// Copyright (C) 2018 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.googlesource.gerrit.plugins.renameproject;

import static com.googlesource.gerrit.plugins.renameproject.RenameOwnProjectCapability.RENAME_OWN_PROJECT;
import static com.googlesource.gerrit.plugins.renameproject.RenameProjectCapability.RENAME_PROJECT;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Joiner;
import com.google.common.base.Strings;
import com.google.common.cache.Cache;
import com.google.gerrit.entities.Change;
import com.google.gerrit.entities.Change.Id;
import com.google.gerrit.entities.Project;
import com.google.gerrit.extensions.annotations.PluginName;
import com.google.gerrit.extensions.api.access.PluginPermission;
import com.google.gerrit.extensions.restapi.AuthException;
import com.google.gerrit.extensions.restapi.BadRequestException;
import com.google.gerrit.extensions.restapi.ResourceConflictException;
import com.google.gerrit.extensions.restapi.Response;
import com.google.gerrit.extensions.restapi.RestModifyView;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.config.GerritIsReplica;
import com.google.gerrit.server.extensions.events.PluginEvent;
import com.google.gerrit.server.permissions.GlobalPermission;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.permissions.PermissionBackendException;
import com.google.gerrit.server.permissions.ProjectPermission;
import com.google.gerrit.server.project.ProjectResource;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import com.google.inject.name.Named;
import com.googlesource.gerrit.plugins.renameproject.RenameProject.Input;
import com.googlesource.gerrit.plugins.renameproject.cache.CacheRenameHandler;
import com.googlesource.gerrit.plugins.renameproject.conditions.RenamePreconditions;
import com.googlesource.gerrit.plugins.renameproject.database.DatabaseRenameHandler;
import com.googlesource.gerrit.plugins.renameproject.database.IndexUpdateHandler;
import com.googlesource.gerrit.plugins.renameproject.fs.FilesystemRenameHandler;
import com.googlesource.gerrit.plugins.renameproject.monitor.ProgressMonitor;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import org.apache.http.auth.AuthenticationException;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.transport.URIish;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Singleton
public class RenameProject implements RestModifyView<ProjectResource, Input> {

  @Override
  public Response<?> apply(ProjectResource resource, Input input)
      throws IOException, AuthException, BadRequestException, ResourceConflictException,
          InterruptedException, ConfigInvalidException, RenameRevertException {
    Optional<ProgressMonitor> optionalProgressMonitor = Optional.empty();
    assertCanRename(resource, input, optionalProgressMonitor);
    List<Id> changeIds = getChanges(resource, optionalProgressMonitor);
    if (startRename(
        resource,
        input,
        Optional.empty(),
        (changeIds == null || changeIds.size() <= WARNING_LIMIT || input.continueWithRename),
        changeIds)) {
      return Response.ok("");
    }
    return Response.none();
  }

  public boolean startRename(
      ProjectResource resource,
      Input input,
      Optional<ProgressMonitor> optionalProgressMonitor,
      boolean continueRename,
      List<Change.Id> changeIds)
      throws ResourceConflictException, BadRequestException, AuthException, IOException,
          ConfigInvalidException, RenameRevertException, InterruptedException {
    if (!isReplica) {
      if (continueRename) {
        doRename(Optional.ofNullable(changeIds), resource, input, optionalProgressMonitor);
      } else {
        log.debug(CANCELLATION_MSG);
        return false;
      }
    } else {
      doRename(Optional.empty(), resource, input, Optional.empty());
    }
    return true;
  }

  public static class Input {

    String name;
    boolean continueWithRename;
  }

  static final int WARNING_LIMIT = 5000;
  static final String CANCELLATION_MSG =
      "Rename cancelled due to number of changes exceeding warning limit and user's will to not continue";

  private static final Logger log = LoggerFactory.getLogger(RenameProject.class);
  private static final String CACHE_NAME = "changeid_project";
  private static final String WITH_AUTHENTICATION = "a";
  public static final String RENAME_ACTION = "rename";
  public static final String PROJECTS_ENDPOINT = "projects";

  private final DatabaseRenameHandler dbHandler;
  private final FilesystemRenameHandler fsHandler;
  private final CacheRenameHandler cacheHandler;
  private final RenamePreconditions renamePreconditions;
  private final IndexUpdateHandler indexHandler;
  private final Provider<CurrentUser> userProvider;
  private final LockUnlockProject lockUnlockProject;
  private final PluginEvent pluginEvent;
  private final String pluginName;
  private final RenameLog renameLog;
  private final boolean isReplica;
  private final PermissionBackend permissionBackend;
  private final Cache<Change.Id, String> changeIdProjectCache;
  private final RevertRenameProject revertRenameProject;
  private final SshHelper sshHelper;
  private HttpSession httpSession;
  private final Configuration cfg;

  private List<Step> stepsPerformed;

