private static final String SSH_SECRET_TYPE = "opaque";

  public static final Pattern VALID_DOMAIN_PATTERN =
      Pattern.compile("^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*$");

  private static final Logger LOG = LoggerFactory.getLogger(SshKeysProvisioner.class);

  private final SshManager sshManager;
  private final RuntimeEventsPublisher runtimeEventsPublisher;

  @Inject
  public SshKeysProvisioner(SshManager sshManager, RuntimeEventsPublisher runtimeEventsPublisher) {
    this.sshManager = sshManager;
    this.runtimeEventsPublisher = runtimeEventsPublisher;
  }

  @Override
  @Traced
  public void provision(KubernetesEnvironment k8sEnv, RuntimeIdentity identity)
      throws InfrastructureException {
    String workspaceId = identity.getWorkspaceId();
    TracingTags.WORKSPACE_ID.set(workspaceId);

    List<SshPairImpl> vcsSshPairs = getVcsSshPairs(k8sEnv, identity);
    List<SshPairImpl> systemSshPairs = getSystemSshPairs(k8sEnv, identity);

    List<SshPairImpl> allSshPairs = new ArrayList<>(vcsSshPairs);
    allSshPairs.addAll(systemSshPairs);

    List<String> invalidSshKeyNames =
        allSshPairs
            .stream()
            .filter(keyPair -> !isValidSshKeyPair(keyPair))
            .map(SshPairImpl::getName)
            .collect(toList());

    if (!invalidSshKeyNames.isEmpty()) {
      String message =
          format(
              Warnings.SSH_KEYS_WILL_NOT_BE_MOUNTED_MESSAGE,
              invalidSshKeyNames.toString(),
              identity.getWorkspaceId());
      LOG.warn(message);
      k8sEnv.addWarning(new WarningImpl(Warnings.SSH_KEYS_WILL_NOT_BE_MOUNTED, message));
      runtimeEventsPublisher.sendRuntimeLogEvent(message, ZonedDateTime.now().toString(), identity);
    }

    doProvisionSshKeys(
        allSshPairs.stream().filter(this::isValidSshKeyPair).collect(toList()),
        k8sEnv,
        workspaceId);
    doProvisionVcsSshConfig(
        vcsSshPairs.stream().filter(this::isValidSshKeyPair).collect(toList()),
        k8sEnv,
        workspaceId);
  }

  /**
   * Return list of keys related to the VCS (Version Control Systems), Git, SVN and etc. Usually
   * managed by user
   *
   * @param identity
   * @return list of ssh pairs
   */
  private List<SshPairImpl> getVcsSshPairs(KubernetesEnvironment k8sEnv, RuntimeIdentity identity)
      throws InfrastructureException {
    List<SshPairImpl> sshPairs;
    try {
      sshPairs = sshManager.getPairs(identity.getOwnerId(), "vcs");
    } catch (ServerException e) {
      String message = format("Unable to get SSH Keys. Cause: %s", e.getMessage());
      LOG.warn(message);
      k8sEnv.addWarning(
          new WarningImpl(
              NOT_ABLE_TO_PROVISION_SSH_KEYS,
              format(NOT_ABLE_TO_PROVISION_SSH_KEYS_MESSAGE, message)));
      throw new InfrastructureException(e);
    }
    if (sshPairs.isEmpty()) {
      try {
        sshPairs =
            singletonList(
                sshManager.generatePair(
                    identity.getOwnerId(), "vcs", "default-" + new Date().getTime()));
      } catch (ServerException | ConflictException e) {
        String message =
            format("Unable to generate the initial SSH key. Cause: %s", e.getMessage());
        LOG.warn(message);
        k8sEnv.addWarning(
            new WarningImpl(
                NOT_ABLE_TO_PROVISION_SSH_KEYS,
                format(NOT_ABLE_TO_PROVISION_SSH_KEYS_MESSAGE, message)));
        throw new InfrastructureException(e);
      }
    }
    return sshPairs;
  }

  /**
   * Return system (aka 'internal') ssh keys, this key used for internal services like rsync via ssh
   * and etc. Not generated or managed by a user
   *
   * @param identity
   * @return list of keys pair
   */
  private List<SshPairImpl> getSystemSshPairs(KubernetesEnvironment k8sEn, RuntimeIdentity identity)
      throws InfrastructureException {
    List<SshPairImpl> sshPairs;
    try {
      sshPairs = sshManager.getPairs(identity.getOwnerId(), "internal");
    } catch (ServerException e) {
      String message = format("Unable to get SSH Keys. Cause: %s", e.getMessage());
      LOG.warn(message);
      k8sEn.addWarning(
          new WarningImpl(
              NOT_ABLE_TO_PROVISION_SSH_KEYS,
              format(NOT_ABLE_TO_PROVISION_SSH_KEYS_MESSAGE, message)));
      throw new InfrastructureException(e);
    }
    return sshPairs;
  }

  private void doProvisionSshKeys(
      List<SshPairImpl> sshPairs, KubernetesEnvironment k8sEnv, String wsId) {

    Map<String, String> data =
        sshPairs
            .stream()
            .filter(sshPair -> !isNullOrEmpty(sshPair.getPrivateKey()))
            .collect(
                toMap(
                    SshPairImpl::getName,
                    sshPair ->
                        Base64.getEncoder().encodeToString(sshPair.getPrivateKey().getBytes())));

