// Copyright (C) 2014 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.project;

import com.google.common.collect.Lists;
import com.google.gerrit.extensions.api.projects.ReflogEntryInfo;
import com.google.gerrit.extensions.restapi.AuthException;
import com.google.gerrit.extensions.restapi.MethodNotAllowedException;
import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
import com.google.gerrit.extensions.restapi.RestApiException;
import com.google.gerrit.extensions.restapi.RestReadView;
import com.google.gerrit.server.CommonConverters;
import com.google.gerrit.server.args4j.TimestampHandler;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.inject.Inject;
import java.io.IOException;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jgit.lib.ReflogEntry;
import org.eclipse.jgit.lib.ReflogReader;
import org.eclipse.jgit.lib.Repository;
import org.kohsuke.args4j.Option;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class GetReflog implements RestReadView<BranchResource> {
  private static final Logger log = LoggerFactory.getLogger(GetReflog.class);

  private final GitRepositoryManager repoManager;

  @Option(
    name = "--limit",
    aliases = {"-n"},
    metaVar = "CNT",
    usage = "maximum number of reflog entries to list"
  )
  public GetReflog setLimit(int limit) {
    this.limit = limit;
    return this;
  }

  @Option(
    name = "--from",
    metaVar = "TIMESTAMP",
    usage =
        "timestamp from which the reflog entries should be listed (UTC, format: "
            + TimestampHandler.TIMESTAMP_FORMAT
            + ")"
  )
  public GetReflog setFrom(Timestamp from) {
    this.from = from;
    return this;
  }

  @Option(
    name = "--to",
    metaVar = "TIMESTAMP",
    usage =
        "timestamp until which the reflog entries should be listed (UTC, format: "
            + TimestampHandler.TIMESTAMP_FORMAT
            + ")"
  )
  public GetReflog setTo(Timestamp to) {
    this.to = to;
    return this;
  }

  private int limit;
  private Timestamp from;
  private Timestamp to;

  @Inject
  public GetReflog(GitRepositoryManager repoManager) {
    this.repoManager = repoManager;
  }

  @Override
  public List<ReflogEntryInfo> apply(BranchResource rsrc) throws RestApiException, IOException {
    if (!rsrc.getControl().isOwner()) {
      throw new AuthException("not project owner");
    }

    try (Repository repo = repoManager.openRepository(rsrc.getNameKey())) {
      ReflogReader r;
      try {
        r = repo.getReflogReader(rsrc.getRef());
      } catch (UnsupportedOperationException e) {
        String msg = "reflog not supported on repo " + rsrc.getNameKey().get();
        log.error(msg);
        throw new MethodNotAllowedException(msg);
      }
      if (r == null) {
        throw new ResourceNotFoundException(rsrc.getRef());
      }
      List<ReflogEntry> entries;
      if (from == null && to == null) {
        entries = limit > 0 ? r.getReverseEntries(limit) : r.getReverseEntries();
      } else {
        entries = limit > 0 ? new ArrayList<>(limit) : new ArrayList<>();
        for (ReflogEntry e : r.getReverseEntries()) {
          Timestamp timestamp = new Timestamp(e.getWho().getWhen().getTime());
          if ((from == null || from.before(timestamp)) && (to == null || to.after(timestamp))) {
            entries.add(e);
          }
          if (limit > 0 && entries.size() >= limit) {
            break;
          }
        }
      }
      return Lists.transform(entries, e -> newReflogEntryInfo(e));
    }
  }

  private ReflogEntryInfo newReflogEntryInfo(ReflogEntry e) {
    return new ReflogEntryInfo(
        e.getOldId().getName(),
        e.getNewId().getName(),
        CommonConverters.toGitPerson(e.getWho()),
        e.getComment());
  }
}