// Copyright (C) 2016 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.git.receive;

import static com.google.gerrit.common.FooterConstants.CHANGE_ID;
import static com.google.gerrit.server.mail.MailUtil.getRecipientsFromFooters;
import static com.google.gerrit.server.mail.MailUtil.getRecipientsFromReviewers;
import static com.google.gerrit.server.notedb.ReviewerStateInternal.REVIEWER;
import static org.eclipse.jgit.lib.Constants.R_HEADS;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.common.data.LabelType;
import com.google.gerrit.extensions.api.changes.NotifyHandling;
import com.google.gerrit.extensions.client.ChangeKind;
import com.google.gerrit.extensions.restapi.RestApiException;
import com.google.gerrit.reviewdb.client.Branch;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.ChangeMessage;
import com.google.gerrit.reviewdb.client.Comment;
import com.google.gerrit.reviewdb.client.PatchSet;
import com.google.gerrit.reviewdb.client.PatchSetApproval;
import com.google.gerrit.reviewdb.client.PatchSetInfo;
import com.google.gerrit.server.ApprovalCopier;
import com.google.gerrit.server.ApprovalsUtil;
import com.google.gerrit.server.ChangeMessagesUtil;
import com.google.gerrit.server.CommentsUtil;
import com.google.gerrit.server.PatchSetUtil;
import com.google.gerrit.server.PublishCommentUtil;
import com.google.gerrit.server.account.AccountResolver;
import com.google.gerrit.server.change.ChangeKindCache;
import com.google.gerrit.server.change.EmailReviewComments;
import com.google.gerrit.server.config.SendEmailExecutor;
import com.google.gerrit.server.extensions.events.CommentAdded;
import com.google.gerrit.server.extensions.events.RevisionCreated;
import com.google.gerrit.server.git.MergedByPushOp;
import com.google.gerrit.server.git.receive.ReceiveCommits.MagicBranchInput;
import com.google.gerrit.server.mail.MailUtil.MailRecipients;
import com.google.gerrit.server.mail.send.ReplacePatchSetSender;
import com.google.gerrit.server.notedb.ChangeNotes;
import com.google.gerrit.server.notedb.ChangeUpdate;
import com.google.gerrit.server.permissions.PermissionBackendException;
import com.google.gerrit.server.project.ProjectCache;
import com.google.gerrit.server.project.ProjectState;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.update.BatchUpdateOp;
import com.google.gerrit.server.update.ChangeContext;
import com.google.gerrit.server.update.Context;
import com.google.gerrit.server.update.RepoContext;
import com.google.gerrit.server.util.RequestScopePropagator;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;
import com.google.inject.util.Providers;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.transport.PushCertificate;
import org.eclipse.jgit.transport.ReceiveCommand;

public class ReplaceOp implements BatchUpdateOp {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  public interface Factory {
    ReplaceOp create(
        ProjectState projectState,
        Branch.NameKey dest,
        boolean checkMergedInto,
        @Assisted("priorPatchSetId") PatchSet.Id priorPatchSetId,
        @Assisted("priorCommitId") ObjectId priorCommit,
        @Assisted("patchSetId") PatchSet.Id patchSetId,
        @Assisted("commitId") ObjectId commitId,
        PatchSetInfo info,
        List<String> groups,
        @Nullable MagicBranchInput magicBranch,
        @Nullable PushCertificate pushCertificate);
  }

  private static final String CHANGE_IS_CLOSED = "change is closed";

  private final AccountResolver accountResolver;
  private final ApprovalCopier approvalCopier;
  private final ApprovalsUtil approvalsUtil;
  private final ChangeData.Factory changeDataFactory;
  private final ChangeKindCache changeKindCache;
  private final ChangeMessagesUtil cmUtil;
  private final CommentsUtil commentsUtil;
  private final PublishCommentUtil publishCommentUtil;
  private final EmailReviewComments.Factory emailCommentsFactory;
  private final ExecutorService sendEmailExecutor;
  private final RevisionCreated revisionCreated;
  private final CommentAdded commentAdded;
  private final MergedByPushOp.Factory mergedByPushOpFactory;
  private final PatchSetUtil psUtil;
  private final ReplacePatchSetSender.Factory replacePatchSetFactory;
  private final ProjectCache projectCache;

