"""Install only the same pinned DWG decoder used on the verified local host.

Build-time only. No drawings, credentials or model generation are involved.
"""
import hashlib
from pathlib import Path
import platform
import shutil
import tarfile
import tempfile
import urllib.request

URL = ('https://conda.anaconda.org/conda-forge/linux-64/'
       'libredwg-0.11.3876-py38pl5321hf1fe3a4_2.tar.bz2')
SHA256 = '23e82c10d5e09b1444ca099c3710893f363d67a98417b0b69afd7155b9759f21'


def install(destination=Path('/opt/libredwg')):
    if platform.machine() not in ('x86_64', 'AMD64'):
        raise RuntimeError('This pinned converter requires a linux/amd64 Docker host')
    members = {'bin/dwg2dxf': 'bin/dwg2dxf',
               'lib/libredwg.so.0.0.11': 'lib/libredwg.so.0.0.11',
               'info/licenses/COPYING': 'licenses/COPYING',
               'info/recipe/meta.yaml': 'licenses/package-source.yaml'}
    with tempfile.TemporaryDirectory(prefix='dwg-runtime-') as tmp:
        archive = Path(tmp) / 'runtime.tar.bz2'
        with urllib.request.urlopen(URL, timeout=120) as response, archive.open('wb') as out:
            shutil.copyfileobj(response, out)
        with archive.open('rb') as stream:
            if hashlib.file_digest(stream, 'sha256').hexdigest() != SHA256:
                raise ValueError('DWG runtime checksum mismatch')
        with tarfile.open(archive) as bundle:
            for source, relative in members.items():
                member = bundle.getmember(source)
                if not member.isfile():
                    raise ValueError('Expected regular DWG runtime file')
                target = destination / relative
                target.parent.mkdir(parents=True, exist_ok=True)
                with bundle.extractfile(member) as inp, target.open('xb') as out:
                    shutil.copyfileobj(inp, out)
                target.chmod(0o755 if relative.startswith(('bin/', 'lib/')) else 0o644)
        (destination / 'lib/libredwg.so.0').symlink_to('libredwg.so.0.0.11')


if __name__ == '__main__':
    install()