Move music transfer main code into main() function

This is both good practice, and also useful for some soon-to-be-added
test cases for the script.

src/.bin/music-transfer.py

@@ -32,21 +32,22 @@ KNOWN_EXTENSIONS: Set[str] = set([
 def munge_path(path: str) -> str:
 	return re.sub(r'[\:*?"|<>]+', '-', path)
 
-if len(sys.argv) != 3:
+def main():
+	if len(sys.argv) != 3:
 		print(f'Usage: {os.path.basename(__file__)} PATHS-FILE DESTINATION-DIR', file=sys.stderr)
 		sys.exit(1)
 
-paths_file: str = sys.argv[1]
+	paths_file: str = sys.argv[1]
-destination_dir: str = sys.argv[2]
+	destination_dir: str = sys.argv[2]
 
-if not os.path.exists(paths_file):
+	if not os.path.exists(paths_file):
 		print(f'PATHS-FILE \'{paths_file}\' does not exist or is not readable', file=sys.stderr)
 		sys.exit(2)
 
 
-print('[DEBUG] Gathering destination files list')
+	print('[DEBUG] Gathering destination files list')
-destination_files: Set[Path] = set()
+	destination_files: Set[Path] = set()
-if os.path.isdir(destination_dir):
+	if os.path.isdir(destination_dir):
 		for dirpath, _, files in os.walk(destination_dir):
 			for file in files:
 				path = Path(os.path.join(dirpath, file)).absolute()
@@ -55,11 +56,11 @@ if os.path.isdir(destination_dir):
 						print(f'Ignoring duplicate input entry: {file}')
 					else:
 						destination_files.add(path)
-print(f'[DEBUG] Gathered {len(destination_files)} destination files')
+	print(f'[DEBUG] Gathered {len(destination_files)} destination files')
 
-print('[DEBUG] Gathering source files list')
+	print('[DEBUG] Gathering source files list')
-source_files: Set[Path] = set()
+	source_files: Set[Path] = set()
-for line in open(paths_file, 'r'):
+	for line in open(paths_file, 'r'):
 		trimmed_line = line.strip()
 		if not trimmed_line:
 			continue
@@ -83,38 +84,38 @@ for line in open(paths_file, 'r'):
 			print(f'[ERROR] Could not find source path: {path}')
 			sys.exit(3)
 
-if len(source_files) == 0:
+	if len(source_files) == 0:
 		print('No source files to transfer')
 		sys.exit()
-else:
+	else:
 		print(f'[DEBUG] Gathered {len(source_files)} source files')
 
-print('[DEBUG] Finding longest common prefix of source files')
+	print('[DEBUG] Finding longest common prefix of source files')
-longest_prefix = next(iter(source_files)).parent
+	longest_prefix = next(iter(source_files)).parent
-for file in source_files:
+	for file in source_files:
 		if longest_prefix.as_posix() == '/':
 			break
 
 		while not file.as_posix().startswith(longest_prefix.as_posix()):
 			longest_prefix = longest_prefix.parent
 
-print('[DEBUG] Filtering files already present in destination')
+	print('[DEBUG] Filtering files already present in destination')
-# NOTE: this assumes all filenames are unique, which should already be the case in my music library
+	# NOTE: this assumes all filenames are unique, which should already be the case in my music library
-#       verify via `find . -type f -not -name '*.jpg' -not -name '*.png' -not -name '*.txt' -exec basename {} \; | sort | uniq -d`
+	#       verify via `find . -type f -not -name '*.jpg' -not -name '*.png' -not -name '*.txt' -exec basename {} \; | sort | uniq -d`
-# TODO: add a hash check so that we can overwrite songs on the target if source
+	# TODO: add a hash check so that we can overwrite songs on the target if source
-#       has a version which is different (new metadata, or better version)
+	#       has a version which is different (new metadata, or better version)
-for source_path in list(source_files)[:]:
+	for source_path in list(source_files)[:]:
 		found_destination_path: Union[Path, None] = next((destination_file for destination_file in destination_files if destination_file.stem == munge_path(source_path.stem)), None)
 		if found_destination_path:
 			source_files.remove(source_path)
 			destination_files.remove(found_destination_path)
 
-if len(source_files) == 0:
+	if len(source_files) == 0:
 		print('All source files already exist in target')
 		sys.exit()
 
-# TODO: improve prompt (print 10+ file paths or exit to `PAGER` to view before prompt so user has more info before confirming)
+	# TODO: improve prompt (print 10+ file paths or exit to `PAGER` to view before prompt so user has more info before confirming)
-if len(destination_files) > 0:
+	if len(destination_files) > 0:
 		delete_selection_made = False
 		while not delete_selection_made:
 			print(f'Files in destination not found in source files list:\n{destination_files}')
@@ -126,11 +127,11 @@ if len(destination_files) > 0:
 			elif delete_input[0] == 'n' or delete_input[0] == 'N':
 				delete_selection_made = True
 
-# TODO: list both number of files in songs list & number of files to be transferred
+	# TODO: list both number of files in songs list & number of files to be transferred
-print(f'Copying {len(source_files)} songs to {destination_dir}')
+	print(f'Copying {len(source_files)} songs to {destination_dir}')
-print(f'[TRACE] Copying the following files to destination:\n{source_files}')
+	print(f'[TRACE] Copying the following files to destination:\n{source_files}')
 
-for source_file in source_files:
+	for source_file in source_files:
 		source_copy_path = source_file.with_suffix('').as_posix().replace(longest_prefix.as_posix(), '', 1)
 		destination_filename = munge_path(source_copy_path)
 		destination_file_path = f'{destination_dir}/{destination_filename}.mp3'
@@ -154,5 +155,8 @@ for source_file in source_files:
 			])
 
 
-# TODO: improve this output (number of deleted files, number of new files, correct plural of 'files')
+	# TODO: improve this output (number of deleted files, number of new files, correct plural of 'files')
-print(f'Finished copying {len(source_files)} new files to {destination_dir}')
+	print(f'Finished copying {len(source_files)} new files to {destination_dir}')
+
+if __name__ == '__main__':
+	main()