  private final ProjectState projectState;
  private final Branch.NameKey dest;
  private final boolean checkMergedInto;
  private final PatchSet.Id priorPatchSetId;
  private final ObjectId priorCommitId;
  private final PatchSet.Id patchSetId;
  private final ObjectId commitId;
  private final PatchSetInfo info;
  private final MagicBranchInput magicBranch;
  private final PushCertificate pushCertificate;
  private List<String> groups = ImmutableList.of();

  private final Map<String, Short> approvals = new HashMap<>();
  private final MailRecipients recipients = new MailRecipients();
  private RevCommit commit;
  private ReceiveCommand cmd;
  private ChangeNotes notes;
  private PatchSet newPatchSet;
  private ChangeKind changeKind;
  private ChangeMessage msg;
  private List<Comment> comments = ImmutableList.of();
  private String rejectMessage;
  private MergedByPushOp mergedByPushOp;
  private RequestScopePropagator requestScopePropagator;

  @Inject
  ReplaceOp(
      AccountResolver accountResolver,
      ApprovalCopier approvalCopier,
      ApprovalsUtil approvalsUtil,
      ChangeData.Factory changeDataFactory,
      ChangeKindCache changeKindCache,
      ChangeMessagesUtil cmUtil,
      CommentsUtil commentsUtil,
      PublishCommentUtil publishCommentUtil,
      EmailReviewComments.Factory emailCommentsFactory,
      RevisionCreated revisionCreated,
      CommentAdded commentAdded,
      MergedByPushOp.Factory mergedByPushOpFactory,
      PatchSetUtil psUtil,
      ReplacePatchSetSender.Factory replacePatchSetFactory,
      ProjectCache projectCache,
      @SendEmailExecutor ExecutorService sendEmailExecutor,
      @Assisted ProjectState projectState,
      @Assisted Branch.NameKey dest,
      @Assisted boolean checkMergedInto,
      @Assisted("priorPatchSetId") PatchSet.Id priorPatchSetId,
      @Assisted("priorCommitId") ObjectId priorCommitId,
      @Assisted("patchSetId") PatchSet.Id patchSetId,
      @Assisted("commitId") ObjectId commitId,
      @Assisted PatchSetInfo info,
      @Assisted List<String> groups,
      @Assisted @Nullable MagicBranchInput magicBranch,
      @Assisted @Nullable PushCertificate pushCertificate) {
    this.accountResolver = accountResolver;
    this.approvalCopier = approvalCopier;
    this.approvalsUtil = approvalsUtil;
    this.changeDataFactory = changeDataFactory;
    this.changeKindCache = changeKindCache;
    this.cmUtil = cmUtil;
    this.commentsUtil = commentsUtil;
    this.publishCommentUtil = publishCommentUtil;
    this.emailCommentsFactory = emailCommentsFactory;
    this.revisionCreated = revisionCreated;
    this.commentAdded = commentAdded;
    this.mergedByPushOpFactory = mergedByPushOpFactory;
    this.psUtil = psUtil;
    this.replacePatchSetFactory = replacePatchSetFactory;
    this.projectCache = projectCache;
    this.sendEmailExecutor = sendEmailExecutor;

    this.projectState = projectState;
    this.dest = dest;
    this.checkMergedInto = checkMergedInto;
    this.priorPatchSetId = priorPatchSetId;
    this.priorCommitId = priorCommitId.copy();
    this.patchSetId = patchSetId;
    this.commitId = commitId.copy();
    this.info = info;
    this.groups = groups;
    this.magicBranch = magicBranch;
    this.pushCertificate = pushCertificate;
  }

  @Override
  public void updateRepo(RepoContext ctx) throws Exception {
    commit = ctx.getRevWalk().parseCommit(commitId);
    ctx.getRevWalk().parseBody(commit);
    changeKind =
        changeKindCache.getChangeKind(
            projectState.getNameKey(),
            ctx.getRevWalk(),
            ctx.getRepoView().getConfig(),
            priorCommitId,
            commitId);

    if (checkMergedInto) {
      String mergedInto = findMergedInto(ctx, dest.get(), commit);
      if (mergedInto != null) {
        mergedByPushOp =
            mergedByPushOpFactory.create(requestScopePropagator, patchSetId, mergedInto);
      }
    }

    cmd = new ReceiveCommand(ObjectId.zeroId(), commitId, patchSetId.toRefName());
    ctx.addRefUpdate(cmd);
  }

