tsdb-kit/src/metrics/metrics_factory.ts

import { InfluxdbMetric } from './influxdb_metric';
import { GraphiteMetric } from './graphite_metric';
import { AbstractMetric, Datasource, DatasourceType, MetricId } from './metric';
import { PrometheusMetric } from './prometheus_metric';
import { PostgresMetric } from './postgres_metric';
import { ElasticsearchMetric } from './elasticsearch_metric';
import { MysqlMetric } from './mysql_metric';

export function metricFactory(
  datasource: Datasource,
  targets: any[],
  id?: MetricId
): AbstractMetric {

  const classMap = {
    [DatasourceType.INFLUXDB]: InfluxdbMetric,
    [DatasourceType.GRAPHITE]: GraphiteMetric,
    [DatasourceType.PROMETHEUS]: PrometheusMetric,
    [DatasourceType.POSTGRES]: PostgresMetric,
    [DatasourceType.ELASTICSEARCH]: ElasticsearchMetric,
    [DatasourceType.MYSQL]: MysqlMetric,
  };
  if(classMap[datasource.type] === undefined) {
    console.error(`Datasources of type ${datasource.type} are not supported currently`);
    throw new Error(`Datasources of type ${datasource.type} are not supported currently`);
  } else {
    return new classMap[datasource.type](datasource, targets, id);
  }
}

export class Metric {
  datasource: Datasource;
  targets: any[];
  id?: MetricId;
  private _metricQuery?: AbstractMetric;

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

  public get metricQuery() {
    if(this._metricQuery === undefined) {
      this._metricQuery = metricFactory(this.datasource, this.targets, this.id);
    }
    return this._metricQuery;
  }


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

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