"""Wheels support."""

import email
import itertools
import functools
import os
import posixpath
import re
import zipfile
import contextlib

from distutils.util import get_platform

import setuptools
from setuptools.extern.packaging.version import Version as parse_version
from setuptools.extern.packaging.tags import sys_tags
from setuptools.extern.packaging.utils import canonicalize_name
from setuptools.command.egg_info import write_requirements, _egg_basename
from setuptools.archive_util import _unpack_zipfile_obj


WHEEL_NAME = re.compile(
    r"""^(?P<project_name>.+?)-(?P<version>\d.*?)
    ((-(?P<build>\d.*?))?-(?P<py_version>.+?)-(?P<abi>.+?)-(?P<platform>.+?)
    )\.whl$""",
    re.VERBOSE).match

NAMESPACE_PACKAGE_INIT = \
    "__import__('pkg_resources').declare_namespace(__name__)\n"


@functools.lru_cache(maxsize=None)
def _get_supported_tags():
    # We calculate the supported tags only once, otherwise calling
    # this method on thousands of wheels takes seconds instead of
    # milliseconds.
    return {(t.interpreter, t.abi, t.platform) for t in sys_tags()}


def unpack(src_dir, dst_dir):
    '''Move everything under `src_dir` to `dst_dir`, and delete the former.'''
    for dirpath, dirnames, filenames in os.walk(src_dir):
        subdir = os.path.relpath(dirpath, src_dir)
        for f in filenames:
            src = os.path.join(dirpath, f)
            dst = os.path.join(dst_dir, subdir, f)
            os.renames(src, dst)
        for n, d in reversed(list(enumerate(dirnames))):
            src = os.path.join(dirpath, d)
            dst = os.path.join(dst_dir, subdir, d)
            if not os.path.exists(dst):
                # Directory does not exist in destination,
                # rename it and prune it from os.walk list.
                os.renames(src, dst)
                del dirnames[n]
    # Cleanup.
    for dirpath, dirnames, filenames in os.walk(src_dir, topdown=True):
        assert not filenames
        os.rmdir(dirpath)


@contextlib.contextmanager
def disable_info_traces():
    """
    Temporarily disable info traces.
    """
    from distutils import log
    saved = log.set_threshold(log.WARN)
    try:
        yield
    finally:
        log.set_threshold(saved)


class Wheel:

    def __init__(self, filename):
        match = WHEEL_NAME(os.path.basename(filename))
        if match is None:
            raise ValueError('invalid wheel name: %r' % filename)
        self.filename = filename
        for k, v in match.groupdict().items():
            setattr(self, k, v)

    def tags(self):
        '''List tags (py_version, abi, platform) supported by this wheel.'''
        return itertools.product(
            self.py_version.split('.'),
            self.abi.split('.'),
            self.platform.split('.'),
        )

    def is_compatible(self):
        '''Is the wheel compatible with the current platform?'''
        return next((True for t in self.tags() if t in _get_supported_tags()), False)

    def egg_name(self):
        return _egg_basename(
            self.project_name,
            self.version,
            platform=(None if self.platform == 'any' else get_platform()),
        ) + ".egg"

    def get_dist_info(self, zf):
        # find the correct name of the .dist-info dir in the wheel file
        for member in zf.namelist():
            dirname = posixpath.dirname(member)
            if (dirname.endswith('.dist-info') and
                    canonicalize_name(dirname).startswith(
                        canonicalize_name(self.project_name))):
                return dirname
        raise ValueError("unsupported wheel format. .dist-info not found")

    def install_as_egg(self, destination_eggdir):
        '''Install wheel as an egg directory.'''
        with zipfile.ZipFile(self.filename) as zf:
            self._install_as_egg(destination_eggdir, zf)

    def _install_as_egg(self, destination_eggdir, zf):
        dist_basename = '%s-%s' % (self.project_name, self.version)
        dist_info = self.get_dist_info(zf)
        dist_data = '%s.data' % dist_basename
        egg_info = os.path.join(destination_eggdir, 'EGG-INFO')

        self._convert_metadata(zf, destination_eggdir, dist_info, egg_info)
        self._move_data_entries(destination_eggdir, dist_data)
        self._fix_namespace_packages(egg_info, destination_eggdir)

