Refactor template list logic into one place

The Jinja template for the ‘choose templates’ page is now pulling in
data from a lot of diparate places in order to work out what to show. As
we add more logic about what to show (in order to make the live search
work) it’s going to get harder to have all this logic in the Jinja
template.

This commit refactors it back into Python where we have more language
features for managing complex logic.

It’s a bit weird to call this file a model, in that it’s dealing with
some presentational logic, rather than just data. Conceptually it’s more
like a view model[1].

1. https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93viewmodel

app/main/views/templates.py

@@ -29,6 +29,7 @@ from app.main.forms import (
 )
 from app.main.views.send import get_example_csv_rows, get_sender_details
 from app.models.service import Service
+from app.models.template_list import TemplateList
 from app.template_previews import TemplatePreview, get_page_count_for_letter
 from app.utils import (
     email_or_sms_not_enabled,
@@ -126,9 +127,7 @@ def choose_template(service_id, template_type='all', template_folder_id=None):
         current_template_folder_id=template_folder_id,
         can_manage_folders=can_manage_folders(),
         template_folder_path=current_service.get_template_folder_path(template_folder_id),
-        template_folder_has_contents=current_service.get_template_folders_and_templates('all', template_folder_id),
-        template_folders=current_service.get_template_folders(template_type, template_folder_id),
-        templates=current_service.get_templates(template_type, template_folder_id),
+        template_list=TemplateList(current_service, template_type, template_folder_id),
         show_search_box=current_service.count_of_templates_and_folders > 7,
         show_template_nav=(
             current_service.has_multiple_template_types

app/models/template_list.py

@@ -0,0 +1,120 @@
+class TemplateList():
+
+    def __init__(
+        self,
+        service,
+        template_type='all',
+        template_folder_id=None,
+    ):
+        self.service = service
+        self.template_type = template_type
+        self.template_folder_id = template_folder_id
+
+    def __iter__(self):
+        for item in self.get_templates_and_folders(
+            self.template_type, self.template_folder_id, ancestors=[]
+        ):
+            yield item
+
+    def get_templates_and_folders(self, template_type, template_folder_id, ancestors):
+
+        for item in self.service.get_template_folders(
+            template_type, template_folder_id
+        ):
+            yield TemplateListFolder(
+                item,
+                folders=self.service.get_template_folders(
+                    self.template_type, item['id']
+                ),
+                templates=self.service.get_templates(
+                    self.template_type, item['id']
+                ),
+                ancestors=ancestors,
+            )
+            for sub_item in self.get_templates_and_folders(
+                template_type, item['id'], ancestors + [item]
+            ):
+                yield sub_item
+
+        for item in self.service.get_templates(
+            self.template_type, template_folder_id
+        ):
+            yield TemplateListTemplate(
+                item,
+                ancestors=ancestors,
+            )
+
+    @property
+    def templates_to_show(self):
+        return any(self)
+
+    @property
+    def folder_is_empty(self):
+        return not any(self.get_templates_and_folders(
+            'all', self.template_folder_id, []
+        ))
+
+
+class TemplateListItem():
+
+    def __init__(
+        self,
+        template_or_folder,
+        ancestors,
+    ):
+        self.id = template_or_folder['id']
+        self.name = template_or_folder['name']
+        self.ancestors = ancestors
+
+
+class TemplateListTemplate(TemplateListItem):
+
+    is_folder = False
+
+    def __init__(
+        self,
+        template,
+        ancestors,
+    ):
+        super().__init__(template, ancestors)
+        self.hint = {
+            'email': 'Email template',
+            'sms': 'Text message template',
+            'letter': 'Letter template',
+        }.get(template['template_type'])
+
+
+class TemplateListFolder(TemplateListItem):
+
+    is_folder = True
+
+    def __init__(
+        self,
+        folder,
+        templates,
+        folders,
+        ancestors,
+    ):
+        super().__init__(folder, ancestors)
+        self.number_of_templates = len(templates)
+        self.number_of_folders = len(folders)
+
+    @property
+    def _hint_parts(self):
+
+        if self.number_of_folders == self.number_of_templates == 0:
+            yield 'Empty'
+
+        if self.number_of_templates == 1:
+            yield '1 template'
+        elif self.number_of_templates > 1:
+            yield '{} templates'.format(self.number_of_templates)
+
+        if self.number_of_folders == 1:
+            yield '1 folder'
+        elif self.number_of_folders > 1:
+            yield '{} folders'.format(self.number_of_folders)
+
+    @property
+    def hint(self):
+        return ', '.join(self._hint_parts)

app/templates/components/message-count-label.html

@@ -55,26 +55,3 @@
     {%- endif -%}
   {%- endif %}
 {%- endmacro %}
-
-
-{% macro folder_contents_count(number_of_folders, number_of_templates) %}
-
-  {% if number_of_folders == number_of_templates == 0 %}
-    Empty
-  {% endif %}
-
-  {% if number_of_templates == 1 %}
-      {{ number_of_templates }} template
-  {%- elif number_of_templates > 1 -%}
-      {{ number_of_templates }} templates
-  {%- endif -%}
-
-  {%- if number_of_folders and number_of_templates %}, {% endif -%}
-
-  {%- if number_of_folders == 1 -%}
-      {{ number_of_folders }} folder
-  {%- elif number_of_folders > 1 -%}
-      {{ number_of_folders }} folders
-  {% endif %}
-
-{%- endmacro %}

app/templates/views/templates/_move_to.html

@@ -1,7 +1,7 @@
 {% from "components/radios.html" import radios %}
 {% from "components/page-footer.html" import page_footer %}
 
