Shorten filenames that are too long

bulkredditdownloader/file_name_formatter.py

@@ -46,13 +46,24 @@ class FileNameFormatter:
     def _format_path(self, resource: Resource, destination_directory: Path, index: Optional[int] = None) -> Path:
         subfolder = destination_directory / self._format_name(resource.source_submission, self.directory_format_string)
         index = f'_{str(index)}' if index else ''
+        if not resource.extension:
+            raise BulkDownloaderException(f'Resource from {resource.url} has no extension')
+        ending = index + resource.extension
+        file_name = str(self._format_name(resource.source_submission, self.file_format_string))
+        file_name = self._limit_file_name_length(file_name, ending)
         try:
-            file_path = subfolder / (str(self._format_name(resource.source_submission,
-                                                           self.file_format_string)) + index + resource.extension)
+            file_path = Path(subfolder, file_name)
         except TypeError:
             raise BulkDownloaderException(f'Could not determine path name: {subfolder}, {index}, {resource.extension}')
         return file_path
 
+    @staticmethod
+    def _limit_file_name_length(filename: str, ending: str) -> str:
+        max_length = 255 - len(ending)
+        if len(filename) > max_length:
+            filename = filename[:max_length]
+        return filename + ending
+
     def format_resource_paths(self, resources: list[Resource],
                               destination_directory: Path) -> list[tuple[Path, Resource]]:
         out = []

bulkredditdownloader/tests/test_file_name_formatter.py

@@ -125,3 +125,28 @@ def test_format_multiple_resources():
     results = test_formatter.format_resource_paths(mocks, Path('.'))
     results = set([str(res[0]) for res in results])
     assert results == {'test_1.png', 'test_2.png', 'test_3.png', 'test_4.png'}
+
+
+@pytest.mark.parametrize(('test_filename', 'test_ending'), (
+    ('A' * 300, '.png'),
+    ('A' * 300, '_1.png'),
+    ('a' * 300, '_1000.jpeg'),
+))
+def test_limit_filename_length(test_filename: str, test_ending: str):
+    result = FileNameFormatter._limit_file_name_length(test_filename, test_ending)
+    assert len(result) <= 255
+
+
+@pytest.mark.online
+@pytest.mark.reddit
+def test_shorten_filenames(reddit_instance: praw.Reddit, tmp_path: Path):
+    test_submission = MagicMock()
+    test_submission.title = 'A' * 300
+    test_submission.author.name = 'test'
+    test_submission.subreddit.display_name = 'test'
+    test_submission.id = 'BBBBBB'
+    test_resource = Resource(test_submission, 'www.example.com/empty', '.jpeg')
+    test_formatter = FileNameFormatter('{REDDITOR}_{TITLE}_{POSTID}', '{SUBREDDIT}')
+    result = test_formatter._format_path(test_resource, tmp_path)
+    result.parent.mkdir(parents=True)
+    result.touch()

bulkredditdownloader/tests/test_integration.py

@@ -43,6 +43,7 @@ def test_cli_download_subreddits(test_args: list[str], tmp_path: Path):
 @pytest.mark.parametrize('test_args', (
     ['-l', 'm2601g'],
     ['-l', 'https://www.reddit.com/r/TrollXChromosomes/comments/m2601g/its_a_step_in_the_right_direction/'],
+    ['-l', 'm3hxzd'],  # Really long title used to overflow filename limit
 ))
 def test_cli_download_links(test_args: list[str], tmp_path: Path):
     runner = CliRunner()