import { Datasource, DatasourceConnector, QueryType } from '../connectors';
import { connectorFactory } from '../connectors/connector_factory';
import { QueryService } from '../services/query_service/base';
import { queryServiceFactory } from '../services/query_service/query_service_factory';


export class QueryConfig {
  queryType: QueryType;
  datasource: Datasource;
  // TODO: Target type (depends on datasource type)
  targets: any[];
  private _datasourceConnector?: DatasourceConnector;
  private _queryService?: QueryService;

  constructor(queryType: QueryType, datasource: Datasource, targets: any[]) {
    if(queryType === undefined) {
      throw new Error('queryType is undefined');
    }
    if(datasource === undefined) {
      throw new Error('datasource is undefined');
    }
    if(targets === undefined) {
      throw new Error('targets is undefined');
    }
    this.queryType = queryType;
    this.datasource = datasource;
    this.targets = targets;
  }

  get datasourceConnector(): DatasourceConnector {
    if(this._datasourceConnector === undefined) {
      this._datasourceConnector = connectorFactory(this);
    }
    return this._datasourceConnector;
  }

  get queryService(): QueryService {
    if(this._queryService === undefined) {
      this._queryService = queryServiceFactory(this);
    }
    return this._queryService;
  }

  public toObject() {
    return {
      queryType: this.queryType,
      datasource: this.datasource,
      targets: this.targets,
    };
  }

  static fromObject(obj: any): QueryConfig {
    if(obj === undefined) {
      throw new Error('obj is undefined');
    }
    return new QueryConfig(
      obj.queryType,
      obj.datasource,
      obj.targets,
    );
  }
}