import { Injectable } from '@angular/core';
import { Data, HelgolandTimeseriesData, Timespan, TimeValueTuple } from '@helgoland/core';

import { D3DataGeneralizer } from './d3-data-generalizer';

@Injectable()
export class D3DataSimpleGeneralizer extends D3DataGeneralizer {

  public generalizeData(data: HelgolandTimeseriesData, imageWidth: number, timespan: Timespan): Data<TimeValueTuple> {
    if (data.values.length > imageWidth) {
      const duration = timespan.to - timespan.from;
      const dataduration = data.values[data.values.length - 1][0] - data.values[0][0];
      const factor = duration / dataduration;
      const realWidth = imageWidth / factor;
      const modulo = data.values.length / realWidth;
      const newData = {
        values: data.values.filter((v, i) => i % Math.round(modulo) === 0),
        referenceValues: data.referenceValues
      };
      return newData;
    }
    return data;
  }
}