    @staticmethod
    def _convert_metadata(zf, destination_eggdir, dist_info, egg_info):
        import pkg_resources

        def get_metadata(name):
            with zf.open(posixpath.join(dist_info, name)) as fp:
                value = fp.read().decode('utf-8')
                return email.parser.Parser().parsestr(value)

        wheel_metadata = get_metadata('WHEEL')
        # Check wheel format version is supported.
        wheel_version = parse_version(wheel_metadata.get('Wheel-Version'))
        wheel_v1 = (
            parse_version('1.0') <= wheel_version < parse_version('2.0dev0')
        )
        if not wheel_v1:
            raise ValueError(
                'unsupported wheel format version: %s' % wheel_version)
        # Extract to target directory.
        _unpack_zipfile_obj(zf, destination_eggdir)
        # Convert metadata.
        dist_info = os.path.join(destination_eggdir, dist_info)
        dist = pkg_resources.Distribution.from_location(
            destination_eggdir, dist_info,
            metadata=pkg_resources.PathMetadata(destination_eggdir, dist_info),
        )

        # Note: Evaluate and strip markers now,
        # as it's difficult to convert back from the syntax:
        # foobar; "linux" in sys_platform and extra == 'test'
        def raw_req(req):
            req.marker = None
            return str(req)
        install_requires = list(map(raw_req, dist.requires()))
        extras_require = {
            extra: [
                req
                for req in map(raw_req, dist.requires((extra,)))
                if req not in install_requires
            ]
            for extra in dist.extras
        }
        os.rename(dist_info, egg_info)
        os.rename(
            os.path.join(egg_info, 'METADATA'),
            os.path.join(egg_info, 'PKG-INFO'),
        )
        setup_dist = setuptools.Distribution(
            attrs=dict(
                install_requires=install_requires,
                extras_require=extras_require,
            ),
        )
        with disable_info_traces():
            write_requirements(
                setup_dist.get_command_obj('egg_info'),
                None,
                os.path.join(egg_info, 'requires.txt'),
            )

    @staticmethod
    def _move_data_entries(destination_eggdir, dist_data):
        """Move data entries to their correct location."""
        dist_data = os.path.join(destination_eggdir, dist_data)
        dist_data_scripts = os.path.join(dist_data, 'scripts')
        if os.path.exists(dist_data_scripts):
            egg_info_scripts = os.path.join(
                destination_eggdir, 'EGG-INFO', 'scripts')
            os.mkdir(egg_info_scripts)
            for entry in os.listdir(dist_data_scripts):
                # Remove bytecode, as it's not properly handled
                # during easy_install scripts install phase.
                if entry.endswith('.pyc'):
                    os.unlink(os.path.join(dist_data_scripts, entry))
                else:
                    os.rename(
                        os.path.join(dist_data_scripts, entry),
                        os.path.join(egg_info_scripts, entry),
                    )
            os.rmdir(dist_data_scripts)
        for subdir in filter(os.path.exists, (
            os.path.join(dist_data, d)
            for d in ('data', 'headers', 'purelib', 'platlib')
        )):
            unpack(subdir, destination_eggdir)
        if os.path.exists(dist_data):
            os.rmdir(dist_data)

    @staticmethod
    def _fix_namespace_packages(egg_info, destination_eggdir):
        namespace_packages = os.path.join(
            egg_info, 'namespace_packages.txt')
        if os.path.exists(namespace_packages):
            with open(namespace_packages) as fp:
                namespace_packages = fp.read().split()
            for mod in namespace_packages:
                mod_dir = os.path.join(destination_eggdir, *mod.split('.'))
                mod_init = os.path.join(mod_dir, '__init__.py')
                if not os.path.exists(mod_dir):
                    os.mkdir(mod_dir)
                if not os.path.exists(mod_init):
                    with open(mod_init, 'w') as fp:
                        fp.write(NAMESPACE_PACKAGE_INIT)
