feat: add basic syncing (untested)

packages/core/api/sync.js

@@ -0,0 +1,96 @@
+/**
+ * GENERAL PROCESS:
+ * make a get request to server with current lastSyncedTimestamp
+ * parse the response. the response should contain everything that user has on the server
+ * decrypt the response
+ * merge everything into the database and look for conflicts
+ * send the conflicts (if any) to the end-user for resolution
+ * once the conflicts have been resolved, send the updated data back to the server
+ */
+
+/**
+ * MERGING:
+ * Locally, get everything that was editted/added after the lastSyncedTimestamp
+ * Run forEach loop on the server response.
+ * Add items that do not exist in the local collections
+ * Remove items (without asking) that need to be removed
+ * Update items that were editted before the lastSyncedTimestamp
+ * Try to merge items that were edited after the lastSyncedTimestamp
+ * Items in which the content has changed, send them for conflict resolution
+ * Otherwise, keep the most recently updated copy.
+ */
+
+/**
+ * CONFLICTS:
+ * Syncing should pause until all the conflicts have been resolved
+ * And then it should continue.
+ */
+import Database from "./index";
+import { HOST } from "../utils/constants";
+import fetch from "node-fetch";
+
+export default class Sync {
+  /**
+   *
+   * @param {Database} db
+   */
+  constructor(db) {
+    this.db = db;
+  }
+
+  async _fetch(lastSyncedTimestamp) {
+    let token = await this.db.user.token();
+    if (!token) return;
+    let response = await fetch(`${HOST}sync?lst=${lastSyncedTimestamp}`, {
+      headers: { ...HEADERS, Authorization: `Bearer ${token}` }
+    });
+    //TODO decrypt the response.
+    return await response.json();
+  }
+
+  async start() {
+    let user = await this.db.user.get();
+    if (!user) return false;
+    let lastSyncedTimestamp = user.lastSyncedTimestamp || 0;
+    let serverResponse = await this._fetch(lastSyncedTimestamp);
+    let data = this._merge(serverResponse, lastSyncedTimestamp);
+    await this._send(data);
+    return true;
+  }
+
+  _merge(serverResponse, lastSyncedTimestamp) {
+    const { notes, notebooks /* tags, colors, trash */ } = serverResponse;
+    notes.forEach(async note => {
+      let localNote = this.db.notes.note(note.id);
+      if (!localNote || note.dateEdited > localNote.data.dateEdited) {
+        await this.db.notes.add({ ...note, remote: true });
+      }
+    });
+    notebooks.forEach(async nb => {
+      let localNb = this.db.notebooks.notebook(nb.id);
+      if (!localNb || nb.dateEdited > localNb.data.dateEdited) {
+        await this.db.notebooks.add({ ...nb, remote: true });
+      }
+    });
+    // TODO trash, colors, tags
+    return {
+      notes: this.db.notes.filter(v => v.dateEdited > lastSyncedTimestamp),
+      notebooks: this.db.notebooks.filter(
+        v => v.dateEdited > lastSyncedTimestamp
+      ),
+      tags: [],
+      colors: [],
+      tags: []
+    };
+  }
+
+  async _send(data) {
+    //TODO encrypt the payload
+    let response = await fetch(`${HOST}sync`, {
+      method: "POST",
+      headers: { ...HEADERS, Authorization: `Bearer ${token}` },
+      body: JSON.stringify(data)
+    });
+    return response.ok;
+  }
+}