feat(router): add wildcard support to req.params type-safety (#17)

* feat(router): add wildcard to string patterns
* chore: swap merge order
* chore: add type-check assertions

Related #16
Co-authored-by: Luke Edwards <luke.edwards05@gmail.com>

src/router.d.ts

@@ -28,17 +28,20 @@ export function listen(handler: ResponseHandler): void;
 export type Route = { params: Params; handler: Handler | false };
 export type Handler<P extends Params = Params> = (req: ServerRequest<P>, res: ServerResponse) => Promisable<Response|void>;
 
-// TODO: wildcard
 export type RouteParams<T extends string> =
-  T extends `${infer S}:${infer P}?/${infer Rest}`
+	T extends `${infer Prev}/*/${infer Rest}`
+		? RouteParams<Prev> & { wild: string } & RouteParams<Rest>
+	: T extends `${string}:${infer P}?/${infer Rest}`
 		? { [K in P]?: string } & RouteParams<Rest>
-  : T extends `${infer S}:${infer P}/${infer Rest}`
-		? { [K in P | keyof RouteParams<Rest>]: string }
-  : T extends `${infer S}:${infer P}?`
+	: T extends `${string}:${infer P}/${infer Rest}`
+		? { [K in P]: string } & RouteParams<Rest>
+	: T extends `${string}:${infer P}?`
 		? { [K in P]?: string }
-  : T extends `${infer S}:${infer P}`
+	: T extends `${string}:${infer P}`
 		? { [K in P]: string }
-  : {};
+	: T extends `${string}*`
+		? { wild: string }
+	: {};
 
 export declare class Router {
 	add<T extends RegExp>(method: string, route: T, handler: Handler<Params>): void;

types/check.ts

@@ -204,7 +204,7 @@ Cache.listen(API.run);
  * > PATTERNS & PARAMS
  */
 
-let foo='', bar='';
+let foo='', bar='', baz='', wild='';
 
 // @ts-expect-error
 assert<RouteParams<'/:foo'>>({ /*empty*/ });
@@ -253,6 +253,34 @@ assert<RouteParams<'/:foo?/baz/:bar?'>>({ /*empty*/ });
 assert<RouteParams<'/:foo?/baz/:bar?'>>({ foo, bar });
 assert<RouteParams<'/:foo?/baz/:bar?'>>({ bar });
 
+// @ts-expect-error
+assert<RouteParams<'/*'>>({ bar });
+assert<RouteParams<'/*'>>({ wild });
+// @ts-expect-error
+assert<RouteParams<'/foo/*'>>({ /*empty*/ });
+assert<RouteParams<'/foo/*'>>({ wild });
+// @ts-expect-error
+assert<RouteParams<'/:foo/*'>>({ foo });
+assert<RouteParams<'/:foo/*'>>({ foo, wild });
+// @ts-expect-error
+assert<RouteParams<'/:foo?/*'>>({ /*empty*/ });
+assert<RouteParams<'/:foo?/*'>>({ foo, wild });
+assert<RouteParams<'/:foo?/*'>>({ wild });
+// @ts-expect-error
+assert<RouteParams<'/:foo/*/:bar?'>>({ bar, wild});
+assert<RouteParams<'/:foo/*/:bar?'>>({ foo, bar, wild});
+// @ts-expect-error
+assert<RouteParams<'/:foo/*/:bar/:baz?'>>({ foo, bar, baz });
+assert<RouteParams<'/:foo/*/:bar/:baz?'>>({ foo, bar, baz, wild });
+// @ts-expect-error
+assert<RouteParams<'/:foo/*/:bar?/:baz'>>({ foo, baz });
+assert<RouteParams<'/:foo/*/:bar?/:baz'>>({ foo, baz, wild });
+assert<RouteParams<'/:foo/*/:bar?/:baz'>>({ foo, bar, baz, wild });
+// @ts-expect-error
+assert<RouteParams<'/:foo?/*/:bar/:baz'>>({ bar, baz });
+assert<RouteParams<'/:foo?/*/:bar/:baz'>>({ bar, baz, wild });
+assert<RouteParams<'/:foo?/*/:bar/:baz'>>({ foo, bar, baz, wild });
+
 API.add('GET', '/foo', (req) => {
 	assert<{}>(req.params);
 	// @ts-expect-error
@@ -276,6 +304,17 @@ API.add('GET', '/foo/:bar?/:baz', (req) => {
 	req.params.hello;
 });
 
+API.add('GET', '/foo/:bar?/*/:baz', (req) => {
+	assert<{ bar?: string, baz: string, wild: string }>(req.params);
+	assert<string|undefined>(req.params.bar);
+	assert<string>(req.params.wild);
+	assert<string>(req.params.baz);
+	// @ts-expect-error
+	assert<string>(req.params.bar);
+	// @ts-expect-error
+	req.params.hello;
+});
+
 API.add('GET', /^[/]foobar[/]?/, (req) => {
 	assert<{}>(req.params);
 	assert<Params>(req.params);