nixpkgs/maintainers/scripts/update-python-libraries

#! /usr/bin/env nix-shell
#! nix-shell -i python3 -p 'python3.withPackages(ps: with ps; [ requests toolz ])'

"""
Update a Python package expression by passing in the `.nix` file, or the directory containing it.
You can pass in multiple files or paths.

You'll likely want to use
``
  $ ./update-python-libraries ../../pkgs/development/python-modules/*
``
to update all libraries in that folder.
"""

import argparse
import logging
import os
import re
import requests
import toolz

INDEX = "https://pypi.io/pypi"
"""url of PyPI"""

EXTENSIONS = ['tar.gz', 'tar.bz2', 'tar', 'zip', '.whl']
"""Permitted file extensions. These are evaluated from left to right and the first occurance is returned."""

import logging
logging.basicConfig(level=logging.INFO)


def _get_values(attribute, text):
    """Match attribute in text and return all matches.

    :returns: List of matches.
    """
    regex = '{}\s+=\s+"(.*)";'.format(attribute)
    regex = re.compile(regex)
    values = regex.findall(text)
    return values

def _get_unique_value(attribute, text):
    """Match attribute in text and return unique match.

    :returns: Single match.
    """
    values = _get_values(attribute, text)
    n = len(values)
    if n > 1:
        raise ValueError("found too many values for {}".format(attribute))
    elif n == 1:
        return values[0]
    else:
        raise ValueError("no value found for {}".format(attribute))

def _get_line_and_value(attribute, text):
    """Match attribute in text. Return the line and the value of the attribute."""
    regex = '({}\s+=\s+"(.*)";)'.format(attribute)
    regex = re.compile(regex)
    value = regex.findall(text)
    n = len(value)
    if n > 1:
        raise ValueError("found too many values for {}".format(attribute))
    elif n == 1:
        return value[0]
    else:
        raise ValueError("no value found for {}".format(attribute))


def _replace_value(attribute, value, text):
    """Search and replace value of attribute in text."""
    old_line, old_value = _get_line_and_value(attribute, text)
    new_line = old_line.replace(old_value, value)
    new_text = text.replace(old_line, new_line)
    return new_text

def _fetch_page(url):
    r = requests.get(url)
    if r.status_code == requests.codes.ok:
        return r.json()
    else:
        raise ValueError("request for {} failed".format(url))

def _get_latest_version_pypi(package, extension):
    """Get latest version and hash from PyPI."""
    url = "{}/{}/json".format(INDEX, package)
    json = _fetch_page(url)

    version = json['info']['version']
    for release in json['releases'][version]:
        if release['filename'].endswith(extension):
            # TODO: In case of wheel we need to do further checks!
            sha256 = release['digests']['sha256']
            break
    else:
        sha256 = None
    return version, sha256


def _get_latest_version_github(package, extension):
    raise ValueError("updating from GitHub is not yet supported.")


FETCHERS = {
    'fetchFromGitHub'   :   _get_latest_version_github,
    'fetchPypi'         :   _get_latest_version_pypi,
    'fetchurl'          :   _get_latest_version_pypi,
}


DEFAULT_SETUPTOOLS_EXTENSION = 'tar.gz'


FORMATS = {
    'setuptools'        :   DEFAULT_SETUPTOOLS_EXTENSION,
    'wheel'             :   'whl'
}

def _determine_fetcher(text):
    # Count occurences of fetchers.
    nfetchers = sum(text.count('src = {}'.format(fetcher)) for fetcher in FETCHERS.keys())
    if nfetchers == 0:
        raise ValueError("no fetcher.")
    elif nfetchers > 1:
        raise ValueError("multiple fetchers.")
    else:
        # Then we check which fetcher to use.
        for fetcher in FETCHERS.keys():
            if 'src = {}'.format(fetcher) in text:
                return fetcher


def _determine_extension(text, fetcher):
    """Determine what extension is used in the expression.

    If we use:
    - fetchPypi, we check if format is specified.
    - fetchurl, we determine the extension from the url.
    - fetchFromGitHub we simply use `.tar.gz`.
    """
    if fetcher == 'fetchPypi':
        try:
            format = _get_unique_value('format', text)
        except ValueError as e:
            format = None   # format was not given

        try:
            extension = _get_unique_value('extension', text)
        except ValueError as e:
            extension = None    # extension was not given

        if extension is None:
            if format is None:
                format = 'setuptools'
            extension = FORMATS[format]

    elif fetcher == 'fetchurl':
        url = _get_unique_value('url', text)
        extension = os.path.splitext(url)[1]
        if 'pypi' not in url:
            raise ValueError('url does not point to PyPI.')

    elif fetcher == 'fetchFromGitHub':
        raise ValueError('updating from GitHub is not yet implemented.')

    return extension


def _update_package(path):



    # Read the expression
    with open(path, 'r') as f:
        text = f.read()

    # Determine pname.
    pname = _get_unique_value('pname', text)

    # Determine version.
    version = _get_unique_value('version', text)

    # First we check how many fetchers are mentioned.
    fetcher = _determine_fetcher(text)

    extension = _determine_extension(text, fetcher)

    new_version, new_sha256 = _get_latest_version_pypi(pname, extension)

    if new_version == version:
        logging.info("Path {}: no update available for {}.".format(path, pname))
        return False
    if not new_sha256:
        raise ValueError("no file available for {}.".format(pname))

    text = _replace_value('version', new_version, text)
    text = _replace_value('sha256', new_sha256, text)

    with open(path, 'w') as f:
        f.write(text)

        logging.info("Path {}: updated {} from {} to {}".format(path, pname, version, new_version))

    return True


def _update(path):

    # We need to read and modify a Nix expression.
    if os.path.isdir(path):
        path = os.path.join(path, 'default.nix')

    # If a default.nix does not exist, we quit.
    if not os.path.isfile(path):
        logging.info("Path {}: does not exist.".format(path))
        return False

    # If file is not a Nix expression, we quit.
    if not path.endswith(".nix"):
        logging.info("Path {}: does not end with `.nix`.".format(path))
        return False

    try:
        return _update_package(path)
    except ValueError as e:
        logging.warning("Path {}: {}".format(path, e))
        return False

def main():

    parser = argparse.ArgumentParser()
    parser.add_argument('package', type=str, nargs='+')

    args = parser.parse_args()

    packages = map(os.path.abspath, args.package)

    count = list(map(_update, packages))

    logging.info("{} package(s) updated".format(sum(count)))

if __name__ == '__main__':
    main()