"""Helpers to install PyPi packages."""
import asyncio
import logging
import os
from subprocess import PIPE, Popen
import sys
from typing import Optional
from urllib.parse import urlparse
from pathlib import Path

import pkg_resources
from importlib_metadata import version, PackageNotFoundError


_LOGGER = logging.getLogger(__name__)


def is_virtual_env() -> bool:
    """Return if we run in a virtual environtment."""
    # Check supports venv && virtualenv
    return (getattr(sys, 'base_prefix', sys.prefix) != sys.prefix or
            hasattr(sys, 'real_prefix'))


def is_docker_env() -> bool:
    """Return True if we run in a docker env."""
    return Path("/.dockerenv").exists()


def is_installed(package: str) -> bool:
    """Check if a package is installed and will be loaded when we import it.

    Returns True when the requirement is met.
    Returns False when the package is not installed or doesn't meet req.
    """
    try:
        req = pkg_resources.Requirement.parse(package)
    except ValueError:
        # This is a zip file. We no longer use this in Home Assistant,
        # leaving it in for custom components.
        req = pkg_resources.Requirement.parse(urlparse(package).fragment)

    try:
        return version(req.project_name) in req
    except PackageNotFoundError:
        return False


def install_package(package: str, upgrade: bool = True,
                    target: Optional[str] = None,
                    constraints: Optional[str] = None,
                    find_links: Optional[str] = None,
                    no_cache_dir: Optional[bool] = False) -> bool:
    """Install a package on PyPi. Accepts pip compatible package strings.

    Return boolean if install successful.
    """
    # Not using 'import pip; pip.main([])' because it breaks the logger
    _LOGGER.info('Attempting install of %s', package)
    env = os.environ.copy()
    args = [sys.executable, '-m', 'pip', 'install', '--quiet', package]
    if no_cache_dir:
        args.append('--no-cache-dir')
    if upgrade:
        args.append('--upgrade')
    if constraints is not None:
        args += ['--constraint', constraints]
    if find_links is not None:
        args += ['--find-links', find_links, '--prefer-binary']
    if target:
        assert not is_virtual_env()
        # This only works if not running in venv
        args += ['--user']
        env['PYTHONUSERBASE'] = os.path.abspath(target)
        if sys.platform != 'win32':
            # Workaround for incompatible prefix setting
            # See http://stackoverflow.com/a/4495175
            args += ['--prefix=']
    process = Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE, env=env)
    _, stderr = process.communicate()
    if process.returncode != 0:
        _LOGGER.error("Unable to install package %s: %s",
                      package, stderr.decode('utf-8').lstrip().strip())
        return False

    return True


async def async_get_user_site(deps_dir: str) -> str:
    """Return user local library path.

    This function is a coroutine.
    """
    env = os.environ.copy()
    env['PYTHONUSERBASE'] = os.path.abspath(deps_dir)
    args = [sys.executable, '-m', 'site', '--user-site']
    process = await asyncio.create_subprocess_exec(
        *args, stdin=asyncio.subprocess.PIPE,
        stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.DEVNULL,
        env=env)
    stdout, _ = await process.communicate()
    lib_dir = stdout.decode().strip()
    return lib_dir