    Secret secret =
        new SecretBuilder()
            .addToData(data)
            .withType(SSH_SECRET_TYPE)
            .withNewMetadata()
            .withName(wsId + SSH_SECRET_NAME_SUFFIX)
            .endMetadata()
            .build();

    k8sEnv.getSecrets().put(secret.getMetadata().getName(), secret);

    k8sEnv
        .getPodsData()
        .values()
        .forEach(
            p -> {
              mountSshKeySecret(
                  secret.getMetadata().getName(), p.getSpec(), p.getRole() != PodRole.INJECTABLE);
            });
  }

  private void mountSshKeySecret(String secretName, PodSpec podSpec, boolean addVolume) {
    if (addVolume) {
      podSpec
          .getVolumes()
          .add(
              new VolumeBuilder()
                  .withName(secretName)
                  .withSecret(
                      new SecretVolumeSourceBuilder()
                          .withSecretName(secretName)
                          .withDefaultMode(0600)
                          .build())
                  .build());
    }

    List<Container> containers = podSpec.getContainers();
    containers.forEach(
        container -> {
          VolumeMount volumeMount =
              new VolumeMountBuilder()
                  .withName(secretName)
                  .withNewReadOnly(true)
                  .withReadOnly(true)
                  .withMountPath(SSH_PRIVATE_KEYS_PATH)
                  .build();
          container.getVolumeMounts().add(volumeMount);
        });
  }

  private void doProvisionVcsSshConfig(
      List<SshPairImpl> vcsSshPairs, KubernetesEnvironment k8sEnv, String wsId) {
    StringBuilder sshConfigData = new StringBuilder();
    for (SshPair sshPair : vcsSshPairs) {
      sshConfigData.append(buildConfig(sshPair.getName()));
    }

    Map<String, String> sshConfig = new HashMap<>();
    sshConfig.put(SSH_CONFIG, sshConfigData.toString());
    ConfigMap configMap =
        new ConfigMapBuilder()
            .withNewMetadata()
            .withName(SSH_CONFIG_MAP_NAME)
            .endMetadata()
            .withData(sshConfig)
            .build();

    k8sEnv.getConfigMaps().put(configMap.getMetadata().getName(), configMap);
    k8sEnv
        .getPodsData()
        .values()
        .forEach(
            p ->
                mountConfigFile(
                    p.getSpec(), SSH_CONFIG_MAP_NAME, p.getRole() != PodRole.INJECTABLE));
  }

  private void mountConfigFile(PodSpec podSpec, String sshConfigMapName, boolean addVolume) {
    String configMapVolumeName = "ssshkeyconfigvolume";
    if (addVolume) {
      podSpec
          .getVolumes()
          .add(
              new VolumeBuilder()
                  .withName(configMapVolumeName)
                  .withConfigMap(
                      new ConfigMapVolumeSourceBuilder().withName(sshConfigMapName).build())
                  .build());
    }

    List<Container> containers = podSpec.getContainers();
    containers.forEach(
        container -> {
          VolumeMount volumeMount =
              new VolumeMountBuilder()
                  .withName(configMapVolumeName)
                  .withMountPath(SSH_CONFIG_PATH)
                  .withSubPath(SSH_CONFIG)
                  .withReadOnly(true)
                  .withNewReadOnly(true)
                  .build();
          container.getVolumeMounts().add(volumeMount);
        });
  }

  @VisibleForTesting
  boolean isValidSshKeyPair(SshPairImpl keyPair) {
    return isValidConfigMapKeyName(keyPair.getName())
        && VALID_DOMAIN_PATTERN.matcher(keyPair.getName()).matches();
  }

  /**
   * Returns the ssh configuration entry which includes host, identity file location and Host Key
   * checking policy
   *
   * <p>Example of provided configuration:
   *
   * <pre>
   * host github.com
   * IdentityFile /etc/ssh/private/github-com/ssh-privatekey
   * StrictHostKeyChecking = no
   * </pre>
   *
   * or
   *
   * <pre>
   * host *
   * IdentityFile /etc/ssh/private/default-123456/ssh-privatekey
   * StrictHostKeyChecking = no
   * </pre>
   *
   * @param name the of key given during generate for vcs service we will consider it as host of
   *     version control service (e.g. github.com, gitlab.com and etc) if name starts from
   *     "default-{anyString}" it will be replaced on wildcard "*" host name. Name with format
   *     "default-{anyString}" will be generated on client side by Theia SSH Plugin, if user doesn't
   *     provide own name. Details see here:
   *     https://github.com/eclipse/che/issues/13494#issuecomment-512761661. Note: behavior can be
   *     improved in 7.x releases after 7.0.0
   * @return the ssh configuration which include host, identity file location and Host Key checking
   *     policy
   */
  private String buildConfig(@NotNull String name) {
    String host = name.startsWith("default-") ? "*" : name;
    return "host "
        + host
        + "\nIdentityFile "
        + SSH_PRIVATE_KEYS_PATH
        + "/"
        + name
        + "\nStrictHostKeyChecking = no"
        + "\n\n";
  }
}
