grungnet/src/hooks/useNetworkedState.ts

127 lines
3.8 KiB
TypeScript

import { useEffect, useState, useRef, useCallback } from "react";
import cloneDeep from "lodash.clonedeep";
import { Diff } from "deep-diff";
import useDebounce from "./useDebounce";
import { diff, applyChanges } from "../helpers/diff";
import Session from "../network/Session";
/**
* @param update The updated state or a state function passed into setState
* @param sync Whether to sync the update with the session
* @param force Whether to force a full update, usefull when partialUpdates is enabled
*/
export type SetNetworkedState<S> = (
update: React.SetStateAction<S>,
sync?: boolean,
force?: boolean
) => void;
type Update<T> = {
id: string;
changes: Diff<T>[];
};
/**
* Helper to sync a react state to a `Session`
*
* @param {S} initialState
* @param {Session} session `Session` instance
* @param {string} eventName Name of the event to send to the session
* @param {number} debounceRate Amount to debounce before sending to the session (ms)
* @param {boolean} partialUpdates Allow sending of partial updates to the session
* @param {string} partialUpdatesKey Key to lookup in the state to identify a partial update
*/
function useNetworkedState<S extends { readonly [x: string]: any } | null>(
initialState: S,
session: Session,
eventName: string,
debounceRate: number = 500,
partialUpdates: boolean = true,
partialUpdatesKey: string = "id"
): [S, SetNetworkedState<S>] {
const [state, _setState] = useState(initialState);
// Used to control whether the state needs to be sent to the socket
const dirtyRef = useRef(false);
// Used to force a full update
const forceUpdateRef = useRef(false);
// Update dirty at the same time as state
const setState = useCallback<SetNetworkedState<S>>(
(update, sync = true, force = false) => {
dirtyRef.current = sync;
forceUpdateRef.current = force;
_setState(update);
},
[]
);
const debouncedState = useDebounce(state, debounceRate);
const lastSyncedStateRef = useRef<S>();
useEffect(() => {
if (dirtyRef.current) {
// If partial updates enabled, send just the changes to the socket
if (
lastSyncedStateRef.current &&
debouncedState &&
partialUpdates &&
!forceUpdateRef.current
) {
const changes = diff(lastSyncedStateRef.current, debouncedState);
if (changes) {
if (!debouncedState) {
return;
}
const update = { id: debouncedState[partialUpdatesKey], changes };
session.socket?.emit(`${eventName}_update`, update);
}
} else {
session.socket?.emit(eventName, debouncedState);
}
dirtyRef.current = false;
forceUpdateRef.current = false;
lastSyncedStateRef.current = cloneDeep(debouncedState);
}
}, [
session.socket,
eventName,
debouncedState,
partialUpdates,
partialUpdatesKey,
]);
useEffect(() => {
function handleSocketEvent(data: S) {
_setState(data);
lastSyncedStateRef.current = data;
}
function handleSocketUpdateEvent(update: Update<S>) {
_setState((prevState) => {
if (prevState && prevState[partialUpdatesKey] === update.id) {
let newState = { ...prevState };
applyChanges(newState, update.changes);
if (lastSyncedStateRef.current) {
applyChanges(lastSyncedStateRef.current, update.changes);
}
return newState;
} else {
return prevState;
}
});
}
session.socket?.on(eventName, handleSocketEvent);
session.socket?.on(`${eventName}_update`, handleSocketUpdateEvent);
return () => {
session.socket?.off(eventName, handleSocketEvent);
session.socket?.off(`${eventName}_update`, handleSocketUpdateEvent);
};
}, [session.socket, eventName, partialUpdatesKey]);
return [state, setState];
}
export default useNetworkedState;