/**
 * Javascript module for helper methods with InfluxDB.
 *
 * Copyright (c) 2022 Markus Sipilä.
 *
 * 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 = {
    getCurrentControl: getCurrentControl,
    getPrices: getPrices,
    getPoints: getPoints,
    writePoints: writePoints,
    deletePoints: deletePoints,
    parseCSV: parseCSV
}

/**
 * Returns InfluxDB connection parameters.
 *
 * @return Object
 *   Object with connection properties.
 */
function getConnectionParams() {
    const params = {
        baseUrl: 'http://localhost:8086/api/v2/',
        org: 'openhab',
        bucket: 'autogen',
        token: 'insert-your-influx-token-here'
    }
    return params;
}

/**
 * Returns current control value for the given measurement and moment.
 *
 * @param string measurement
 *   Name of the Influx measurement.
 * @param Date start
 *   Pass current full hour as a Date object.
 *
 * @return int
 *   Returns 1 or 0. If no control is found, defaults to 1.
 */
function getCurrentControl(measurement, start) {
    console.log('influx.js: Getting the current control value for ' + measurement + '...');
    const stop = new Date(start.getTime());
    stop.setHours(stop.getHours() + 1);
    const csv = getPoints(measurement, start, stop);
    const points = parseCSV(csv, 5, 6);
    if (points.length) {
	const control = points[0].value;
	console.log('influx.js: Current control: ' + control);
	return control;
    }
    else {
	console.log('influx.js: Current control not found, defaulting to 1!');
	return 1;
    }
}

/**
 * Reads spot prices from the database.
 *
 * @param Date start
 *   Start of the time range.
 * @param Date stop
 *   Stop of the time range.
 *
 * @return array
 *   Array of spot price objects.
 */
function getPrices(start, stop) {
    console.log('influx.js: Reading spot prices from the database...');
    const csv = getPoints('spot_price', start, stop);
    const prices = parseCSV(csv, 5, 6);
    return prices;
}

/**
 * Reads points of given measurements from given range.
 *
 * @param string measurement
 *   Name of the Influx measurement.
 * @param Date start
 *   Start of the range as a Date object.
 * @param Date stop
 *   Stop of the range as a Date object.
 *
 * @return string
 *   Influx response in CSV format.
 */
function getPoints(measurement, start, stop) {
    const http = Java.type("org.openhab.core.model.script.actions.HTTP");
    const params = getConnectionParams();
    const url = params.baseUrl + 'query?' + 'org=' + params.org + '&bucket=' + params.bucket;
    const headers = {
	'Authorization': 'Token ' + params.token,
	'Content-Type': 'application/vnd.flux'
    };
    const fluxQuery = 'from(bucket: \"' + params.bucket + '\") ' +
          '|> range(start: ' + start.toISOString() + ', stop: ' + stop.toISOString() + ') ' +
          '|> filter(fn: (r) => r[\"_measurement\"] == \"' + measurement + '\")';
    // console.debug('influx.js: ' + fluxQuery);
    let response = '';
    try {
	response = http.sendHttpPostRequest(url, 'application/json', fluxQuery, headers, 5000);
	// console.debug('influx.js: Points read from the database.');
    }
    catch (exception) {
	console.error('influx.js: Exception reading points from the database: ' + exception.message);
    }
    return response;
}

/**
 * Parses the timestamps and values from the CSV response.
 *
 * @param string csv
 *   CSV response from Influx.
 * @param int colTimestamp
 *   Column index for the timestamp.
 * @param colValue
 *   Column index for the value.
 *
 * @return array
 *   Array of point objects.
 */
function parseCSV(csv, colDatetime, colValue) {
    let results = [];
    const rows = csv.split('\n');
    const n = rows.length;

    // Ignore the header row and last empty rows.
    for (let i = 1; i < n-2; i++) {
	// console.debug('influx.js: ' + rows[i]);
	let row = rows[i];
	let cols = row.split(',');
	let point = {
	    datetime: cols[colDatetime],
	    value: parseFloat(cols[colValue])
	}
	results.push(point);
    }
    if (results.length == 0) {
	console.warn('influx.js: query did not return any data!');
    }

    return results;
}

/**
 * Writes points to the database.
 *
 * @param string measurement
 *   Name of the Influx measurement.
 * @param array points
 *   Array of timestamp-value objects.
 *
 * @return bool
 */
function writePoints(measurement, points) {
    const n = Object.keys(points).length;
    console.log('influx.js: Preparing to write ' + n + ' points to the database for ' + measurement);
    const http = Java.type("org.openhab.core.model.script.actions.HTTP");
    const params = getConnectionParams();
    const url = params.baseUrl + 'write?' + 'org=' + params.org + '&bucket=' + params.bucket + '&precision=ms';
    const headers = {
	Authorization: 'Token ' + params.token
    };

    let response = false;
    try {
	for (let i = 0; i < n; i++) {
	    let value = points[i].value;
	    let datetime = points[i].datetime;
	    let timestamp = new Date(datetime).getTime();
	    let data = measurement + ' value=' + value + ' ' + timestamp;
	    //console.debug('influx.js: ' + data);
	    http.sendHttpPostRequest(url, 'application/json', data, headers, 5000);
	}
	response = true;
	console.log('influx.js: Points successfully saved for measurement ' + measurement);
    }
    catch (exception) {
	console.error('influx.js: Exception saving points for measurement ' + measurement + ': ' + exception.message);
    }
    return response;
}

/**
 * Deletes previously saved points for given measurement and given range.
 *
 * @param string measurement
 *   Name of the Influx measurement.
 * @param string start
 *   Start datetime of the range in ISO8601 format, e.g. 2022-06-27T00:00:00.000Z
 * @param string stop
 *   Stop datetime of the range in ISO8601 format, e.g. 2022-06-28T00:00:00.000Z
 */
function deletePoints(measurement, start, stop) {
    const http = Java.type("org.openhab.core.model.script.actions.HTTP");
    const params = getConnectionParams();
    const url = params.baseUrl + 'delete?' + 'org=' + params.org + '&bucket=' + params.bucket;
    const headers = {
	Authorization: 'Token ' + params.token
    };

    const deleteFlux = {
      start: start,
      stop: stop,
      predicate: '_measurement="' + measurement + '"'
    };

    try {
	http.sendHttpPostRequest(url, 'application/json', JSON.stringify(deleteFlux), headers, 5000);
	console.log('influx.js: Points successfully deleted. Measurement: ' + measurement + '. Range: ' + start + ' - ' + stop);
    }
    catch (exception) {
	console.error('influx.js: Exception deleting points. Measurement: ' + measurement + '. Range: ' + start + ' - ' + stop + '. Exception: ' + exception.message);
    }
}