refactor: fix PEP violations

udib/clibella.py

@@ -5,6 +5,7 @@ import sys
 import colorama
 from colorama import Fore, Style
 
+
 class _Prefix:
     """The Prefix class represents text which is prepended to text output.
 
@@ -39,15 +40,17 @@ class _Prefix:
 
         return longest_prefix_length
 
-_prefix_info    = _Prefix("INFO", Fore.WHITE)
+
-_prefix_ok      = _Prefix("OK", Fore.GREEN)
+_prefix_info = _Prefix("INFO", Fore.WHITE)
+_prefix_ok = _Prefix("OK", Fore.GREEN)
 _prefix_success = _Prefix("SUCCESS", Fore.GREEN)
-_prefix_debug   = _Prefix("DEBUG", Fore.BLUE)
+_prefix_debug = _Prefix("DEBUG", Fore.BLUE)
-_prefix_input  = _Prefix("PROMPT", Fore.CYAN)
+_prefix_input = _Prefix("PROMPT", Fore.CYAN)
 _prefix_warning = _Prefix("WARNING", Fore.YELLOW)
-_prefix_error   = _Prefix("ERROR", Fore.RED)
+_prefix_error = _Prefix("ERROR", Fore.RED)
 _prefix_failure = _Prefix("FAILURE", Fore.RED)
 
+
 class Printer:
     """Printer objects print prefixed output to the specified output stream."""
 
@@ -98,7 +101,8 @@ class Printer:
 
         Printer._num_of_active_printers -= 1
 
-    def _print_prefixed_output(self, prefix, *args, color_enabled=True, **kwargs):
+    def _print_prefixed_output(self, prefix, *args, color_enabled=True,
+                               **kwargs):
         """Prints the output with the specified prefix prepended.
 
         This method works the same as the standard library print() function,

udib/gpgverify.py

@@ -18,13 +18,14 @@ def gpg_signature_is_valid(
         path_to_data_file,
         fallback_keyserver_name
 ):
-    """ Validates a PGP signature for a data file. The detached signature is
+    """Validates a PGP signature for a data file.
-        provided as plaintext (UTF8) in the specified file.
 
-        If the discovered signing key is unknown to gpg on this system for the
+    The detached signature must be provided as plaintext (UTF8) in the
-        invoking user, and if 'fallback_keyserver_name' is not None, an attempt
+    specified signature file.
-        is made to import the key from the specified keyserver using its ID
+    If the discovered signing key is unknown to gpg on this system for the
-        after prompting the user for permission to import the key.
+    invoking user, and if 'fallback_keyserver_name' is not None, an attempt is
+    made to import the key from the specified keyserver using its ID after
+    prompting the user for permission to import the key.
 
     Parameters
     ----------
@@ -45,6 +46,7 @@ def gpg_signature_is_valid(
     False : bool
         If the signature is invalid or could not be validated.
     """
+
     path_to_signature_file = Path(path_to_signature_file)
     path_to_data_file = Path(path_to_data_file)
 
@@ -65,15 +67,15 @@ def gpg_signature_is_valid(
             f"Not a valid PGP signature file: '{path_to_signature_file}'."
         )
     else:
-        p.info(f"Signature mentions a key with ID "\
+        p.info(f"Signature mentions a key with ID "
-              f"{verification.key_id} and fingerprint "\
+               f"{verification.key_id} and fingerprint "
-              f"{verification.fingerprint}."
+               f"{verification.fingerprint}."
-        )
+               )
 
     if verification.valid:
-        p.ok(f"GPG signature is valid with trustlevel "\
+        p.ok(f"GPG signature is valid with trustlevel "
-              f"'{verification.trust_level}'."
+             f"'{verification.trust_level}'."
-        )
+             )
         return True
 
     # this case commonly occurrs when the GPG key has not been imported
@@ -84,7 +86,7 @@ def gpg_signature_is_valid(
         key_will_be_imported = None
         while key_will_be_imported is None:
             key_will_be_imported = userinput.prompt_yes_or_no(
-                f"[PROMPT] Do you want to import the GPG key from "\
+                f"[PROMPT] Do you want to import the GPG key from "
                 f"'{fallback_keyserver_name}'?"
             )
 
