rewrite frontend and logic in core app

core/templates/registration/login.html

@@ -0,0 +1,22 @@
+{% extends "core/base.html" %}
+
+{% block navi %}
+    <a href="{% url 'admin:index' %}">admin</a>
+{% endblock %}
+
+{% block content %}
+    <form id="login-form" method="post" action="{% url 'login' %}">
+        {% csrf_token %}
+        <label for="id_username">username</label>
+        <input id="id_username" name="username" type="text" placeholder="username">
+        <label for="id_password">password</label>
+        <input id="id_password" name="password" type="password" placeholder="password">
+        {% if form.errors %}
+            <div id="login-warning">
+                nope.
+            </div>
+        {% endif %}
+        <input id="login-button" type="submit" value="login"/>
+        <input type="hidden" name="next" value="{{ next }}"/>
+    </form>
+{% endblock %}