  @Override
  public boolean updateChange(ChangeContext ctx)
      throws RestApiException, OrmException, IOException, PermissionBackendException {
    notes = ctx.getNotes();
    Change change = notes.getChange();
    if (change == null || change.getStatus().isClosed()) {
      rejectMessage = CHANGE_IS_CLOSED;
      return false;
    }
    if (groups.isEmpty()) {
      PatchSet prevPs = psUtil.current(ctx.getDb(), notes);
      groups = prevPs != null ? prevPs.getGroups() : ImmutableList.<String>of();
    }

    ChangeUpdate update = ctx.getUpdate(patchSetId);
    update.setSubjectForCommit("Create patch set " + patchSetId.get());

    String reviewMessage = null;
    String psDescription = null;
    if (magicBranch != null) {
      recipients.add(magicBranch.getMailRecipients());
      reviewMessage = magicBranch.message;
      psDescription = magicBranch.message;
      approvals.putAll(magicBranch.labels);
      Set<String> hashtags = magicBranch.hashtags;
      if (hashtags != null && !hashtags.isEmpty()) {
        hashtags.addAll(notes.getHashtags());
        update.setHashtags(hashtags);
      }
      if (magicBranch.topic != null && !magicBranch.topic.equals(ctx.getChange().getTopic())) {
        update.setTopic(magicBranch.topic);
      }
      if (magicBranch.removePrivate) {
        change.setPrivate(false);
        update.setPrivate(false);
      } else if (magicBranch.isPrivate) {
        change.setPrivate(true);
        update.setPrivate(true);
      }
      if (magicBranch.ready) {
        change.setWorkInProgress(false);
        change.setReviewStarted(true);
        update.setWorkInProgress(false);
      } else if (magicBranch.workInProgress) {
        change.setWorkInProgress(true);
        update.setWorkInProgress(true);
      }
      if (shouldPublishComments()) {
        boolean workInProgress = change.isWorkInProgress();
        if (magicBranch != null && magicBranch.workInProgress) {
          workInProgress = true;
        }
        comments = publishComments(ctx, workInProgress);
      }
    }

    newPatchSet =
        psUtil.insert(
            ctx.getDb(),
            ctx.getRevWalk(),
            update,
            patchSetId,
            commitId,
            groups,
            pushCertificate != null ? pushCertificate.toTextWithSignature() : null,
            psDescription);

    update.setPsDescription(psDescription);
    recipients.add(getRecipientsFromFooters(accountResolver, commit.getFooterLines()));
    recipients.remove(ctx.getAccountId());
    ChangeData cd = changeDataFactory.create(ctx.getDb(), ctx.getNotes());
    MailRecipients oldRecipients = getRecipientsFromReviewers(cd.reviewers());
    Iterable<PatchSetApproval> newApprovals =
        approvalsUtil.addApprovalsForNewPatchSet(
            ctx.getDb(),
            update,
            projectState.getLabelTypes(),
            newPatchSet,
            ctx.getUser(),
            approvals);
    approvalCopier.copyInReviewDb(
        ctx.getDb(),
        ctx.getNotes(),
        ctx.getUser(),
        newPatchSet,
        ctx.getRevWalk(),
        ctx.getRepoView().getConfig(),
        newApprovals);
    approvalsUtil.addReviewers(
        ctx.getDb(),
        update,
        projectState.getLabelTypes(),
        change,
        newPatchSet,
        info,
        recipients.getReviewers(),
        oldRecipients.getAll());

    // Check if approvals are changing in with this update. If so, add current user to reviewers.
    // Note that this is done separately as addReviewers is filtering out the change owner as
    // reviewer which is needed in several other code paths.
    if (magicBranch != null && !magicBranch.labels.isEmpty()) {
      update.putReviewer(ctx.getAccountId(), REVIEWER);
    }

    recipients.add(oldRecipients);

    msg = createChangeMessage(ctx, reviewMessage);
    cmUtil.addChangeMessage(ctx.getDb(), update, msg);

    if (mergedByPushOp == null) {
      resetChange(ctx);
    } else {
      mergedByPushOp.setPatchSetProvider(Providers.of(newPatchSet)).updateChange(ctx);
    }

