#!/usr/bin/env python3
"""

Utility for building Buildroot packages for existing PyPI packages

Any package built by scanpypi should be manually checked for
errors.
"""
from __future__ import print_function
from __future__ import absolute_import
import argparse
import json
import sys
import os
import shutil
import tarfile
import zipfile
import errno
import hashlib
import re
import textwrap
import tempfile
import imp
from functools import wraps
import six.moves.urllib.request
import six.moves.urllib.error
import six.moves.urllib.parse
from six.moves import map
from six.moves import zip
from six.moves import input
if six.PY2:
    import StringIO
else:
    import io

BUF_SIZE = 65536

try:
    import spdx_lookup as liclookup
except ImportError:
    # spdx_lookup is not installed
    print('spdx_lookup module is not installed. This can lead to an '
          'inaccurate licence detection. Please install it via\n'
          'pip install spdx_lookup')
    liclookup = None


def setup_decorator(func, method):
    """
    Decorator for distutils.core.setup and setuptools.setup.
    Puts the arguments with which setup is called as a dict
    Add key 'method' which should be either 'setuptools' or 'distutils'.

    Keyword arguments:
    func -- either setuptools.setup or distutils.core.setup
    method -- either 'setuptools' or 'distutils'
    """

    @wraps(func)
    def closure(*args, **kwargs):
        # Any python packages calls its setup function to be installed.
        # Argument 'name' of this setup function is the package's name
        BuildrootPackage.setup_args[kwargs['name']] = kwargs
        BuildrootPackage.setup_args[kwargs['name']]['method'] = method
    return closure

# monkey patch
import setuptools  # noqa E402
setuptools.setup = setup_decorator(setuptools.setup, 'setuptools')
import distutils   # noqa E402
distutils.core.setup = setup_decorator(setuptools.setup, 'distutils')


def find_file_upper_case(filenames, path='./'):
    """
    List generator:
    Recursively find files that matches one of the specified filenames.
    Returns a relative path starting with path argument.

    Keyword arguments:
    filenames -- List of filenames to be found
    path -- Path to the directory to search
    """
    for root, dirs, files in os.walk(path):
        for file in files:
            if file.upper() in filenames:
                yield (os.path.join(root, file))


def pkg_buildroot_name(pkg_name):
    """
    Returns the Buildroot package name for the PyPI package pkg_name.
    Remove all non alphanumeric characters except -
    Also lowers the name and adds 'python-' suffix

    Keyword arguments:
    pkg_name -- String to rename
    """
    name = re.sub(r'[^\w-]', '', pkg_name.lower())
    name = name.replace('_', '-')
    prefix = 'python-'
    pattern = re.compile(r'^(?!' + prefix + ')(.+?)$')
    name = pattern.sub(r'python-\1', name)
    return name


class DownloadFailed(Exception):
    pass


class BuildrootPackage():
    """This class's methods are not meant to be used individually please
    use them in the correct order:

    __init__

    download_package

    extract_package

    load_module

    get_requirements

    create_package_mk

    create_hash_file

    create_config_in

    """
    setup_args = {}

    def __init__(self, real_name, pkg_folder):
        self.real_name = real_name
        self.buildroot_name = pkg_buildroot_name(self.real_name)
        self.pkg_dir = os.path.join(pkg_folder, self.buildroot_name)
        self.mk_name = self.buildroot_name.upper().replace('-', '_')
        self.as_string = None
        self.md5_sum = None
        self.metadata = None
        self.metadata_name = None
        self.metadata_url = None
        self.pkg_req = None
        self.setup_metadata = None
        self.tmp_extract = None
        self.used_url = None
        self.filename = None
        self.url = None
        self.version = None
        self.license_files = []