@@ -121,9 +123,9 @@ def gpg_signature_is_valid(
         )
 
     if verification.valid:
-        p.ok(f"GPG signature is valid with trustlevel "\
+        p.ok(f"GPG signature is valid with trustlevel "
-              f"'{verification.trust_level}'."
+             f"'{verification.trust_level}'."
-        )
+             )
         return True
     else:
         p.error("GPG signature is not valid!!!")

udib/udib.py

@@ -3,6 +3,7 @@
 from pathlib import Path
 import subprocess
 
+
 def extract_iso(path_to_output_dir, path_to_input_file):
     """Extracts the input ISO-file into the specified directory using 'bsdtar'.
 
@@ -42,7 +43,7 @@ def extract_iso(path_to_output_dir, path_to_input_file):
     try:
         subprocess.run(["command", "-v", "bsdtar"], check=True)
     except subprocess.CalledProcessError:
-        raise RuntimeError(f"Program not found in $PATH: 'bsdtar'.")
+        raise RuntimeError("Program not found in $PATH: 'bsdtar'.")
 
     # extract file to destination
     try:

udib/userinput.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-""" This module is responsible for (interactive) user input handling. """
+"""This module provides functions for (interactive) user input handling."""
 
 import re
 
@@ -10,11 +10,11 @@ import clibella
 p = clibella.Printer()
 
 
-def prompt_yes_or_no(question, ask_until_valid = False):
+def prompt_yes_or_no(question, ask_until_valid=False):
-    """ Prompts the user with the specified yes/no question.
+    """Prompts the user for an answer to the specified yes/no question.
 
-        If 'ask_until_valid' is True, keeps repeating the prompt until the user
+    If 'ask_until_valid' is True, keeps repeating the prompt until the user
-        provides recognizable input to answer the question.
+    provides recognizable input to answer the question.
 
     Parameters
     ----------
@@ -35,10 +35,11 @@ def prompt_yes_or_no(question, ask_until_valid = False):
         If 'ask_until_valid' is False and the user has provided an ambiguous
         response to the prompt.
     """
+
     user_input_is_valid = False
 
     regex_yes = re.compile(r"^(y)$|^(Y)$|^(YES)$|^(Yes)$|^(yes)$")
-    regex_no  = re.compile(r"^(n)$|^(N)$|^(NO)$|^(No)$|^(no)$")
+    regex_no = re.compile(r"^(n)$|^(N)$|^(NO)$|^(No)$|^(no)$")
 
     while(not user_input_is_valid):
         user_input = p.input(f"{question} (Yes/No): ")

udib/webdownload.py

@@ -2,9 +2,10 @@
 
 """This module downloads Debian Linux installation images from the web."""
 
-import os, re, subprocess, zipfile
+import os
+import re
+import subprocess
 from pathlib import Path
-from datetime import date
 
 import requests
 from bs4 import BeautifulSoup
@@ -17,9 +18,11 @@ import gpgverify
 p = clibella.Printer()
 
 
-def download_file(path_to_output_file, url_to_file, show_progress = False):
+def download_file(path_to_output_file, url_to_file, show_progress=False):
-    """ Downloads the file at the specified URL via HTTP and saves it as the
+    """Downloads the file at the input URL to the specified path.
-        specified output file. Optionally, displays a nice status bar.
+
+    The file is downloaded via HTTP/HTTPS and saved to the specified path.
+    Optionally, displays a nice status bar.
 
     Parameters
     ----------
@@ -70,18 +73,21 @@ def download_file(path_to_output_file, url_to_file, show_progress = False):
 
         p.ok(f"Received '{output_file_name}'.")
 
+
 def debian_obtain_image(path_to_output_dir):
-    """ Obtains the latest official debian installation image, the SHA512SUMS
+    """Downloads the latest debian installation image and its hashes.
-        file it is listed in, as well as the GPG signature for the SHA512SUMS
-        file.
 
