#!/usr/bin/env python
"""A wrapper script around clang-format, suitable for linting multiple files
and to use for continuous integration.
This is an alternative API for the clang-format command line.
It runs over multiple files and directories in parallel.
A diff output is produced and a sensible exit code is returned.

Copied from:
https://github.com/DoozyX/clang-format-lint-action/blob/master/run-clang-format.py
"""

from __future__ import print_function, unicode_literals

import argparse
import codecs
import difflib
import errno
import fnmatch
import io
import multiprocessing
import os
import signal
import subprocess
import sys
import traceback
from distutils.util import strtobool

from functools import partial

try:
    from subprocess import DEVNULL  # py3k
except ImportError:
    DEVNULL = open(os.devnull, "wb")


DEFAULT_EXTENSIONS = 'c,h,C,H,cpp,hpp,cc,hh,c++,h++,cxx,hxx'
DEFAULT_CLANG_FORMAT_IGNORE = '.clang-format-ignore'


class ExitStatus:
    SUCCESS = 0
    DIFF = 1
    TROUBLE = 2


def excludes_from_file(ignore_file):
    excludes = []
    try:
        with io.open(ignore_file, 'r', encoding='utf-8') as f:
            for line in f:
                if line.startswith('#'):
                    # ignore comments
                    continue
                pattern = line.rstrip()
                if not pattern:
                    # allow empty lines
                    continue
                excludes.append(pattern)
    except EnvironmentError as e:
        if e.errno != errno.ENOENT:
            raise
    return excludes


def list_files(files, recursive=False, extensions=None, exclude=None):
    if extensions is None:
        extensions = []
    if exclude is None:
        exclude = []

    out = []
    for file in files:
        if recursive and os.path.isdir(file):
            for dirpath, dnames, fnames in os.walk(file):
                fpaths = [os.path.join(dirpath, fname) for fname in fnames]
                for pattern in exclude:
                    # os.walk() supports trimming down the dnames list
                    # by modifying it in-place,
                    # to avoid unnecessary directory listings.
                    dnames[:] = [
                        x for x in dnames
                        if
                        not fnmatch.fnmatch(os.path.join(dirpath, x), pattern)
                    ]
                    fpaths = [
                        x for x in fpaths if not fnmatch.fnmatch(x, pattern)
                    ]
                for f in fpaths:
                    ext = os.path.splitext(f)[1][1:]
                    if ext in extensions:
                        out.append(f)
        else:
            out.append(file)
    return out


def make_diff(file, original, reformatted):
    return list(
        difflib.unified_diff(
            original,
            reformatted,
            fromfile='{}\t(original)'.format(file),
            tofile='{}\t(reformatted)'.format(file),
            n=3))


class DiffError(Exception):
    def __init__(self, message, errs=None):
        super(DiffError, self).__init__(message)
        self.errs = errs or []


class UnexpectedError(Exception):
    def __init__(self, message, exc=None):
        super(UnexpectedError, self).__init__(message)
        self.formatted_traceback = traceback.format_exc()
        self.exc = exc


def run_clang_format_diff_wrapper(args, file):
    try:
        ret = run_clang_format_diff(args, file)
        return ret
    except DiffError:
        raise
    except Exception as e:
        raise UnexpectedError('{}: {}: {}'.format(file, e.__class__.__name__,
                                                  e), e)


def run_clang_format_diff(args, file):
    try:
        with io.open(file, 'r', encoding='utf-8') as f:
            original = f.readlines()
    except IOError as exc:
        raise DiffError(str(exc))
    invocation = [args.clang_format_executable, file]
    if args.style:
        invocation.append('-style=' + args.style)
    if args.inplace:
        invocation.append('-i')