    def fetch_package_info(self):
        """
        Fetch a package's metadata from the python package index
        """
        self.metadata_url = 'https://pypi.org/pypi/{pkg}/json'.format(
            pkg=self.real_name)
        try:
            pkg_json = six.moves.urllib.request.urlopen(self.metadata_url).read().decode()
        except six.moves.urllib.error.HTTPError as error:
            print('ERROR:', error.getcode(), error.msg, file=sys.stderr)
            print('ERROR: Could not find package {pkg}.\n'
                  'Check syntax inside the python package index:\n'
                  'https://pypi.python.org/pypi/ '
                  .format(pkg=self.real_name))
            raise
        except six.moves.urllib.error.URLError:
            print('ERROR: Could not find package {pkg}.\n'
                  'Check syntax inside the python package index:\n'
                  'https://pypi.python.org/pypi/ '
                  .format(pkg=self.real_name))
            raise
        self.metadata = json.loads(pkg_json)
        self.version = self.metadata['info']['version']
        self.metadata_name = self.metadata['info']['name']

    def download_package(self):
        """
        Download a package using metadata from pypi
        """
        download = None
        try:
            self.metadata['urls'][0]['filename']
        except IndexError:
            print(
                'Non-conventional package, ',
                'please check carefully after creation')
            self.metadata['urls'] = [{
                'packagetype': 'sdist',
                'url': self.metadata['info']['download_url'],
                'digests': None}]
            # In this case, we can't get the name of the downloaded file
            # from the pypi api, so we need to find it, this should work
            urlpath = six.moves.urllib.parse.urlparse(
                self.metadata['info']['download_url']).path
            # urlparse().path give something like
            # /path/to/file-version.tar.gz
            # We use basename to remove /path/to
            self.metadata['urls'][0]['filename'] = os.path.basename(urlpath)
        for download_url in self.metadata['urls']:
            if 'bdist' in download_url['packagetype']:
                continue
            try:
                print('Downloading package {pkg} from {url}...'.format(
                    pkg=self.real_name, url=download_url['url']))
                download = six.moves.urllib.request.urlopen(download_url['url'])
            except six.moves.urllib.error.HTTPError as http_error:
                download = http_error
            else:
                self.used_url = download_url
                self.as_string = download.read()
                if not download_url['digests']['md5']:
                    break
                self.md5_sum = hashlib.md5(self.as_string).hexdigest()
                if self.md5_sum == download_url['digests']['md5']:
                    break

        if download is None:
            raise DownloadFailed('Failed to download package {pkg}: '
                                 'No source archive available'
                                 .format(pkg=self.real_name))
        elif download.__class__ == six.moves.urllib.error.HTTPError:
            raise download

        self.filename = self.used_url['filename']
        self.url = self.used_url['url']

    def check_archive(self, members):
        """
        Check archive content before extracting

        Keyword arguments:
        members -- list of archive members
        """
        # Protect against https://github.com/snyk/zip-slip-vulnerability
        # Older python versions do not validate that the extracted files are
        # inside the target directory. Detect and error out on evil paths
        evil = [e for e in members if os.path.relpath(e).startswith(('/', '..'))]
        if evil:
            print('ERROR: Refusing to extract {} with suspicious members {}'.format(
                self.filename, evil))
            sys.exit(1)

    def extract_package(self, tmp_path):
        """
        Extract the package contents into a directrory

        Keyword arguments:
        tmp_path -- directory where you want the package to be extracted
        """
        if six.PY2:
            as_file = StringIO.StringIO(self.as_string)
        else:
            as_file = io.BytesIO(self.as_string)
        if self.filename[-3:] == 'zip':
            with zipfile.ZipFile(as_file) as as_zipfile:
                tmp_pkg = os.path.join(tmp_path, self.buildroot_name)
                try:
                    os.makedirs(tmp_pkg)
                except OSError as exception:
                    if exception.errno != errno.EEXIST:
                        print("ERROR: ", exception.strerror, file=sys.stderr)
                        return
                    print('WARNING:', exception.strerror, file=sys.stderr)
                    print('Removing {pkg}...'.format(pkg=tmp_pkg))
                    shutil.rmtree(tmp_pkg)
                    os.makedirs(tmp_pkg)
                self.check_archive(as_zipfile.namelist())
                as_zipfile.extractall(tmp_pkg)
                pkg_filename = self.filename.split(".zip")[0]
        else:
            with tarfile.open(fileobj=as_file) as as_tarfile:
                tmp_pkg = os.path.join(tmp_path, self.buildroot_name)
                try:
                    os.makedirs(tmp_pkg)
                except OSError as exception:
                    if exception.errno != errno.EEXIST:
                        print("ERROR: ", exception.strerror, file=sys.stderr)
                        return
                    print('WARNING:', exception.strerror, file=sys.stderr)
                    print('Removing {pkg}...'.format(pkg=tmp_pkg))
                    shutil.rmtree(tmp_pkg)
                    os.makedirs(tmp_pkg)
                self.check_archive(as_tarfile.getnames())
                as_tarfile.extractall(tmp_pkg)
                pkg_filename = self.filename.split(".tar")[0]

