# -*- coding: utf-8 -*-

"""

    vcs.backends.git.repository

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Git repository implementation.

    :created_on: Apr 8, 2010

    :copyright: (c) 2010-2011 by Marcin Kuzminski, Lukasz Balcerzak.

"""

import errno

import logging

import os

import re

import time

import urllib.error

import urllib.parse

import urllib.request

from collections import OrderedDict

import mercurial.util  # import url as hg_url

from dulwich.client import SubprocessGitClient

from dulwich.config import ConfigFile

from dulwich.objects import Tag

from dulwich.repo import NotGitRepository, Repo

from dulwich.server import update_server_info

from kallithea.lib.vcs import subprocessio

from kallithea.lib.vcs.backends.base import BaseRepository, CollectionGenerator

from kallithea.lib.vcs.conf import settings

from kallithea.lib.vcs.exceptions import (BranchDoesNotExistError, ChangesetDoesNotExistError, EmptyRepositoryError, RepositoryError, TagAlreadyExistError,

                                          TagDoesNotExistError)

from kallithea.lib.vcs.utils import ascii_bytes, ascii_str, date_fromtimestamp, makedate, safe_bytes, safe_str

from kallithea.lib.vcs.utils.helpers import get_urllib_request_handlers

from kallithea.lib.vcs.utils.lazy import LazyProperty

from kallithea.lib.vcs.utils.paths import abspath, get_user_home

from . import changeset, inmemory, workdir

SHA_PATTERN = re.compile(r'^([0-9a-fA-F]{12}|[0-9a-fA-F]{40})$')

log = logging.getLogger(__name__)

class GitRepository(BaseRepository):

    """

    Git repository backend.

    """

    DEFAULT_BRANCH_NAME = 'master'

    scm = 'git'

    def __init__(self, repo_path, create=False, src_url=None,

                 update_after_clone=False, bare=False, baseui=None):

        baseui  # unused

        self.path = abspath(repo_path)

        self.repo = self._get_repo(create, src_url, update_after_clone, bare)

        self.bare = self.repo.bare

    @property

    def _config_files(self):

        return [

            self.bare and abspath(self.path, 'config')

                      or abspath(self.path, '.git', 'config'),

             abspath(get_user_home(), '.gitconfig'),

         ]

    @property

    def _repo(self):

        return self.repo

    @property

    def head(self):

        try:

            return self._repo.head()

        except KeyError:

            return None

    @property

    def _empty(self):

        """

        Checks if repository is empty ie. without any changesets

        """

        try:

            self.revisions[0]

        except (KeyError, IndexError):

            return True

        return False

    @LazyProperty

    def revisions(self):

        """

        Returns list of revisions' ids, in ascending order.  Being lazy

        attribute allows external tools to inject shas from cache.

        """

        return self._get_all_revisions()

    @classmethod

    def _run_git_command(cls, cmd, cwd=None):

        """

        Runs given ``cmd`` as git command and returns output bytes in a tuple

        (stdout, stderr) ... or raise RepositoryError.

        :param cmd: git command to be executed

        :param cwd: passed directly to subprocess

        """

        # need to clean fix GIT_DIR !

        gitenv = dict(os.environ)

        gitenv.pop('GIT_DIR', None)

        gitenv['GIT_CONFIG_NOGLOBAL'] = '1'

        assert isinstance(cmd, list), cmd

        cmd = [settings.GIT_EXECUTABLE_PATH, '-c', 'core.quotepath=false'] + cmd

        try:

            p = subprocessio.SubprocessIOChunker(cmd, cwd=cwd, env=gitenv, shell=False)

        except (EnvironmentError, OSError) as err:

            # output from the failing process is in str(EnvironmentError)

            msg = ("Couldn't run git command %s.\n"

                   "Subprocess failed with '%s': %s\n" %

                   (cmd, type(err).__name__, err)

            ).strip()

            log.error(msg)

            raise RepositoryError(msg)

        try:

            stdout = b''.join(p.output)

            stderr = b''.join(p.error)

        finally:

            p.close()

        # TODO: introduce option to make commands fail if they have any stderr output?

        if stderr:

            log.debug('stderr from %s:\n%s', cmd, stderr)

        else:

            log.debug('stderr from %s: None', cmd)

        return stdout, stderr

    def run_git_command(self, cmd):

        """

        Runs given ``cmd`` as git command with cwd set to current repo.

