/**
 * Javascript module for waterheater helper methods.
 *
 * 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 = {
    determineHours: determineHours
};

/**
 * Calculates the on/off hours for the waterheater..
 *
 * @param Date start
 *   Start of the time range where to find the cheap hours.
 * @param Date stop
 *   Stop of the time range where to find the cheap hours.
 * @param int num
 *   Number of hours the waterheater must be on.
 *
 * @return array
 *   Array of point objects.
 */
function determineHours(start, stop, num) {
    console.log('waterheater.js: Starting to calculate on/off hours for the waterheater...' + num);
    const prices = influx.getPrices(start, stop);
    const startIndex = findStartIndex(prices, num);
    const points = preparePoints(prices, startIndex, num);
    return points;
}

/**
 * Finds the cheapester hours for the waterheater.
 *
 * The power must be on for 'num' hours in a row so that the waterheater
 * can reach it's max temperature. Reaching the max tempereature is important
 * to avoid legionella bacteria. 
 *
 * @param array prices
 *   Array of point objects containing prices for each hour.
 * @param int num
 *   Number of hours the waterheater must be on. 
 *
 * @return int
 *   Index of 'prices' array when the heating shoud start.
 */
function findStartIndex(prices, num) {
    let cheapestSum = 0;
    let cheapestIndex = 0;

    for (let i = 0; i <= prices.length - num; i++) {
	let sum = 0;
	// Calculate the sum of the hourly prices for the current 'num' hours.
	for (let j = i; j < i + num; j++) {
	    let point = prices[j];
	    sum += point.value;
	}
	// Initial value for the cheapestSum.
	if (i == 0) {
	    cheapestSum = sum;
	}
	if (sum < cheapestSum) {
	    cheapestSum = sum;
	    cheapestIndex = i;
	}
    }
    console.debug('waterheater.js: Cheapest index: ' + cheapestIndex + ', sum: ' + cheapestSum);
    return cheapestIndex;
}

/**
 * Prepares the control points to be written to the database.
 *
 * @param array prices
 *   Array of point objects.
 * @param int startIndex
 *   Index of the 'prices' array when heating shoud start.
 * @param int num
 *   Number of hours the waterheater must be on.
 *
 * @return array
 *   Array of point objects.
 */
function preparePoints(prices, startIndex, num) {
    let points = [];
    for (let i = 0; i < prices.length; i++) {
	let value = 0;
	if ((i >= startIndex) && (i < startIndex + num)) {
	    value = 1;
	}
	let point = {
	    datetime: prices[i].datetime,
	    value: value
	}
	points.push(point);
    }
    return points;
}