        tmp_extract = '{folder}/{name}'
        self.tmp_extract = tmp_extract.format(
            folder=tmp_pkg,
            name=pkg_filename)

    def load_setup(self):
        """
        Loads the corresponding setup and store its metadata
        """
        current_dir = os.getcwd()
        os.chdir(self.tmp_extract)
        sys.path.append(self.tmp_extract)
        s_file, s_path, s_desc = imp.find_module('setup', [self.tmp_extract])
        setup = imp.load_module('setup', s_file, s_path, s_desc)
        if self.metadata_name in self.setup_args:
            pass
        elif self.metadata_name.replace('_', '-') in self.setup_args:
            self.metadata_name = self.metadata_name.replace('_', '-')
        elif self.metadata_name.replace('-', '_') in self.setup_args:
            self.metadata_name = self.metadata_name.replace('-', '_')
        try:
            self.setup_metadata = self.setup_args[self.metadata_name]
        except KeyError:
            # This means setup was not called which most likely mean that it is
            # called through the if __name__ == '__main__' directive.
            # In this case, we can only pray that it is called through a
            # function called main() in setup.py.
            setup.main()  # Will raise AttributeError if not found
            self.setup_metadata = self.setup_args[self.metadata_name]
        # Here we must remove the module the hard way.
        # We must do this because of a very specific case: if a package calls
        # setup from the __main__ but does not come with a 'main()' function,
        # for some reason setup.main() will successfully call the main
        # function of a previous package...
        sys.modules.pop('setup', None)
        del setup
        os.chdir(current_dir)
        sys.path.remove(self.tmp_extract)

    def get_requirements(self, pkg_folder):
        """
        Retrieve dependencies from the metadata found in the setup.py script of
        a pypi package.

        Keyword Arguments:
        pkg_folder -- location of the already created packages
        """
        if 'install_requires' not in self.setup_metadata:
            self.pkg_req = None
            return set()
        self.pkg_req = self.setup_metadata['install_requires']
        self.pkg_req = [re.sub(r'([-.\w]+).*', r'\1', req)
                        for req in self.pkg_req]

        # get rid of commented lines and also strip the package strings
        self.pkg_req = [item.strip() for item in self.pkg_req
                        if len(item) > 0 and item[0] != '#']

        req_not_found = self.pkg_req
        self.pkg_req = list(map(pkg_buildroot_name, self.pkg_req))
        pkg_tuples = list(zip(req_not_found, self.pkg_req))
        # pkg_tuples is a list of tuples that looks like
        # ('werkzeug','python-werkzeug') because I need both when checking if
        # dependencies already exist or are already in the download list
        req_not_found = set(
            pkg[0] for pkg in pkg_tuples
            if not os.path.isdir(pkg[1])
            )
        return req_not_found

    def __create_mk_header(self):
        """
        Create the header of the <package_name>.mk file
        """
        header = ['#' * 80 + '\n']
        header.append('#\n')
        header.append('# {name}\n'.format(name=self.buildroot_name))
        header.append('#\n')
        header.append('#' * 80 + '\n')
        header.append('\n')
        return header

    def __create_mk_download_info(self):
        """
        Create the lines refering to the download information of the
        <package_name>.mk file
        """
        lines = []
        version_line = '{name}_VERSION = {version}\n'.format(
            name=self.mk_name,
            version=self.version)
        lines.append(version_line)

        if self.buildroot_name != self.real_name:
            targz = self.filename.replace(
                self.version,
                '$({name}_VERSION)'.format(name=self.mk_name))
            targz_line = '{name}_SOURCE = {filename}\n'.format(
                name=self.mk_name,
                filename=targz)
            lines.append(targz_line)

        if self.filename not in self.url:
            # Sometimes the filename is in the url, sometimes it's not
            site_url = self.url
        else:
            site_url = self.url[:self.url.find(self.filename)]
        site_line = '{name}_SITE = {url}'.format(name=self.mk_name,
                                                 url=site_url)
        site_line = site_line.rstrip('/') + '\n'
        lines.append(site_line)
        return lines

    def __create_mk_setup(self):
        """
        Create the line refering to the setup method of the package of the
        <package_name>.mk file

