import type { State } from "./application.ts";import type { Context } from "./context.ts";
export interface Middleware< S extends State = Record<string, any>, T extends Context = Context<S>,> { (context: T, next: () => Promise<void>): Promise<void> | void;}
export function compose< S extends State = Record<string, any>, T extends Context = Context<S>,>( middleware: Middleware<S, T>[],): (context: T, next?: () => Promise<void>) => Promise<void> { return function composedMiddleware( context: T, next?: () => Promise<void>, ): Promise<void> { let index = -1;
async function dispatch(i: number): Promise<void> { if (i <= index) { throw new Error("next() called multiple times."); } index = i; let fn: Middleware<S, T> | undefined = middleware[i]; if (i === middleware.length) { fn = next; } if (!fn) { return; } await fn(context, dispatch.bind(null, i + 1)); }
return dispatch(0); };}