"""Format C code according to QMK's style.
"""
import subprocess
from os import path
from shutil import which

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 = subprocess.Popen([find_clang_format(), file], stdout=subprocess.PIPE, stderr=subprocess.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 + list(map(str, files)), check=True, capture_output=False)
        cli.log.info('Successfully formatted the C code.')
        return True

    except subprocess.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 cformat(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)

        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 cformat -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)