undo / redo behaviour, workspace concept

src/workspace/workspaceCommands.ts

@@ -0,0 +1,84 @@
+import type { PageRef } from '../pdf/pdfTypes';
+
+export interface WorkspaceCommandState {
+  pages: PageRef[];
+  selectedPageIds: string[];
+  lastSelectedVisualIndex: number | null;
+}
+
+export interface WorkspaceCommandPayload {
+  before: WorkspaceCommandState;
+  after: WorkspaceCommandState;
+  details?: Record<string, unknown>;
+}
+
+export interface WorkspaceCommandRecord {
+  id: string;
+  type: string;
+  label: string;
+  timestamp: string;
+  payload: WorkspaceCommandPayload;
+}
+
+export interface WorkspaceCommand extends WorkspaceCommandRecord {
+  do: (state: WorkspaceCommandState) => WorkspaceCommandState;
+  undo: (state: WorkspaceCommandState) => WorkspaceCommandState;
+}
+
+export function cloneCommandState(
+  state: WorkspaceCommandState
+): WorkspaceCommandState {
+  return {
+    pages: state.pages.map((page) => ({ ...page })),
+    selectedPageIds: [...state.selectedPageIds],
+    lastSelectedVisualIndex: state.lastSelectedVisualIndex,
+  };
+}
+
+export function createSnapshotCommand(params: {
+  id: string;
+  type: string;
+  label: string;
+  timestamp?: string;
+  before: WorkspaceCommandState;
+  after: WorkspaceCommandState;
+  details?: Record<string, unknown>;
+}): WorkspaceCommand {
+  return reviveWorkspaceCommand({
+    id: params.id,
+    type: params.type,
+    label: params.label,
+    timestamp: params.timestamp ?? new Date().toISOString(),
+    payload: {
+      before: cloneCommandState(params.before),
+      after: cloneCommandState(params.after),
+      details: params.details,
+    },
+  });
+}
+
+export function reviveWorkspaceCommand(
+  record: WorkspaceCommandRecord
+): WorkspaceCommand {
+  return {
+    ...record,
+    do: () => cloneCommandState(record.payload.after),
+    undo: () => cloneCommandState(record.payload.before),
+  };
+}
+
+export function toWorkspaceCommandRecord(
+  command: WorkspaceCommand
+): WorkspaceCommandRecord {
+  return {
+    id: command.id,
+    type: command.type,
+    label: command.label,
+    timestamp: command.timestamp,
+    payload: {
+      before: cloneCommandState(command.payload.before),
+      after: cloneCommandState(command.payload.after),
+      details: command.payload.details,
+    },
+  };
+}