use exp/ttl in remember_me plug

lib/guardian/plug.ex

@@ -42,7 +42,7 @@ if Code.ensure_loaded?(Plug) do
     end
 
     @default_key "default"
-    @default_cookie_options [max_age: 60 * 60 * 24 * 7 * 4]
+    @default_cookie_max_age [max_age: 60 * 60 * 24 * 7 * 4]
 
     import Guardian, only: [returning_tuple: 1]
     import Guardian.Plug.Keys
@@ -255,6 +255,13 @@ if Code.ensure_loaded?(Plug) do
       put_resp_cookie(conn, key, token, opts)
     end
 
+    @doc """
+    Sets a token of type refresh directly on a cookie
+    The max_age of the cookie till be the expire time of the Token, if available
+    If the token does not have an exp,t the default will be 30 days.
+    The max age can be overridden by setting the cookie option config.
+    """
+
     @spec remember_me(Plug.Conn.t(), module, any, Guardian.Token.claims(), Guardian.options()) :: Plug.Conn.t()
     def remember_me(conn, mod, resource, claims \\ %{}, opts \\ []) do
       opts = Keyword.put_new(opts, :token_type, "refresh")
@@ -317,11 +324,11 @@ if Code.ensure_loaded?(Plug) do
 
     defp cookie_options(mod, %{"exp" => timestamp}) do
       max_age = timestamp - Guardian.timestamp()
-      [max_age: max_age] ++ cookie_options(mod, %{})
+      Keyword.merge([max_age: max_age], mod.config(:cookie_options, []))
     end
 
-    defp cookie_options(mod, _claims) do
-      Keyword.merge(@default_cookie_options, mod.config(:cookie_options, []))
+    defp cookie_options(mod, _) do
+      Keyword.merge(@default_cookie_max_age, mod.config(:cookie_options, []))
     end
 
     defp add_data_to_conn(conn, resource, token, claims, opts) do

test/guardian/plug_test.exs

@@ -431,6 +431,32 @@ defmodule Guardian.PlugTest do
       assert gather_function_calls() == expected
     end
 
+    test "it creates a cookie with the default token and key and a exp in claimss ", ctx do
+      conn = ctx.conn
+
+      exp = Guardian.timestamp() + 10000
+
+      assert %Plug.Conn{} = xconn = Guardian.Plug.remember_me(conn, ctx.impl, @resource, %{exp: exp}, [])
+
+      assert Map.has_key?(xconn.resp_cookies, "guardian_default_token")
+      %{value: token, max_age: max_age} = Map.get(xconn.resp_cookies, "guardian_default_token")
+
+      # default max age
+      assert max_age <= 10000
+      assert token
+
+      claims = %{"sub" => @resource.id, "typ" => "refresh", "exp" => exp}
+      ops = [token_type: "refresh"]
+
+      expected = [
+        {ctx.impl, :subject_for_token, [@resource, %{"exp" => exp}]},
+        {Guardian.Support.TokenModule, :build_claims, [ctx.impl, @resource, "bobby", %{"exp" => exp}, ops]},
+        {Guardian.Support.TokenModule, :create_token, [ctx.impl, claims, ops]}
+      ]
+
+      assert gather_function_calls() == expected
+    end
+
     test "it creates a cookie with a default token and custom key", ctx do
       conn = ctx.conn