Sync engine (#298)

Fixes #261

common/syscalls/sync.ts

@@ -0,0 +1,65 @@
+import { SysCallMapping } from "../../plugos/system.ts";
+import type { SyncEndpoint } from "../../plug-api/silverbullet-syscall/sync.ts";
+import { SpaceSync, SyncStatusItem } from "../spaces/sync.ts";
+import { HttpSpacePrimitives } from "../spaces/http_space_primitives.ts";
+import { SpacePrimitives } from "../spaces/space_primitives.ts";
+
+export function syncSyscalls(localSpace: SpacePrimitives): SysCallMapping {
+  return {
+    "sync.sync": async (
+      _ctx,
+      endpoint: SyncEndpoint,
+      snapshot: Record<string, SyncStatusItem>,
+    ): Promise<
+      {
+        snapshot: Record<string, SyncStatusItem>;
+        operations: number;
+        // The reason to not just throw an Error is so that the partially updated snapshot can still be saved
+        error?: string;
+      }
+    > => {
+      const syncSpace = new HttpSpacePrimitives(
+        endpoint.url,
+        endpoint.user,
+        endpoint.password,
+        // Base64 PUTs to support mobile
+        true,
+      );
+      // Convert from JSON to a Map
+      const syncStatusMap = new Map<string, SyncStatusItem>(
+        Object.entries(snapshot),
+      );
+      const spaceSync = new SpaceSync(
+        localSpace,
+        syncSpace,
+        syncStatusMap,
+      );
+
+      try {
+        const operations = await spaceSync.syncFiles(
+          SpaceSync.primaryConflictResolver,
+        );
+        return {
+          // And convert back to JSON
+          snapshot: Object.fromEntries(spaceSync.snapshot),
+          operations,
+        };
+      } catch (e: any) {
+        return {
+          snapshot: Object.fromEntries(spaceSync.snapshot),
+          operations: -1,
+          error: e.message,
+        };
+      }
+    },
+    "sync.check": async (_ctx, endpoint: SyncEndpoint): Promise<void> => {
+      const syncSpace = new HttpSpacePrimitives(
+        endpoint.url,
+        endpoint.user,
+        endpoint.password,
+      );
+      // Let's just fetch the file list to see if it works
+      await syncSpace.fetchFileList();
+    },
+  };
+}