import glob
import os
import platform
import sysconfig
import sys
import shutil
import tarfile
import textwrap
import time
import zipfile

from tempfile import mkstemp, gettempdir
from urllib.request import urlopen, Request
from urllib.error import HTTPError

OPENBLAS_V = '0.3.21.dev'
OPENBLAS_LONG = 'v0.3.20-571-g3dec11c6'
BASE_LOC = 'https://anaconda.org/multibuild-wheels-staging/openblas-libs'
BASEURL = f'{BASE_LOC}/{OPENBLAS_LONG}/download'
SUPPORTED_PLATFORMS = [
    'linux-aarch64',
    'linux-x86_64',
    'musllinux-x86_64',
    'linux-i686',
    'linux-ppc64le',
    'linux-s390x',
    'win-amd64',
    'win-32',
    'macosx-x86_64',
    'macosx-arm64',
]
IS_32BIT = sys.maxsize < 2**32


def get_plat():
    plat = sysconfig.get_platform()
    plat_split = plat.split("-")
    arch = plat_split[-1]
    if arch == "win32":
        plat = "win-32"
    elif arch in ["universal2", "intel"]:
        plat = f"macosx-{platform.uname().machine}"
    elif len(plat_split) > 2:
        plat = f"{plat_split[0]}-{arch}"
    assert plat in SUPPORTED_PLATFORMS,  f'invalid platform {plat}'
    return plat


def get_ilp64():
    if os.environ.get("NPY_USE_BLAS_ILP64", "0") == "0":
        return None
    if IS_32BIT:
        raise RuntimeError("NPY_USE_BLAS_ILP64 set on 32-bit arch")
    return "64_"


def get_manylinux(arch):
    if arch in ('i686'):
        default = '2010'
    else:
        default = '2014'
    ml_ver = os.environ.get("MB_ML_VER", default)
    # XXX For PEP 600 this can be a glibc version
    assert ml_ver in ('2010', '2014', '_2_24'), f'invalid MB_ML_VER {ml_ver}'
    suffix = f'manylinux{ml_ver}_{arch}.tar.gz'
    return suffix


def get_musllinux(arch):
    musl_ver = "1_1"
    suffix = f'musllinux_{musl_ver}_{arch}.tar.gz'
    return suffix


def get_linux(arch):
    # best way of figuring out whether manylinux or musllinux is to look
    # at the packaging tags. If packaging isn't installed (it's not by default)
    # fallback to sysconfig (which may be flakier)
    try:
        from packaging.tags import sys_tags
        tags = list(sys_tags())
        plat = tags[0].platform
    except ImportError:
        # fallback to sysconfig for figuring out if you're using musl
        plat = 'manylinux'
        # value could be None
        v = sysconfig.get_config_var('HOST_GNU_TYPE') or ''
        if 'musl' in v:
            plat = 'musllinux'

    if 'manylinux' in plat:
        return get_manylinux(arch)
    elif 'musllinux' in plat:
        return get_musllinux(arch)


def download_openblas(target, plat, ilp64):
    osname, arch = plat.split("-")
    fnsuffix = {None: "", "64_": "64_"}[ilp64]
    filename = ''
    headers = {'User-Agent':
                   ('Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 ; '
                    '(KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.3')}
    suffix = None
    if osname == "linux":
        suffix = get_linux(arch)
        typ = 'tar.gz'
    elif plat == 'macosx-x86_64':
        suffix = 'macosx_10_9_x86_64-gf_c469a42.tar.gz'
        typ = 'tar.gz'
    elif plat == 'macosx-arm64':
        suffix = 'macosx_11_0_arm64-gf_5272328.tar.gz'
        typ = 'tar.gz'
    elif osname == 'win':
        if plat == "win-32":
            suffix = 'win32-gcc_8_3_0.zip'
        else:
            suffix = 'win_amd64-gcc_10_3_0.zip'
        typ = 'zip'

    if not suffix:
        return None
    filename = f'{BASEURL}/openblas{fnsuffix}-{OPENBLAS_LONG}-{suffix}'
    req = Request(url=filename, headers=headers)

