"""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', 'platforms/chibios/boards')


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)