Improves change password flow

There are two changes: one is to require the current password to change
your password (which is a security improvement), and the other is error
reporting when you either get your current password wrong or your new
password doesn't match it's second entry.

bookwyrm/templates/preferences/change_password.html

@@ -8,15 +8,46 @@
 {% endblock %}
 
 {% block panel %}
+{% if success %}
+<div class="notification is-success is-light">
+    <span class="icon icon-check" aria-hidden="true"></span>
+    <span>
+        {% trans "Successfully changed password" %}
+    </span>
+</div>
+{% endif %}
 <form name="edit-profile" action="{% url 'prefs-password' %}" method="post" enctype="multipart/form-data">
     {% csrf_token %}
+    <div class="field">
+        <label class="label" for="id_password">{% trans "Current password:" %}</label>
+        <input
+            type="password"
+            name="current_password"
+            maxlength="128"
+            class="input"
+            required=""
+            id="id_current_password"
+            aria-describedby="desc_current_password"
+        >
+        {% include 'snippets/form_errors.html' with errors_list=errors.current_password id="desc_current_password" %}
+    </div>
+    <hr aria-hidden="true" />
     <div class="field">
         <label class="label" for="id_password">{% trans "New password:" %}</label>
         <input type="password" name="password" maxlength="128" class="input" required="" id="id_password">
     </div>
     <div class="field">
         <label class="label" for="id_confirm_password">{% trans "Confirm password:" %}</label>
-        <input type="password" name="confirm-password" maxlength="128" class="input" required="" id="id_confirm_password">
+        <input
+            type="password"
+            name="confirm-password"
+            maxlength="128"
+            class="input"
+            required=""
+            id="id_confirm_password"
+            aria-describedby="desc_confirm_password"
+        >
+        {% include 'snippets/form_errors.html' with errors_list=errors.confirm_password id="desc_confirm_password" %}
     </div>
     <button class="button is-primary" type="submit">{% trans "Change Password" %}</button>
 </form>

bookwyrm/views/preferences/change_password.py

@@ -1,10 +1,13 @@
 """ class views for password management """
 from django.contrib.auth import login
 from django.contrib.auth.decorators import login_required
-from django.shortcuts import redirect
 from django.template.response import TemplateResponse
 from django.utils.decorators import method_decorator
+from django.utils.translation import gettext_lazy as _
 from django.views import View
+from django.views.decorators.debug import sensitive_variables, sensitive_post_parameters
+
+from bookwyrm import models
 
 
 # pylint: disable= no-self-use
@@ -17,15 +20,30 @@ class ChangePassword(View):
         data = {"user": request.user}
         return TemplateResponse(request, "preferences/change_password.html", data)
 
+    @sensitive_variables("new_password")
+    @sensitive_variables("confirm_password")
+    @method_decorator(sensitive_post_parameters("current_password"))
+    @method_decorator(sensitive_post_parameters("password"))
+    @method_decorator(sensitive_post_parameters("confirm__password"))
     def post(self, request):
         """allow a user to change their password"""
+        data = {"user": request.user}
+
+        # check current password
+        user = models.User.objects.get(id=request.user.id)
+        if not user.check_password(request.POST.get("current_password")):
+            data["errors"] = {"current_password": [_("Incorrect password")]}
+            return TemplateResponse(request, "preferences/change_password.html", data)
+
         new_password = request.POST.get("password")
         confirm_password = request.POST.get("confirm-password")
 
         if new_password != confirm_password:
-            return redirect("prefs-password")
+            data["errors"] = {"confirm_password": [_("Password does not match")]}
+            return TemplateResponse(request, "preferences/change_password.html", data)
 
         request.user.set_password(new_password)
         request.user.save(broadcast=False, update_fields=["password"])
         login(request, request.user)
-        return redirect("user-feed", request.user.localname)
+        data["success"] = True
+        return TemplateResponse(request, "preferences/change_password.html", data)