    return true;
  }

  private ChangeMessage createChangeMessage(ChangeContext ctx, String reviewMessage)
      throws OrmException, IOException {
    String approvalMessage =
        ApprovalsUtil.renderMessageWithApprovals(
            patchSetId.get(), approvals, scanLabels(ctx, approvals));
    String kindMessage = changeKindMessage(changeKind);
    StringBuilder message = new StringBuilder(approvalMessage);
    if (!Strings.isNullOrEmpty(kindMessage)) {
      message.append(kindMessage);
    } else {
      message.append('.');
    }
    if (comments.size() == 1) {
      message.append("\n\n(1 comment)");
    } else if (comments.size() > 1) {
      message.append(String.format("\n\n(%d comments)", comments.size()));
    }
    if (!Strings.isNullOrEmpty(reviewMessage)) {
      message.append("\n\n").append(reviewMessage);
    }
    boolean workInProgress = ctx.getChange().isWorkInProgress();
    if (magicBranch != null && magicBranch.workInProgress) {
      workInProgress = true;
    }
    return ChangeMessagesUtil.newMessage(
        patchSetId,
        ctx.getUser(),
        ctx.getWhen(),
        message.toString(),
        ChangeMessagesUtil.uploadedPatchSetTag(workInProgress));
  }

  private String changeKindMessage(ChangeKind changeKind) {
    switch (changeKind) {
      case MERGE_FIRST_PARENT_UPDATE:
        return ": New merge patch set was added with a new first parent relative to Patch Set "
            + priorPatchSetId.get()
            + ".";
      case TRIVIAL_REBASE:
        return ": Patch Set " + priorPatchSetId.get() + " was rebased.";
      case NO_CHANGE:
        return ": New patch set was added with same tree, parent"
            + (commit.getParentCount() != 1 ? "s" : "")
            + ", and commit message as Patch Set "
            + priorPatchSetId.get()
            + ".";
      case NO_CODE_CHANGE:
        return ": Commit message was updated.";
      case REWORK:
      default:
        return null;
    }
  }

  private Map<String, PatchSetApproval> scanLabels(ChangeContext ctx, Map<String, Short> approvals)
      throws OrmException, IOException {
    Map<String, PatchSetApproval> current = new HashMap<>();
    // We optimize here and only retrieve current when approvals provided
    if (!approvals.isEmpty()) {
      for (PatchSetApproval a :
          approvalsUtil.byPatchSetUser(
              ctx.getDb(),
              ctx.getNotes(),
              ctx.getUser(),
              priorPatchSetId,
              ctx.getAccountId(),
              ctx.getRevWalk(),
              ctx.getRepoView().getConfig())) {
        if (a.isLegacySubmit()) {
          continue;
        }

        LabelType lt = projectState.getLabelTypes().byLabel(a.getLabelId());
        if (lt != null) {
          current.put(lt.getName(), a);
        }
      }
    }
    return current;
  }

  private void resetChange(ChangeContext ctx) {
    Change change = ctx.getChange();
    if (!change.currentPatchSetId().equals(priorPatchSetId)) {
      return;
    }

    if (magicBranch != null && magicBranch.topic != null) {
      change.setTopic(magicBranch.topic);
    }
    change.setStatus(Change.Status.NEW);
    change.setCurrentPatchSet(info);

    List<String> idList = commit.getFooterLines(CHANGE_ID);
    if (idList.isEmpty()) {
      change.setKey(new Change.Key("I" + commitId.name()));
    } else {
      change.setKey(new Change.Key(idList.get(idList.size() - 1).trim()));
    }
  }

  private List<Comment> publishComments(ChangeContext ctx, boolean workInProgress)
      throws OrmException {
    List<Comment> comments =
        commentsUtil.draftByChangeAuthor(ctx.getDb(), ctx.getNotes(), ctx.getUser().getAccountId());
    publishCommentUtil.publish(
        ctx, patchSetId, comments, ChangeMessagesUtil.uploadedPatchSetTag(workInProgress));
    return comments;
  }

  @Override
  public void postUpdate(Context ctx) throws Exception {
    if (changeKind != ChangeKind.TRIVIAL_REBASE) {
      // TODO(dborowitz): Merge email templates so we only have to send one.
      Runnable e = new ReplaceEmailTask(ctx);
      if (requestScopePropagator != null) {
        @SuppressWarnings("unused")
        Future<?> possiblyIgnoredError = sendEmailExecutor.submit(requestScopePropagator.wrap(e));
      } else {
        e.run();
      }
    }

