refactor progress

packages/api/src/utils/AttachmentDecay.tsx

@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {ms} from 'itty-time';
+
+export interface AttachmentDecayInput {
+	sizeBytes: bigint | number;
+	uploadedAt: Date;
+	curve?: number;
+	pricePerTBPerMonth?: number;
+}
+
+export interface AttachmentDecayResult {
+	expiresAt: Date;
+	days: number;
+	cost: number;
+}
+
+export const DEFAULT_DECAY_CONSTANTS = {
+	MIN_MB: 5,
+	MAX_MB: 500,
+	MIN_DAYS: 14,
+	MAX_DAYS: 365 * 3,
+	PLAN_MB: 500,
+	CURVE: 0.5,
+	PRICE_PER_TB_PER_MONTH: 0.0081103 * 1000,
+};
+
+export const DEFAULT_RENEWAL_CONSTANTS = {
+	RENEW_THRESHOLD_DAYS: 30,
+	RENEW_WINDOW_DAYS: 30,
+	MIN_WINDOW_DAYS: 7,
+	MAX_WINDOW_DAYS: 30,
+	MIN_THRESHOLD_DAYS: 3,
+	MAX_THRESHOLD_DAYS: 14,
+};
+
+function toMb(sizeBytes: bigint | number): number {
+	const n = typeof sizeBytes === 'bigint' ? Number(sizeBytes) : sizeBytes;
+	return n / 1024 / 1024;
+}
+
+export function computeDecay({
+	sizeBytes,
+	uploadedAt,
+	curve = DEFAULT_DECAY_CONSTANTS.CURVE,
+	pricePerTBPerMonth = DEFAULT_DECAY_CONSTANTS.PRICE_PER_TB_PER_MONTH,
+}: AttachmentDecayInput): AttachmentDecayResult | null {
+	const constants = DEFAULT_DECAY_CONSTANTS;
+	const sizeMB = toMb(sizeBytes);
+
+	if (sizeMB > constants.PLAN_MB) return null;
+
+	let lifetimeDays: number;
+	if (sizeMB <= constants.MIN_MB) {
+		lifetimeDays = constants.MAX_DAYS;
+	} else if (sizeMB >= constants.MAX_MB) {
+		lifetimeDays = constants.MIN_DAYS;
+	} else {
+		const linearFrac = (sizeMB - constants.MIN_MB) / (constants.MAX_MB - constants.MIN_MB);
+		const logFrac = Math.log(sizeMB / constants.MIN_MB) / Math.log(constants.MAX_MB / constants.MIN_MB);
+		const blend = (1 - curve) * linearFrac + curve * logFrac;
+		lifetimeDays = constants.MAX_DAYS - blend * (constants.MAX_DAYS - constants.MIN_DAYS);
+	}
+
+	const expiresAt = new Date(uploadedAt);
+	expiresAt.setUTCDate(expiresAt.getUTCDate() + lifetimeDays);
+
+	const sizeTB = (typeof sizeBytes === 'bigint' ? Number(sizeBytes) : sizeBytes) / 1024 / 1024 / 1024 / 1024;
+	const lifetimeMonths = lifetimeDays / 30;
+	const cost = sizeTB * pricePerTBPerMonth * lifetimeMonths;
+
+	return {
+		expiresAt,
+		cost,
+		days: Math.round(lifetimeDays),
+	};
+}
+
+const MS_PER_DAY = ms('1 day');
+
+export function computeRenewalWindowDays(
+	sizeMB: number,
+	{
+		minMB = DEFAULT_DECAY_CONSTANTS.MIN_MB,
+		maxMB = DEFAULT_DECAY_CONSTANTS.MAX_MB,
+	}: {minMB?: number; maxMB?: number} = {},
+	{
+		minWindowDays = DEFAULT_RENEWAL_CONSTANTS.MIN_WINDOW_DAYS,
+		maxWindowDays = DEFAULT_RENEWAL_CONSTANTS.MAX_WINDOW_DAYS,
+	}: {minWindowDays?: number; maxWindowDays?: number} = {},
+): number {
+	if (sizeMB <= minMB) return maxWindowDays;
+	if (sizeMB >= maxMB) return minWindowDays;
+
+	const frac = Math.log(sizeMB / minMB) / Math.log(maxMB / minMB);
+	const window = maxWindowDays - frac * (maxWindowDays - minWindowDays);
+	return Math.round(window);
+}
+
+export function computeRenewalThresholdDays(
+	windowDays: number,
+	{
+		minThresholdDays = DEFAULT_RENEWAL_CONSTANTS.MIN_THRESHOLD_DAYS,
+		maxThresholdDays = DEFAULT_RENEWAL_CONSTANTS.MAX_THRESHOLD_DAYS,
+	}: {minThresholdDays?: number; maxThresholdDays?: number} = {},
+): number {
+	const clampedWindow = Math.max(
+		DEFAULT_RENEWAL_CONSTANTS.MIN_WINDOW_DAYS,
+		Math.min(DEFAULT_RENEWAL_CONSTANTS.MAX_WINDOW_DAYS, windowDays),
+	);
+	const threshold = Math.round(clampedWindow / 2);
+	return Math.max(minThresholdDays, Math.min(maxThresholdDays, threshold));
+}
+
+export function computeCost({
+	sizeBytes,
+	lifetimeDays,
+	pricePerTBPerMonth = DEFAULT_DECAY_CONSTANTS.PRICE_PER_TB_PER_MONTH,
+}: {
+	sizeBytes: bigint | number;
+	lifetimeDays: number;
+	pricePerTBPerMonth?: number;
+}): number {
+	const sizeTB = (typeof sizeBytes === 'bigint' ? Number(sizeBytes) : sizeBytes) / 1024 / 1024 / 1024 / 1024;
+	const lifetimeMonths = lifetimeDays / 30;
+	return sizeTB * pricePerTBPerMonth * lifetimeMonths;
+}
+
+export function getExpiryBucket(expiresAt: Date): number {
+	return Number(
+		`${expiresAt.getUTCFullYear()}${String(expiresAt.getUTCMonth() + 1).padStart(2, '0')}${String(
+			expiresAt.getUTCDate(),
+		).padStart(2, '0')}`,
+	);
+}
+
+export function extendExpiry(currentExpiry: Date | null, newlyComputed: Date): Date {
+	if (!currentExpiry) return newlyComputed;
+	return currentExpiry > newlyComputed ? currentExpiry : newlyComputed;
+}
+
+export function maybeRenewExpiry({
+	currentExpiry,
+	now,
+	thresholdDays = DEFAULT_RENEWAL_CONSTANTS.RENEW_THRESHOLD_DAYS,
+	windowDays = DEFAULT_RENEWAL_CONSTANTS.RENEW_WINDOW_DAYS,
+	maxExpiry,
+}: {
+	currentExpiry: Date | null;
+	now: Date;
+	thresholdDays?: number;
+	windowDays?: number;
+	maxExpiry?: Date;
+}): Date | null {
+	if (!currentExpiry) return null;
+	if (windowDays <= 0) return null;
+
+	const remainingMs = currentExpiry.getTime() - now.getTime();
+	if (remainingMs > thresholdDays * MS_PER_DAY) {
+		return null;
+	}
+
+	const targetMs = now.getTime() + windowDays * MS_PER_DAY;
+	const cappedTargetMs = maxExpiry ? Math.min(maxExpiry.getTime(), targetMs) : targetMs;
+
+	if (cappedTargetMs <= currentExpiry.getTime()) {
+		return null;
+	}
+
+	const target = new Date(now);
+	target.setTime(cappedTargetMs);
+	return target;
+}