        Returns stdout as unicode str ... or raise RepositoryError.

        """

        cwd = None

        if os.path.isdir(self.path):

            cwd = self.path

        stdout, _stderr = self._run_git_command(cmd, cwd=cwd)

        return safe_str(stdout)

        """

        """

        # check first if it's not an local url

        if os.path.isabs(url) and os.path.isdir(url):

        if url.startswith('git://'):

            try:

                _git_colon, _empty, _host, path = url.split('/', 3)

            except ValueError:

                raise urllib.error.URLError("Invalid URL: %r" % url)

            # Mitigate problems elsewhere with incorrect handling of encoded paths.

            # Don't trust urllib.parse.unquote but be prepared for more flexible implementations elsewhere.

            # Space is the only allowed whitespace character - directly or % encoded. No other % or \ is allowed.

            for c in path.replace('%20', ' '):

                if c in '%\\':

                    raise urllib.error.URLError("Invalid escape character in path: '%s'" % c)

                if c.isspace() and c != ' ':

                    raise urllib.error.URLError("Invalid whitespace character in path: %r" % c)

        if not url.startswith('http://') and not url.startswith('https://'):

            raise urllib.error.URLError("Unsupported protocol in URL %s" % url)

        url_obj = mercurial.util.url(safe_bytes(url))

        test_uri, handlers = get_urllib_request_handlers(url_obj)

        if not test_uri.endswith(b'info/refs'):

            test_uri = test_uri.rstrip(b'/') + b'/info/refs'

        url_obj.passwd = b'*****'

        cleaned_uri = str(url_obj)

        o = urllib.request.build_opener(*handlers)

        o.addheaders = [('User-Agent', 'git/1.7.8.0')]  # fake some git

        req = urllib.request.Request(

            "%s?%s" % (

                safe_str(test_uri),

                urllib.parse.urlencode({"service": 'git-upload-pack'})

            ))

        try:

            resp = o.open(req)

            if resp.code != 200:

                raise Exception('Return Code is not 200')

        except Exception as e:

            # means it cannot be cloned

            raise urllib.error.URLError("[%s] org_exc: %s" % (cleaned_uri, e))

        # now detect if it's proper git repo

        gitdata = resp.read()

        if b'service=git-upload-pack' not in gitdata:

            raise urllib.error.URLError(

                "url [%s] does not look like an git" % cleaned_uri)

    def _get_repo(self, create, src_url=None, update_after_clone=False,

                  bare=False):

        if create and os.path.exists(self.path):

            raise RepositoryError("Location already exist")

        if src_url and not create:

            raise RepositoryError("Create should be set to True if src_url is "

                                  "given (clone operation creates repository)")

        try:

            if create and src_url:

                GitRepository._check_url(src_url)

                self.clone(src_url, update_after_clone, bare)

                return Repo(self.path)

            elif create:

                os.makedirs(self.path)

                if bare:

                    return Repo.init_bare(self.path)

                else:

                    return Repo.init(self.path)

            else:

                return Repo(self.path)

        except (NotGitRepository, OSError) as err:

            raise RepositoryError(err)

    def _get_all_revisions(self):

        # we must check if this repo is not empty, since later command

        # fails if it is. And it's cheaper to ask than throw the subprocess

        # errors

        try:

            self._repo.head()

        except KeyError:

            return []

        rev_filter = settings.GIT_REV_FILTER

        cmd = ['rev-list', rev_filter, '--reverse', '--date-order']

        try:

            so = self.run_git_command(cmd)

        except RepositoryError:

            # Can be raised for empty repositories

            return []

        return so.splitlines()

    def _get_all_revisions2(self):

        # alternate implementation using dulwich

        includes = [ascii_str(sha) for key, (sha, type_) in self._parsed_refs.items()

                    if type_ != b'T']

        return [c.commit.id for c in self._repo.get_walker(include=includes)]

    def _get_revision(self, revision):

        """

        Given any revision identifier, returns a 40 char string with revision hash.