-{% if templates_and_folders_form.move_to.choices and (templates or template_folders) %}
+{% if templates_and_folders_form.move_to.choices and template_list.templates_to_show %}
   {{ radios(templates_and_folders_form.move_to) }}
   {{ page_footer('Move selected', button_name='operation', button_value='move') }}
 {% endif %}

app/templates/views/templates/_template_list.html

@@ -1,52 +1,38 @@
 {% from "components/checkbox.html" import unlabelled_checkbox %}
 {% from "components/message-count-label.html" import folder_contents_count, message_count_label %}
 
-{% if service_has_templates_or_folders and not templates and not template_folders %}
+{% if not template_list.templates_to_show %}
   <p class="template-list-empty">
-    {% if template_folder_has_contents %}
-      There are no {{ message_count_label(1, template_type, suffix='') }} templates in this folder
-    {% else %}
+    {% if template_list.folder_is_empty %}
       This folder is empty
+    {% else %}
+      There are no {{ message_count_label(1, template_type, suffix='') }} templates in this folder
     {% endif %}
   </p>
 {% else %}
   <nav id=template-list>
-    {% for template_folder in template_folders %}
+    {% for item in template_list %}
       <div class="template-list-item {% if can_manage_folders %}template-list-item-with-checkbox{% endif %}">
         {% if can_manage_folders %}
           {{ unlabelled_checkbox(
-            id='templates-or-folder-{}'.format(template_folder.id),
+            id='templates-or-folder-{}'.format(item.id),
             name='templates_and_folders',
-            value=template_folder.id,
+            value=item.id,
           ) }}
         {% endif %}
-        <h2 class="message-name template-list-folder">
-          <a href="{{ url_for('.choose_template', service_id=current_service.id, template_type=template_type, template_folder_id=template_folder.id) }}">
-            {{ template_folder.name }}
-          </a>
-        </h2>
-        <p class="message-type">
-          {{ folder_contents_count(
-            current_service.get_template_folders(template_type, template_folder.id)|length,
-            current_service.get_templates(template_type, template_folder.id)|length,
-          ) }}
-        </p>
-      </div>
-    {% endfor %}
-    {% for template in templates %}
-      <div class="template-list-item {% if can_manage_folders %}template-list-item-with-checkbox{% endif %}">
-        {% if can_manage_folders %}
-          {{ unlabelled_checkbox(
-            id='templates-or-folder-{}'.format(template.id),
-            name='templates_and_folders',
-            value=template.id,
-          ) }}
+        {% if item.is_folder %}
+          <h2 class="message-name template-list-folder">
+            <a href="{{ url_for('.choose_template', service_id=current_service.id, template_type=template_type, template_folder_id=item.id) }}">
+              {{ item.name }}
+            </a>
+          </h2>
+        {% else %}
+          <h2 class="message-name">
+            <a href="{{ url_for('.view_template', service_id=current_service.id, template_id=item.id) }}">{{ item.name }}</a>
+          </h2>
         {% endif %}
-        <h2 class="message-name">
-          <a href="{{ url_for('.view_template', service_id=current_service.id, template_id=template.id) }}">{{ template.name }}</a>
-        </h2>
         <p class="message-type">
-          {{ message_count_label(1, template.template_type, suffix='')|capitalize }} template
+          {{ item.hint }}
         </p>
       </div>
     {% endfor %}

app/templates/views/templates/choose.html

@@ -77,29 +77,11 @@
 
     {% if can_manage_folders %}
       <form method="post">
-        {% with
-          templates=templates,
-          template_folders=template_folders,
-          service_has_templates_or_folders=(current_service.has_templates or current_service.has_folders),
-          template_type=template_type,
-          template_folder_has_contents=template_folder_has_contents
-        %}
-          {% include 'views/templates/_template_list.html' %}
-        {% endwith %}
-        {% with templates=templates, template_folders=template_folders, templates_and_folders_form=templates_and_folders_form %}
-          {% include 'views/templates/_move_to.html' %}
-        {% endwith %}
+        {% include 'views/templates/_template_list.html' %}
+        {% include 'views/templates/_move_to.html' %}
       </form>
     {% else %}
-      {% with
-        templates=templates,
-        template_folders=template_folders,
-        service_has_templates_or_folders=(current_service.has_templates or current_service.has_folders),
-        template_type=template_type,
-        template_folder_has_contents=template_folder_has_contents
-      %}
-        {% include 'views/templates/_template_list.html' %}
-      {% endwith %}
+      {% include 'views/templates/_template_list.html' %}
     {% endif %}
   {% endif %}