/**
 * @author Martin Karkowski
 * @email m.karkowski@zema.de
 * @create date 2022-01-03 13:46:51
 * @modify date 2022-01-03 13:46:51
 * @desc [description]
 */

import { maxOfArray, minOfArray } from "../helpers/arrayMethods";
import {
  INopeDispatcher,
  ValidDefaultSelectors,
  ValidSelectorFunction
} from "../types/nope";

/**
 * A Helper Function, to generate the Basic selector Functions.
 *
 * @author M.Karkowski
 * @export
 * @param {ValidDefaultSelectors} selector
 * @param {INopeDispatcher} dispatcher
 * @return {*}
 */
export function generateSelector(
  selector: ValidDefaultSelectors,
  dispatcher: INopeDispatcher
): ValidSelectorFunction {
  switch (selector) {
    default:
    case "first":
      return async () => {
        const data = dispatcher.externalDispatchers.getContent();

        if (data.length) {
          return data[0].id;
        }
        throw Error("No matching dispatcher present.");
      };
    case "dispatcher":
      // Our selector compares the dispatcher - id
      return async () => {
        const ids = dispatcher.externalDispatchers
          .getContent()
          .map((item) => item.id);

        if (ids.includes(dispatcher.id)) {
          return dispatcher.id;
        }

        throw Error("No matching dispatcher present.");
      };
    case "host":
      // Our selector compares the host-name:
      // 1. Get the current Host name of our dispatcher
      const host = dispatcher.info.host.name;
      return async () => {
        const dispatchers = dispatcher.externalDispatchers.getContent();

        for (const item of dispatchers) {
          if (host == item.host.name) {
            return item.id;
          }
        }

        throw Error("No matching dispatcher present.");
      };
    case "cpu-usage":
      return async () => {
        // Now we find the Min CPU usage:
        const dispatchers = dispatcher.externalDispatchers.getContent();
        const bestOption = minOfArray(dispatchers, "host.cpu.usage");

        if (bestOption.index >= 0) {
          return dispatchers[bestOption.index].id;
        }

        throw Error("No matching dispatcher present.");
      };
    case "free-ram":
      return async () => {
        // Now we find the Min CPU usage:
        const dispatchers = dispatcher.externalDispatchers.getContent();
        const bestOption = maxOfArray(dispatchers, "host.ram.free");

        if (bestOption.index >= 0) {
          return dispatchers[bestOption.index].id;
        }

        throw Error("No matching dispatcher present.");
      };
  }
}