1 files changed, 137 insertions, 0 deletions
diff --git a/lib/python/qmk/cli/format/c.py b/lib/python/qmk/cli/format/c.py
new file mode 100644
index 0000000000..b7263e19f3
--- /dev/null
+++ b/lib/python/qmk/cli/format/c.py
@@ -0,0 +1,137 @@
+"""Format C code according to QMK's style.
+"""
+from os import path
+from shutil import which
+from subprocess import CalledProcessError, DEVNULL, Popen, PIPE
+
+from argcomplete.completers import FilesCompleter
+from milc import cli
+
+from qmk.path import normpath
+from qmk.c_parse import c_source_files
+
+c_file_suffixes = ('c', 'h', 'cpp')
+core_dirs = ('drivers', 'quantum', 'tests', 'tmk_core', 'platforms')
+ignored = ('tmk_core/protocol/usb_hid', 'quantum/template', 'platforms/chibios')
+
+
+def find_clang_format():
+    """Returns the path to clang-format.
+    """
+    for clang_version in range(20, 6, -1):
+        binary = f'clang-format-{clang_version}'
+
+        if which(binary):
+            return binary
+
+    return 'clang-format'
+
+
+def find_diffs(files):
+    """Run clang-format and diff it against a file.
+    """
+    found_diffs = False
+
+    for file in files:
+        cli.log.debug('Checking for changes in %s', file)
+        clang_format = Popen([find_clang_format(), file], stdout=PIPE, stderr=PIPE, universal_newlines=True)
+        diff = cli.run(['diff', '-u', f'--label=a/{file}', f'--label=b/{file}', str(file), '-'], stdin=clang_format.stdout, capture_output=True)
+
+        if diff.returncode != 0:
+            print(diff.stdout)
+            found_diffs = True
+
+    return found_diffs
+
+
+def cformat_run(files):
+    """Spawn clang-format subprocess with proper arguments
+    """
+    # Determine which version of clang-format to use
+    clang_format = [find_clang_format(), '-i']
+
+    try:
+        cli.run([*clang_format, *map(str, files)], check=True, capture_output=False, stdin=DEVNULL)
+        cli.log.info('Successfully formatted the C code.')
+        return True
+
+    except CalledProcessError as e:
+        cli.log.error('Error formatting C code!')
+        cli.log.debug('%s exited with returncode %s', e.cmd, e.returncode)
+        cli.log.debug('STDOUT:')
+        cli.log.debug(e.stdout)
+        cli.log.debug('STDERR:')
+        cli.log.debug(e.stderr)
+        return False
+
+
+def filter_files(files, core_only=False):
+    """Yield only files to be formatted and skip the rest
+    """
+    if core_only:
+        # Filter non-core files
+        for index, file in enumerate(files):
+            # The following statement checks each file to see if the file path is
+            # - in the core directories
+            # - not in the ignored directories
+            if not any(i in str(file) for i in core_dirs) or any(i in str(file) for i in ignored):
+                files[index] = None
+                cli.log.debug("Skipping non-core file %s, as '--core-only' is used.", file)
+
+    for file in files:
+        if file and file.name.split('.')[-1] in c_file_suffixes:
+            yield file
+        else:
+            cli.log.debug('Skipping file %s', file)
+
+
+@cli.argument('-n', '--dry-run', arg_only=True, action='store_true', help="Flag only, don't automatically format.")
+@cli.argument('-b', '--base-branch', default='origin/master', help='Branch to compare to diffs to.')
+@cli.argument('-a', '--all-files', arg_only=True, action='store_true', help='Format all core files.')
+@cli.argument('--core-only', arg_only=True, action='store_true', help='Format core files only.')
+@cli.argument('files', nargs='*', arg_only=True, type=normpath, completer=FilesCompleter('.c'), help='Filename(s) to format.')
+@cli.subcommand("Format C code according to QMK's style.", hidden=False if cli.config.user.developer else True)
+def format_c(cli):
+    """Format C code according to QMK's style.
+    """
+    # Find the list of files to format
+    if cli.args.files:
+        files = list(filter_files(cli.args.files, cli.args.core_only))
+
+        if not files:
+            cli.log.error('No C files in filelist: %s', ', '.join(map(str, cli.args.files)))
+            exit(0)
+
+        if cli.args.all_files:
+            cli.log.warning('Filenames passed with -a, only formatting: %s', ','.join(map(str, files)))
+
+    elif cli.args.all_files:
+        all_files = c_source_files(core_dirs)
+        files = list(filter_files(all_files, True))
+
+    else:
+        git_diff_cmd = ['git', 'diff', '--name-only', cli.args.base_branch, *core_dirs]
+        git_diff = cli.run(git_diff_cmd, stdin=DEVNULL)
+
+        if git_diff.returncode != 0:
+            cli.log.error("Error running %s", git_diff_cmd)
+            print(git_diff.stderr)
+            return git_diff.returncode
+
+        files = []
+
+        for file in git_diff.stdout.strip().split('\n'):
+            if not any([file.startswith(ignore) for ignore in ignored]):
+                if path.exists(file) and file.split('.')[-1] in c_file_suffixes:
+                    files.append(file)
+
+    # Sanity check
+    if not files:
+        cli.log.error('No changed files detected. Use "qmk format-c -a" to format all core files')
+        return False
+
+    # Run clang-format on the files we've found
+    if cli.args.dry_run:
+        return not find_diffs(files)
+    else:
+        return cformat_run(files)