// Copyright (C) 2011 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.rules.prolog;

import com.google.gerrit.entities.Account;
import com.google.gerrit.entities.Change;
import com.google.gerrit.entities.PatchSet;
import com.google.gerrit.entities.Project;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.server.AnonymousUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.PatchSetUtil;
import com.google.gerrit.server.account.AccountCache;
import com.google.gerrit.server.account.Accounts;
import com.google.gerrit.server.account.Emails;
import com.google.gerrit.server.config.PluginConfigFactory;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.patch.DiffNotAvailableException;
import com.google.gerrit.server.patch.DiffOperations;
import com.google.gerrit.server.patch.DiffOptions;
import com.google.gerrit.server.patch.filediff.FileDiffOutput;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.project.ProjectState;
import com.google.gerrit.server.query.change.ChangeData;
import com.googlecode.prolog_cafe.exceptions.SystemException;
import com.googlecode.prolog_cafe.lang.Prolog;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;

public final class StoredValues {
  public static final StoredValue<Accounts> ACCOUNTS = StoredValue.create(Accounts.class);
  public static final StoredValue<AccountCache> ACCOUNT_CACHE =
      StoredValue.create(AccountCache.class);
  public static final StoredValue<Emails> EMAILS = StoredValue.create(Emails.class);
  public static final StoredValue<ChangeData> CHANGE_DATA = StoredValue.create(ChangeData.class);
  public static final StoredValue<ProjectState> PROJECT_STATE =
      StoredValue.create(ProjectState.class);

  public static Change getChange(Prolog engine) throws SystemException {
    ChangeData cd = CHANGE_DATA.get(engine);
    try {
      return cd.change();
    } catch (StorageException e) {
      throw new SystemException(
          String.format("Cannot load change %s: %s", cd.getId(), e.getMessage()));
    }
  }

  public static PatchSet getPatchSet(Prolog engine) throws SystemException {
    ChangeData cd = CHANGE_DATA.get(engine);
    try {
      return cd.currentPatchSet();
    } catch (StorageException e) {
      throw new SystemException(e.getMessage());
    }
  }

  public static final StoredValue<RevCommit> COMMIT =
      new StoredValue<>() {
        @Override
        public RevCommit createValue(Prolog engine) {
          Change change = getChange(engine);
          PatchSet ps = getPatchSet(engine);
          PrologEnvironment env = (PrologEnvironment) engine.control;
          PatchSetUtil patchSetUtil = env.getArgs().getPatchsetUtil();
          try {
            return patchSetUtil.getRevCommit(change.getProject(), ps);
          } catch (IOException e) {
            throw new SystemException(e.getMessage());
          }
        }
      };

  public static final StoredValue<Map<String, FileDiffOutput>> DIFF_LIST =
      new StoredValue<>() {
        @Override
        public Map<String, FileDiffOutput> createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          PatchSet ps = getPatchSet(engine);
          DiffOperations diffOperations = env.getArgs().getDiffOperations();
          Change change = getChange(engine);
          Project.NameKey project = change.getProject();
          Map<String, FileDiffOutput> diffList;
          try {
            diffList =
                diffOperations.listModifiedFilesAgainstParent(
                    project, ps.commitId(), /* parentNum= */ 0, DiffOptions.DEFAULTS);
          } catch (DiffNotAvailableException e) {
            throw new SystemException(
                String.format(
                    "Cannot create modified files for project %s, commit Id %s: %s",
                    project, ps.commitId(), e.getMessage()));
          }
          return diffList;
        }
      };

  // Accessing GitRepositoryManager could be slow.
  // It should be minimized or cached to reduce pause time
  // when evaluating Prolog submit rules.
  public static final StoredValue<GitRepositoryManager> REPO_MANAGER =
      new StoredValue<>() {
        @Override
        public GitRepositoryManager createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          return env.getArgs().getGitRepositoryManager();
        }
      };

  public static final StoredValue<PluginConfigFactory> PLUGIN_CONFIG_FACTORY =
      new StoredValue<>() {
        @Override
        public PluginConfigFactory createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          return env.getArgs().getPluginConfigFactory();
        }
      };

  public static final StoredValue<Repository> REPOSITORY =
      new StoredValue<>() {
        @Override
        public Repository createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          GitRepositoryManager gitMgr = env.getArgs().getGitRepositoryManager();
          Change change = getChange(engine);
          Project.NameKey projectKey = change.getProject();
          Repository repo;
          try {
            repo = gitMgr.openRepository(projectKey);
          } catch (IOException e) {
            throw new SystemException(e.getMessage());
          }
          env.addToCleanup(repo::close);
          return repo;
        }
      };

  public static final StoredValue<PermissionBackend> PERMISSION_BACKEND =
      new StoredValue<>() {
        @Override
        protected PermissionBackend createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          return env.getArgs().getPermissionBackend();
        }
      };

  public static final StoredValue<AnonymousUser> ANONYMOUS_USER =
      new StoredValue<>() {
        @Override
        protected AnonymousUser createValue(Prolog engine) {
          PrologEnvironment env = (PrologEnvironment) engine.control;
          return env.getArgs().getAnonymousUser();
        }
      };

  public static final StoredValue<Map<Account.Id, IdentifiedUser>> USERS =
      new StoredValue<>() {
        @Override
        protected Map<Account.Id, IdentifiedUser> createValue(Prolog engine) {
          return new HashMap<>();
        }
      };

  private StoredValues() {}
}