    # Use of utf-8 to decode the process output.
    #
    # Hopefully, this is the correct thing to do.
    #
    # It's done due to the following assumptions (which may be incorrect):
    # - clang-format will returns the bytes read from the files as-is,
    #   without conversion, and it is already assumed that the files use utf-8.
    # - if the diagnostics were internationalized, they would use utf-8:
    #   > Adding Translations to Clang
    #   >
    #   > Not possible yet!
    #   > Diagnostic strings should be written in UTF-8,
    #   > the client can translate to the relevant code page if needed.
    #   > Each translation completely replaces the format string
    #   > for the diagnostic.
    #   > -- http://clang.llvm.org/docs/InternalsManual.html#internals-diag-translation
    #
    # It's not pretty, due to Python 2 & 3 compatibility.
    encoding_py3 = {}
    if sys.version_info[0] >= 3:
        encoding_py3['encoding'] = 'utf-8'

    try:
        proc = subprocess.Popen(
            invocation,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            universal_newlines=True,
            **encoding_py3)
    except OSError as exc:
        raise DiffError(
            "Command '{}' failed to start: {}".format(
                subprocess.list2cmdline(invocation), exc
            )
        )
    proc_stdout = proc.stdout
    proc_stderr = proc.stderr
    if sys.version_info[0] < 3:
        # make the pipes compatible with Python 3,
        # reading lines should output unicode
        encoding = 'utf-8'
        proc_stdout = codecs.getreader(encoding)(proc_stdout)
        proc_stderr = codecs.getreader(encoding)(proc_stderr)
    # hopefully the stderr pipe won't get full and block the process
    outs = list(proc_stdout.readlines())
    errs = list(proc_stderr.readlines())
    proc.wait()
    if proc.returncode:
        raise DiffError(
            "Command '{}' returned non-zero exit status {}".format(
                subprocess.list2cmdline(invocation), proc.returncode
            ),
            errs,
        )
    return make_diff(file, original, outs), errs


def bold_red(s):
    return '\x1b[1m\x1b[31m' + s + '\x1b[0m'


def colorize(diff_lines):
    def bold(s):
        return '\x1b[1m' + s + '\x1b[0m'

    def cyan(s):
        return '\x1b[36m' + s + '\x1b[0m'

    def green(s):
        return '\x1b[32m' + s + '\x1b[0m'

    def red(s):
        return '\x1b[31m' + s + '\x1b[0m'

    for line in diff_lines:
        if line[:4] in ['--- ', '+++ ']:
            yield bold(line)
        elif line.startswith('@@ '):
            yield cyan(line)
        elif line.startswith('+'):
            yield green(line)
        elif line.startswith('-'):
            yield red(line)
        else:
            yield line


def print_diff(diff_lines, use_color):
    if use_color:
        diff_lines = colorize(diff_lines)
    if sys.version_info[0] < 3:
        sys.stdout.writelines((l.encode('utf-8') for l in diff_lines))
    else:
        sys.stdout.writelines(diff_lines)


def print_trouble(prog, message, use_colors):
    error_text = 'error:'
    if use_colors:
        error_text = bold_red(error_text)
    print("{}: {} {}".format(prog, error_text, message), file=sys.stderr)


def split_list_arg(arg):
    """
    If arg is a list containing a single argument it is split into multiple elements.
    Otherwise it is returned unchanged
    Workaround for GHA not allowing list arguments
    """
    return arg[0].split() if len(arg) == 1 else arg


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        '--clang-format-executable',
        metavar='EXECUTABLE',
        help='path to the clang-format executable',
        default='clang-format')
    parser.add_argument(
        '--extensions',
        help='comma separated list of file extensions (default: {})'.format(
            DEFAULT_EXTENSIONS),
        default=DEFAULT_EXTENSIONS)
    parser.add_argument(
        '-r',
        '--recursive',
        action='store_true',
        help='run recursively over directories')
    parser.add_argument('files', metavar='file', nargs='+')
    parser.add_argument(
        '-q',
        '--quiet',
        action='store_true',
        help="disable output, useful for the exit code")
    parser.add_argument(
        '-j',
        metavar='N',
        type=int,
        default=0,
        help='run N clang-format jobs in parallel'
        ' (default number of cpus + 1)')
    parser.add_argument(
        '--color',
        default='auto',
        choices=['auto', 'always', 'never'],
        help='show colored diff (default: auto)')
    parser.add_argument(
        '-e',
        '--exclude',
        metavar='PATTERN',
        action='append',
        default=[],
        help='exclude paths matching the given glob-like pattern(s)'
        ' from recursive search')
    parser.add_argument(
        '--style',
        help='Formatting style to use (default: file)',
        default='file')
    parser.add_argument(
        '-i',
        '--inplace',
        type=lambda x: bool(strtobool(x)),
        default=False,
        help='Just fix files (`clang-format -i`) instead of returning a diff')

