Add a date format for download names

The new setting gives the strftime format of {pubdate}, {timestamp} and {last_modified}.
The default is Calibre's "%b, %Y".

tests/js/flows.test.mjs

@@ -110,18 +110,25 @@ test('the jobs list settings load and save all four fields', async () => {
 });
 
 test('the download template loads, lists its fields, and saves the stored form', async () => {
-  api.on('GET', 'settings', { recent_chapters: 0, personal_ini: '', download_template: '{title}' });
+  api.on('GET', 'settings', {
+    recent_chapters: 0, personal_ini: '', download_template: '{title}', download_date_format: '%b, %Y',
+  });
   settingsPage(main, {}, config);
   await settle();
   const card = section(main, 'Book Downloads');
   assert.equal(field(main, 'download-template').value, '{title}');
+  assert.equal(field(main, 'download-date-format').value, '%b, %Y');
   assert.ok(find(card, 'code', '{id}'));
   assert.match(card.textContent, /\{title\}The title\{id\}The story ID/);
   field(main, 'download-template').value = ' {title} - {authors} ';
-  api.on('PUT', 'settings', { download_template: '{title} - {authors}' });
+  field(main, 'download-date-format').value = '';
+  api.on('PUT', 'settings', { download_template: '{title} - {authors}', download_date_format: '%b, %Y' });
   await click(card, 'Save');
-  assert.deepEqual(api.sent('PUT', 'settings')[0].body, { download_template: ' {title} - {authors} ' });
+  assert.deepEqual(api.sent('PUT', 'settings')[0].body, {
+    download_template: ' {title} - {authors} ', download_date_format: '',
+  });
   assert.equal(field(main, 'download-template').value, '{title} - {authors}');
+  assert.equal(field(main, 'download-date-format').value, '%b, %Y');
   api.on('PUT', 'settings', { error: 'Bindery does not support template functions' }, 400);
   field(main, 'download-template').value = '{title:uppercase()}';
   await click(card, 'Save');

tests/test_api.py

@@ -473,6 +473,7 @@ def test_settings(client, monkeypatch, tmp_path):
         "ingest_available": True,
         "personal_ini": "[defaults]\nis_adult:true\n",
         "download_template": "{title} - {authors}",
+        "download_date_format": "%b, %Y",
         "story_jobs_hours": 36,
         "story_jobs_count": 10,
         "main_jobs_hours": 6,

tests/test_api_flows.py

@@ -174,6 +174,24 @@ def test_download_template_names_the_file(client, story):
     assert "filename*=UTF-8''Caf%C3%A9%20-%20Ann%20Writer.epub" in download_name(client, sid)
 
 
+def test_date_format_of_download_names(client, story):
+    sid, _ = story
+    o.store.update_story(sid, metahtml=metahtml(), site_values={"pubdate": "2020-05-06T00:00:00"})
+    client.put("/api/settings", json={"download_template": "{title} {pubdate}"}, headers=H)
+    assert 'filename="Story May, 2020.epub"' in download_name(client, sid)
+    saved = client.put("/api/settings", json={"download_date_format": " %Y-%m-%d "}, headers=H).json
+    assert saved["download_date_format"] == "%Y-%m-%d"
+    assert "filename=Story 2020-05-06.epub" in download_name(client, sid).replace('"', "")
+    response = client.put("/api/settings", json={"download_date_format": 5}, headers=H)
+    assert (response.status_code, response.json) == (400, {"error": "The date format must be text"})
+    response = client.put("/api/settings", json={"download_date_format": "%Y" * 51}, headers=H)
+    assert (response.status_code, response.json) == (400, {"error": "A date format can have 100 characters at most"})
+    # An empty format restores the default.
+    assert client.put("/api/settings", json={"download_date_format": ""}, headers=H).json["download_date_format"] == (
+        "%b, %Y"
+    )
+
+
 def test_download_template_that_fails_gives_the_title(client, story, caplog):
     sid, _ = story
     o.store.update_story(sid, metahtml=metahtml())

tests/test_filename_template.py

@@ -91,6 +91,16 @@ def test_values_follow_the_rules_of_calibre():
         "Dec, 1999 Oct, 2026"
     )
     assert expand("{pubdate}", pubdate="not a date") == ""
+
+
+def test_date_format():
+    # Calibre's helper_date reference case.
+    assert ft.expand("{pubdate}", ft.prepare(BOOK, 42, date_format="%b %Y")) == "May 2020"
+    assert ft.expand("{pubdate}", ft.prepare(BOOK, 42, date_format="%d/%m/%Y")) == "06_05_2020"
+    assert ft.expand("x{pubdate}x", ft.prepare(BOOK, 42, date_format="")) == "xx"
+    ft.check_date_format("%Y-%m-%d " * 10)
+    with pytest.raises(ft.TemplateError, match="A date format can have 100 characters at most"):
+        ft.check_date_format("x" * 101)
     # A series without a number has no series_index, and a book without a series has neither.
     assert expand("{series}{series_index:| [|]}", series_index=None) == "Saga, The"
     assert ft.expand("{series_index:03d}|{series}", ft.prepare(NO_SERIES, 42)) == "|"