57 lines
2.1 KiB
JavaScript
57 lines
2.1 KiB
JavaScript
/**
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* Checks if the given Object is a correct last N limit mapping, coverts both keys and values to numbers and sorts
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* the keys in ascending order.
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*
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* @param {Object} lastNLimits - The Object to be verified.
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* @returns {undefined|Map<number, number>}
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*/
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export function validateLastNLimits(lastNLimits) {
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// Checks if only numbers are used
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if (typeof lastNLimits !== 'object'
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|| !Object.keys(lastNLimits).length
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|| Object.keys(lastNLimits)
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.find(limit => limit === null || isNaN(Number(limit))
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|| lastNLimits[limit] === null || isNaN(Number(lastNLimits[limit])))) {
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return undefined;
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}
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// Converts to numbers and sorts the keys
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const sortedMapping = new Map();
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const orderedLimits = Object.keys(lastNLimits)
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.map(n => Number(n))
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.sort((n1, n2) => n1 - n2);
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for (const limit of orderedLimits) {
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sortedMapping.set(limit, Number(lastNLimits[limit]));
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}
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return sortedMapping;
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}
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/**
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* Returns "last N" value which corresponds to a level defined in the {@code lastNLimits} mapping. See
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* {@code config.js} for more detailed explanation on how the mapping is defined.
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*
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* @param {number} participantsCount - The current number of participants in the conference.
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* @param {Map<number, number>} [lastNLimits] - The mapping of number of participants to "last N" values. NOTE that
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* this function expects a Map that has been preprocessed by {@link validateLastNLimits}, because the keys must be
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* sorted in ascending order and both keys and values should be numbers.
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* @returns {number|undefined} - A "last N" number if there was a corresponding "last N" value matched with the number
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* of participants or {@code undefined} otherwise.
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*/
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export function limitLastN(participantsCount, lastNLimits) {
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if (!lastNLimits || !lastNLimits.keys) {
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return undefined;
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}
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let selectedLimit;
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for (const participantsN of lastNLimits.keys()) {
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if (participantsCount >= participantsN) {
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selectedLimit = participantsN;
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}
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}
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return selectedLimit ? lastNLimits.get(selectedLimit) : undefined;
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}
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