chore(json-crdt): 🤖 start a history folder

Author: streamich

src/json-crdt/file/PatchLog.ts

@@ -2,8 +2,8 @@ import {ITimestampStruct, Patch, compare} from '../../json-crdt-patch';
 import {printTree} from '../../util/print/printTree';
 import {AvlMap} from '../../util/trees/avl/AvlMap';
 import {Model} from '../model';
-import type {Printable} from '../../util/print/types';
 import {first, next} from '../../util/trees/util';
+import type {Printable} from '../../util/print/types';
 
 export class PatchLog implements Printable {
   public static fromModel(model: Model<any>): PatchLog {

src/json-crdt/history/types.ts

@@ -0,0 +1,50 @@
+import {Patch} from "../../json-crdt-patch";
+import {PatchLog} from "../file/PatchLog";
+import {Model} from "../model";
+
+/**
+ * A history of patches that have been applied to a model, stored on the
+ * "remote": (1) server; (2) content addressable storage; or (3) peer-to-peer
+ * network.
+ * 
+ * Cases:
+ * 
+ * - `RemoteHistoryServer`
+ * - `RemoteHistoryServerIdempotent`
+ * - `RemoteHistoryCAS`
+ * - `RemoteHistoryP2P`
+ */
+export interface RemoteHistory<Cursor> {
+  /**
+   * Load latest state of the model, and any unmerged "tip" of patches
+   * it might have.
+   * 
+   * @todo Maybe `state` and `tip` should be serialized to JSON?
+   */
+  loadLatest(id: string): Promise<[cursor: Cursor, state: Model]>;
+
+  loadAfter(id: string, cursor: Cursor): Promise<[cursor: Cursor, tip: Patch[]]>;
+
+  loadBefore(id: string, cursor: Cursor): Promise<[cursor: Cursor, state: Model, tip: Patch[]]>;
+
+  apply(id: string, patches: Patch[]): Promise<void>;
+
+  /**
+   * Subscribe to the latest changes to the model.
+   * @param callback 
+   */
+  subscribe(id: string, cursor: Cursor, callback: (changes: Patch[]) => void): void;
+}
+
+export interface LocalHistory {
+  load(id: string): Promise<EditingSessionHistory>;
+  // loadHistory(id: string): Promise<PatchLog>;
+  apply(id: string, patches: Patch[]): Promise<void>;
+}
+
+export interface EditingSessionHistory {
+  load(id: string): Promise<Model>;
+  loadHistory(id: string): Promise<PatchLog>;
+  undo(id: string): Promise<void>;
+  redo(id: string): Promise<void>;
+}