详解Jotai Immer如何实现undo redo功能示例详解

import { Patch, applyPatches, produceWithPatches } from "immer";
import { atomWithImmer } from "jotai-immer";
import { atom, createStore } from "jotai/vanilla";
import { JSONSchema7 } from "json-schema";
interface HistoryInfo {
  patch: Patch;
  inverse: Patch;
}
interface HistoryState {
  undo: HistoryInfo[];
  redo: HistoryInfo[];
}
// 业务代码涉及的undo、redo数据
export interface HistoryItem {
  businessA: { [key: string]: any };
  businessB: Record<string, JSONSchema7>;
  businessC: any;
}
// 构建一个undo、redo的数据起点
const historyItemAtom = atomWithImmer<HistoryItem>({
  businessA: {},
  businessB: {},
  businessC: {},
});
// 触发需要保存的undo的一个操作事件
export const fireHistoryAtom = atom(0.0);
export const businessAAtom = atomWithImmer<{ [key: string]: any }>({});
export const businessBAtom = atomWithImmer<Record<string, JSONSchema7>>({});
export const businessCAtom = atomWithImmer<any>();
export const historyAtom = atomWithImmer<HistoryState>({
  undo: [],
  redo: [],
});
export const store = createStore();
// 页面数据加载完毕写入初始化history
export const dataInit = () => {
  const newHis: HistoryItem = {
    businessA: store.get(businessAAtom),
    businessB: store.get(businessBAtom),
    businessC: store.get(businessCAtom),
  };
  store.set(historyItemAtom, newHis);
};
// ----------------------------------------------------------------
// atom subscriptions
store.sub(fireHistoryAtom, () => {
  const newHis: HistoryItem = {
    businessA: store.get(businessAAtom),
    businessB: store.get(businessBAtom),
    businessC: store.get(businessCAtom),
  };
  const oldHis = store.get(historyItemAtom);
  const [next, patch, inverse] = produceWithPatches(oldHis, (draft) => {
    draft = newHis;
    return draft;
  });
  store.set(historyItemAtom, next);
  store.set(historyAtom, (draft) => {
    draft.undo.push({
      patch: patch[0],
      inverse: inverse[0],
    });
    draft.redo = [];
  });
});
export const fireHistory = () => {
  setTimeout(() => {
    store.set(fireHistoryAtom, Math.random());
  }, 20);
};
// 执行业务代码
const doAction = (item: HistoryItem) => {
  store.set(businessAAtom, (draft) => {
    draft = item.businessA;
    return draft;
  });
  store.set(businessBAtom, (draft) => {
    draft = item.businessB;
    return draft;
  });
  store.set(businessCAtom, (draft) => {
    draft = item.businessC;
    return draft;
  });
  store.set(historyItemAtom, (draft) => {
    draft = item;
    return draft;
  });
};
export const undoAction = () => {
  const history = store.get(historyAtom);
  if (history.undo.length === 0) {
    return;
  }
  const old = history.undo[history.undo.length - 1];
  const currentItem = store.get(historyItemAtom);
  const item = applyPatches(currentItem, [old.inverse]);
  doAction(item);
  store.set(historyAtom, (draft) => {
    const current = draft.undo.pop();
    if (current) {
      draft.redo.push(current);
    }
  });
};
export const redoAction = () => {
  const history = store.get(historyAtom);
  if (history.redo.length === 0) {
    return;
  }
  const old = history.redo[history.redo.length - 1];
  const currentItem = store.get(historyItemAtom);
  const item = applyPatches(currentItem, [old.patch]);
  doAction(item);
  store.set(historyAtom, (draft) => {
    const current = draft.redo.pop();
    if (current) {
      draft.undo.push(current);
    }
  });
};

<Provider store={mainStore}>
	<MainPage />
</Provider>