from __future__ import unicode_literals

import contextlib
import io
import os.path
import shutil
import tarfile

from pre_commit.envcontext import envcontext
from pre_commit.envcontext import Var
from pre_commit.languages import helpers
from pre_commit.util import CalledProcessError
from pre_commit.util import clean_path_on_failure
from pre_commit.util import resource_filename
from pre_commit.xargs import xargs


ENVIRONMENT_DIR = 'rbenv'


def get_env_patch(venv, language_version):
    patches = (
        ('GEM_HOME', os.path.join(venv, 'gems')),
        ('RBENV_ROOT', venv),
        ('PATH', (
            os.path.join(venv, 'gems', 'bin'), os.pathsep,
            os.path.join(venv, 'shims'), os.pathsep,
            os.path.join(venv, 'bin'), os.pathsep, Var('PATH'),
        )),
    )
    if language_version != 'default':
        patches += (('RBENV_VERSION', language_version),)
    return patches


@contextlib.contextmanager
def in_env(repo_cmd_runner, language_version):
    envdir = os.path.join(
        repo_cmd_runner.prefix_dir,
        helpers.environment_dir(ENVIRONMENT_DIR, language_version),
    )
    with envcontext(get_env_patch(envdir, language_version)):
        yield


def _install_rbenv(repo_cmd_runner, version='default'):
    directory = helpers.environment_dir(ENVIRONMENT_DIR, version)

    with tarfile.open(resource_filename('rbenv.tar.gz')) as tf:
        tf.extractall(repo_cmd_runner.path('.'))
    shutil.move(
        repo_cmd_runner.path('rbenv'), repo_cmd_runner.path(directory),
    )

    # Only install ruby-build if the version is specified
    if version != 'default':
        # ruby-download
        with tarfile.open(resource_filename('ruby-download.tar.gz')) as tf:
            tf.extractall(repo_cmd_runner.path(directory, 'plugins'))

        # ruby-build
        with tarfile.open(resource_filename('ruby-build.tar.gz')) as tf:
            tf.extractall(repo_cmd_runner.path(directory, 'plugins'))

    activate_path = repo_cmd_runner.path(directory, 'bin', 'activate')
    with io.open(activate_path, 'w') as activate_file:
        # This is similar to how you would install rbenv to your home directory
        # However we do a couple things to make the executables exposed and
        # configure it to work in our directory.
        # We also modify the PS1 variable for manual debugging sake.
        activate_file.write(
            '#!/usr/bin/env bash\n'
            "export RBENV_ROOT='{directory}'\n"
            'export PATH="$RBENV_ROOT/bin:$PATH"\n'
            'eval "$(rbenv init -)"\n'
            'export PS1="(rbenv)$PS1"\n'
            # This lets us install gems in an isolated and repeatable
            # directory
            "export GEM_HOME='{directory}/gems'\n"
            'export PATH="$GEM_HOME/bin:$PATH"\n'
            '\n'.format(directory=repo_cmd_runner.path(directory))
        )

        # If we aren't using the system ruby, add a version here
        if version != 'default':
            activate_file.write('export RBENV_VERSION="{}"\n'.format(version))


def _install_ruby(runner, version):
    try:
        helpers.run_setup_cmd(runner, ('rbenv', 'download', version))
    except CalledProcessError:  # pragma: no cover (usually find with download)
        # Failed to download from mirror for some reason, build it instead
        helpers.run_setup_cmd(runner, ('rbenv', 'install', version))


def install_environment(
        repo_cmd_runner,
        version='default',
        additional_dependencies=(),
):
    additional_dependencies = tuple(additional_dependencies)
    directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
    with clean_path_on_failure(repo_cmd_runner.path(directory)):
        # TODO: this currently will fail if there's no version specified and
        # there's no system ruby installed.  Is this ok?
        _install_rbenv(repo_cmd_runner, version=version)
        with in_env(repo_cmd_runner, version):
            # Need to call this before installing so rbenv's directories are
            # set up
            helpers.run_setup_cmd(repo_cmd_runner, ('rbenv', 'init', '-'))
            if version != 'default':
                _install_ruby(repo_cmd_runner, version)
            # Need to call this after installing to set up the shims
            helpers.run_setup_cmd(repo_cmd_runner, ('rbenv', 'rehash'))
            helpers.run_setup_cmd(
                repo_cmd_runner,
                ('gem', 'build') + repo_cmd_runner.star('.gemspec'),
            )
            helpers.run_setup_cmd(
                repo_cmd_runner,
                (
                    ('gem', 'install', '--no-ri', '--no-rdoc') +
                    repo_cmd_runner.star('.gem') + additional_dependencies
                ),
            )


def run_hook(repo_cmd_runner, hook, file_args):
    with in_env(repo_cmd_runner, hook['language_version']):
        return xargs((hook['entry'],) + tuple(hook['args']), file_args)