create error validation page

lib/hits_web/controllers/hit_controller.ex

@@ -30,7 +30,11 @@ defmodule HitsWeb.HitController do
         render_invalid_badge(conn)
       end
     else
-      render(conn, "index.html", params)
+      if user_valid?(user) and repository_valid?(repository) do
+        render(conn, "index.html", params)
+      else
+        redirect(conn, to: "/error/#{user}/#{repository}")
+      end
     end
   end
 

lib/hits_web/controllers/page_controller.ex

@@ -4,4 +4,8 @@ defmodule HitsWeb.PageController do
   def index(conn, _params) do
     render(conn, "index.html")
   end
+
+  def error(conn, %{"user" => user, "repository" => repository} = params) do
+    render(conn, "error.html", user: user, repository: repository)
+  end
 end

lib/hits_web/router.ex

@@ -18,6 +18,7 @@ defmodule HitsWeb.Router do
     pipe_through(:browser)
 
     get("/", PageController, :index)
+    get("/error/:user/:repository", PageController, :error)
 
     get("/:user/:repository", HitController, :index)
     get("/:etc/:user/:repository", HitController, :edgecase)

lib/hits_web/templates/page/error.html.eex

@@ -0,0 +1,26 @@
+<h2 class="bg-teal white h-25 tc ttu f1 lh-title lh-solid mt0 pa2 pb3 mb0 pb0">
+  Validation Error!
+</h2>
+
+<div class="pa3">
+    <p>Please make sure the username and the repository values are valid:</p>
+
+    <ul>
+      <li><strong><%=@user%></strong> - username may only contain alphanumeric characters or single hyphens, and cannot begin or end with a hyphen</li> 
+      <li><strong><%=@repository%></strong> - repository may contain alphanumeric values and the following characters: "-", "_" "."</li>
+    </ul>
+
+    <%= link "Create a new badge", to: "/", class: "f6 link dim br2 ph3 pv2 mb2 dib white bg-teal" %>
+</div>
+
+<style>
+  .teal {
+    color: #4DB6AC;
+  }
+  .bg-teal {
+    background: #4DB6AC;
+  }
+  body { /* dwyl font */
+    font-family: "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
+  }
+</style>

test/hits_web/controllers/page_controller_test.exs

@@ -5,4 +5,19 @@ defmodule HitsWeb.PageControllerTest do
     conn = get(conn, "/")
     assert html_response(conn, 200) =~ "Hits!"
   end
+
+  test "GET /user/repo", %{conn: conn} do
+    conn = get(conn, "/user/repo")
+    assert html_response(conn, 200) =~ "dashboard"
+  end
+
+  test "GET /--user/repo$", %{conn: conn} do
+    conn = get(conn, "/--user/repo$")
+    assert html_response(conn, 302)
+  end
+
+  test "GET /error/--user/repo$", %{conn: conn} do
+    conn = get(conn, "/error/--user/repo$")
+    assert html_response(conn, 200) =~ "Validation Error!"
+  end
 end