From 59aa3649328dc1650f3b532438897b5e5093147d Mon Sep 17 00:00:00 2001
From: Tommi Reiman <tommi@iki.fi>
Date: Sun, 3 Dec 2017 17:42:47 +0200
Subject: [PATCH] middleware/chain

---
 .../reitit-ring/src/reitit/ring/middleware.cljc |  8 ++++++++
 test/cljc/reitit/middleware_test.cljc           | 17 +++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/modules/reitit-ring/src/reitit/ring/middleware.cljc b/modules/reitit-ring/src/reitit/ring/middleware.cljc
index f76e8045..ffd00217 100644
--- a/modules/reitit-ring/src/reitit/ring/middleware.cljc
+++ b/modules/reitit-ring/src/reitit/ring/middleware.cljc
@@ -101,3 +101,11 @@
                :result
                :handler))
     {::router router}))
+
+(defn chain
+  "Creates a vanilla ring middleware chain out of sequence of
+  IntoMiddleware thingies."
+  ([middleware handler data]
+    (chain middleware handler data nil))
+  ([middleware handler data opts]
+   (compile-handler (expand middleware data opts) handler)))
diff --git a/test/cljc/reitit/middleware_test.cljc b/test/cljc/reitit/middleware_test.cljc
index 3a66de61..9fc40a4a 100644
--- a/test/cljc/reitit/middleware_test.cljc
+++ b/test/cljc/reitit/middleware_test.cljc
@@ -170,3 +170,20 @@
                                       :middleware
                                       (map :name))))))))))
 
+(deftest chain-test
+  (testing "chain can produce middlware chain of any IntoMiddleware"
+    (let [mw (fn [handler value]
+               #(conj (handler (conj % value)) value))
+          handler #(conj % :ok)
+          mw1 {:gen-wrap (constantly #(mw % ::mw1))}
+          mw2 {:gen-wrap (constantly nil)}
+          mw3 {:wrap #(mw % ::mw3)}
+          mw4 #(mw % ::mw4)
+          mw5 {:gen-wrap (fn [{:keys [mount?]} _]
+                           (when mount?
+                             #(mw % ::mw5)))}
+          chain1 (middleware/chain [mw1 mw2 mw3 mw4 mw5] handler {:mount? true})
+          chain2 (middleware/chain [mw1 mw2 mw3 mw4 mw5] handler {:mount? false})]
+      (is (= [::mw1 ::mw3 ::mw4 ::mw5 :ok ::mw5 ::mw4 ::mw3 ::mw1] (chain1 [])))
+      (is (= [::mw1 ::mw3 ::mw4 :ok ::mw4 ::mw3 ::mw1] (chain2 []))))))
+