jeroentvb/node-knmi-fetch

import { DailyVars, TimeSpan, HourlyVars, StationCode } from '../types';
import { BodyInit } from 'node-fetch';

/**
 * Pass in all the parameters and return the query as a string.
 * @param stationCode string or number
 * @param variables string | string []
 * @param timeSpan { start: string, end: string }
 * @param inSeason boolean
 * @returns string
 */
function create(
   stationCode: StationCode,
   variables?: DailyVars | HourlyVars,
   timeSpan?: TimeSpan,
   inSeason?: boolean
): BodyInit {
   const params = {
      stationCode: parseStationCode(stationCode),
      vars: parseVars(variables),
      timeSpan: parseTimeSpan(timeSpan),
      inSeason: setInseason(inSeason)
   };

   return `stns=${params.stationCode}&vars=${params.vars}${params.timeSpan}${params.inSeason}`;
}

function parseStationCode(stationCode: StationCode): string | number {
   if (Array.isArray(stationCode)) {
      return stationCode.join(':');
   }

   return stationCode;
}

/**
 * Parse the vars to usable params.
 * Returns 'ALL' if there are no vars.
 * Joins the array of vars, or returns the vars variable.
 * @param vars 
 * @returns string
 */
function parseVars(vars: DailyVars | HourlyVars | undefined): string {
   if (!vars) return 'ALL';

   return Array.isArray(vars) ? vars.join(':') : vars;
}

/**
 * Checks if the timeSpan was passed in and returns a string.
 * @param timeSpan { start: string, end: string }
 * @returns string
 */
function parseTimeSpan(timeSpan?: TimeSpan): string {
   if (timeSpan) {
      return `&start=${timeSpan.start}&end=${timeSpan.end}`;
   }

   return '';
}

/**
 * Checks if inSeason is set to true and if there is a timeSpan.
 * @param inSeason boolean
 * @param timeSpan { start: string, end: string }
 * @returns string
 */
function setInseason(inSeason?: boolean): string {
   if (inSeason) {
      return '&inseason=Y';
   }

   return '';
}

export default {
   create
};