// Copyright 2018 The Nomulus Authors. All Rights Reserved.
//
// 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 google.registry.bigquery;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Sets.newConcurrentHashSet;

import com.google.api.services.bigquery.Bigquery;
import com.google.api.services.bigquery.model.Dataset;
import com.google.api.services.bigquery.model.DatasetReference;
import com.google.api.services.bigquery.model.Table;
import com.google.api.services.bigquery.model.TableFieldSchema;
import com.google.api.services.bigquery.model.TableReference;
import com.google.api.services.bigquery.model.TableSchema;
import com.google.common.collect.ImmutableList;
import com.google.common.flogger.FluentLogger;
import jakarta.inject.Inject;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Set;

/** Wrapper of {@link Bigquery} with validation helpers. */
public class CheckedBigquery {

  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  // Cross-request caches to avoid unnecessary RPCs.
  private static Set<String> knownExistingDatasets = newConcurrentHashSet();
  private static Set<String> knownExistingTables = newConcurrentHashSet();

  @Inject Map<String, ImmutableList<TableFieldSchema>> bigquerySchemas;
  @Inject Bigquery bigquery;

  @Inject
  CheckedBigquery() {}

  /**
   * Returns a new connection to Bigquery, first ensuring that the given dataset exists in the
   * project with the given id, creating it if required.
   */
  public Bigquery ensureDataSetExists(String projectId, String datasetId) throws IOException {
    // Note: it's safe for multiple threads to call this as the dataset will only be created once.
    if (!knownExistingDatasets.contains(datasetId)) {
      ensureDataset(bigquery, projectId, datasetId);
      knownExistingDatasets.add(datasetId);
    }

    return bigquery;
  }

  /**
   * Returns a new connection to Bigquery, first ensuring that the given dataset and table exist in
   * project with the given id, creating them if required.
   */
  public Bigquery ensureDataSetAndTableExist(String projectId, String datasetId, String tableId)
      throws IOException {
    ensureDataSetExists(projectId, datasetId);
    checkArgument(bigquerySchemas.containsKey(tableId), "Unknown table ID: %s", tableId);

    if (!knownExistingTables.contains(tableId)) {
      ensureTable(
          bigquery,
          new TableReference()
              .setDatasetId(datasetId)
              .setProjectId(projectId)
              .setTableId(tableId),
            bigquerySchemas.get(tableId));
      knownExistingTables.add(tableId);
    }

    return bigquery;
  }

  /**
   * Ensures the dataset exists by trying to create it. Note that it's not appreciably cheaper
   * to check for dataset existence than it is to try to create it and check for exceptions.
   */
  // Note that these are not static so they can be mocked for testing.
  private void ensureDataset(Bigquery bigquery, String projectId, String datasetId)
      throws IOException {
    try {
      bigquery.datasets()
          .insert(projectId,
              new Dataset().setDatasetReference(
                  new DatasetReference()
                      .setProjectId(projectId)
                      .setDatasetId(datasetId)))
          .execute();
    } catch (IOException e) {
      // Swallow errors about a duplicate dataset, and throw any other ones.
      if (!BigqueryJobFailureException.create(e).getReason().equals("duplicate")) {
        throw e;
      }
    }
  }

  /** Ensures the table exists in Bigquery. */
  private void ensureTable(Bigquery bigquery, TableReference table, List<TableFieldSchema> schema)
      throws IOException {
    try {
      bigquery.tables().insert(table.getProjectId(), table.getDatasetId(), new Table()
          .setSchema(new TableSchema().setFields(schema))
          .setTableReference(table))
          .execute();
      logger.atInfo().log(
          "Created BigQuery table %s:%s.%s.",
          table.getProjectId(), table.getDatasetId(), table.getTableId());
    } catch (IOException e) {
      // Swallow errors about a table that exists, and throw any other ones.
      if (!BigqueryJobFailureException.create(e).getReason().equals("duplicate")) {
        throw e;
      }
    }
  }
}