    for _ in range(3):
        try:
            time.sleep(1)
            response = urlopen(req)
            break
        except HTTPError:
            print(f'Could not download "{filename}"', file=sys.stderr)
            raise

    length = response.getheader('content-length')
    if response.status != 200:
        print(f'Could not download "{filename}"', file=sys.stderr)
        return None
    print(f"Downloading {length} from {filename}", file=sys.stderr)
    data = response.read()
    print("Saving to file", file=sys.stderr)
    with open(target, 'wb') as fid:
        fid.write(data)
    return typ


def setup_openblas(plat=get_plat(), ilp64=get_ilp64()):
    '''
    Download and setup an openblas library for building. If successful,
    the configuration script will find it automatically.

    Returns
    -------
    msg : str
        path to extracted files on success, otherwise indicates what went wrong
        To determine success, do ``os.path.exists(msg)``
    '''
    _, tmp = mkstemp()
    if not plat:
        raise ValueError('unknown platform')
    typ = download_openblas(tmp, plat, ilp64)
    if not typ:
        return ''
    osname, arch = plat.split("-")
    if osname == 'win':
        if not typ == 'zip':
            return f'expecting to download zipfile on windows, not {typ}'
        return unpack_windows_zip(tmp)
    else:
        if not typ == 'tar.gz':
            return 'expecting to download tar.gz, not %s' % str(typ)
        return unpack_targz(tmp)


def unpack_windows_zip(fname):
    with zipfile.ZipFile(fname, 'r') as zf:
        # Get the openblas.a file, but not openblas.dll.a nor openblas.dev.a
        lib = [x for x in zf.namelist() if OPENBLAS_LONG in x and
               x.endswith('a') and not x.endswith('dll.a') and
               not x.endswith('dev.a')]
        if not lib:
            return 'could not find libopenblas_%s*.a ' \
                    'in downloaded zipfile' % OPENBLAS_LONG
        if get_ilp64() is None:
            target = os.path.join(gettempdir(), 'openblas.a')
        else:
            target = os.path.join(gettempdir(), 'openblas64_.a')
        with open(target, 'wb') as fid:
            fid.write(zf.read(lib[0]))
    return target


def unpack_targz(fname):
    target = os.path.join(gettempdir(), 'openblas')
    if not os.path.exists(target):
        os.mkdir(target)
    with tarfile.open(fname, 'r') as zf:
        # Strip common prefix from paths when unpacking
        prefix = os.path.commonpath(zf.getnames())
        extract_tarfile_to(zf, target, prefix)
        return target


def extract_tarfile_to(tarfileobj, target_path, archive_path):
    """Extract TarFile contents under archive_path/ to target_path/"""

    target_path = os.path.abspath(target_path)

    def get_members():
        for member in tarfileobj.getmembers():
            if archive_path:
                norm_path = os.path.normpath(member.name)
                if norm_path.startswith(archive_path + os.path.sep):
                    member.name = norm_path[len(archive_path)+1:]
                else:
                    continue

            dst_path = os.path.abspath(os.path.join(target_path, member.name))
            if os.path.commonpath([target_path, dst_path]) != target_path:
                # Path not under target_path, probably contains ../
                continue

            yield member

    tarfileobj.extractall(target_path, members=get_members())


def make_init(dirname):
    '''
    Create a _distributor_init.py file for OpenBlas
    '''
    with open(os.path.join(dirname, '_distributor_init.py'), 'w') as fid:
        fid.write(textwrap.dedent("""
            '''
            Helper to preload windows dlls to prevent dll not found errors.
            Once a DLL is preloaded, its namespace is made available to any
            subsequent DLL. This file originated in the numpy-wheels repo,
            and is created as part of the scripts that build the wheel.
            '''
            import os
            import glob
            if os.name == 'nt':
                # convention for storing / loading the DLL from
                # numpy/.libs/, if present
                try:
                    from ctypes import WinDLL
                    basedir = os.path.dirname(__file__)
                except:
                    pass
                else:
                    libs_dir = os.path.abspath(os.path.join(basedir, '.libs'))
                    DLL_filenames = []
                    if os.path.isdir(libs_dir):
                        for filename in glob.glob(os.path.join(libs_dir,
                                                               '*openblas*dll')):
                            # NOTE: would it change behavior to load ALL
                            # DLLs at this path vs. the name restriction?
                            WinDLL(os.path.abspath(filename))
                            DLL_filenames.append(filename)
                    if len(DLL_filenames) > 1:
                        import warnings
                        warnings.warn("loaded more than 1 DLL from .libs:"
                                      "\\n%s" % "\\n".join(DLL_filenames),
                                      stacklevel=1)
    """))