  @Inject
  RenameProject(
      DatabaseRenameHandler dbHandler,
      FilesystemRenameHandler fsHandler,
      CacheRenameHandler cacheHandler,
      RenamePreconditions renamePreconditions,
      IndexUpdateHandler indexHandler,
      Provider<CurrentUser> userProvider,
      LockUnlockProject lockUnlockProject,
      PluginEvent pluginEvent,
      @PluginName String pluginName,
      @GerritIsReplica Boolean isReplica,
      RenameLog renameLog,
      PermissionBackend permissionBackend,
      @Named(CACHE_NAME) Cache<Change.Id, String> changeIdProjectCache,
      RevertRenameProject revertRenameProject,
      SshHelper sshHelper,
      HttpSession httpSession,
      Configuration cfg) {
    this.dbHandler = dbHandler;
    this.fsHandler = fsHandler;
    this.cacheHandler = cacheHandler;
    this.renamePreconditions = renamePreconditions;
    this.indexHandler = indexHandler;
    this.userProvider = userProvider;
    this.lockUnlockProject = lockUnlockProject;
    this.pluginEvent = pluginEvent;
    this.pluginName = pluginName;
    this.renameLog = renameLog;
    this.permissionBackend = permissionBackend;
    this.changeIdProjectCache = changeIdProjectCache;
    this.revertRenameProject = revertRenameProject;
    this.sshHelper = sshHelper;
    this.httpSession = httpSession;
    this.cfg = cfg;
    this.stepsPerformed = new ArrayList<>();
    this.isReplica = isReplica;
  }

  private void assertNewNameNotNull(Input input) throws BadRequestException {
    if (input == null || Strings.isNullOrEmpty(input.name)) {
      throw new BadRequestException("Name of the repo cannot be null or empty");
    }
  }

  private void assertNewNameMatchesRegex(Input input) throws BadRequestException {
    if (!input.name.matches(cfg.getRenameRegex())) {
      throw new BadRequestException(
          String.format(
              "Name of the repo should match the expected regex: %s", cfg.getRenameRegex()));
    }
  }

  private void assertRenamePermission(ProjectResource rsrc) throws AuthException {
    if ((isReplica && !isAdmin()) || !canRename(rsrc)) {
      throw new AuthException("Not allowed to rename project");
    }
  }

  private PermissionBackend.WithUser getUserPermissions() {
    return permissionBackend.user(userProvider.get());
  }

  protected boolean canRename(ProjectResource rsrc) {
    PermissionBackend.WithUser userPermission = getUserPermissions();
    return isAdmin()
        || userPermission.testOrFalse(new PluginPermission(pluginName, RENAME_PROJECT))
        || (userPermission.testOrFalse(new PluginPermission(pluginName, RENAME_OWN_PROJECT))
            && isOwner(rsrc));
  }

  boolean isAdmin() {
    return getUserPermissions().testOrFalse(GlobalPermission.ADMINISTRATE_SERVER);
  }

  private boolean isOwner(ProjectResource project) {
    try {
      permissionBackend
          .user(project.getUser())
          .project(project.getNameKey())
          .check(ProjectPermission.WRITE_CONFIG);
    } catch (AuthException | PermissionBackendException noWriter) {
      try {
        permissionBackend.user(project.getUser()).check(GlobalPermission.ADMINISTRATE_SERVER);
      } catch (AuthException | PermissionBackendException noAdmin) {
        return false;
      }
    }
    return true;
  }

