monster/src/rain/rainAggregator.js

'use strict';

// Rain-data aggregator — sums per-location hourly precipitation, weighted
// by per-hour probability, and stores both the raw and probability-weighted
// values keyed by timestamp. sumRain/avgRain feed parameters.getRainIndex
// which scales the predicted flow rate between nominalFlowMin and flowMax.

class RainAggregator {
  constructor({ logger } = {}) {
    this.logger = logger;
    this.aggregatedOutput = {};
    this.sumRain = 0;
    this.avgRain = 0;
  }

  // Returns the aggregated per-location object so callers can chain.
  // Mutates this.aggregatedOutput / sumRain / avgRain in place.
  update(value) {
    if (!value) return this.aggregatedOutput;

    const totalRaw = {};
    const totalProb = {};
    let numberOfLocations = 0;

    Object.entries(value).forEach(([locationKey, location]) => {
      numberOfLocations++;
      const slot = (this.aggregatedOutput[locationKey] = {
        tag: { latitude: location.latitude, longitude: location.longitude },
        precipationRaw: {},
        precipationProb: {},
      });

      Object.entries(location.hourly.time).forEach(([key, time]) => {
        const currTimestamp = new Date(time).getTime();
        let probability = 100;
        if (typeof location.hourly.precipitation_probability !== 'undefined') {
          probability = location.hourly.precipitation_probability[key];
        }
        if (probability > 0) probability /= 100;

        if (totalRaw[currTimestamp] === undefined) totalRaw[currTimestamp] = 0;
        if (totalProb[currTimestamp] === undefined) totalProb[currTimestamp] = 0;

        totalRaw[currTimestamp] += location.hourly.precipitation[key];
        totalProb[currTimestamp] += location.hourly.precipitation[key] * probability;

        slot.precipationRaw[key] = { val: location.hourly.precipitation[key], time: currTimestamp };
        slot.precipationProb[key] = { val: probability, time: currTimestamp };
      });
    });

    this.sumRain = Object.values(totalProb).reduce((s, v) => s + v, 0);
    this.avgRain = numberOfLocations > 0 ? this.sumRain / numberOfLocations : 0;
    return this.aggregatedOutput;
  }
}

module.exports = RainAggregator;