# utils.py -- Git compatibility utilities
# Copyright (C) 2010 Google, Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2
# of the License or (at your option) any later version of
# the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA  02110-1301, USA.

"""Utilities for interacting with cgit."""

import errno
import functools
import os
import shutil
import socket
import stat
import subprocess
import sys
import tempfile
import time

from dulwich.repo import Repo
from dulwich.protocol import TCP_GIT_PORT

from dulwich.tests import (
    get_safe_env,
    SkipTest,
    TestCase,
    )

_DEFAULT_GIT = 'git'
_VERSION_LEN = 4
_REPOS_DATA_DIR = os.path.abspath(os.path.join(
    os.path.dirname(__file__), os.pardir, 'data', 'repos'))


def git_version(git_path=_DEFAULT_GIT):
    """Attempt to determine the version of git currently installed.

    :param git_path: Path to the git executable; defaults to the version in
        the system path.
    :return: A tuple of ints of the form (major, minor, point, sub-point), or
        None if no git installation was found.
    """
    try:
        output = run_git_or_fail(['--version'], git_path=git_path)
    except OSError:
        return None
    version_prefix = b'git version '
    if not output.startswith(version_prefix):
        return None

    parts = output[len(version_prefix):].split(b'.')
    nums = []
    for part in parts:
        try:
            nums.append(int(part))
        except ValueError:
            break

    while len(nums) < _VERSION_LEN:
        nums.append(0)
    return tuple(nums[:_VERSION_LEN])


def require_git_version(required_version, git_path=_DEFAULT_GIT):
    """Require git version >= version, or skip the calling test.

    :param required_version: A tuple of ints of the form (major, minor, point,
        sub-point); ommitted components default to 0.
    :param git_path: Path to the git executable; defaults to the version in
        the system path.
    :raise ValueError: if the required version tuple has too many parts.
    :raise SkipTest: if no suitable git version was found at the given path.
    """
    found_version = git_version(git_path=git_path)
    if found_version is None:
        raise SkipTest('Test requires git >= %s, but c git not found' %
                       (required_version, ))

    if len(required_version) > _VERSION_LEN:
        raise ValueError('Invalid version tuple %s, expected %i parts' %
                         (required_version, _VERSION_LEN))

    required_version = list(required_version)
    while len(found_version) < len(required_version):
        required_version.append(0)
    required_version = tuple(required_version)

    if found_version < required_version:
        required_version = '.'.join(map(str, required_version))
        found_version = '.'.join(map(str, found_version))
        raise SkipTest('Test requires git >= %s, found %s' %
                       (required_version, found_version))


def run_git(args, git_path=_DEFAULT_GIT, input=None, capture_stdout=False,
            **popen_kwargs):
    """Run a git command.

    Input is piped from the input parameter and output is sent to the standard
    streams, unless capture_stdout is set.

    :param args: A list of args to the git command.
    :param git_path: Path to to the git executable.
    :param input: Input data to be sent to stdin.
    :param capture_stdout: Whether to capture and return stdout.
    :param popen_kwargs: Additional kwargs for subprocess.Popen;
        stdin/stdout args are ignored.
    :return: A tuple of (returncode, stdout contents). If capture_stdout is
        False, None will be returned as stdout contents.
    :raise OSError: if the git executable was not found.
    """

    env = get_safe_env(popen_kwargs.pop('env', None))
    env['LC_ALL'] = env['LANG'] = 'C'

    args = [git_path] + args
    popen_kwargs['stdin'] = subprocess.PIPE
    if capture_stdout:
        popen_kwargs['stdout'] = subprocess.PIPE
    else:
        popen_kwargs.pop('stdout', None)
    p = subprocess.Popen(args, env=env, **popen_kwargs)
    stdout, stderr = p.communicate(input=input)
    return (p.returncode, stdout)


def run_git_or_fail(args, git_path=_DEFAULT_GIT, input=None, **popen_kwargs):
    """Run a git command, capture stdout/stderr, and fail if git fails."""
    if 'stderr' not in popen_kwargs:
        popen_kwargs['stderr'] = subprocess.STDOUT
    returncode, stdout = run_git(args, git_path=git_path, input=input,
                                 capture_stdout=True, **popen_kwargs)
    if returncode != 0:
        raise AssertionError("git with args %r failed with %d: %r" % (
            args, returncode, stdout))
    return stdout


def import_repo_to_dir(name):
    """Import a repo from a fast-export file in a temporary directory.

