tsdb-kit/src/index.ts

import { MetricResults, QueryType } from './metrics/metric';
import { Metric } from './metrics/metrics_factory';
import { queryDirect } from './services/direct_service';
import { queryGrafana } from './services/grafana_service';
import { BadRange } from './types';

export { Metric } from './metrics/metrics_factory';
export { Datasource } from './metrics/metric'
export { DatasourceUnavailable } from './types';
export { GrafanaUnavailable } from './services/grafana_service';


const CHUNK_SIZE = 50000;


/**
 * @param metric to query to Grafana
 * @returns { values: [time, value][], columns: string[] }
 */
export async function queryByMetric(
  // TODO: check how did we wanna use `url` field
  metric: Metric, url: string, from: number, to: number, queryType: QueryType,
  // TODO: we need an abstract DatasourceConfig class which will differ in direct and grafana queries
  apiKey?: string
): Promise<MetricResults> {

  if(from > to) {
    throw new BadRange(
      `Data-kit got wrong range: from ${from} > to ${to}`,
      metric.datasource.type,
      url
    );
  }

  if(from === to) {
    console.warn(`Data-kit got from === to`);
  }

  let data: MetricResults = {
    values: [],
    columns: []
  };

  while(true) {
    let query = metric.metricQuery.getQuery(from, to, CHUNK_SIZE, data.values.length);
    let res: any;
    // TODO: use polymorphic `query` method instead
    switch(queryType) {
      case QueryType.GRAFANA:
        res = await queryGrafana(query, apiKey as string, metric.datasource);
        break;
      case QueryType.DIRECT:
        res = await queryDirect(query, metric.datasource);
        break;
      default:
        throw new Error(`Unknown query type: ${queryType}`);
    }
    let chunk = metric.metricQuery.getResults(res);
    let values = chunk.values;
    data.values = data.values.concat(values);
    data.columns = chunk.columns;

    if(values.length < CHUNK_SIZE) {
      // because if we get less that we could, then there is nothing more
      break;
    }
  }
  return data;
}