# Copyright 2020 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
"""Sets up a Python 3 virtualenv for Pigweed."""

from __future__ import print_function

import glob
import os
import subprocess
import sys


def git_stdout(*args, **kwargs):
    """Run git, passing args as git params and kwargs to subprocess."""
    return subprocess.check_output(['git'] + list(args), **kwargs).strip()


def git_list_files(*args, **kwargs):
    """Run git ls-files, passing args as git params and kwargs to subprocess."""
    return git_stdout('ls-files', *args, **kwargs).split()


def git_repo_root(path='./'):
    """Find git repository root."""
    try:
        return git_stdout('-C', path, 'rev-parse', '--show-toplevel')
    except subprocess.CalledProcessError:
        return None


class GitRepoNotFound(Exception):
    """Git repository not found."""


def _installed_packages(venv_python):
    cmd = (venv_python, '-m', 'pip', 'list', '--disable-pip-version-check')
    output = subprocess.check_output(cmd).splitlines()
    return set(x.split()[0].lower() for x in output[2:])


def _required_packages(requirements):
    packages = set()

    for req in requirements:
        with open(req, 'r') as ins:
            for line in ins:
                line = line.strip()
                if not line or line.startswith('#'):
                    continue
                packages.add(line.split('=')[0])

    return packages


def _pw_package_names(setup_py_files):
    # TODO(pwbug/42) find a more reliable way to get this.
    del setup_py_files  # Unused for now.
    return set((
        'pw-bloat',
        'pw-cli',
        'pw-module',
        'pw-presubmit',
        'pw-unit-test',
        'stm32f429i-disc1-utils',
    ))


def install(
    venv_path,
    full_envsetup=True,
    requirements=(),
    python=sys.executable,
    env=None,
):
    """Creates a venv and installs all packages in this Git repo."""

    pyvenv_cfg = os.path.join(venv_path, 'pyvenv.cfg')
    if full_envsetup or not os.path.exists(pyvenv_cfg):
        print('Creating venv at', venv_path)
        cmd = (python, '-m', 'venv', '--clear', venv_path)
        subprocess.check_call(cmd)

    # The bin/ directory is called Scripts/ on Windows. Don't ask.
    venv_bin = os.path.join(venv_path, 'Scripts' if os.name == 'nt' else 'bin')
    venv_python = os.path.join(venv_bin, 'python')

    pw_root = os.environ.get('PW_ROOT', git_repo_root())
    if not pw_root:
        raise GitRepoNotFound()

    setup_py_files = git_list_files('setup.py', '*/setup.py', cwd=pw_root)

    # Don't install the env_setup "module".
    setup_py_files = [x for x in setup_py_files if b'env_setup' not in x]

    # If not forcing full setup, check if all expected packages are installed,
    # ignoring versions. If they are, skip reinstalling.
    if not full_envsetup:
        installed = _installed_packages(venv_python)
        required = _required_packages(requirements)
        pw_pkgs = _pw_package_names(setup_py_files)

        if required.issubset(installed) and pw_pkgs.issubset(installed):
            print('Python packages already installed, exiting')
            return

        # Sometimes we get an error saying "Egg-link ... does not match
        # installed location". This gets around that. The egg-link files
        # all come from 'pw'-prefixed packages we installed with --editable.
        # Source: https://stackoverflow.com/a/48972085
        for egg_link in glob.glob(
                os.path.join(venv_path,
                             'lib/python*/site-packages/*.egg-link')):
            os.unlink(egg_link)

    def pip_install(*args):
        cmd = [venv_python, '-m', 'pip', 'install'] + list(args)
        print(' '.join(cmd))
        return subprocess.check_call(cmd)

    pip_install('--upgrade', 'pip')

    def package(pkg_path):
        return os.path.join(pw_root, os.path.dirname(pkg_path.decode()))

    package_args = tuple('--editable={}'.format(package(path))
                         for path in setup_py_files)

    requirement_args = tuple('--requirement={}'.format(req)
                             for req in requirements)

    pip_install('--log', os.path.join(venv_path, 'pip-requirements.log'),
                *requirement_args)
    pip_install('--log', os.path.join(venv_path, 'pip-packages.log'),
                *package_args)

    if env:
        env.set('VIRTUAL_ENV', venv_path)
        env.prepend('PATH', venv_bin)
        env.clear('PYTHONHOME')