/*
    * Copyright (c) 2015 Maxim Yunusov
    *    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 org.maxur.perfmodel.backend.infrastructure;
  
  import org.iq80.leveldb.WriteBatch;
  import org.jvnet.hk2.annotations.Service;
  import org.maxur.perfmodel.backend.domain.ConflictException;
  import org.maxur.perfmodel.backend.domain.Project;
  import org.maxur.perfmodel.backend.domain.Repository;
  import org.maxur.perfmodel.backend.service.Benchmark;
  import org.maxur.perfmodel.backend.service.DataSource;
  import org.slf4j.Logger;
  
  import javax.inject.Inject;
  import java.io.IOException;
  import java.util.Collection;
  import java.util.Optional;
  
  import static java.lang.String.format;
  import static java.util.Optional.empty;
  import static org.slf4j.LoggerFactory.getLogger;
  
  /**
   * Level Db Implementation of Project Repository.
   *
   * @author myunusov
   * @version 1.0
   * @since <pre>30.08.2015</pre>
   */
  @Service
  public class ProjectRepositoryLevelDbImpl implements Repository<Project> {
  
      private static final Logger LOGGER = getLogger(ProjectRepositoryLevelDbImpl.class);
  
      public static final String ROOT_PREFIX = "/";
  
      @Inject
      private DataSource dataSource;
  
      @Override
      @Benchmark
      public Optional<Project> get(final String key) {
          try {
              return dataSource.get(key);
          } catch (IOException | ClassNotFoundException e) {
              return throwError(e, "Cannot find project by id '%s'", key);
          }
      }
  
      @Override
      @Benchmark
      public Collection<Project> findAll() {
          try {
              return dataSource.findAllByPrefix(ROOT_PREFIX);
          } catch (IOException | ClassNotFoundException e) {
              return throwError(e, "Cannot get all projects");
          }
      }
  
      @Override
      @Benchmark
      public Optional<Project> findByName(final String name) {
          try {
              return dataSource.get(path(name));
          } catch (IOException | ClassNotFoundException e) {
              return throwError(e, "Cannot find project by name '%s'", name);
          }
      }
  
      @Override
      @Benchmark
      public Optional<Project> remove(final String key) {
          try (WriteBatch batch = dataSource.createWriteBatch()) {
              final Optional<Project> result = dataSource.get(key);
              if (result.isPresent()) {
                  dataSource.delete(key);
                  dataSource.delete(path(result.get().getName()));
                  dataSource.commit(batch);
              }
              return result;
          } catch (IOException | ClassNotFoundException e) {
              return throwError(e, "Cannot remove project '%s'", key);
          }
  
      }
  
     @Override
     @Benchmark
     public Optional<Project> add(final Project value) throws ConflictException {
         final String id = value.getId();
         final String newName = value.getName();
         try (WriteBatch batch = dataSource.createWriteBatch()) {
             final Optional<Project> other = dataSource.get(id);
             if (value.isSame(other)) {
                 return other;
             }
             value.checkUniqueId(other);
             value.checkNamesakes(findByName(newName));
             value.makeVersion();
             dataSource.put(id, value);
             dataSource.put(path(newName), value.brief());
             dataSource.commit(batch);
             return Optional.of(value);
         } catch (IOException | ClassNotFoundException e) {
             return throwError(e, "Cannot save project '%s'", newName);
         }
     }
 
     @Override
     @Benchmark
     // idempotent
     public Optional<Project> amend(final Project value) throws ConflictException  {
         final String id = value.getId();
         final String newName = value.getName();
         value.incVersion();
 
         try (WriteBatch batch = dataSource.createWriteBatch()) {
             final Optional<Project> prev = dataSource.get(id);
             if (!prev.isPresent()) {
                 return empty();
             }
             if (value.isSame(prev)) {
                 return prev;
             }
             value.checkConflictWith(prev);
             final boolean mustBeRenamed = !prev.get().getName().equals(newName);
             if (mustBeRenamed) {
                 value.checkNamesakes(findByName(newName));
                 dataSource.delete(path(prev.get().getName()));
             }
             dataSource.put(id, value);
             dataSource.put(path(newName), value.brief());
             dataSource.commit(batch);
             return Optional.of(value);
         } catch (IOException | ClassNotFoundException e) {
             return throwError(e, "Cannot save project '%s'", newName);
         }
     }
 
     private String path(final String name) {
         return ROOT_PREFIX + name;
     }
 
     private static <T> T throwError(final Exception e, final String message, final String... args) {
         final String msg = format(message, args);
         LOGGER.error(msg, e);
         throw new IllegalStateException(msg, e);
     }
 
 }