loadout.py: flake8 & mypy pass

* Catch if an empty string (or other not-None Falsey value) is passed in.
* Use pathlib for constructed filename.

loadout.py

@@ -1,48 +1,67 @@
-# Export ship loadout in Companion API json format
+"""Export ship loadout in Companion API json format."""
 
 import json
 import os
-from os.path import join
+import pathlib
 import re
 import time
+from os.path import join
+from typing import Optional
 
-from config import config
 import companion
 import util_ships
+from config import config
+from EDMCLogging import get_main_logger
+
+logger = get_main_logger()
 
 
-def export(data, filename=None):
+def export(data: companion.CAPIData, requested_filename: Optional[str] = None) -> None:
+    """
+    Write Ship Loadout in Companion API JSON format.
 
+    :param data: CAPI data containing ship loadout.
+    :param requested_filename: Name of file to write to.
+    """
     string = json.dumps(
         companion.ship(data), cls=companion.CAPIDataEncoder,
         ensure_ascii=False, indent=2, sort_keys=True, separators=(',', ': ')
     )  # pretty print
 
-    if filename:
+    if requested_filename is not None and requested_filename:
-        with open(filename, 'wt') as h:
+        with open(requested_filename, 'wt') as h:
             h.write(string)
         return
 
+    elif not requested_filename:
+        logger.error(f"{requested_filename=} is not valid")
+        return
+
     # Look for last ship of this type
     ship = util_ships.ship_file_name(data['ship'].get('shipName'), data['ship']['name'])
-    regexp = re.compile(re.escape(ship) + '\.\d\d\d\d\-\d\d\-\d\dT\d\d\.\d\d\.\d\d\.txt')
+    regexp = re.compile(re.escape(ship) + r'\.\d\d\d\d\-\d\d\-\d\dT\d\d\.\d\d\.\d\d\.txt')
     oldfiles = sorted([x for x in os.listdir(config.get_str('outdir')) if regexp.match(x)])
     if oldfiles:
         with open(join(config.get_str('outdir'), oldfiles[-1]), 'rU') as h:
             if h.read() == string:
-                return	# same as last time - don't write
+                return  # same as last time - don't write
 
-    querytime = config.get_int('querytime', default=int(time.time()))
+    query_time = config.get_int('querytime', default=int(time.time()))
 
     # Write
     #
     #  When this is refactored into multi-line CHECK IT WORKS, avoiding the
     #  brainfart we had with dangling commas in commodity.py:export() !!!
     #
-    filename = join(config.get_str('outdir'), '%s.%s.txt' % (ship, time.strftime('%Y-%m-%dT%H.%M.%S', time.localtime(querytime))))
+    output_path = pathlib.Path(config.get_str('outdir'))
+    output_filename = pathlib.Path(
+        ship + '.' + time.strftime('%Y-%m-%dT%H.%M.%S', time.localtime(query_time)) + '.txt'
+    )
+    # Can't re-use `filename`, different type
+    file_name = output_path / output_filename
     #
     #  When this is refactored into multi-line CHECK IT WORKS, avoiding the
     #  brainfart we had with dangling commas in commodity.py:export() !!!
     #
-    with open(filename, 'wt') as h:
+    with open(file_name, 'wt') as h:
         h.write(string)