    These are used rather than binary repos for compat tests because they are
    more compact and human-editable, and we already depend on git.

    :param name: The name of the repository export file, relative to
        dulwich/tests/data/repos.
    :returns: The path to the imported repository.
    """
    temp_dir = tempfile.mkdtemp()
    export_path = os.path.join(_REPOS_DATA_DIR, name)
    temp_repo_dir = os.path.join(temp_dir, name)
    export_file = open(export_path, 'rb')
    run_git_or_fail(['init', '--quiet', '--bare', temp_repo_dir])
    run_git_or_fail(['fast-import'], input=export_file.read(),
                    cwd=temp_repo_dir)
    export_file.close()
    return temp_repo_dir


def check_for_daemon(limit=10, delay=0.1, timeout=0.1, port=TCP_GIT_PORT):
    """Check for a running TCP daemon.

    Defaults to checking 10 times with a delay of 0.1 sec between tries.

    :param limit: Number of attempts before deciding no daemon is running.
    :param delay: Delay between connection attempts.
    :param timeout: Socket timeout for connection attempts.
    :param port: Port on which we expect the daemon to appear.
    :returns: A boolean, true if a daemon is running on the specified port,
        false if not.
    """
    for _ in range(limit):
        time.sleep(delay)
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.settimeout(delay)
        try:
            s.connect(('localhost', port))
            return True
        except socket.timeout:
            pass
        except socket.error as e:
            if getattr(e, 'errno', False) and e.errno != errno.ECONNREFUSED:
                raise
            elif e.args[0] != errno.ECONNREFUSED:
                raise
        finally:
            s.close()
    return False


class CompatTestCase(TestCase):
    """Test case that requires git for compatibility checks.

    Subclasses can change the git version required by overriding
    min_git_version.
    """

    min_git_version = (1, 5, 0)

    def setUp(self):
        super(CompatTestCase, self).setUp()
        require_git_version(self.min_git_version)

    def assertObjectStoreEqual(self, store1, store2):
        self.assertEqual(sorted(set(store1)), sorted(set(store2)))

    def assertReposEqual(self, repo1, repo2):
        self.assertEqual(repo1.get_refs(), repo2.get_refs())
        self.assertObjectStoreEqual(repo1.object_store, repo2.object_store)

    def assertReposNotEqual(self, repo1, repo2):
        refs1 = repo1.get_refs()
        objs1 = set(repo1.object_store)
        refs2 = repo2.get_refs()
        objs2 = set(repo2.object_store)
        self.assertFalse(refs1 == refs2 and objs1 == objs2)

    def import_repo(self, name):
        """Import a repo from a fast-export file in a temporary directory.

        :param name: The name of the repository export file, relative to
            dulwich/tests/data/repos.
        :returns: An initialized Repo object that lives in a temporary directory.
        """
        path = import_repo_to_dir(name)
        repo = Repo(path)
        def cleanup():
            repo.close()
            rmtree_ro(os.path.dirname(path.rstrip(os.sep)))
        self.addCleanup(cleanup)
        return repo


if sys.platform == 'win32':
    def remove_ro(action, name, exc):
        os.chmod(name, stat.S_IWRITE)
        os.remove(name)

    rmtree_ro = functools.partial(shutil.rmtree, onerror=remove_ro)
else:
    rmtree_ro = shutil.rmtree
