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/*
 * Copyright The Stargate Authors
 *
 * 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 io.stargate.sgv2.graphql.schema.graphqlfirst.fetchers.deployed;

import com.apollographql.federation.graphqljava._Entity;
import graphql.schema.DataFetchingEnvironment;
import io.stargate.bridge.proto.QueryOuterClass.ResultSet;
import io.stargate.bridge.proto.Schema.CqlKeyspaceDescribe;
import io.stargate.sgv2.common.cql.builder.BuiltCondition;
import io.stargate.sgv2.graphql.schema.graphqlfirst.processor.EntityModel;
import io.stargate.sgv2.graphql.schema.graphqlfirst.processor.MappingModel;
import io.stargate.sgv2.graphql.web.resources.StargateGraphqlContext;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;

/**
 * Executes the {@code _entities} query of GraphQL federation.
 *
 * @see The
 *     Apollo Federation spec
 */
public class FederatedEntityFetcher extends DeployedFetcher> {

  private final MappingModel mappingModel;

  public FederatedEntityFetcher(MappingModel mappingModel, CqlKeyspaceDescribe keyspace) {
    super(mappingModel, keyspace);
    this.mappingModel = mappingModel;
  }

  @Override
  protected List get(
      DataFetchingEnvironment environment, StargateGraphqlContext context) {

    List result = new ArrayList<>();
    for (Map representation :
        environment.>>getArgument(_Entity.argumentName)) {
      result.add(getEntity(representation, context));
    }
    return result;
  }

  private FederatedEntity getEntity(
      Map representation, StargateGraphqlContext context) {
    Object rawTypeName = representation.get("__typename");
    if (!(rawTypeName instanceof String)) {
      throw new IllegalArgumentException(
          "Entity representations must contain a '__typename' string field");
    }
    String entityName = (String) rawTypeName;
    EntityModel entityModel = mappingModel.getEntities().get(entityName);

    if (entityModel == null) {
      throw new IllegalArgumentException(String.format("Unknown entity type %s", entityName));
    }
    List whereConditions =
        bindWhere(
            entityModel.getPrimaryKeyWhereConditions(),
            representation::containsKey,
            representation::get,
            entityModel::validateNoFiltering,
            keyspace);
    ResultSet resultSet =
        query(entityModel, whereConditions, Optional.empty(), DEFAULT_PARAMETERS, context);
    Map entity = toSingleEntity(resultSet, entityModel);
    return FederatedEntity.wrap(entityModel, entity);
  }
}