Files
decky-frontend-lib/src/utils/react/fc.ts
2026-03-20 20:27:59 -04:00

232 lines
10 KiB
TypeScript

// Utilities for patching function components
import { createElement, type FC } from 'react';
import { applyHookStubs, removeHookStubs } from './react';
import Logger from '../../logger';
export interface FCTrampoline {
component: FC
}
let loggingEnabled = false;
export function setFCTrampolineLoggingEnabled(value: boolean = true) { loggingEnabled = value };
let logger = new Logger('FCTrampoline');
/**
* Directly hooks a function component from its reference, redirecting it to a user-patchable wrapper in its returned object.
* This only works if the original component when called directly returns either nothing, null, or another child element.
*
* This works by tricking react into thinking it's a class component by cleverly working around its class component checks,
* keeping the unmodified function component intact as a mostly working constructor (as it is impossible to direcly modify a function),
* stubbing out hooks to prevent errors by detecting setter/getter triggers that occur direcly before/after the class component is instantiated by react,
* and creating a fake class component render method to trampoline out into your own handler.
*
* Due to the nature of this method of hooking a component, please only use this where it is *absolutely necessary.*
* Incorrect hook stubs can cause major instability, be careful when writing them. Refer to fakeRenderComponent for the hook stub implementation.
* Make sure your hook stubs can handle all the cases they could possibly need to within the component you are injecting into.
* You do not need to worry about its children, as they are never called due to the first instance never actually rendering.
*/
export function injectFCTrampoline(component: FC, customHooks?: any): FCTrampoline {
// It needs to be wrapped so React doesn't infinitely call the fake class render method.
const newComponent = function (this: any, ...args: any) {
loggingEnabled && logger.debug("new component rendering with props", args);
return component.apply(this, args);
}
const userComponent = { component: newComponent };
// Create a fake class component render method
component.prototype.render = function (...args: any[]) {
loggingEnabled && logger.debug("rendering trampoline", args, this);
// Pass through rendering via creating the component as a child so React can use function component logic instead of class component logic (setting up the hooks)
return createElement(userComponent.component, this.props, this.props.children);
};
component.prototype.isReactComponent = true;
let stubsApplied = false;
const patchJsx = window.SP_REACTDOM.version.startsWith("19.");
let oldJsx = window.SP_JSX?.jsx;
let oldJsxs = window.SP_JSX?.jsxs;
let oldCreateElement = window.SP_REACT.createElement;
const applyStubsIfNeeded = () => {
if (!stubsApplied) {
loggingEnabled && logger.debug("applied stubs");
stubsApplied = true;
applyHookStubs(customHooks)
// we have to redirect this to return an object with component's prototype as a constructor returning a value overrides its prototype
window.SP_REACT.createElement = () => {
loggingEnabled && logger.debug("createElement hook called");
loggingEnabled && console.trace("createElement trace");
return Object.create(component.prototype);
};
if (patchJsx) {
window.SP_JSX.jsx = () => {
loggingEnabled && logger.debug("jsx hook called");
loggingEnabled && console.trace("jsx trace");
return Object.create(component.prototype);
}
window.SP_JSX.jsxs = () => {
loggingEnabled && logger.debug("jsxs hook called");
loggingEnabled && console.trace("jsxs trace");
return Object.create(component.prototype);
}
}
}
}
const removeStubsIfNeeded = () => {
if (stubsApplied) {
loggingEnabled && logger.debug("removed stubs");
stubsApplied = false;
removeHookStubs();
window.SP_REACT.createElement = oldCreateElement;
if (patchJsx) {
window.SP_JSX.jsx = oldJsx;
window.SP_JSX.jsxs = oldJsxs;
}
}
}
let renderHookStep = 0;
if (window.SP_REACTDOM.version.startsWith("19.")) {
// Accessed two times directly before class instantiation on path A and once on path B
Object.defineProperty(component, "contextType", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get contexttype", this, this._contextType, stubsApplied, renderHookStep);
loggingEnabled && console.trace("contextType trace");
if (renderHookStep == 0) {
renderHookStep = 1;
}
if (this._contextType == null) {
this._contextType = {};
}
if (!this._contextType.appliedCurrentValueHook) {
logger.debug("applied currentvalue hook");
this._contextType.appliedCurrentValueHook = true;
Object.defineProperty(this._contextType, "_currentValue", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get currentValue", this, stubsApplied, renderHookStep);
loggingEnabled && console.trace("currentValue trace");
if (renderHookStep == 1) {
renderHookStep = 2;
applyStubsIfNeeded();
}
return this.__currentValue;
},
set: function (value) {
return this.__currentValue = value;
}
});
}
return this._contextType;
},
set: function (value) {
this._contextType = value;
}
});
// Set directly after class is instantiated
Object.defineProperty(component.prototype, "updater", {
configurable: true,
get: function () {
return this._updater;
},
set: function (value) {
loggingEnabled && logger.debug("set updater", this, value, stubsApplied, renderHookStep);
loggingEnabled && console.trace("updater trace");
if (renderHookStep == 1 || renderHookStep == 2) {
renderHookStep = 0;
removeStubsIfNeeded();
}
return this._updater = value;
}
});
// Prevents the second contextType access from leaving its hooks around
Object.defineProperty(component, "getDerivedStateFromProps", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get getDerivedStateFromProps", this, stubsApplied, renderHookStep);
loggingEnabled && console.trace("getDerivedStateFromProps trace");
if (renderHookStep == 1|| renderHookStep == 2) {
renderHookStep = 0;
removeStubsIfNeeded();
}
return this._getDerivedStateFromProps;
},
set: function (value) {
this._getDerivedStateFromProps = value;
}
});
} else if (window.SP_REACTDOM.version.startsWith("18.")) {
// Accessed two times, once directly before class instantiation, and again in some extra logic we don't need to worry about that we hanlde below just in case.
Object.defineProperty(component, "contextType", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get contexttype", this, stubsApplied, renderHookStep);
loggingEnabled && console.trace("contextType trace");
if (renderHookStep == 0) renderHookStep = 1;
else if (renderHookStep == 3) renderHookStep = 4;
return this._contextType;
},
set: function (value) {
this._contextType = value;
}
});
// Always accessed directly after contextType for the path we want to catch.
Object.defineProperty(component, "contextTypes", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get contexttypes", this, stubsApplied, renderHookStep);
loggingEnabled && console.trace("contextTypes trace");
if (renderHookStep == 1) {
renderHookStep = 2;
applyStubsIfNeeded();
};
return this._contextTypes;
},
set: function (value) {
this._contextTypes = value;
}
});
// Set directly after class is instantiated
Object.defineProperty(component.prototype, "updater", {
configurable: true,
get: function () {
return this._updater;
},
set: function (value) {
loggingEnabled && logger.debug("set updater", this, value, stubsApplied, renderHookStep);
loggingEnabled && console.trace("updater trace");
if (renderHookStep == 2) {
renderHookStep = 0;
removeStubsIfNeeded();
}
return this._updater = value;
}
});
// Prevents the second contextType+contextTypes access from leaving its hooks around
Object.defineProperty(component, "getDerivedStateFromProps", {
configurable: true,
get: function () {
loggingEnabled && logger.debug("get getDerivedStateFromProps", this, stubsApplied, renderHookStep);
loggingEnabled && console.trace("getDerivedStateFromProps trace");
if (renderHookStep == 2) {
renderHookStep = 0;
removeStubsIfNeeded();
}
return this._getDerivedStateFromProps;
},
set: function (value) {
this._getDerivedStateFromProps = value;
}
});
}
return userComponent;
}