    args = parser.parse_args()

    # use default signal handling, like diff return SIGINT value on ^C
    # https://bugs.python.org/issue14229#msg156446
    signal.signal(signal.SIGINT, signal.SIG_DFL)
    try:
        signal.SIGPIPE
    except AttributeError:
        # compatibility, SIGPIPE does not exist on Windows
        pass
    else:
        signal.signal(signal.SIGPIPE, signal.SIG_DFL)

    colored_stdout = False
    colored_stderr = False
    if args.color == 'always':
        colored_stdout = True
        colored_stderr = True
    elif args.color == 'auto':
        colored_stdout = sys.stdout.isatty()
        colored_stderr = sys.stderr.isatty()

    version_invocation = [args.clang_format_executable, str("--version")]
    try:
        subprocess.check_call(version_invocation, stdout=DEVNULL)
    except subprocess.CalledProcessError as e:
        print_trouble(parser.prog, str(e), use_colors=colored_stderr)
        return ExitStatus.TROUBLE
    except OSError as e:
        print_trouble(
            parser.prog,
            "Command '{}' failed to start: {}".format(
                subprocess.list2cmdline(version_invocation), e
            ),
            use_colors=colored_stderr,
        )
        return ExitStatus.TROUBLE

    retcode = ExitStatus.SUCCESS

    excludes = excludes_from_file(DEFAULT_CLANG_FORMAT_IGNORE)
    excludes.extend(split_list_arg(args.exclude))

    files = list_files(
        split_list_arg(args.files),
        recursive=args.recursive,
        exclude=excludes,
        extensions=args.extensions.split(','))

    if not files:
        print_trouble(parser.prog, 'No files found', use_colors=colored_stderr)
        return ExitStatus.TROUBLE

    if not args.quiet:
      print('Processing %s files: %s' % (len(files), ', '.join(files)))

    njobs = args.j
    if njobs == 0:
        njobs = multiprocessing.cpu_count() + 1
    njobs = min(len(files), njobs)

    if njobs == 1:
        # execute directly instead of in a pool,
        # less overhead, simpler stacktraces
        it = (run_clang_format_diff_wrapper(args, file) for file in files)
        pool = None
    else:
        pool = multiprocessing.Pool(njobs)
        it = pool.imap_unordered(
            partial(run_clang_format_diff_wrapper, args), files)
    while True:
        try:
            outs, errs = next(it)
        except StopIteration:
            break
        except DiffError as e:
            print_trouble(parser.prog, str(e), use_colors=colored_stderr)
            retcode = ExitStatus.TROUBLE
            sys.stderr.writelines(e.errs)
        except UnexpectedError as e:
            print_trouble(parser.prog, str(e), use_colors=colored_stderr)
            sys.stderr.write(e.formatted_traceback)
            retcode = ExitStatus.TROUBLE
            # stop at the first unexpected error,
            # something could be very wrong,
            # don't process all files unnecessarily
            if pool:
                pool.terminate()
            break
        else:
            sys.stderr.writelines(errs)
            if outs == []:
                continue
            if not args.inplace:
                if not args.quiet:
                    print_diff(outs, use_color=colored_stdout)
                if retcode == ExitStatus.SUCCESS:
                    retcode = ExitStatus.DIFF

    return retcode


if __name__ == '__main__':
    sys.exit(main())