Changing default ordering of extensions for fetching ebooks

gutenberg/acquire/text.py

@@ -52,18 +52,29 @@ def _check_mirror_exists(mirror):
             .format(mirror))
 
 
-def _format_download_uri(etextno, mirror=None):
+def _format_download_uri(etextno, mirror=None, prefer_ascii=False):
     """Returns the download location on the Project Gutenberg servers for a
     given text.
 
+    Use prefer_ascii to control whether you want to fetch plaintext us-ascii
+    file first (default old behavior) or if you prefer UTF-8 then 8-bits then
+    plaintext.
+
     Raises:
         UnknownDownloadUri: If no download location can be found for the text.
     """
     uri_root = mirror or _GUTENBERG_MIRROR
     uri_root = uri_root.strip().rstrip('/')
     _check_mirror_exists(uri_root)
 
-    extensions = ('.txt', '-8.txt', '-0.txt')
+    # Check https://www.gutenberg.org/files/ for details about available
+    # extensions ;
+    #  - .txt is plaintext us-ascii
+    #  - -8.txt is 8-bit plaintext, multiple encodings
+    #  - -0.txt is UTF-8
+    ascii_first = ('.txt', '-0.txt', '-8.txt')
+    utf8_first = ('-0.txt', '-8.txt', '.txt')
+    extensions = ascii_first if prefer_ascii else utf8_first
     for extension in extensions:
         path = _etextno_to_uri_subdirectory(etextno)
         uri = '{root}/{path}/{etextno}{extension}'.format(
@@ -79,7 +90,7 @@ def _format_download_uri(etextno, mirror=None):
                                       .format(etextno, uri_root))
 
 
-def load_etext(etextno, refresh_cache=False, mirror=None):
+def load_etext(etextno, refresh_cache=False, mirror=None, prefer_ascii=False):
     """Returns a unicode representation of the full body of a Project Gutenberg
     text. After making an initial remote call to Project Gutenberg's servers,
     the text is persisted locally.
@@ -92,8 +103,18 @@ def load_etext(etextno, refresh_cache=False, mirror=None):
         remove(cached)
     if not os.path.exists(cached):
         makedirs(os.path.dirname(cached))
-        download_uri = _format_download_uri(etextno, mirror)
+        download_uri = _format_download_uri(etextno, mirror, prefer_ascii)
         response = requests.get(download_uri)
+        # Ensure proper UTF-8 saving. There might be instances of ebooks or
+        # mirrors which advertise a broken encoding, and this will break
+        # downstream usages. For example, #55517 from aleph.gutenberg.org:
+        #
+        # from gutenberg.acquire import load_etext
+        # print(load_etext(55517, refresh_cache=True)[0:1000])
+        #
+        # response.encoding will be 'ISO-8859-1' while the file is UTF-8
+        if response.encoding != response.apparent_encoding:
+            response.encoding = response.apparent_encoding
         text = response.text
         with closing(gzip.open(cached, 'w')) as cache:
             cache.write(text.encode('utf-8'))
@@ -115,12 +136,13 @@ def _main():
     parser.add_argument('etextno', type=int)
     parser.add_argument('outfile', type=FileType('w'))
     parser.add_argument('--mirror', '-m', type=str)
+    parser.add_argument('--prefer-ascii', '-a', type=bool, default=False)
     args = parser.parse_args()
 
     mirror = args.mirror or os.environ.get('GUTENBERG_MIRROR')
 
     try:
-        text = load_etext(args.etextno, mirror=mirror)
+        text = load_etext(args.etextno, mirror=mirror, prefer_ascii=args.prefer_ascii)
         with reopen_encoded(args.outfile, 'w', 'utf8') as outfile:
             outfile.write(text)
     except Error as error:

tests/test_acquire.py

@@ -80,6 +80,69 @@ def test_unreachable_mirror(self):
         with self.assertRaises(UnknownDownloadUriException):
             text.load_etext(1)
 
+class TestExtensionsLoadEtext(unittest.TestCase):
+    def setUp(self):
+        self._original_head = text.requests.head
+        self._original_check = text._check_mirror_exists
+
+    def tearDown(self):
+        text.requests.head = self._original_head
+        text._check_mirror_exists = self._original_check
+
+    def request_head_response(self, valid_files):
+        response = namedtuple('Response', 'ok')
+
+        def head(*args, **kwargs):
+            req_file = args[0].split('/')[-1]
+            return response(req_file in valid_files)
+        text.requests.head = head
+
+        def mirror_exist(*args, **kwargs):
+            return response(True)
+        text._check_mirror_exists = mirror_exist
+
+    def test_extensions_order_utf8_only(self):
+        utf8_filename = '12345-0.txt'
+        self.request_head_response(valid_files=[utf8_filename])
+
+        extensions = text._format_download_uri(12345)
+        self.assertEqual(extensions.split('/')[-1], utf8_filename)
+
+        extensions = text._format_download_uri(12345, prefer_ascii=False)
+        self.assertEqual(extensions.split('/')[-1], utf8_filename)
+
+    def test_extensions_order_ascii_only(self):
+        ascii_filename = '12345.txt'
+        self.request_head_response(valid_files=[ascii_filename])
+
+        extensions = text._format_download_uri(12345)
+        self.assertEqual(extensions.split('/')[-1], ascii_filename)
+
+        extensions = text._format_download_uri(12345, prefer_ascii=True)
+        self.assertEqual(extensions.split('/')[-1], ascii_filename)
+
+    def test_extensions_order_utf8_first(self):
+        utf8_filename = '12345-0.txt'
+        all_files = ['12345.txt', '12345-8.txt', '12345-0.txt']
+        self.request_head_response(valid_files=all_files)
+
+        extensions = text._format_download_uri(12345)
+        self.assertEqual(extensions.split('/')[-1], utf8_filename)
+
+        extensions = text._format_download_uri(12345, prefer_ascii=False)
+        self.assertEqual(extensions.split('/')[-1], utf8_filename)
+
+    def test_extensions_order_ascii_first(self):
+        ascii_filename = '12345.txt'
+        all_files = ['12345-8.txt', '12345-0.txt', '12345.txt']
+        self.request_head_response(valid_files=all_files)
+
+        extensions = text._format_download_uri(12345)
+        self.assertNotEqual(extensions.split('/')[-1], ascii_filename)
+
+        extensions = text._format_download_uri(12345, prefer_ascii=True)
+        self.assertEqual(extensions.split('/')[-1], ascii_filename)
+
 
 if __name__ == '__main__':
     unittest.main()