RocketChat/Rocket.Chat

import { addPatch } from './addPatch';
import { calledFunctions, functions } from './data';
import type { BaseFunction, PatchData, PatchFunction, PatchedFunction } from './definition';

export const makeFunction = <T extends BaseFunction>(fn: T): PatchedFunction<T> => {
    const patches = new Set<PatchData<T>>();

    patches.add({
        patchFunction: (_next, ...args) => fn(...args),
    });

    const result = ((...args: Parameters<T>): ReturnType<T> => {
        let newFn: T = fn;

        for (const patch of patches) {
            if (patch.condition && !patch.condition()) {
                continue;
            }

            const nextFn = newFn;
            newFn = ((...args: Parameters<T>) => patch.patchFunction(nextFn, ...args)) as T;
        }

        calledFunctions.add(result);
        return newFn(...args);
    }) as PatchedFunction<T>;

    functions.set(result, patches as Set<PatchData<BaseFunction>>);

    result.patch = (patch: PatchFunction<T>, condition?: () => boolean) => addPatch(result, patch, condition);

    return result;
};