prepare for better integration and testing

js/sync.js

@@ -0,0 +1,129 @@
+// Background Sync Module for RTS
+
+import { db } from "./db.js";
+
+let syncInterval = null;
+let debounceTimeout = null;
+let currentStatus = "saved"; // "saved", "syncing", "failed"
+
+/**
+ * Update the sync UI state
+ * @param {string} status - "saved", "syncing", "failed"
+ */
+export function updateSyncUI(status) {
+  currentStatus = status;
+  const container = document.getElementById("sync-status");
+  if (!container) return;
+
+  let html = "";
+  switch (status) {
+    case "syncing":
+      html = `
+        <span class="sync-dot syncing"></span>
+        <span class="sync-text">Saving to server...</span>
+      `;
+      break;
+    case "failed":
+      html = `
+        <span class="sync-dot failed"></span>
+        <span class="sync-text">Offline - Save failed</span>
+      `;
+      break;
+    case "saved":
+    default:
+      html = `
+        <span class="sync-dot saved"></span>
+        <span class="sync-text">Saved to server</span>
+      `;
+      break;
+  }
+  container.innerHTML = html;
+}
+
+/**
+ * Perform background synchronization of unsynced answers
+ */
+export async function performSync(exam_details, URLS) {
+  if (!exam_details || !exam_details.eid) return;
+
+  // Find all unsynced answers for this exam/cid/aid
+  const unsynced = await db.answers
+    .where({
+      aid: exam_details.aid,
+      cid: exam_details.cid,
+      eid: exam_details.eid,
+    })
+    .filter(ans => ans.synced === false)
+    .toArray();
+
+  if (unsynced.length === 0) {
+    if (currentStatus === "syncing") {
+      updateSyncUI("saved");
+    }
+    return;
+  }
+
+  updateSyncUI("syncing");
+
+  const json = {
+    eid: exam_details.eid,
+    cid: exam_details.cid,
+    start_time: exam_details.start_time,
+    answers: JSON.stringify(unsynced),
+    in_progress: "true",
+  };
+
+  try {
+    const response = await new Promise((resolve, reject) => {
+      $.post(URLS.exam_submit_url, json, null, "json")
+        .done(resolve)
+        .fail(reject);
+    });
+
+    if (response && response.success) {
+      // Mark as synced in Dexie database
+      await db.transaction("rw", db.answers, async () => {
+        for (const ans of unsynced) {
+          ans.synced = true;
+          await db.answers.put(ans);
+        }
+      });
+      updateSyncUI("saved");
+    } else {
+      updateSyncUI("failed");
+    }
+  } catch (error) {
+    console.error("Autosubmission failed:", error);
+    updateSyncUI("failed");
+  }
+}
+
+/**
+ * Trigger an immediate, debounced sync (2s delay after last change)
+ */
+export function triggerImmediateSync(exam_details, URLS) {
+  if (debounceTimeout) {
+    clearTimeout(debounceTimeout);
+  }
+  debounceTimeout = setTimeout(() => {
+    performSync(exam_details, URLS);
+  }, 2000);
+}
+
+/**
+ * Initialize background sync process
+ */
+export function initSync(exam_details, URLS) {
+  // Clear any existing sync process
+  if (syncInterval) {
+    clearInterval(syncInterval);
+  }
+
+  // Set initial state
+  updateSyncUI("saved");
+
+  // Run periodic sync every 15 seconds
+  syncInterval = setInterval(() => {
+    performSync(exam_details, URLS);
+  }, 15000);
+}