def test_setup(plats):
    '''
    Make sure all the downloadable files exist and can be opened
    '''
    def items():
        """ yields all combinations of arch, ilp64
        """
        for plat in plats:
            yield plat, None
            osname, arch = plat.split("-")
            if arch not in ('i686', 'arm64', '32'):
                yield plat, '64_'
            if osname == "linux" and arch in ('i686', 'x86_64'):
                oldval = os.environ.get('MB_ML_VER', None)
                os.environ['MB_ML_VER'] = '1'
                yield plat, None
                # Once we create x86_64 and i686 manylinux2014 wheels...
                # os.environ['MB_ML_VER'] = '2014'
                # yield arch, None, False
                if oldval:
                    os.environ['MB_ML_VER'] = oldval
                else:
                    os.environ.pop('MB_ML_VER')

    errs = []
    for plat, ilp64 in items():
        osname, _ = plat.split("-")
        if plat not in plats:
            continue
        target = None
        try:
            try:
                target = setup_openblas(plat, ilp64)
            except Exception as e:
                print(f'Could not setup {plat} with ilp64 {ilp64}, ')
                print(e)
                errs.append(e)
                continue
            if not target:
                raise RuntimeError(f'Could not setup {plat}')
            print(target)
            if osname == 'win':
                if not target.endswith('.a'):
                    raise RuntimeError("Not .a extracted!")
            else:
                files = glob.glob(os.path.join(target, "lib", "*.a"))
                if not files:
                    raise RuntimeError("No lib/*.a unpacked!")
        finally:
            if target is not None:
                if os.path.isfile(target):
                    os.unlink(target)
                else:
                    shutil.rmtree(target)
    if errs:
        raise errs[0]


def test_version(expected_version, ilp64=get_ilp64()):
    """
    Assert that expected OpenBLAS version is
    actually available via SciPy
    """
    import scipy
    import scipy.linalg
    import ctypes

    dll = ctypes.CDLL(scipy.linalg.cython_blas.__file__)
    if ilp64 == "64_":
        get_config = dll.openblas_get_config64_
    else:
        get_config = dll.openblas_get_config
    get_config.restype = ctypes.c_char_p
    res = get_config()
    print('OpenBLAS get_config returned', str(res))
    if not expected_version:
        expected_version = OPENBLAS_V
    check_str = b'OpenBLAS %s' % expected_version.encode()
    print(check_str)
    assert check_str in res, f'{expected_version} not found in {res}'
    if ilp64:
        assert b"USE64BITINT" in res
    else:
        assert b"USE64BITINT" not in res


if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser(
        description='Download and expand an OpenBLAS archive for this '
                    'architecture')
    parser.add_argument('--test', nargs='*', default=None,
                        help='Test different architectures. "all", or any of '
                             f'{SUPPORTED_PLATFORMS}')
    parser.add_argument('--write-init', nargs=1,
                        metavar='OUT_SCIPY_DIR',
                        help='Write distribution init to named dir')
    parser.add_argument('--check_version', nargs='?', default='',
                        help='Check provided OpenBLAS version string '
                             'against available OpenBLAS')
    args = parser.parse_args()
    if args.check_version != '':
        test_version(args.check_version)
    elif args.write_init:
        make_init(args.write_init[0])
    elif args.test is None:
        print(setup_openblas())
    else:
        if len(args.test) == 0 or 'all' in args.test:
            test_setup(SUPPORTED_PLATFORMS)
        else:
            test_setup(args.test)