  void assertCanRename(ProjectResource rsrc, Input input, Optional<ProgressMonitor> opm)
      throws ResourceConflictException, BadRequestException, AuthException {
    try {
      opm.ifPresent(progressMonitor -> progressMonitor.beginTask("Checking preconditions"));
      assertNewNameNotNull(input);
      assertNewNameMatchesRegex(input);
      assertRenamePermission(rsrc);
      if (!isReplica) {
        renamePreconditions.assertCanRename(rsrc, Project.nameKey(input.name));
      }
      log.debug("Rename preconditions check successful.");
    } catch (CannotRenameProjectException e) {
      throw new ResourceConflictException(e.getMessage());
    }
  }

  void doRename(
      Optional<List<Change.Id>> opChangeIds,
      ProjectResource rsrc,
      Input input,
      Optional<ProgressMonitor> opm)
      throws InterruptedException, ConfigInvalidException, IOException, RenameRevertException {
    Project.NameKey oldProjectKey = rsrc.getNameKey();
    Project.NameKey newProjectKey = Project.nameKey(input.name);
    Exception ex = null;
    stepsPerformed.clear();
    try {
      fsRenameStep(oldProjectKey, newProjectKey, opm);

      if (!isReplica) {

        cacheRenameStep(rsrc.getNameKey(), newProjectKey);

        List<Change.Id> updatedChangeIds =
            dbRenameStep(opChangeIds.get(), oldProjectKey, newProjectKey, opm);

        // if the DB update is successful, update the secondary index
        indexRenameStep(updatedChangeIds, oldProjectKey, newProjectKey, opm);

        // no need to revert this since newProjectKey will be removed from project cache before
        lockUnlockProject.unlock(newProjectKey);
        log.debug("Unlocked the repo {} after rename operation.", newProjectKey.get());

        // flush old changeId -> Project cache for given changeIds
        changeIdProjectCache.invalidateAll(opChangeIds.get());

        pluginEvent.fire(pluginName, pluginName, oldProjectKey.get() + ":" + newProjectKey.get());

        // replicate rename-project operation to other replica instances
        replicateRename(sshHelper, httpSession, input, oldProjectKey, opm);
      }
    } catch (Exception e) {
      if (stepsPerformed.isEmpty()) {
        log.error("Renaming procedure failed. Exception caught: {}", e.toString());
      } else {
        log.error(
            "Renaming procedure failed, last successful step {}. Exception caught: {}",
            stepsPerformed.get(stepsPerformed.size() - 1).toString(),
            e.toString());
      }
      try {
        revertRenameProject.performRevert(
            stepsPerformed, opChangeIds.get(), oldProjectKey, newProjectKey, opm);
      } catch (Exception revertEx) {
        log.error(
            "Failed to revert renaming procedure for {}. Exception caught: {}",
            oldProjectKey.get(),
            revertEx.toString());
        ex = revertEx;
        throw new RenameRevertException(revertEx, e);
      }
      ex = e;
      throw e;
    } finally {
      renameLog.onRename((IdentifiedUser) userProvider.get(), oldProjectKey, input, ex);
    }
  }

  void fsRenameStep(
      Project.NameKey oldProjectKey, Project.NameKey newProjectKey, Optional<ProgressMonitor> opm)
      throws IOException {
    fsHandler.rename(oldProjectKey, newProjectKey, opm);
    logPerformedStep(Step.FILESYSTEM, newProjectKey, oldProjectKey);
  }

  void cacheRenameStep(Project.NameKey oldProjectKey, Project.NameKey newProjectKey)
      throws IOException {
    cacheHandler.update(oldProjectKey, newProjectKey);
    logPerformedStep(Step.CACHE, newProjectKey, oldProjectKey);
  }

  List<Change.Id> dbRenameStep(
      List<Change.Id> changeIds,
      Project.NameKey oldProjectKey,
      Project.NameKey newProjectKey,
      Optional<ProgressMonitor> opm)
      throws IOException, ConfigInvalidException, RenameRevertException {
    List<Change.Id> updatedChangeIds = dbHandler.rename(changeIds, newProjectKey, opm);
    logPerformedStep(Step.DATABASE, newProjectKey, oldProjectKey);
    return updatedChangeIds;
  }

  void indexRenameStep(
      List<Change.Id> updatedChangeIds,
      Project.NameKey oldProjectKey,
      Project.NameKey newProjectKey,
      Optional<ProgressMonitor> opm)
      throws InterruptedException {
    indexHandler.updateIndex(updatedChangeIds, newProjectKey, opm);
    logPerformedStep(Step.INDEX, newProjectKey, oldProjectKey);
  }

