feat(code-style.sh): Format Python files using black

Signed-off-by: Rahix <rahix@rahix.de>

tools/code-style.sh

 #!/bin/bash
 set -e
 
+###########################
 # Check tools
-if ! command -v clang-format >/dev/null 2>&1; then
-    echo "$0: requires clang-format." >&2
-    exit 127
+
+# If any C files are formatted
+if [[ "$*" == *.c* ]]; then
+    if ! command -v clang-format >/dev/null 2>&1; then
+        echo "$0: requires clang-format." >&2
+        exit 127
+    fi
+
+    if ! command -v python3 >/dev/null 2>&1; then
+        echo "$0: requires python3." >&2
+        exit 127
+    fi
 fi
 
-if ! command -v python3 >/dev/null 2>&1; then
-    echo "$0: requires python3." >&2
-    exit 127
+# If any Python files are formatted
+if [[ "$*" == *.py* ]]; then
+    if ! command -v black >/dev/null 2>&1; then
+        echo "$0: requires black (python formatter)." >&2
+        echo "" >&2
+        echo "You can install \`black\` using pip3:" >&2
+        echo "" >&2
+        echo "	pip3 install --user black" >&2
+        echo "" >&2
+        exit 127
+    fi
 fi
 
 if [[ "$#" == 0 ]]; then
@@ -20,12 +38,24 @@ fi
 script_dir="$(dirname "$0")"
 
 for source_file in "$@"; do
+    # Check if file is actually one which we want to check
+    rel_path="$(realpath --relative-to="$script_dir/.." "$source_file")"
+    if [[ ( "$rel_path" == lib/* && "$rel_path" != lib/card10/* ) ||
+          ( "$rel_path" == openocd/* ) ||
+          ( "$rel_path" == ble/* ) ]]; then
+        echo " - Ignoring $source_file"
+        continue
+    fi
+
     if [[ "$source_file" == *.c ]]; then
-        echo "Formatting $source_file ..."
+        echo " - Formatting $source_file ..."
         clang-format -i "$source_file"
         python3 "$script_dir/fix-multi-decl.py" "$source_file"
+    elif [[ "$source_file" == *.py ]]; then
+        echo " - Formatting $source_file ..."
+        black -q "$source_file"
     else
-        echo "Not a C file: $source_file" >&2
+        echo " - Ignoring $source_file" >&2
         continue
     fi
 done