implement redirection when user should be logged in/logged out

src/login.ml

@@ -5,6 +5,13 @@ open Syntax
 let get request =
   let** () = User.assert_not_logged request in
   let title = "Pellest|Login" in
+
+  let action =
+    match Dream.query request "redirect" with
+    | None -> "/login"
+    | Some r -> Format.sprintf "/login?redirect=%s" r
+  in
+
   let login =
     let submit = button ~a:[ a_id "submit_login" ] [ txt "submit" ] in
     let login =
@@ -13,8 +20,7 @@ let get request =
     let password =
       input ~a:[ a_id "password"; a_name "password"; a_input_type `Password ] ()
     in
-    div
-      [ make_form request ~action:"/login" ~items:[ login; password; submit ] ]
+    div [ make_form request ~action ~items:[ login; password; submit ] ]
   in
   let text = div [ txt "login ~!" ] in
   let page = div [ text; login ] in
@@ -32,5 +38,5 @@ let post request =
     in
     Dream.respond ~status:`See_Other
       ~headers:[ ("Location", url) ]
-      "Logged in: Happy geo-posting!"
+      "Logged in: Happy pellesting!"
   | _form -> Template.err (`Bad_Request, "invalid form")