# mypy: allow-untyped-defs

import os
import shutil
import sys
import logging
from shutil import which

# The `pkg_resources` module is provided by `setuptools`, which is itself a
# dependency of `virtualenv`. Tolerate its absence so that this module may be
# evaluated when that module is not available. Because users may not recognize
# the `pkg_resources` module by name, raise a more descriptive error if it is
# referenced during execution.
try:
    import pkg_resources as _pkg_resources
    get_pkg_resources = lambda: _pkg_resources
except ImportError:
    def get_pkg_resources():
        raise ValueError("The Python module `virtualenv` is not installed.")

from tools.wpt.utils import call

logger = logging.getLogger(__name__)

class Virtualenv:
    def __init__(self, path, skip_virtualenv_setup):
        self.path = path
        self.skip_virtualenv_setup = skip_virtualenv_setup
        if not skip_virtualenv_setup:
            self.virtualenv = which("virtualenv")
            if not self.virtualenv:
                raise ValueError("virtualenv must be installed and on the PATH")
            self._working_set = None

    @property
    def exists(self):
        # We need to check also for lib_path because different python versions
        # create different library paths.
        return os.path.isdir(self.path) and os.path.isdir(self.lib_path)

    @property
    def broken_link(self):
        python_link = os.path.join(self.path, ".Python")
        return os.path.lexists(python_link) and not os.path.exists(python_link)

    def create(self):
        if os.path.exists(self.path):
            shutil.rmtree(self.path)
            self._working_set = None
        call(self.virtualenv, self.path, "-p", sys.executable)

    @property
    def bin_path(self):
        if sys.platform in ("win32", "cygwin"):
            return os.path.join(self.path, "Scripts")
        return os.path.join(self.path, "bin")

    @property
    def pip_path(self):
        path = which("pip3", path=self.bin_path)
        if path is None:
            raise ValueError("pip3 not found")
        return path

    @property
    def lib_path(self):
        base = self.path

        # this block is literally taken from virtualenv 16.4.3
        IS_PYPY = hasattr(sys, "pypy_version_info")
        IS_JYTHON = sys.platform.startswith("java")
        if IS_JYTHON:
            site_packages = os.path.join(base, "Lib", "site-packages")
        elif IS_PYPY:
            site_packages = os.path.join(base, "site-packages")
        else:
            IS_WIN = sys.platform == "win32"
            if IS_WIN:
                site_packages = os.path.join(base, "Lib", "site-packages")
            else:
                site_packages = os.path.join(base, "lib", f"python{sys.version[:3]}", "site-packages")

        return site_packages

    @property
    def working_set(self):
        if not self.exists:
            raise ValueError("trying to read working_set when venv doesn't exist")

        if self._working_set is None:
            self._working_set = get_pkg_resources().WorkingSet((self.lib_path,))

        return self._working_set

    def activate(self):
        if sys.platform == 'darwin':
            # The default Python on macOS sets a __PYVENV_LAUNCHER__ environment
            # variable which affects invocation of python (e.g. via pip) in a
            # virtualenv. Unset it if present to avoid this. More background:
            # https://github.com/web-platform-tests/wpt/issues/27377
            # https://github.com/python/cpython/pull/9516
            os.environ.pop('__PYVENV_LAUNCHER__', None)
        path = os.path.join(self.bin_path, "activate_this.py")
        with open(path) as f:
            exec(f.read(), {"__file__": path})

    def start(self):
        if not self.exists or self.broken_link:
            self.create()
        self.activate()

    def install(self, *requirements):
        try:
            self.working_set.require(*requirements)
        except Exception:
            pass
        else:
            return

        # `--prefer-binary` guards against race conditions when installation
        # occurs while packages are in the process of being published.
        call(self.pip_path, "install", "--prefer-binary", *requirements)

    def install_requirements(self, *requirements_paths):
        install = []
        # Check which requirements are already satisfied, to skip calling pip
        # at all in the case that we've already installed everything, and to
        # minimise the installs in other cases.
        for requirements_path in requirements_paths:
            with open(requirements_path) as f:
                try:
                    self.working_set.require(f.read())
                except Exception:
                    install.append(requirements_path)

        if install:
            # `--prefer-binary` guards against race conditions when installation
            # occurs while packages are in the process of being published.
            cmd = [self.pip_path, "install", "--prefer-binary"]
            for path in install:
                cmd.extend(["-r", path])
            call(*cmd)