From 8a158dd3cff218223afb9dd77c567023795bfc7e Mon Sep 17 00:00:00 2001
From: Asko Nõmm <asko@bien.ee>
Date: Sat, 2 Oct 2021 01:26:07 -0300
Subject: Initial commit

---
 src/ruuter/core.clj | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 src/ruuter/core.clj

(limited to 'src/ruuter/core.clj')

diff --git a/src/ruuter/core.clj b/src/ruuter/core.clj
new file mode 100644
index 0000000..2504b6f
--- /dev/null
+++ b/src/ruuter/core.clj
@@ -0,0 +1,97 @@
+(ns ruuter.core
+  (:require [clojure.string :as string]
+            [org.httpkit.server :as http]))
+
+
+(def routes [{:path "/"
+              :method :get
+              :response {:status 200
+                         :body "Hello, World."}}
+             {:path "/some/page/goes/here"
+              :method :get
+              :response {:status 200
+                         :body ":)"}}
+             {:path "/hi/:name"
+              :method :get
+              :response (fn [req]
+                          {:status 200
+                           :body (str "Hi, " (:name (:params req)))})}
+             {:path :not-found
+              :response {:status 404
+                         :body "Not found."}}])
+
+
+(defn- path->regex-path
+  [path]
+  (if (= "/" path)
+    path
+    (->> (string/split path #"/")
+         (map (fn [piece]
+                (if (string/starts-with? piece ":")
+                  ".*"
+                  piece)))
+         (string/join "/"))))
+
+
+(defn- path+uri->path-params
+  [path uri]
+  (if (= "/" path)
+    {}
+    (let [split-path (string/split path #"/")
+          split-uri (string/split uri #"/")]
+      (into {} (map-indexed
+                 (fn [idx item]
+                   (when (string/starts-with? item ":")
+                     {(keyword (subs item 1)) (get split-uri idx)}))
+                 split-path)))))
+
+
+(defn- match-route
+  [routes uri request-method]
+  (->> routes
+       (filter #(not (= :not-found (:path %))))
+       (map #(merge % {:regex-path (path->regex-path (:path %))}))
+       (filter #(and (re-matches (re-pattern (:regex-path %)) uri)
+                     (= (:method %) request-method)))
+       first))
+
+
+(defn- route+req->response
+  [{:keys [path response]} {:keys [uri] :as req}]
+  (cond
+    ; responses are maps, so there's no reason they can't be
+    ; direct maps.
+    (map? response)
+    response
+    ; responses can also be functions that return maps, and
+    ; when using a function, you get the whole `req` and params
+    ; with it as well.
+    (fn? response)
+    (response (->> {:params (path+uri->path-params path uri)}
+                   (merge req)))
+    ; if by whatever reason we make it here it must mean the
+    ; route is invalid, or doesn't exist, in which case we return
+    ; an error message.
+    :else
+    {:status 404
+     :body "Not found."}))
+
+
+(defn- router
+  [routes {:keys [uri request-method] :as req}]
+  (if-let [route (match-route routes uri request-method)]
+    (route+req->response route req)
+    (route+req->response (->> routes
+                              (filter #(= :not-found (:path %)))
+                              first) req)))
+
+
+(defn route!
+  ([routes]
+   (route! routes {:port 9600}))
+  ([routes opts]
+   (http/run-server #(router routes %) opts)))
+
+
+(defn -main [& opts]
+  (route! routes))
\ No newline at end of file
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