// Copyright (C) 2008 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.httpd.rpc.changedetail;

import com.google.gerrit.common.data.PatchSetDetail;
import com.google.gerrit.common.errors.NoSuchEntityException;
import com.google.gerrit.httpd.rpc.Handler;
import com.google.gerrit.reviewdb.Account;
import com.google.gerrit.reviewdb.AccountDiffPreference;
import com.google.gerrit.reviewdb.AccountDiffPreference.Whitespace;
import com.google.gerrit.reviewdb.AccountPatchReview;
import com.google.gerrit.reviewdb.Patch;
import com.google.gerrit.reviewdb.PatchLineComment;
import com.google.gerrit.reviewdb.PatchSet;
import com.google.gerrit.reviewdb.Project;
import com.google.gerrit.reviewdb.ReviewDb;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.patch.PatchList;
import com.google.gerrit.server.patch.PatchListCache;
import com.google.gerrit.server.patch.PatchListKey;
import com.google.gerrit.server.patch.PatchSetInfoFactory;
import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
import com.google.gerrit.server.project.ChangeControl;
import com.google.gerrit.server.project.NoSuchChangeException;
import com.google.gwtorm.client.OrmException;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;

import org.eclipse.jgit.lib.ObjectId;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Nullable;

/** Creates a {@link PatchSetDetail} from a {@link PatchSet}. */
class PatchSetDetailFactory extends Handler<PatchSetDetail> {

  private static final Logger log =
    LoggerFactory.getLogger(PatchSetDetailFactory.class);

  interface Factory {
    PatchSetDetailFactory create(@Assisted("psIdNew") PatchSet.Id psIdA,
        @Assisted("psIdOld") PatchSet.Id psIdB, AccountDiffPreference diffPrefs);
  }

  private final PatchSetInfoFactory infoFactory;
  private final ReviewDb db;
  private final PatchListCache patchListCache;
  private final ChangeControl.Factory changeControlFactory;

  private Project.NameKey projectKey;
  private final PatchSet.Id psIdNew;
  private final PatchSet.Id psIdOld;
  private final AccountDiffPreference diffPrefs;
  private ObjectId oldId;
  private ObjectId newId;

  private PatchSetDetail detail;
  ChangeControl control;
  PatchSet patchSet;

  @Inject
  PatchSetDetailFactory(final PatchSetInfoFactory psif, final ReviewDb db,
      final PatchListCache patchListCache,
      final ChangeControl.Factory changeControlFactory,
      @Assisted("psIdNew") final PatchSet.Id psIdNew,
      @Assisted("psIdOld") @Nullable final PatchSet.Id psIdOld,
      @Assisted @Nullable final AccountDiffPreference diffPrefs) {
    this.infoFactory = psif;
    this.db = db;
    this.patchListCache = patchListCache;
    this.changeControlFactory = changeControlFactory;

    this.psIdNew = psIdNew;
    this.psIdOld = psIdOld;
    this.diffPrefs = diffPrefs;
  }

  @Override
  public PatchSetDetail call() throws OrmException, NoSuchEntityException,
      PatchSetInfoNotAvailableException, NoSuchChangeException {
    if (control == null || patchSet == null) {
      control = changeControlFactory.validateFor(psIdNew.getParentKey());
      patchSet = db.patchSets().get(psIdNew);
      if (patchSet == null) {
        throw new NoSuchEntityException();
      }
    }

    final PatchList list;

    if (psIdOld != null) {
      newId = toObjectId(psIdNew);
      oldId = psIdOld != null ? toObjectId(psIdOld) : null;

      projectKey = control.getProject().getNameKey();

      list = listFor(keyFor(diffPrefs.getIgnoreWhitespace()));
    } else { // OK, means use base to compare
      list = patchListCache.get(control.getChange(), patchSet);
      if (list == null) {
        throw new NoSuchEntityException();
      }
    }

    final List<Patch> patches = list.toPatchList(patchSet.getId());
    final Map<Patch.Key, Patch> byKey = new HashMap<Patch.Key, Patch>();
    for (final Patch p : patches) {
      byKey.put(p.getKey(), p);
    }

    for (final PatchLineComment c : db.patchComments().published(psIdNew)) {
      final Patch p = byKey.get(c.getKey().getParentKey());
      if (p != null) {
        p.setCommentCount(p.getCommentCount() + 1);
      }
    }

    detail = new PatchSetDetail();
    detail.setPatchSet(patchSet);

    detail.setInfo(infoFactory.get(psIdNew));
    detail.setPatches(patches);

    final CurrentUser user = control.getCurrentUser();
    if (user instanceof IdentifiedUser) {
      // If we are signed in, compute the number of draft comments by the
      // current user on each of these patch files. This way they can more
      // quickly locate where they have pending drafts, and review them.
      //
      final Account.Id me = ((IdentifiedUser) user).getAccountId();
      for (final PatchLineComment c : db.patchComments().draft(psIdNew, me)) {
        final Patch p = byKey.get(c.getKey().getParentKey());
        if (p != null) {
          p.setDraftCount(p.getDraftCount() + 1);
        }
      }

      for (AccountPatchReview r : db.accountPatchReviews().byReviewer(me, psIdNew)) {
        final Patch p = byKey.get(r.getKey().getPatchKey());
        if (p != null) {
          p.setReviewedByCurrentUser(true);
        }
      }
    }

    return detail;
  }

  private ObjectId toObjectId(final PatchSet.Id psId) throws OrmException,
      NoSuchEntityException {
    final PatchSet ps = db.patchSets().get(psId);
    if (ps == null) {
      throw new NoSuchEntityException();
    }

    try {
      return ObjectId.fromString(ps.getRevision().get());
    } catch (IllegalArgumentException e) {
      log.error("Patch set " + psId + " has invalid revision");
      throw new NoSuchEntityException();
    }
  }

  private PatchListKey keyFor(final Whitespace whitespace) {
    return new PatchListKey(projectKey, oldId, newId, whitespace);
  }

  private PatchList listFor(final PatchListKey key) {
    return patchListCache.get(key);
  }
}