  enum Step {
    FILESYSTEM,
    CACHE,
    DATABASE,
    INDEX
  }

  private void logPerformedStep(
      Step step, Project.NameKey newProjectKey, Project.NameKey oldProjectKey) {
    stepsPerformed.add(step);
    switch (step) {
      case FILESYSTEM:
        log.debug("Renamed the git repo to {} successfully.", newProjectKey.get());
        break;
      case CACHE:
        log.debug("Successfully updated project cache for project {}.", newProjectKey.get());
        break;
      case DATABASE:
        log.debug("Updated the changes in DB successfully for project {}.", oldProjectKey.get());
        break;
      case INDEX:
        log.debug("Updated the secondary index successfully for project {}.", oldProjectKey.get());
    }
  }

  @VisibleForTesting
  List<Step> getStepsPerformed() {
    return stepsPerformed;
  }

  List<Change.Id> getChanges(ProjectResource rsrc, Optional<ProgressMonitor> opm)
      throws IOException {
    opm.ifPresent(pm -> pm.beginTask("Retrieving the list of changes from DB"));
    Project.NameKey oldProjectKey = rsrc.getNameKey();
    return dbHandler.getChangeIds(oldProjectKey);
  }

  void replicateRename(
      SshHelper sshHelper,
      HttpSession httpSession,
      Input input,
      Project.NameKey oldProjectKey,
      Optional<ProgressMonitor> opm) {
    opm.ifPresent(
        pm ->
            pm.beginTask(
                String.format(
                    "Replicating the rename of %s to %s", oldProjectKey.get(), input.name)));

    Set<String> urls = cfg.getUrls();
    int nbRetries = cfg.getRenameReplicationRetries();

    for (int i = 0; i < nbRetries && urls.size() > 0; ++i) {
      urls = tryRenameReplication(urls, sshHelper, httpSession, input, oldProjectKey);
    }
    for (String url : urls) {
      log.error(
          "Failed to replicate the renaming of {} to {} on {} during {} attempts",
          oldProjectKey.get(),
          input.name,
          url,
          cfg.getUrls());
    }
  }

  void sshReplicateRename(
      SshHelper sshHelper, Input input, Project.NameKey oldProjectKey, String url)
      throws RenameReplicationException, URISyntaxException, IOException {
    OutputStream errStream = sshHelper.newErrorBufferStream();
    sshHelper.executeRemoteSsh(
        new URIish(url), pluginName + " " + oldProjectKey.get() + " " + input.name, errStream);
    String errorMessage = errStream.toString();
    if (!errorMessage.isEmpty()) {
      throw new RenameReplicationException(errorMessage);
    }
  }

  void httpReplicateRename(
      HttpSession httpSession, Input input, Project.NameKey oldProjectKey, String url)
      throws AuthenticationException, IOException, RenameReplicationException {
    String request =
        Joiner.on("/")
            .join(
                url,
                WITH_AUTHENTICATION,
                PROJECTS_ENDPOINT,
                oldProjectKey.get(),
                pluginName + "~" + RENAME_ACTION);
    HttpResponseHandler.HttpResult result = httpSession.post(request, input);
    if (!result.isSuccessful()) {
      throw new RenameReplicationException(
          String.format("Unable to replicate rename to %s : %s", url, result.getMessage()));
    }
  }

  private Set<String> tryRenameReplication(
      Set<String> replicas,
      SshHelper sshHelper,
      HttpSession httpSession,
      Input input,
      Project.NameKey oldProjectKey) {
    Set<String> failedReplicas = new HashSet<>();
    for (String url : replicas) {
      try {
        if (url.matches("http(.*)")) {
          httpReplicateRename(httpSession, input, oldProjectKey, url);
        }
        if (url.matches("ssh(.*)")) {
          sshReplicateRename(sshHelper, input, oldProjectKey, url);
        }
      } catch (AuthenticationException
          | IOException
          | URISyntaxException
          | RenameReplicationException e) {
        log.info(
            "Rescheduling a rename replication for retry for {} on project {}",
            url,
            oldProjectKey.get());
        e.printStackTrace();
        failedReplicas.add(url);
      }
    }
    return failedReplicas;
  }
}