        There are two things you can use to make an installer
        for a python package: distutils or setuptools
        distutils comes with python but does not support dependencies.
        distutils is mostly still there for backward support.
        setuptools is what smart people use,
        but it is not shipped with python :(
        """
        lines = []
        setup_type_line = '{name}_SETUP_TYPE = {method}\n'.format(
            name=self.mk_name,
            method=self.setup_metadata['method'])
        lines.append(setup_type_line)
        return lines

    def __get_license_names(self, license_files):
        """
        Try to determine the related license name.

        There are two possibilities. Either the script tries to
        get license name from package's metadata or, if spdx_lookup
        package is available, the script compares license files with
        SPDX database.
        """
        license_line = ''
        if liclookup is None:
            license_dict = {
                'Apache Software License': 'Apache-2.0',
                'BSD License': 'FIXME: please specify the exact BSD version',
                'European Union Public Licence 1.0': 'EUPL-1.0',
                'European Union Public Licence 1.1': 'EUPL-1.1',
                "GNU General Public License": "GPL",
                "GNU General Public License v2": "GPL-2.0",
                "GNU General Public License v2 or later": "GPL-2.0+",
                "GNU General Public License v3": "GPL-3.0",
                "GNU General Public License v3 or later": "GPL-3.0+",
                "GNU Lesser General Public License v2": "LGPL-2.1",
                "GNU Lesser General Public License v2 or later": "LGPL-2.1+",
                "GNU Lesser General Public License v3": "LGPL-3.0",
                "GNU Lesser General Public License v3 or later": "LGPL-3.0+",
                "GNU Library or Lesser General Public License": "LGPL-2.0",
                "ISC License": "ISC",
                "MIT License": "MIT",
                "Mozilla Public License 1.0": "MPL-1.0",
                "Mozilla Public License 1.1": "MPL-1.1",
                "Mozilla Public License 2.0": "MPL-2.0",
                "Zope Public License": "ZPL"
                }
            regexp = re.compile(r'^License :* *.* *:+ (.*)( \(.*\))?$')
            classifiers_licenses = [regexp.sub(r"\1", lic)
                                    for lic in self.metadata['info']['classifiers']
                                    if regexp.match(lic)]
            licenses = [license_dict[x] if x in license_dict else x for x in classifiers_licenses]
            if not len(licenses):
                print('WARNING: License has been set to "{license}". It is most'
                      ' likely wrong, please change it if need be'.format(
                          license=', '.join(licenses)))
                licenses = [self.metadata['info']['license']]
            licenses = set(licenses)
            license_line = '{name}_LICENSE = {license}\n'.format(
                name=self.mk_name,
                license=', '.join(licenses))
        else:
            license_names = []
            for license_file in license_files:
                with open(license_file) as lic_file:
                    match = liclookup.match(lic_file.read())
                if match is not None and match.confidence >= 90.0:
                    license_names.append(match.license.id)
                else:
                    license_names.append("FIXME: license id couldn't be detected")
            license_names = set(license_names)

            if len(license_names) > 0:
                license_line = ('{name}_LICENSE ='
                                ' {names}\n'.format(
                                    name=self.mk_name,
                                    names=', '.join(license_names)))

        return license_line

    def __create_mk_license(self):
        """
        Create the lines referring to the package's license informations of the
        <package_name>.mk file

