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