Free gifting on thanksgiving

src/utils/subscriptions.ts

@@ -5,3 +5,27 @@ export function subscriptionValid(subscriptionExpiresTimestamp?: number) {
 
     return subscriptionExpiresTimestamp + GRACE > Math.ceil(Date.now() / 1000);
 }
+
+export function isFreeGiftingDay() {
+    const today = new Date();
+    // days are 1 indexed, months are 0 indexed
+    const isChristmas = today.getDate() === 25 && today.getMonth() === 11;
+
+    return isChristmas || isThanksgiving(today);
+}
+
+function isThanksgiving(today: Date) {
+    if (today.getMonth() !== 10) return false;
+
+    const year = today.getFullYear();
+    const thanksgivingDay = new Date(year, 10, 1);
+
+    // Find out what day of the week Nov 1 is
+    const dayOfWeek = thanksgivingDay.getDay();
+
+    // Calculate the date of the fourth Thursday in November
+    thanksgivingDay.setDate(1 + ((4 - dayOfWeek) % 7) + 3 * 7);
+
+    // Compare the current date with Thanksgiving date
+    return today.getDate() === thanksgivingDay.getDate();
+}