[ENG-6208] implemented unwithdraw specific preprint version (#10964)

## Purpose

Allow to unwithdraw preprint versions in the admin app

## Ticket

(https://openscience.atlassian.net/browse/ENG-6208)

admin/preprints/urls.py

@@ -26,4 +26,5 @@
     re_path(r'^(?P<guid>\w+)/reject_withdrawal/$', views.PreprintRejectWithdrawalRequest.as_view(), name='reject-withdrawal'),
     re_path(r'^(?P<guid>\w+)/resync_crossref/$', views.PreprintResyncCrossRefView.as_view(), name='resync-crossref'),
     re_path(r'^(?P<guid>\w+)/make_published/$', views.PreprintMakePublishedView.as_view(), name='make-published'),
+    re_path(r'^(?P<guid>\w+)/unwithdraw/$', views.PreprintUnwithdrawView.as_view(), name='unwithdraw'),
 ]

admin/preprints/views.py

@@ -560,3 +560,38 @@ def post(self, request, *args, **kwargs):
         preprint = self.get_object()
         preprint.set_published(True, request, True)
         return redirect(self.get_success_url())
+
+class PreprintUnwithdrawView(PreprintMixin, View):
+    """ Allows authorized users to unwithdraw a preprint that was previously withdrawn.
+    """
+    permission_required = ('osf.change_node')
+
+    def post(self, request, *args, **kwargs):
+        preprint = self.get_object()
+
+        if preprint.machine_state != 'withdrawn':
+            messages.error(request, f'Preprint {preprint._id} is not withdrawn')
+            return redirect(self.get_success_url())
+
+        withdraw_action = preprint.actions.filter(to_state='withdrawn').last()
+        last_action = preprint.actions.last()
+
+        preprint.withdrawal_justification = ''
+        preprint.date_withdrawn = None
+
+        if withdraw_action:
+            preprint.machine_state = withdraw_action.from_state
+            withdraw_action.delete()
+        else:
+            if last_action:
+                preprint.machine_state = last_action.to_state
+            else:
+                # Default to put it back in moderation if we don't know where it came from
+                preprint.machine_state = 'pending'
+
+        from osf.utils.migrations import disable_auto_now_fields
+        with disable_auto_now_fields():
+            preprint.save()
+
+        messages.success(request, f'Successfully unwithdrawn preprint {preprint._id}')
+        return redirect(self.get_success_url())

admin/templates/preprints/preprint.html

@@ -116,7 +116,7 @@ <h2>Preprint: <b>{{ preprint.title }}</b> <a href="{{ preprint.absolute_url }}">
                     {% include "preprints/contributors.html" with preprint=preprint %}
                     {% include "nodes/spam_status.html" with resource=preprint %}
                     {% include "preprints/withdraw_request.html" with preprint=preprint %}
-
+                    {% include "preprints/unwithdraw_request.html" with preprint=preprint %}
                 </tbody>
             </table>
         </div>

admin/templates/preprints/unwithdraw_request.html

@@ -0,0 +1,41 @@
+{% load node_extras %}
+
+{% if perms.osf.change_preprintrequest %}
+    <tr>
+        <td>Unwithdraw Version</td>
+        <td>
+            <div class="form-inline">
+                {% if preprint.machine_state == 'withdrawn' %}
+                    Version {{ preprint.version }}
+                    <button type="button" class="btn btn-danger" onclick="$('#confirmUnwithdraw').modal('show')">
+                        Unwithdraw
+                    </button>
+                    <div class="modal" id="confirmUnwithdraw">
+                        <div class="modal-dialog">
+                            <div class="modal-content">
+                                <form class="well" method="post" action="{% url 'admin:unwithdraw' guid=preprint.guid %}">
+                                    <div class="modal-header">
+                                        <button type="button" class="close" data-dismiss="modal">x</button>
+                                        <h3>Are you sure you want to unwithdraw this version?</h3>
+                                    </div>
+                                    {% csrf_token %}
+                                    <div class="modal-footer">
+                                        <button class="btn btn-danger" type="submit">
+                                            Unwithdraw
+                                        </button>
+                                        <button type="button" class="btn btn-default" data-dismiss="modal">
+                                            Cancel
+                                        </button>
+                                    </div>
+                                </form>
+                            </div>
+                        </div>
+                    </div>
+                {% else %}
+                    Not withdrawn version
+                    <button type="submit" class="btn btn-danger" disabled>Unwithdraw</button>
+                {% endif %}
+            </div>
+        </td>
+    </tr>
+{% endif %}