/*
 * ToroDB
 * Copyright © 2014 8Kdata Technology (www.8kdata.com)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.torodb.backend.rid;

import com.torodb.core.TableRef;
import com.torodb.core.annotations.TorodbIdleService;
import com.torodb.core.d2r.ReservedIdGenerator;
import com.torodb.core.services.IdleTorodbService;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadFactory;

import javax.inject.Inject;

public class ReservedIdGeneratorImpl extends IdleTorodbService implements ReservedIdGenerator {

  private final Map<String, Map<String, Generator>> generators = new ConcurrentHashMap<>();
  private final ReservedIdInfoFactory factory;

  @Inject
  public ReservedIdGeneratorImpl(ReservedIdInfoFactory factory,
      @TorodbIdleService ThreadFactory threadFactory) {
    super(threadFactory);
    this.factory = factory;
  }

  private Generator find(String dbName, String collectionName) {
    Map<String, Generator> collectionsMap = generators.computeIfAbsent(dbName,
        (key) -> new ConcurrentHashMap<>());
    return collectionsMap.computeIfAbsent(collectionName, (key) -> new Generator(dbName,
        collectionName));
  }

  @Override
  public int nextRid(String dbName, String collectionName, TableRef tableRef) {
    return getDocPartRidGenerator(dbName, collectionName).nextRid(tableRef);
  }

  @Override
  public void setNextRid(String dbName, String collectionName, TableRef tableRef, int nextRid) {
    getDocPartRidGenerator(dbName, collectionName).setNextRid(tableRef, nextRid);
  }

  @Override
  public DocPartRidGenerator getDocPartRidGenerator(String dbName, String collectionName) {
    return find(dbName, collectionName);
  }

  @Override
  protected void startUp() throws Exception {
    factory.startAsync();
    factory.awaitRunning();
  }

  @Override
  protected void shutDown() throws Exception {
    factory.stopAsync();
    factory.awaitTerminated();
  }

  private class Generator implements DocPartRidGenerator {

    private String dbName;
    private String collectionName;
    private ConcurrentHashMap<TableRef, ReservedIdInfo> map = new ConcurrentHashMap<>();

    public Generator(String dbName, String collectionName) {
      this.dbName = dbName;
      this.collectionName = collectionName;
    }

    private ReservedIdInfo get(TableRef tableRef) {
      return this.map.computeIfAbsent(tableRef, tr -> factory.create(dbName, collectionName, tr));
    }

    @Override
    public int nextRid(TableRef tableRef) {
      return get(tableRef).getAndAddLastUsedId(1) + 1;
    }

    @Override
    public void setNextRid(TableRef tableRef, int nextRid) {
      get(tableRef).setLastUsedId(nextRid);
    }

  }
}