"""File containing utility functions"""

import os
import tempfile
import shutil
import urllib
import sys
import subprocess
from .custom_exceptions import CalledProcessError
import tarfile

from .config import (CLANG_FORMAT_VERSION,
                    CLANG_FORMAT_HTTP_LINUX_CACHE,
                    CLANG_FORMAT_HTTP_DARWIN_CACHE,
                    CLANG_FORMAT_SOURCE_TAR_BASE, )

import logging
logger = logging.getLogger("clang-format")


def get_base_dir():
    """Get the base directory for the Git Repo.

    This script assumes that it is running in buildscripts/, and uses
    that to find the base directory.
    """
    try:
        return subprocess.check_output(
            ['git', 'rev-parse', '--show-toplevel']).rstrip()
    except:
        # We are not in a valid git directory. Use the script path instead.
        return os.path.dirname(os.path.dirname(os.path.realpath(__file__)))


def get_clang_format_from_linux_cache(dest_file):
    """Get clang-format from mongodb's cache
    """
    get_clang_format_from_cache_and_extract(
        CLANG_FORMAT_HTTP_LINUX_CACHE,
        ".gz")

    # Destination Path
    shutil.move("build/bin/clang-format", dest_file)


def get_clang_format_from_darwin_cache(dest_file):
    """Download clang-format from llvm.org, unpack the tarball,
    and put clang-format in the specified place
    """
    get_clang_format_from_cache_and_extract(
        CLANG_FORMAT_HTTP_DARWIN_CACHE,
        ".xz")

    # Destination Path
    shutil.move(get_tar_path(CLANG_FORMAT_VERSION, "x86_64-apple-darwin"),
                dest_file)


def get_clang_format_from_cache_and_extract(url, tarball_ext):
    """Get clang-format from mongodb's cache
    and extract the tarball
    """
    dest_dir = tempfile.gettempdir()
    temp_tar_file = os.path.join(dest_dir, "temp.tar" + tarball_ext)

    # Download from file
    logger.info("Downloading clang-format (Version = %s) from %s, saving to \"%s\""
                % (CLANG_FORMAT_VERSION, url, temp_tar_file))
    urllib.urlretrieve(url, temp_tar_file)

    extract_clang_format(temp_tar_file)


def get_tar_path(version, tar_path):
    """ Get the path to clang-format in the llvm tarball
    """
    return CLANG_FORMAT_SOURCE_TAR_BASE.substitute(
        version=version,
        tar_path=tar_path)


# Copied from python 2.7 version of subprocess.py
def _check_output(*popenargs, **kwargs):
    r"""Run command with arguments and return its output as a byte string.

    If the exit code was non-zero it raises a CalledProcessError.  The
    CalledProcessError object will have the return code in the returncode
    attribute and output in the output attribute.

    The arguments are the same as for the Popen constructor.  Example:

    >>> check_output(["ls", "-l", "/dev/null"])
    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'

    The stdout argument is not allowed as it is used internally.
    To capture standard error in the result, use stderr=STDOUT.

    >>> _check_output(["/bin/sh", "-c",
    ...               "ls -l non_existent_file ; exit 0"],
    ...              stderr=STDOUT)
    'ls: non_existent_file: No such file or directory\n'
    """
    if 'stdout' in kwargs:
        raise ValueError('stdout argument not allowed, it will be overridden.')
    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
    output, unused_err = process.communicate()
    retcode = process.poll()
    if retcode:
        cmd = kwargs.get("args")
        if cmd is None:
            cmd = popenargs[0]
        raise CalledProcessError(retcode, cmd, output)
    return output


def callo(args):
    """Call a program, and capture its output
    """
    return _check_output(args)


def extract_clang_format(tar_path):
    """ Extract just the clang-format binary.
    On OSX, we shell out to tar because tarfile doesn't support xz compression
    """
    if sys.platform == 'darwin':
        subprocess.call(['tar', '-xzf', tar_path, '*clang-format*'])
    # Otherwise we use tarfile because some versions of tar don't support
    # wildcards without a special flag
    else:
        tarfp = tarfile.open(tar_path)
        for name in tarfp.getnames():
            if name.endswith('clang-format'):
                tarfp.extract(name)
        tarfp.close()
