pacificclimate/climate-explorer-frontend

/************************************************************************
 * map-helpers.js - helper functions for MapControllers
 *
 * Functions in this file fall into three general categories:
 *
 *   0. Data processing helper functions, which extract information from
 *      a MapController props object or piece of one.
 *
 *   1. WMS parameter generation functions, which generate initial
 *      parameters for ncWMS layers of various types.
 *
 *   2. State and handler functions shared by multiple MapControllers
 ************************************************************************/
import _ from "lodash";

import { getTimeMetadata } from "../../data-services/ce-backend";
import { getVariableOptions } from "../../core/util";

/************************************************************************
 * 0. Data processing helpers
 ************************************************************************/

export function hasValidData(symbol, props) {
  // Returns true if props contains enough information to generate a map
  // for the primary (symbol is 'variable') or secondary ('comparand') variable.
  var dataLocation = symbol === "variable" ? "meta" : "comparandMeta";
  var dataName = `${symbol}_id`;

  return (
    !_.isUndefined(props[dataName]) &&
    !_.isUndefined(props[dataLocation]) &&
    props[dataLocation].length > 0
  );
}

export function hasComparand(props) {
  return this.hasValidData("comparand", props);
}

// predicate that detects whether a timestamp index is a 0th index:
// either January, winter, or the first year in a file.
export const is0thIndex = (timestamp) =>
  Number(JSON.parse(timestamp).timeidx) === 0;

// This function returns two values that are used to request climate layers from
// ncWMS. Because this app now allows for two different ways to request those
// layers (simple and dynamic datasets), which require two different kinds of
// identifiers, we must supply both. (The decision of which to use is deferred
// until to the moment the request is made.)
// TODO: https://github.com/pacificclimate/climate-explorer-frontend/issues/118
// TODO: There may also be a second issue to do with encoding timeVarIdx
// TODO: Fix this ugliness. Specifically, we are passing in params `props` and
//  `state`, which just happens to be convenient for the callers, but is a
//  horrible interface design. This should be factored out to the elements
//  of props and state actually used, something perhaps like a first argument
//  `{ run, start_date, end_date, ...}`, but this gets tangled up with how
//  `hasValidData` works ... sigh.
export function getDatasetIdentifiers(
  props,
  state,
  varSymbol,
  relevantMeta,
  encodedVarTimeIdx,
) {
  let metadata = undefined;
  if (encodedVarTimeIdx) {
    if (hasValidData(varSymbol, props)) {
      const timeIndex = JSON.parse(encodedVarTimeIdx);
      metadata = _.find(relevantMeta, {
        ensemble_member: state.run,
        start_date: state.start_date,
        end_date: state.end_date,
        timescale: timeIndex.timescale,
      });
    }
  }
  // dataset may not exist if generating a map for a single-variable portal
  return (
    metadata && {
      dataset: metadata.unique_id,
      filepath: metadata.filepath,
    }
  );
}

/********************************************************************
 * 1. WMS parameter generating functions
 ********************************************************************/

export function getTimeParametersPromise(dataSpec, meta) {
  // Returns a promise for an indexed list of all timestamps available for the
  // selected data specification in files whose metadata is in the "meta" array.
  // The indices are stringified objects with timescale
  // and timeidx attributes, for example, for a climatological mean:
  //   {timescale: monthly, timeidx: 0} is January.
  //   {timescale: seasonal, timeidx: 2} is Summer
  // For a nominal-time dataset, the indices would look like:
  //   {timescale: annual, timeidx: 0} is 1950
  //   {timescale: annual, timeidx: 1} is 1951
  // The timestamps are timestamp strings suitable for ncWMS.
  const { start_date, end_date, ensemble_member } = dataSpec;
  let datafiles = _.filter(meta, { ensemble_member, start_date, end_date });
  const timestampPromises = datafiles.map((df) =>
    getTimeMetadata(df.unique_id),
  );

  return Promise.all(timestampPromises).then((responses) => {
    let times = {};

    for (let i = 0; i < responses.length; i++) {
      let id = Object.keys(responses[i].data)[0];
      for (let timeidx in responses[i].data[id].times) {
        var idxString = JSON.stringify({
          timescale: responses[i].data[id].timescale,
          timeidx,
        });

        // This assumes only one variable per file.
        times[idxString] = responses[i].data[id].times[timeidx];
      }
    }
    return times;
  });
}

export function scalarParams(variable, times) {
  // return an object containing initial parameters common to
  // all scalar WMS layers (raster, isoline, annotated isoline):
  //   * variableId (name of displayed variable)
  //   * times (list of all available times)
  //   * timeIdx (the index of a selected starting time)
  //   * wmsTime (the actual timestamp of the selected starting time)
  //   * logscale (boolean string, 'true' meaning logarithmic colour scaling)
  //   * range (empty object, as ncWMS won't have been queried yet)
  // given the results of the getTimesPromise
  // These are default parameters, not based on user selection or MapController
  // state, and will likely need to be tweaked by the calling MapController.
  const logscale = "false";
  const variableId = variable;
  const startingIndex = _.find(Object.keys(times), is0thIndex);

  return {
    variableId,
    times,
    logscale,
    timeIdx: startingIndex,
    wmsTime: times[startingIndex],
    range: {},
  };
}

export function selectRasterPalette(params) {
  // add a default raster palette to a ncWMS params object: either rainbow (x-Occam)
  // or a variable default palette if the config file has one.
  let palette = "x-Occam";
  if (
    !_.isUndefined(
      getVariableOptions(params.variableId, "defaultRasterPalette"),
    )
  ) {
    palette = getVariableOptions(params.variableId, "defaultRasterPalette");
  }
  params.palette = palette;
  return params;
}

export function selectIsolinePalette(params) {
  // adds the default isoline palette (rainbow / x-Occam) to the params object.
  // TODO: add isoline numContours here when we get it working
  params.palette = "x-Occam";
  return params;
}

/**************************************************************************
 * 2. State handling functions shared by MapControllers
 **************************************************************************/

// TODO: https://github.com/pacificclimate/climate-explorer-frontend/issues/118
export function currentDataSpec({ run, start_date, end_date }) {
  // Return encoding of currently selected dataspec
  return `${run} ${start_date}-${end_date}`;
}

export function updateLayerSimpleState(layerType, name, value) {
  this.setState((prevState) => ({
    [layerType]: {
      ...prevState[layerType],
      [name]: value,
    },
  }));
}

export function updateLayerTime(layerType, timeIdx) {
  // update the timestamp in state
  // timeIdx is a stringified object with a resolution  (monthly, annual, seasonal)
  // and an index denoting the timestamp's position with the file
  this.setState((prevState) => ({
    [layerType]: {
      ...prevState[layerType], // This should not be necessary
      timeIdx,
      wmsTime: prevState[layerType].times[timeIdx],
    },
  }));
}