# 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 hashlib
import os
import re
import subprocess
import sys
import tempfile


class GnTarget(object):  # pylint: disable=useless-object-inheritance
    def __init__(self, val):
        self.directory, self.target = val.split('#', 1)
        # hash() doesn't necessarily give the same value in new runs of Python,
        # so compute a unique id for this object that's consistent from run to
        # run.
        try:
            val = val.encode()
        except AttributeError:
            pass
        self._unique_id = hashlib.md5(val).hexdigest()

    @property
    def name(self):
        """A reasonably stable and unique name for each pair."""
        result = '{}-{}'.format(
            os.path.basename(os.path.normpath(self.directory)),
            self._unique_id)
        return re.sub(r'[:/#_]+', '_', result)


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_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


# TODO(pwbug/135) Move to common utility module.
def _check_call(args, **kwargs):
    stdout = kwargs.get('stdout', sys.stdout)

    with tempfile.TemporaryFile(mode='w+') as temp:
        try:
            kwargs['stdout'] = temp
            kwargs['stderr'] = subprocess.STDOUT
            print(args, kwargs, file=temp)
            subprocess.check_call(args, **kwargs)
        except subprocess.CalledProcessError:
            temp.seek(0)
            stdout.write(temp.read())
            raise


def _find_files_by_name(roots, name, allow_nesting=False):
    matches = []
    for root in roots:
        for dirpart, dirs, files in os.walk(root):
            if name in files:
                matches.append(os.path.join(dirpart, name))
                # If this directory is a match don't recurse inside it looking
                # for more matches.
                if not allow_nesting:
                    dirs[:] = []

            # Filter directories starting with . to avoid searching unnecessary
            # paths and finding files that should be hidden.
            dirs[:] = [d for d in dirs if not d.startswith('.')]
    return matches


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

    version = subprocess.check_output(
        (python, '--version'), stderr=subprocess.STDOUT).strip().decode()
    # We expect Python 3.8, but if it came from CIPD let it pass anyway.
    if ('3.8' not in version and '3.9' not in version
            and 'chromium' not in version):
        print('=' * 60, file=sys.stderr)
        print('Unexpected Python version:', version, file=sys.stderr)
        print('=' * 60, file=sys.stderr)
        return False

    # 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')

    # Delete activation scripts. Typically they're created read-only and venv
    # will complain when trying to write over them fails.
    if os.path.isdir(venv_bin):
        for entry in os.listdir(venv_bin):
            if entry.lower().startswith('activate'):
                os.unlink(os.path.join(venv_bin, entry))

    pyvenv_cfg = os.path.join(venv_path, 'pyvenv.cfg')
    if full_envsetup or not os.path.exists(pyvenv_cfg):
        # On Mac sometimes the CIPD Python has __PYVENV_LAUNCHER__ set to
        # point to the system Python, which causes CIPD Python to create
        # virtualenvs that reference the system Python instead of the CIPD
        # Python. Clearing __PYVENV_LAUNCHER__ fixes that. See also pwbug/59.
        envcopy = os.environ.copy()
        if '__PYVENV_LAUNCHER__' in envcopy:
            del envcopy['__PYVENV_LAUNCHER__']

        cmd = (python, '-m', 'venv', '--upgrade', venv_path)
        _check_call(cmd, env=envcopy)

    venv_python = os.path.join(venv_bin, 'python')

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

    # 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)
        return _check_call(cmd)

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

    if requirements:
        requirement_args = tuple('--requirement={}'.format(req)
                                 for req in requirements)
        pip_install('--log', os.path.join(venv_path, 'pip-requirements.log'),
                    *requirement_args)

    def install_packages(gn_target):
        if gn_out_dir is None:
            build_dir = os.path.join(project_root, 'out')
        else:
            build_dir = gn_out_dir

        env_log = 'env-{}.log'.format(gn_target.name)
        env_log_path = os.path.join(venv_path, env_log)
        with open(env_log_path, 'w') as outs:
            for key, value in sorted(os.environ.items()):
                if key.upper().endswith('PATH'):
                    print(key, '=', file=outs)
                    # pylint: disable=invalid-name
                    for v in value.split(os.pathsep):
                        print('   ', v, file=outs)
                    # pylint: enable=invalid-name
                else:
                    print(key, '=', value, file=outs)

        gn_log = 'gn-gen-{}.log'.format(gn_target.name)
        gn_log_path = os.path.join(venv_path, gn_log)
        try:
            with open(gn_log_path, 'w') as outs:
                gn_cmd = (
                    'gn',
                    'gen',
                    build_dir,
                    '--args=dir_pigweed="{}"'.format(pw_root),
                )
                print(gn_cmd, file=outs)
                subprocess.check_call(gn_cmd,
                                      cwd=os.path.join(project_root,
                                                       gn_target.directory),
                                      stdout=outs,
                                      stderr=outs)
        except subprocess.CalledProcessError as err:
            with open(gn_log_path, 'r') as ins:
                raise subprocess.CalledProcessError(err.returncode, err.cmd,
                                                    ins.read())

        ninja_log = 'ninja-{}.log'.format(gn_target.name)
        ninja_log_path = os.path.join(venv_path, ninja_log)
        try:
            with open(ninja_log_path, 'w') as outs:
                ninja_cmd = ['ninja', '-C', build_dir, '-v']
                ninja_cmd.append(gn_target.target)
                print(ninja_cmd, file=outs)
                subprocess.check_call(ninja_cmd, stdout=outs, stderr=outs)
        except subprocess.CalledProcessError as err:
            with open(ninja_log_path, 'r') as ins:
                raise subprocess.CalledProcessError(err.returncode, err.cmd,
                                                    ins.read())

        with open(os.path.join(venv_path, 'pip-list.log'), 'w') as outs:
            subprocess.check_call(
                [venv_python, '-m', 'pip', 'list'],
                stdout=outs,
            )

    if gn_targets:
        if env:
            env.set('VIRTUAL_ENV', venv_path)
            env.prepend('PATH', venv_bin)
            env.clear('PYTHONHOME')
            env.clear('__PYVENV_LAUNCHER__')
            with env():
                for gn_target in gn_targets:
                    install_packages(gn_target)
        else:
            for gn_target in gn_targets:
                install_packages(gn_target)

    return True