further changes to module routing

http4k-core/src/main/kotlin/org/http4k/core/Http4k.kt

@@ -1,5 +1,7 @@
 package org.http4k.core
 
+import org.http4k.routing.RoutingHttpHandler
+
 typealias HttpHandler = (Request) -> Response
 
 interface Filter : (HttpHandler) -> HttpHandler {
@@ -10,6 +12,8 @@ interface Filter : (HttpHandler) -> HttpHandler {
     }
 }
 
+fun Filter.then(router: RoutingHttpHandler): RoutingHttpHandler = router.copy(filter = this)
+
 fun Filter.then(next: Filter): Filter = Filter { this(next(it)) }
 
 fun Filter.then(next: HttpHandler): HttpHandler = { this(next)(it) }

http4k-core/src/main/kotlin/org/http4k/routing/Routing.kt

@@ -1,5 +1,6 @@
 package org.http4k.routing
 
+import org.http4k.core.Filter
 import org.http4k.core.HttpHandler
 import org.http4k.core.Method
 import org.http4k.core.Request
@@ -8,26 +9,29 @@ import org.http4k.core.Status.Companion.NOT_FOUND
 import org.http4k.core.UriTemplate
 import org.http4k.core.UriTemplate.Companion.from
 import org.http4k.core.findSingle
+import org.http4k.core.then
 
 data class Route(val method: Method, val template: UriTemplate, val handler: HttpHandler)
 
-fun routes(vararg routes: Route): RoutesRouter = RoutesRouter(routes.asList())
+fun routes(vararg routes: Route): RoutingHttpHandler = RoutingHttpHandler(routes.asList())
 
 fun routes(module: Module, vararg then: Module): HttpHandler = then.fold(module) { memo, next -> memo.then(next) }.toHttpHandler()
 
 fun Request.path(name: String): String? = uriTemplate().extract(uri.toString())[name]
 
 infix fun Pair<Method, String>.by(action: HttpHandler): Route = Route(first, from(second), action)
 
-infix fun String.by(router: RoutesRouter): Module = object : Module {
-    override fun toRouter(): Router = RoutesRouter(router.routes.map { it.copy(template = it.template.prefixedWith(this@by)) })
+infix fun String.by(router: RoutingHttpHandler): Module = object : Module {
+    override fun toRouter(): Router = RoutingHttpHandler(router.routes.map { it.copy(template = it.template.prefixedWith(this@by)) })
 }
 
-data class RoutesRouter(internal val routes: List<Route>) : Router, HttpHandler {
+data class RoutingHttpHandler(internal val routes: List<Route>, internal val filter: Filter? = null) : Router, HttpHandler {
     private val routers = routes.map(Route::asRouter)
     private val noMatch: HttpHandler? = null
 
-    override fun invoke(request: Request): Response = match(request)?.invoke(request) ?: Response(NOT_FOUND.description("Route not found"))
+    override fun invoke(request: Request) = match(request)
+        ?.let { handler -> (filter?.then(handler) ?: handler).invoke(request) }
+        ?: Response(NOT_FOUND.description("Route not found"))
 
     override fun match(request: Request): HttpHandler? = routers.fold(noMatch, { memo, router -> memo ?: router.match(request) })
 }

http4k-core/src/test/kotlin/org/http4k/routing/RoutingTest.kt

@@ -2,13 +2,15 @@ package org.http4k.routing
 
 import com.natpryce.hamkrest.assertion.assertThat
 import com.natpryce.hamkrest.equalTo
+import org.http4k.core.Filter
 import org.http4k.core.Method.GET
 import org.http4k.core.Method.POST
 import org.http4k.core.Request
 import org.http4k.core.Response
 import org.http4k.core.Status.Companion.METHOD_NOT_ALLOWED
 import org.http4k.core.Status.Companion.NOT_FOUND
 import org.http4k.core.Status.Companion.OK
+import org.http4k.core.then
 import org.junit.Assert.fail
 import org.junit.Ignore
 import org.junit.Test
@@ -135,4 +137,14 @@ class RoutingTest {
         assertThat(app(Request(GET, "/asd/a/something")).status, equalTo(NOT_FOUND))
     }
 
+    @Test
+    fun `can apply a filter to a Router`() {
+        val routes = Filter { next -> { next(it.header("name", "value")) } }
+            .then(routes(
+                GET to "/a/thing" by { Response(OK).body(it.header("name")!!) }
+            ))
+
+        assertThat(routes(Request(GET, "/a/thing")).bodyString(), equalTo("value"))
+    }
+
 }

src/test/kotlin/cookbook/module_routing.kt

@@ -6,16 +6,21 @@ import org.http4k.core.Method.POST
 import org.http4k.core.Request
 import org.http4k.core.Response
 import org.http4k.core.Status.Companion.OK
+import org.http4k.core.then
+import org.http4k.filter.DebuggingFilters.PrintRequestAndResponse
 import org.http4k.routing.by
 import org.http4k.routing.path
 import org.http4k.routing.routes
 
 fun main(args: Array<String>) {
 
-    val routes = routes(
-        GET to "/get/{name}" by { req: Request -> Response(OK).body(req.path("name")!!) },
-        POST to "/post/{name}" by { _: Request -> Response(OK) }
-    )
+    val routes =
+        PrintRequestAndResponse().then(
+            routes(
+                GET to "/get/{name}" by { req: Request -> Response(OK).body(req.path("name")!!) },
+                POST to "/post/{name}" by { _: Request -> Response(OK) }
+            )
+        )
     println(routes(Request(GET, "/get/value")))
 
     val app = routes(