(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/server/lib/DocSession.ts

@@ -0,0 +1,49 @@
+import {BrowserSettings} from 'app/common/BrowserSettings';
+import {ActiveDoc} from 'app/server/lib/ActiveDoc';
+import {Authorizer, RequestWithLogin} from 'app/server/lib/Authorizer';
+import {Client} from 'app/server/lib/Client';
+
+/**
+ * OptDocSession allows for certain ActiveDoc operations to work with or without an open document.
+ * It is useful in particular for actions when importing a file to create a new document.
+ */
+export interface OptDocSession {
+  client: Client|null;
+  shouldBundleActions?: boolean;
+  linkId?: number;
+  browserSettings?: BrowserSettings;
+  req?: RequestWithLogin;
+}
+
+export function makeOptDocSession(client: Client|null, browserSettings?: BrowserSettings): OptDocSession {
+  if (client && !browserSettings) { browserSettings = client.browserSettings; }
+  return {client, browserSettings};
+}
+
+/**
+ * DocSession objects maintain information for a single session<->doc instance.
+ */
+export class DocSession implements OptDocSession {
+  /**
+   * Flag to indicate that user actions 'bundle' process is started and in progress (`true`),
+   * otherwise it's `false`
+   */
+  public shouldBundleActions?: boolean;
+
+  /**
+   * Indicates the actionNum of the previously applied action
+   * to which the first action in actions should be linked.
+   * Linked actions appear as one action and can be undone/redone in a single step.
+   */
+  public linkId?: number;
+
+  constructor(
+    public readonly activeDoc: ActiveDoc,
+    public readonly client: Client,
+    public readonly fd: number,
+    public readonly authorizer: Authorizer
+  ) {}
+
+  // Browser settings (like timezone) obtained from the Client.
+  public get browserSettings(): BrowserSettings { return this.client.browserSettings; }
+}