        The license's files are found by searching the package (case insensitive)
        for files named license, license.txt etc. If more than one license file
        is found, the user is asked to select which ones he wants to use.
        """
        lines = []

        filenames = ['LICENCE', 'LICENSE', 'LICENSE.RST', 'LICENSE.TXT',
                     'COPYING', 'COPYING.TXT']
        self.license_files = list(find_file_upper_case(filenames, self.tmp_extract))

        lines.append(self.__get_license_names(self.license_files))

        license_files = [license.replace(self.tmp_extract, '')[1:]
                         for license in self.license_files]
        if len(license_files) > 0:
            if len(license_files) > 1:
                print('More than one file found for license:',
                      ', '.join(license_files))
            license_files = [filename
                             for index, filename in enumerate(license_files)]
            license_file_line = ('{name}_LICENSE_FILES ='
                                 ' {files}\n'.format(
                                     name=self.mk_name,
                                     files=' '.join(license_files)))
            lines.append(license_file_line)
        else:
            print('WARNING: No license file found,'
                  ' please specify it manually afterwards')
            license_file_line = '# No license file found\n'

        return lines

    def __create_mk_requirements(self):
        """
        Create the lines referring to the dependencies of the of the
        <package_name>.mk file

        Keyword Arguments:
        pkg_name -- name of the package
        pkg_req -- dependencies of the package
        """
        lines = []
        dependencies_line = ('{name}_DEPENDENCIES ='
                             ' {reqs}\n'.format(
                                 name=self.mk_name,
                                 reqs=' '.join(self.pkg_req)))
        lines.append(dependencies_line)
        return lines

    def create_package_mk(self):
        """
        Create the lines corresponding to the <package_name>.mk file
        """
        pkg_mk = '{name}.mk'.format(name=self.buildroot_name)
        path_to_mk = os.path.join(self.pkg_dir, pkg_mk)
        print('Creating {file}...'.format(file=path_to_mk))
        lines = self.__create_mk_header()
        lines += self.__create_mk_download_info()
        lines += self.__create_mk_setup()
        lines += self.__create_mk_license()

        lines.append('\n')
        lines.append('$(eval $(python-package))')
        lines.append('\n')
        with open(path_to_mk, 'w') as mk_file:
            mk_file.writelines(lines)

    def create_hash_file(self):
        """
        Create the lines corresponding to the <package_name>.hash files
        """
        pkg_hash = '{name}.hash'.format(name=self.buildroot_name)
        path_to_hash = os.path.join(self.pkg_dir, pkg_hash)
        print('Creating {filename}...'.format(filename=path_to_hash))
        lines = []
        if self.used_url['digests']['md5'] and self.used_url['digests']['sha256']:
            hash_header = '# md5, sha256 from {url}\n'.format(
                url=self.metadata_url)
            lines.append(hash_header)
            hash_line = '{method}  {digest}  {filename}\n'.format(
                method='md5',
                digest=self.used_url['digests']['md5'],
                filename=self.filename)
            lines.append(hash_line)
            hash_line = '{method}  {digest}  {filename}\n'.format(
                method='sha256',
                digest=self.used_url['digests']['sha256'],
                filename=self.filename)
            lines.append(hash_line)

        if self.license_files:
            lines.append('# Locally computed sha256 checksums\n')
        for license_file in self.license_files:
            sha256 = hashlib.sha256()
            with open(license_file, 'rb') as lic_f:
                while True:
                    data = lic_f.read(BUF_SIZE)
                    if not data:
                        break
                    sha256.update(data)
            hash_line = '{method}  {digest}  {filename}\n'.format(
                method='sha256',
                digest=sha256.hexdigest(),
                filename=license_file.replace(self.tmp_extract, '')[1:])
            lines.append(hash_line)

        with open(path_to_hash, 'w') as hash_file:
            hash_file.writelines(lines)

    def create_config_in(self):
        """
        Creates the Config.in file of a package
        """
        path_to_config = os.path.join(self.pkg_dir, 'Config.in')
        print('Creating {file}...'.format(file=path_to_config))
        lines = []
        config_line = 'config BR2_PACKAGE_{name}\n'.format(
            name=self.mk_name)
        lines.append(config_line)

        bool_line = '\tbool "{name}"\n'.format(name=self.buildroot_name)
        lines.append(bool_line)
        if self.pkg_req:
            self.pkg_req.sort()
            for dep in self.pkg_req:
                dep_line = '\tselect BR2_PACKAGE_{req} # runtime\n'.format(
                    req=dep.upper().replace('-', '_'))
                lines.append(dep_line)

        lines.append('\thelp\n')

        help_lines = textwrap.wrap(self.metadata['info']['summary'], 62,
                                   initial_indent='\t  ',
                                   subsequent_indent='\t  ')

        # make sure a help text is terminated with a full stop
        if help_lines[-1][-1] != '.':
            help_lines[-1] += '.'

