/*
 * 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.core.transaction.metainf;

import com.google.common.base.Preconditions;
import com.torodb.core.annotations.DoNotChange;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;

/**
 *
 */
public class ImmutableMetaSnapshot implements MetaSnapshot {

  private final Map<String, ImmutableMetaDatabase> dbsByIdentifier;
  private final Map<String, ImmutableMetaDatabase> dbsByName;

  public ImmutableMetaSnapshot(Iterable<ImmutableMetaDatabase> dbs) {
    Map<String, ImmutableMetaDatabase> byName = new HashMap<>();
    Map<String, ImmutableMetaDatabase> byId = new HashMap<>();
    for (ImmutableMetaDatabase database : dbs) {
      byName.put(database.getName(), database);
      byId.put(database.getIdentifier(), database);
    }
    this.dbsByName = Collections.unmodifiableMap(byName);
    this.dbsByIdentifier = Collections.unmodifiableMap(byId);
  }

  public ImmutableMetaSnapshot(@DoNotChange Map<String, ImmutableMetaDatabase> dbsById) {
    this.dbsByIdentifier = Collections.unmodifiableMap(dbsById);
    this.dbsByName = new HashMap<>(dbsById.size());
    for (ImmutableMetaDatabase schema : dbsById.values()) {
      dbsByName.put(schema.getName(), schema);
    }
  }

  @Override
  public Stream<ImmutableMetaDatabase> streamMetaDatabases() {
    return dbsByIdentifier.values().stream();
  }

  @Override
  public ImmutableMetaDatabase getMetaDatabaseByName(String schemaDocName) {
    return dbsByName.get(schemaDocName);
  }

  @Override
  public ImmutableMetaDatabase getMetaDatabaseByIdentifier(String schemaDbName) {
    return dbsByIdentifier.get(schemaDbName);
  }

  public static class Builder {

    private boolean built = false;
    private final Map<String, ImmutableMetaDatabase> dbsByIdentifier;

    public Builder() {
      dbsByIdentifier = new HashMap<>();
    }

    public Builder(int expectedDbs) {
      dbsByIdentifier = new HashMap<>(expectedDbs);
    }

    public Builder(ImmutableMetaSnapshot other) {
      this.dbsByIdentifier = new HashMap<>(other.dbsByIdentifier);
    }

    public Builder put(ImmutableMetaDatabase.Builder dbBuilder) {
      return Builder.this.put(dbBuilder.build());
    }

    public Builder put(ImmutableMetaDatabase db) {
      Preconditions.checkState(!built, "This builder has already been built");
      dbsByIdentifier.put(db.getIdentifier(), db);
      return this;
    }

    public Builder remove(MetaDatabase metaDb) {
      Preconditions.checkState(!built, "This builder has already been built");
      dbsByIdentifier.remove(metaDb.getIdentifier());
      return this;
    }

    public ImmutableMetaSnapshot build() {
      Preconditions.checkState(!built, "This builder has already been built");
      built = true;
      return new ImmutableMetaSnapshot(dbsByIdentifier);
    }
  }
}