Backup module: Implement downloading archives

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/backups/templates/backups.html

@@ -118,6 +118,10 @@
               <td class="export-label">{{ label }}</td>
               <td class="export-name">{{ name }}</td>
               <td class="export-operations">
+                <a class="download btn btn-sm btn-default" target="_blank"
+                   href="{% url 'backups:download' label|urlencode name|urlencode %}">
+                  {% trans "Download" %}
+                </a>
                 <a class="restore btn btn-sm btn-default"
                    href="{% url 'backups:restore' label|urlencode name|urlencode %}">
                   {% trans "Restore" %}

plinth/modules/backups/urls.py

@@ -20,14 +20,16 @@ URLs for the backups module.
 
 from django.conf.urls import url
 
-from .views import IndexView, CreateArchiveView, ExportArchiveView, \
+from .views import IndexView, CreateArchiveView, DownloadArchiveView, \
-    DeleteArchiveView, RestoreView
+    ExportArchiveView, DeleteArchiveView, RestoreView
 
 urlpatterns = [
     url(r'^sys/backups/$', IndexView.as_view(), name='index'),
     url(r'^sys/backups/create/$', CreateArchiveView.as_view(), name='create'),
     url(r'^sys/backups/export/(?P<name>[^/]+)/$',
         ExportArchiveView.as_view(), name='export'),
+    url(r'^sys/backups/download/(?P<label>[^/]+)/(?P<name>[^/]+)/$',
+        DownloadArchiveView.as_view(), name='download'),
     url(r'^sys/backups/delete/(?P<name>[^/]+)/$',
         DeleteArchiveView.as_view(), name='delete'),
     url(r'^sys/backups/restore/(?P<label>[^/]+)/(?P<name>[^/]+)/$',

plinth/modules/backups/views.py

@@ -18,20 +18,22 @@
 Views for the backups app.
 """
 
+import mimetypes
 from datetime import datetime
 from urllib.parse import unquote
 
 from django.contrib import messages
 from django.contrib.messages.views import SuccessMessageMixin
-from django.http import Http404
+from django.core.files.base import File
+from django.http import Http404, HttpResponse
 from django.shortcuts import redirect
 from django.urls import reverse_lazy
 from django.utils.translation import ugettext as _
-from django.views.generic import FormView, TemplateView
+from django.views.generic import View, FormView, TemplateView
 
 from plinth.modules import backups
 
-from . import backups as backups_api
+from . import backups as backups_api, find_exported_archive
 from .forms import CreateArchiveForm, ExportArchiveForm, RestoreForm
 
 
@@ -101,6 +103,24 @@ class DeleteArchiveView(SuccessMessageMixin, TemplateView):
         return redirect(reverse_lazy('backups:index'))
 
 
+class DownloadArchiveView(View):
+    """View to download an archive."""
+    def get(self, request, label, name):
+        label = unquote(label)
+        name = unquote(name)
+        filepath = find_exported_archive(label, name)
+        (content_type, encoding) = mimetypes.guess_type(name)
+        with open(filepath, 'rb') as file_handle:
+            response = HttpResponse(File(file_handle),
+                content_type=content_type)
+            content_disposition = 'attachment; filename="%s"' % name
+            response['Content-Disposition'] = content_disposition
+            if encoding:
+                response['Content-Encoding'] = encoding
+
+        return response
+
+
 class ExportArchiveView(SuccessMessageMixin, FormView):
     """View to export an archive."""
     form_class = ExportArchiveForm