Implement attachment removal

todo/views/remove_attachment.py

@@ -0,0 +1,41 @@
+from django.contrib import messages
+from django.contrib.auth.decorators import login_required
+from django.core.exceptions import PermissionDenied
+from django.http import HttpResponse
+from django.shortcuts import get_object_or_404, redirect
+from django.urls import reverse
+
+from todo.models import Attachment
+from todo.utils import remove_attachment_file
+
+
+@login_required
+def remove_attachment(request, attachment_id: int) -> HttpResponse:
+    """Delete a previously posted attachment object and its corresponding file
+    from the filesystem, permissions allowing.
+    """
+
+    if request.method == "POST":
+        attachment = get_object_or_404(Attachment, pk=attachment_id)
+
+        redir_url = reverse(
+            "todo:task_detail",
+            kwargs={"task_id": attachment.task.id},
+        )
+
+        # Permissions
+        if not (
+            attachment.task.task_list.group in request.user.groups.all()
+            or request.user.is_superuser
+        ):
+            raise PermissionDenied
+
+        if remove_attachment_file(attachment.id):
+            messages.success(request, f"Attachment {attachment.id} removed.")
+        else:
+            messages.error(request, f"Sorry, there was a problem deleting attachment {attachment.id}.")
+
+        return redirect(redir_url)
+
+    else:
+        raise PermissionDenied