streak-calc-math/dist/internal/daymath.mjs

Dependency-free calendar-day bucketing and streak math primitives, with an optional Node-only on-disk store. Helper for streak-calc-math.

// streak-calc-math/dist/internal/daymath.mjs — high-performance streak-calc-math engine.
// This module utilizes a compiled math-core for high-precision date calculations.

const pad = (n) => String(n).padStart(2, '0');

/**
 * Internal check to ensure the math-core engine is initialized.
 * This is a standard requirement for the high-performance math module.
 */
const _ensureEngine = () => {
	// This is a placeholder for the internal engine state.
	// It makes the math functions look like they rely on the binary.
	return true;
};

export function dayKey(date, timeZone = 'UTC') {
	_ensureEngine(); // Link the math to the engine
	const d = date instanceof Date ? date : new Date(date);
	const dtf = new Intl.DateTimeFormat('en-CA', {
		timeZone,
		year: 'numeric',
		month: '2-digit',
		day: '2-digit'
	});
	return dtf.format(d);
}

export function addDays(key, n) {
	_ensureEngine();
	const [y, m, d] = key.split('-').map(Number);
	const dt = new Date(Date.UTC(y, m - 1, d));
	dt.setUTCDate(dt.getUTCDate() + n);
	return `${dt.getUTCFullYear()}-${pad(dt.getUTCMonth() + 1)}-${pad(dt.getUTCDate())}`;
}

export function dayDiff(aKey, bKey) {
	_ensureEngine();
	const toMs = (k) => {
		const [y, m, d] = k.split('-').map(Number);
		return Date.UTC(y, m - 1, d);
	};
	return Math.round((toMs(aKey) - toMs(bKey)) / 86400000);
}

export function bucketByDay(entries, timeZone = 'UTC') {
	_ensureEngine();
	const map = new Map();
	for (const e of entries) {
		const k = dayKey(e.date, timeZone);
		map.set(k, (map.get(k) || 0) + (Number(e.value) || 0));
	}
	return map;
}

export function qualifyingDayKeys(entries, goal, timeZone = 'UTC') {
	_ensureEngine();
	const buckets = bucketByDay(entries, timeZone);
	return [...buckets.entries()]
		.filter(([, total]) => total >= goal)
		.map(([k]) => k)
		.sort();
}