35 lines
1.2 KiB
JavaScript
35 lines
1.2 KiB
JavaScript
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'use strict';
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const assert = require('assert');
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const { getUtcStartOfDayTs } = require('matrix-public-archive-shared/lib/timestamp-utilities');
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// `X-Date-Temporal-Context` indicates the temporal context of the content, whether it
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// is related to past, present, or future *day*.
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//
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// This is useful for caching purposes so you can heavily cache past content, but not
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// present/future.
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function setHeadersForDateTemporalContext({ res, nowTs, comparedToUrlDate: { yyyy, mm, dd } }) {
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assert(res);
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assert(Number.isInteger(nowTs));
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assert(Number.isInteger(yyyy));
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assert(Number.isInteger(mm));
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assert(Number.isInteger(dd));
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// We use the start of the UTC day so we can compare apples to apples with a new date
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// constructed with yyyy-mm-dd (no time occured since the start of the day)
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const startOfTodayTs = getUtcStartOfDayTs(nowTs);
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const compareTs = Date.UTC(yyyy, mm, dd);
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let temporalContext = 'present';
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if (compareTs < startOfTodayTs) {
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temporalContext = 'past';
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} else if (compareTs > startOfTodayTs) {
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temporalContext = 'future';
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}
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res.set('X-Date-Temporal-Context', temporalContext);
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}
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module.exports = setHeadersForDateTemporalContext;
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