pylinter

#!/usr/bin/env python

"""
Lint python files before commit with flake8 lint tool.

INSTALL:
1. sudo pip install flake8
2. to setup up pre-commit hook run "./nbslint --setup"

To run on the entire repo run
$ ./nbslint --all
"""
import sys
import subprocess
import argparse
import os
try:
    import flake8
except Exception:
    print('you need to install flake8. Run "pip install flake8" and try again.')
    raise

LINTER = 'flake8'

# available settings list
AVAILABLE_SETTINGS = (
    'exclude', 'filename', 'select', 'ignore', 'max-line-length', 'count',
    'quiet', 'show-pep8', 'show-source', 'statistics', 'verbose'
)
SETTINGS_WITH_PARAMS = (
    'exclude', 'filename', 'select', 'ignore', 'max-line-length', 'format'
)

FILES_TO_IGNORE = [
    '.tox/',
    'build/',
    'docs/source/conf.py'
]

CONFIG = {
    'max-line-length': 100,
    'exclude': ','.join(FILES_TO_IGNORE),
    'ignore': 'F401,E402,W503,E711'
}


def parse_settings():
    """
    Get lint settings
    """
    settings = list()

    for key, value in CONFIG.items():
        if key in SETTINGS_WITH_PARAMS:
            settings.append("--%s=%s" % (key, value))
        else:
            settings.append("--%s" % key)

    return settings


def system(*args, **kwargs):
    """
    Run system command.
    """
    kwargs.setdefault('stdout', subprocess.PIPE)
    proc = subprocess.Popen(args, **kwargs)
    out, err = proc.communicate()
    return out


def get_changed_files():
    """
    Get python files from 'files to commit' git cache list.
    """
    files = []
    filelist = system('git', 'diff', '--cached', '--name-status').strip()
    for line in filelist.split('\n'):
        try:
            action, filename = line.strip().split()
            if filename.endswith('.py') and action != 'D':
                files.append(filename)
        except Exception:
            pass
    return files


def lint(files, settings):
    """
    Run linter.
    """
    args = settings[:]
    args.insert(0, LINTER)
    args.extend(files)
    out = system(*args)
    return filter(None, out.decode('utf8').strip().split('\n'))


def setup():
    src = '../../nbslint'
    dst = '.git/hooks/pre-commit'
    if os.path.exists(dst):
        print('%s already exists' % dst)
        return
    print("creating sym link from %s to %s" % (src, dst))
    os.symlink(src, dst)
    return


def main(args):
    """
    Do work
    """
    if args.setup:
        setup()
        return
    settings = parse_settings()

    errors = list()

    if args.all:
        files = ['.']
    else:
        files = get_changed_files()

    if len(files) == 0:
        print("No files are staged for commit. Run with the --all flag to run on all files")
        return

    for err in lint(files, settings):
        divider = err.find(' ', err.find(' ') + 1)
        pep8_error = err[0:divider]
        if not any(error[0:divider] == pep8_error for error in errors):
            errors.append(err)

    if not errors:
        print("Python lint: OK")
        return

    print("Python lint: FAIL")
    print
    print("\n".join(sorted(errors)))
    print
    print("Aborting commit due to python lint errors.")
    sys.exit(1)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description="Process Config Location")
    parser.add_argument('--all', action='store_true')
    parser.add_argument('--setup', action='store_true')
    args = parser.parse_args()
    main(args)