Use a cache directory instead of temporary files

Temporary files behave differently on Windows from how they do on Unix:
https://stackoverflow.com/a/23212515 which was causing permission errors
when creating and writing docx files. To avoid this, we will use a
regular cache directory. However, note that files no longer get cleaned
up automatically (issue #27).

requirements.txt

@@ -1,3 +1,4 @@
+appdirs~=1.4.4
 attrs~=21.2.0
 cattrs~=22.1.0
 docxtpl~=0.15.2

tests/test_pypew.py

@@ -1,5 +1,6 @@
 import unittest
 from datetime import date
+from pathlib import Path
 from unittest.mock import patch
 from urllib.parse import urlencode
 
@@ -15,6 +16,10 @@
 from utils import advent
 
 
+def m_create_docx_impl(path):
+    Path(path).touch()
+
+
 class TestDates(unittest.TestCase):
     @parameterized.expand([
         # Christmas Day in 2021 was a Saturday
@@ -159,7 +164,7 @@ def test_feast_detail_view_handles_not_found(self):
         )
         self.assertEqual(r.status_code, 404)
 
-    @patch('pypew.views.feast_views.Feast.create_docx')
+    @patch('pypew.views.feast_views.Feast.create_docx', side_effect=m_create_docx_impl)
     def test_feast_docx_view(self, m_create_docx):
         r = self.client.get(
             url_for('feast_docx_view', slug='christmas-day')
@@ -175,7 +180,7 @@ def test_feast_docx_view(self, m_create_docx):
             r.headers['Content-Type'],
         )
 
-    @patch('pypew.views.pew_sheet_views.Service.create_docx')
+    @patch('pypew.views.pew_sheet_views.Service.create_docx', side_effect=m_create_docx_impl)
     def test_pew_sheet_docx_view(self, m_create_docx):
         r = self.client.get(
             url_for('pew_sheet_docx_view') + '?' + urlencode(

utils.py

@@ -4,6 +4,8 @@
 from functools import lru_cache
 from typing import Optional
 
+from appdirs import AppDirs
+
 try:
     import pandas as pd
 except ImportError:
@@ -14,6 +16,9 @@ class NoPandasError(RuntimeError):
     pass
 
 
+cache_dir = AppDirs("pypew").user_cache_dir
+os.makedirs(cache_dir, exist_ok=True)
+
 logger = logging.getLogger("pypew")
 logger.setLevel(logging.INFO)
 

views/feast_views.py

@@ -1,5 +1,7 @@
 import datetime
-from tempfile import NamedTemporaryFile
+import os
+import uuid
+from tempfile import TemporaryDirectory
 
 import cattrs
 from flask import (flash, make_response, render_template, send_file,
@@ -8,7 +10,7 @@
 from filters import english_date
 from models import Feast
 from models_base import NotFoundError, get
-from utils import str2date
+from utils import str2date, cache_dir
 
 __all__ = ['feast_index_view', 'feast_index_api', 'feast_date_api',
            'feast_upcoming_api', 'feast_detail_view', 'feast_detail_api',
@@ -89,8 +91,8 @@ def feast_docx_view(slug):
         return make_response(feast_index_view(), 404)
 
     filename = f'{feast.name}.docx'
-    with NamedTemporaryFile() as tf:
-        feast.create_docx(path=tf.name)
-        return send_file(
-            tf.name, as_attachment=True, attachment_filename=filename
-        )
+    temp_docx = os.path.join(cache_dir, f"feast_{str(uuid.uuid4())}.docx")
+    feast.create_docx(path=temp_docx)
+    return send_file(
+        temp_docx, as_attachment=True, attachment_filename=filename
+    )

views/pew_sheet_views.py

@@ -1,5 +1,5 @@
 import os
-from tempfile import NamedTemporaryFile
+import uuid
 from urllib.parse import parse_qs, urlencode
 
 import dotenv
@@ -9,7 +9,7 @@
 
 from forms import PewSheetForm
 from models import Service, Feast
-from utils import logger
+from utils import logger, cache_dir
 
 __all__ = ['pew_sheet_create_view', 'pew_sheet_clear_history_endpoint', 'pew_sheet_docx_view']
 
@@ -79,10 +79,9 @@ def pew_sheet_docx_view():
 
     datestamp = service.date.strftime("%Y-%m-%d")
 
-    with NamedTemporaryFile() as tf:
-        service.create_docx(tf.name)
-        return send_file(
-            tf.name,
-            as_attachment=True,
-            attachment_filename=f'{datestamp} {service.title}.docx'
-        )
+    filename = f'{datestamp} {service.title}.docx'
+    temp_docx = os.path.join(cache_dir, f"pew_sheet_{str(uuid.uuid4())}.docx")
+    service.create_docx(temp_docx)
+    return send_file(
+        temp_docx, as_attachment=True, attachment_filename=filename
+    )