feat: persist booked dates in JSON file and exclude booked dates from selection

public/datetime.js

@@ -18,6 +18,7 @@
   today.setHours(0, 0, 0, 0);
 
   let availableDatesMap = new Map();
+  let bookedDatesSet = new Set();
   let viewYear = today.getFullYear();
   let viewMonth = today.getMonth();
   let selectedDate = null;
@@ -36,15 +37,28 @@
     return `${year}-${month}-${day}`;
   }
 
-  fetch("appsettings.json")
-    .then((response) => response.json())
-    .then((settings) => {
+  Promise.all([
+    fetch("appsettings.json").then((res) => res.json()),
+    fetch("/api/booked-dates")
+      .then((res) => (res.ok ? res.json() : []))
+      .catch(() => []),
+  ])
+    .then(([settings, bookedDates]) => {
+      bookedDatesSet = new Set(bookedDates || []);
+
       const datesList = settings.availableDates || [];
       datesList.forEach((item) => {
+        let key = "";
+        let type = "long";
         if (typeof item === "string") {
-          availableDatesMap.set(item, { type: "long" });
+          key = item;
         } else if (item && item.date) {
-          availableDatesMap.set(item.date, { type: item.type || "long" });
+          key = item.date;
+          type = item.type || "long";
+        }
+
+        if (key && !bookedDatesSet.has(key)) {
+          availableDatesMap.set(key, { type });
         }
       });