    NotifyHandling notify = magicBranch != null ? magicBranch.getNotify(notes) : NotifyHandling.ALL;

    if (shouldPublishComments()) {
      emailCommentsFactory
          .create(
              notify,
              magicBranch != null ? magicBranch.getAccountsToNotify() : ImmutableListMultimap.of(),
              notes,
              newPatchSet,
              ctx.getUser().asIdentifiedUser(),
              msg,
              comments,
              msg.getMessage(),
              ImmutableList.of()) // TODO(dborowitz): Include labels.
          .sendAsync();
    }

    revisionCreated.fire(notes.getChange(), newPatchSet, ctx.getAccount(), ctx.getWhen(), notify);
    try {
      fireCommentAddedEvent(ctx);
    } catch (Exception e) {
      logger.atWarning().withCause(e).log("comment-added event invocation failed");
    }
    if (mergedByPushOp != null) {
      mergedByPushOp.postUpdate(ctx);
    }
  }

  private class ReplaceEmailTask implements Runnable {
    private final Context ctx;

    private ReplaceEmailTask(Context ctx) {
      this.ctx = ctx;
    }

    @Override
    public void run() {
      try {
        ReplacePatchSetSender cm =
            replacePatchSetFactory.create(projectState.getNameKey(), notes.getChangeId());
        cm.setFrom(ctx.getAccount().getAccount().getId());
        cm.setPatchSet(newPatchSet, info);
        cm.setChangeMessage(msg.getMessage(), ctx.getWhen());
        if (magicBranch != null) {
          cm.setNotify(magicBranch.getNotify(notes));
          cm.setAccountsToNotify(magicBranch.getAccountsToNotify());
        }
        cm.addReviewers(recipients.getReviewers());
        cm.addExtraCC(recipients.getCcOnly());
        cm.send();
      } catch (Exception e) {
        logger.atSevere().withCause(e).log(
            "Cannot send email for new patch set %s", newPatchSet.getId());
      }
    }

    @Override
    public String toString() {
      return "send-email newpatchset";
    }
  }

  private void fireCommentAddedEvent(Context ctx) throws IOException {
    if (approvals.isEmpty()) {
      return;
    }

    /* For labels that are not set in this operation, show the "current" value
     * of 0, and no oldValue as the value was not modified by this operation.
     * For labels that are set in this operation, the value was modified, so
     * show a transition from an oldValue of 0 to the new value.
     */
    List<LabelType> labels =
        projectCache
            .checkedGet(ctx.getProject())
            .getLabelTypes(notes, ctx.getUser())
            .getLabelTypes();
    Map<String, Short> allApprovals = new HashMap<>();
    Map<String, Short> oldApprovals = new HashMap<>();
    for (LabelType lt : labels) {
      allApprovals.put(lt.getName(), (short) 0);
      oldApprovals.put(lt.getName(), null);
    }
    for (Map.Entry<String, Short> entry : approvals.entrySet()) {
      if (entry.getValue() != 0) {
        allApprovals.put(entry.getKey(), entry.getValue());
        oldApprovals.put(entry.getKey(), (short) 0);
      }
    }

    commentAdded.fire(
        notes.getChange(),
        newPatchSet,
        ctx.getAccount(),
        null,
        allApprovals,
        oldApprovals,
        ctx.getWhen());
  }

  public PatchSet getPatchSet() {
    return newPatchSet;
  }

  public Change getChange() {
    return notes.getChange();
  }

  public String getRejectMessage() {
    return rejectMessage;
  }

  public ReceiveCommand getCommand() {
    return cmd;
  }

  public ReplaceOp setRequestScopePropagator(RequestScopePropagator requestScopePropagator) {
    this.requestScopePropagator = requestScopePropagator;
    return this;
  }

  private static String findMergedInto(Context ctx, String first, RevCommit commit) {
    try {
      RevWalk rw = ctx.getRevWalk();
      Optional<ObjectId> firstId = ctx.getRepoView().getRef(first);
      if (firstId.isPresent() && rw.isMergedInto(commit, rw.parseCommit(firstId.get()))) {
        return first;
      }

      for (Map.Entry<String, ObjectId> e : ctx.getRepoView().getRefs(R_HEADS).entrySet()) {
        if (rw.isMergedInto(commit, rw.parseCommit(e.getValue()))) {
          return R_HEADS + e.getKey();
        }
      }
      return null;
    } catch (IOException e) {
      logger.atWarning().withCause(e).log("Can't check for already submitted change");
      return null;
    }
  }

  private boolean shouldPublishComments() {
    return magicBranch != null && magicBranch.shouldPublishComments();
  }
}