        # \t + two spaces is 3 char long
        help_lines.append('')
        help_lines.append('\t  ' + self.metadata['info']['home_page'])
        help_lines = [x + '\n' for x in help_lines]
        lines += help_lines

        with open(path_to_config, 'w') as config_file:
            config_file.writelines(lines)


def main():
    # Building the parser
    parser = argparse.ArgumentParser(
        description="Creates buildroot packages from the metadata of "
                    "an existing PyPI packages and include it "
                    "in menuconfig")
    parser.add_argument("packages",
                        help="list of packages to be created",
                        nargs='+')
    parser.add_argument("-o", "--output",
                        help="""
                        Output directory for packages.
                        Default is ./package
                        """,
                        default='./package')

    args = parser.parse_args()
    packages = list(set(args.packages))

    # tmp_path is where we'll extract the files later
    tmp_prefix = 'scanpypi-'
    pkg_folder = args.output
    tmp_path = tempfile.mkdtemp(prefix=tmp_prefix)
    try:
        for real_pkg_name in packages:
            package = BuildrootPackage(real_pkg_name, pkg_folder)
            print('buildroot package name for {}:'.format(package.real_name),
                  package.buildroot_name)
            # First we download the package
            # Most of the info we need can only be found inside the package
            print('Package:', package.buildroot_name)
            print('Fetching package', package.real_name)
            try:
                package.fetch_package_info()
            except (six.moves.urllib.error.URLError, six.moves.urllib.error.HTTPError):
                continue
            if package.metadata_name.lower() == 'setuptools':
                # setuptools imports itself, that does not work very well
                # with the monkey path at the begining
                print('Error: setuptools cannot be built using scanPyPI')
                continue

            try:
                package.download_package()
            except six.moves.urllib.error.HTTPError as error:
                print('Error: {code} {reason}'.format(code=error.code,
                                                      reason=error.reason))
                print('Error downloading package :', package.buildroot_name)
                print()
                continue

            # extract the tarball
            try:
                package.extract_package(tmp_path)
            except (tarfile.ReadError, zipfile.BadZipfile):
                print('Error extracting package {}'.format(package.real_name))
                print()
                continue

            # Loading the package install info from the package
            try:
                package.load_setup()
            except ImportError as err:
                if 'buildutils' in err.message:
                    print('This package needs buildutils')
                else:
                    raise
                continue
            except AttributeError as error:
                print('Error: Could not install package {pkg}: {error}'.format(
                    pkg=package.real_name, error=error))
                continue

            # Package requirement are an argument of the setup function
            req_not_found = package.get_requirements(pkg_folder)
            req_not_found = req_not_found.difference(packages)

            packages += req_not_found
            if req_not_found:
                print('Added packages \'{pkgs}\' as dependencies of {pkg}'
                      .format(pkgs=", ".join(req_not_found),
                              pkg=package.buildroot_name))
            print('Checking if package {name} already exists...'.format(
                name=package.pkg_dir))
            try:
                os.makedirs(package.pkg_dir)
            except OSError as exception:
                if exception.errno != errno.EEXIST:
                    print("ERROR: ", exception.message, file=sys.stderr)
                    continue
                print('Error: Package {name} already exists'
                      .format(name=package.pkg_dir))
                del_pkg = input(
                    'Do you want to delete existing package ? [y/N]')
                if del_pkg.lower() == 'y':
                    shutil.rmtree(package.pkg_dir)
                    os.makedirs(package.pkg_dir)
                else:
                    continue
            package.create_package_mk()

            package.create_hash_file()

            package.create_config_in()
            print("NOTE: Remember to also make an update to the DEVELOPERS file")
            print("      and include an entry for the pkg in packages/Config.in")
            print()
            # printing an empty line for visual confort
    finally:
        shutil.rmtree(tmp_path)


if __name__ == "__main__":
    main()