/**
 * Javascript module for reading weather data from FMI API - HARMONIE.
 *
 * Copyright (c) 2022-2023 Markus Sipilä, Updated for HARMONIE Rainer Keto
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/**
 * Exports.
 */
module.exports = {
    makeApiCall: makeApiCall,
    preparePoints: preparePoints,
    calculateWindChillTempPoints: calculateWindChillTempPoints
};

/**
 * Makes an API call to the Finnish Meteorology Institute.
 *
 * @param string place
 *   Place recoginzed by FMI API.
 *
 * @return string
 *   XML response from FMI API.
 */
function makeApiCall(place) {
    const http = Java.type("org.openhab.core.model.script.actions.HTTP");
    console.log('fmi.js: Making an API call to FMI API...');
    const url = 'http://opendata.fmi.fi/wfs?service=WFS&version=2.0.0&request=getFeature&storedquery_id=fmi::forecast::harmonie::surface::point::simple&place=' + place + '&parameters=Temperature,PrecipitationAmount,WindSpeedMS,TotalCloudCover';
    const xml = http.sendHttpGetRequest(url, 10000);
    return xml;
}

/**
 * Parses the forecast from the XML response.
 *
 * @param string xml
 *   FMI response in XML format.
 * @param string parameterName
 *   Parameter name of interest: temperature, PrecipitationAmount, WindSpeedMS, TotalCloudCover
 *
 * @return array
 *   Array of point objects.
 */
function preparePoints(xml, parameterName) {
    console.log('fmi.js: transforming XML to JSON and parsing forecast for ' + parameterName + '...');
    const transformation = Java.type("org.openhab.core.transform.actions.Transformation");
    let points = [];

    // Early exit in case XML is null.
    if (xml == null) {
        console.error('fmi.js: XML empty, parsing aborted.')
        return points;
    }
    try {
        const jsObject = JSON.parse(transformation.transform('XSLT', 'xml2json.xsl', xml));
        const members = jsObject['wfs:FeatureCollection']['wfs:member'];
        for (let i = 0; i < members.length; i++) {
            if (members[i]['BsWfs:BsWfsElement']['BsWfs:ParameterName'] == parameterName) {
                let point = {
                    datetime: members[i]['BsWfs:BsWfsElement']['BsWfs:Time'],
                    value: members[i]['BsWfs:BsWfsElement']['BsWfs:ParameterValue']
                };
                points.push(point);
            }
        }
        console.debug('fmi.js: ' + parameterName + ' parsed!');
    }
    catch (exception) {
        console.error('fmi.js: Exception parsing ' + parameterName +': ' + exception.message);
    }

    return points;
}

/**
 * Calculates the wind chill factor for the temperature
 *
 * @param array temperaturePoints
 * @param array windspeedPoints
 *
 * @return array
 *   Array of point objects.
 */
function calculateWindChillTempPoints(temperaturePoints, windspeedPoints) {
    console.log('fmi.js: Calculating wind chill factors from the temperature and wind speed...');
    let points = [];
    if (temperaturePoints.length != windspeedPoints.length) {
        console.log('Different number of temperature and wind speed points!');
        return points;
    }

    for (let i = 0; i < temperaturePoints.length; i++) {
        let datetime = temperaturePoints[i].datetime;
        let temp = temperaturePoints[i].value;
        let wind_ms = windspeedPoints[i].value;
        let wind_kmh = 3.6 * wind_ms;

        // https://en.wikipedia.org/wiki/Wind_chill#North_American_and_United_Kingdom_wind_chill_index
        let windchill = temp;
        if (temp < 10 && wind_kmh > 4.8) {
            windchill = 13.12 + 0.6215 * temp - 11.37 * (wind_kmh ** 0.16) + 0.3965 * temp * (wind_kmh ** 0.16);
        }

        let point = {
            datetime: datetime,
            value: windchill
        }
        points.push(point);
    }

    return points;
}