-        File are obtained from the debian.org HTTPS mirrors and stored in the
+    The image file, the SHA512SUMS file it is listed in, as well as the GPG
-        specified directory. The obtained image is the FOSS-only, stable x64
+    signature for the SHA512SUMS file are downloaded from the debian.org HTTPS
-        build.
+    mirrors and written into the specified output directory.
+    The obtained image is for the FOSS-only, stable x64 build.
 
-        First, the GPG signature of the hash is validated. Then, the hash of
+    Once the image file is downloaded, the GPG signature of the hash is
-        the image file is checked. If either check fails, an exception is
+    validated. Then, the hash of the image file is verified. If either check
-        raised.
+    fails, an exception is raised.
+
+    If the verification suceeds, the hash file and GPG signature file are
+    removed again.
 
     Parameters
     ----------
@@ -115,29 +121,30 @@ def debian_obtain_image(path_to_output_dir):
         name="a",
         string=re.compile(r"debian-[0-9.]*-amd64-netinst.iso"))
     if len(image_file_links) != 1:
-        raise RuntimeError("Failed to find an exact match while looking for "\
+        raise RuntimeError("Failed to find an exact match while looking for "
-            "a link to the latest debian image file.")
+                           "a link to the latest debian image file."
+                           )
     image_file_name = image_file_links[0]['href']
     image_file_url = releases_url + image_file_name
 
     # download the SHA512SUMS file
-    download_file(path_to_output_dir / hash_file_name, hash_file_url)
+    download_file(path_to_output_dir/hash_file_name, hash_file_url)
     # download the GPG signature file
-    download_file(path_to_output_dir / signature_file_name, signature_file_url)
+    download_file(path_to_output_dir/signature_file_name, signature_file_url)
 
     # verify GPG signature of hash file
     if not gpgverify.gpg_signature_is_valid(
-            path_to_output_dir / signature_file_name,
+            path_to_output_dir/signature_file_name,
-            path_to_output_dir / hash_file_name,
+            path_to_output_dir/hash_file_name,
             "keyring.debian.org"
     ):
         raise RuntimeError("GPG signature verification failed!")
 
     # download the image file
-    download_file(path_to_output_dir / image_file_name, image_file_url, True)
+    download_file(path_to_output_dir/image_file_name, image_file_url, True)
 
     # remove unwanted lines from hash file
-    hash_file = open(path_to_output_dir / hash_file_name, "r")
+    hash_file = open(path_to_output_dir/hash_file_name, "r")
     hash_file_lines = hash_file.readlines()
     hash_file_lines_to_keep = []
     for line in hash_file_lines:
@@ -146,16 +153,16 @@ def debian_obtain_image(path_to_output_dir):
     hash_file.close()
     if len(hash_file_lines_to_keep) != 1:
         raise RuntimeError("Unexpected error while truncating hash file.")
-    os.remove(path_to_output_dir / hash_file_name)
+    os.remove(path_to_output_dir/hash_file_name)
-    with open(path_to_output_dir / hash_file_name, "w") as hash_file:
+    with open(path_to_output_dir/hash_file_name, "w") as hash_file:
         hash_file.writelines(hash_file_lines_to_keep)
 
     # validate SHA512 checksum
     p.info("Validating file integrity...")
     hash_check_result = subprocess.run(
-        ["sha512sum", "--check", path_to_output_dir / hash_file_name],
+        ["sha512sum", "--check", path_to_output_dir/hash_file_name],
-        capture_output = True,
+        capture_output=True,
-        cwd = path_to_output_dir
+        cwd=path_to_output_dir
     )
 
     stdout_lines = hash_check_result.stdout.decode("utf-8").split('\n')
@@ -177,9 +184,9 @@ def debian_obtain_image(path_to_output_dir):
 
     # clean up obsolete files
     p.info("Cleaning up files...")
-    os.remove(path_to_output_dir / hash_file_name)
+    os.remove(path_to_output_dir/hash_file_name)
-    os.remove(path_to_output_dir / signature_file_name)
+    os.remove(path_to_output_dir/signature_file_name)
 
     p.success("Debian image obtained.")
 
-    return str(path_to_output_dir / image_file_name)
+    return str(path_to_output_dir/image_file_name)