Added admin-only page, and updated server backend to actually work with

admin stuff (IsAdmin).

Scripts/Garden/AdminAccess.js

@@ -0,0 +1,133 @@
+const AdminApiUrl =
+    "https://api.srhtnin.garden";
+
+const AdminSaveKeyName =
+    "SarahtoninGardenSaveKey";
+
+
+function GetStoredAdminSaveKey() {
+    const SaveKey =
+        localStorage.getItem(
+            AdminSaveKeyName
+        );
+
+    if (
+        typeof SaveKey !== "string" ||
+        !/^[0-9A-Fa-f]{64}$/.test(
+            SaveKey
+        )
+    ) {
+        return null;
+    }
+
+    return SaveKey;
+}
+
+
+async function GetAdminStatus() {
+    const SaveKey =
+        GetStoredAdminSaveKey();
+
+    if (SaveKey === null) {
+        return {
+            Success: true,
+            IsAdmin: false
+        };
+    }
+
+    const Response = await fetch(
+        AdminApiUrl +
+        "/AdminStatus.php",
+        {
+            method: "POST",
+
+            headers: {
+                "Content-Type":
+                    "application/json"
+            },
+
+            body: JSON.stringify({
+                SaveKey: SaveKey
+            })
+        }
+    );
+
+    const Result =
+        await Response.json();
+
+    if (!Response.ok) {
+        throw new Error(
+            Result.Error ??
+            "Couldn't verify admin access."
+        );
+    }
+
+    return Result;
+}
+
+
+async function RenderAdminAccess() {
+    const NavbarLink =
+        document.getElementById(
+            "AdminNavbarLink"
+        );
+
+    const AdminContent =
+        document.getElementById(
+            "AdminContent"
+        );
+
+    const AdminMessage =
+        document.getElementById(
+            "AdminAccessMessage"
+        );
+
+
+    try {
+        const Status =
+            await GetAdminStatus();
+
+        const IsAdmin =
+            Status.Success === true &&
+            Status.IsAdmin === true;
+
+
+        if (IsAdmin) {
+            if (NavbarLink !== null) {
+                NavbarLink.hidden = false;
+            }
+
+            if (AdminContent !== null) {
+                AdminContent.hidden = false;
+            }
+
+            if (AdminMessage !== null) {
+                AdminMessage.hidden = true;
+            }
+
+            return;
+        }
+
+
+        if (AdminMessage !== null) {
+            AdminMessage.textContent =
+                "Admin access required.";
+        }
+    } catch (Error) {
+        console.error(
+            "Couldn't verify admin access:",
+            Error
+        );
+
+        if (AdminMessage !== null) {
+            AdminMessage.textContent =
+                "Couldn't verify admin access.";
+        }
+    }
+}
+
+
+document.addEventListener(
+    "DOMContentLoaded",
+    RenderAdminAccess
+);