        """

        if self._empty:

            raise EmptyRepositoryError("There are no changesets yet")

        if revision in (None, '', 'tip', 'HEAD', 'head', -1):

            revision = -1

        if isinstance(revision, int):

            try:

                return self.revisions[revision]

            except IndexError:

                msg = "Revision %r does not exist for %s" % (revision, self.name)

                raise ChangesetDoesNotExistError(msg)

        if isinstance(revision, str):

            if revision.isdigit() and (len(revision) < 12 or len(revision) == revision.count('0')):

                try:

                    return self.revisions[int(revision)]

                except IndexError:

                    msg = "Revision %r does not exist for %s" % (revision, self)

                    raise ChangesetDoesNotExistError(msg)

            # get by branch/tag name

            _ref_revision = self._parsed_refs.get(safe_bytes(revision))

            if _ref_revision:  # and _ref_revision[1] in [b'H', b'RH', b'T']:

                return ascii_str(_ref_revision[0])

            if revision in self.revisions:

                return revision

            # maybe it's a tag ? we don't have them in self.revisions

            if revision in self.tags.values():

                return revision

            if SHA_PATTERN.match(revision):

                msg = "Revision %r does not exist for %s" % (revision, self.name)

                raise ChangesetDoesNotExistError(msg)

        raise ChangesetDoesNotExistError("Given revision %r not recognized" % revision)

    def get_ref_revision(self, ref_type, ref_name):

        """

        Returns ``GitChangeset`` object representing repository's

        changeset at the given ``revision``.

        """

        return self._get_revision(ref_name)

    def _get_archives(self, archive_name='tip'):

        for i in [('zip', '.zip'), ('gz', '.tar.gz'), ('bz2', '.tar.bz2')]:

            yield {"type": i[0], "extension": i[1], "node": archive_name}

    def _get_url(self, url):

        """

        Returns normalized url. If schema is not given, would fall to

        filesystem (``file:///``) schema.

        """

        if url != 'default' and '://' not in url:

            url = ':///'.join(('file', url))

        return url

    @LazyProperty

    def name(self):

        return os.path.basename(self.path)

    @LazyProperty

    def last_change(self):

        """

        Returns last change made on this repository as datetime object

        """

        return date_fromtimestamp(self._get_mtime(), makedate()[1])

    def _get_mtime(self):

        try:

            return time.mktime(self.get_changeset().date.timetuple())

        except RepositoryError:

            idx_loc = '' if self.bare else '.git'

            # fallback to filesystem

            in_path = os.path.join(self.path, idx_loc, "index")

            he_path = os.path.join(self.path, idx_loc, "HEAD")

            if os.path.exists(in_path):

                return os.stat(in_path).st_mtime

            else:

                return os.stat(he_path).st_mtime

    @LazyProperty

    def description(self):

        return safe_str(self._repo.get_description() or b'unknown')

    @LazyProperty

    def contact(self):

        undefined_contact = 'Unknown'

        return undefined_contact

    @property

    def branches(self):

        if not self.revisions:

            return {}

        _branches = [(safe_str(key), ascii_str(sha))

                     for key, (sha, type_) in self._parsed_refs.items() if type_ == b'H']

        return OrderedDict(sorted(_branches, key=(lambda ctx: ctx[0]), reverse=False))

    @LazyProperty

    def closed_branches(self):

        return {}

    @LazyProperty

    def tags(self):

        return self._get_tags()

    def _get_tags(self):

        if not self.revisions:

            return {}

        _tags = [(safe_str(key), ascii_str(sha))

                 for key, (sha, type_) in self._parsed_refs.items() if type_ == b'T']

        return OrderedDict(sorted(_tags, key=(lambda ctx: ctx[0]), reverse=True))

    def tag(self, name, user, revision=None, message=None, date=None,

            **kwargs):

        """

        Creates and returns a tag for the given ``revision``.

        :param name: name for new tag

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param revision: changeset id for which new tag would be created

        :param message: message of the tag's commit

        :param date: date of tag's commit

        :raises TagAlreadyExistError: if tag with same name already exists

        """

        if name in self.tags:

            raise TagAlreadyExistError("Tag %s already exists" % name)

        changeset = self.get_changeset(revision)

        message = message or "Added tag %s for commit %s" % (name,

            changeset.raw_id)

        self._repo.refs[b"refs/tags/%s" % safe_bytes(name)] = changeset._commit.id

        self._parsed_refs = self._get_parsed_refs()

        self.tags = self._get_tags()

        return changeset

    def remove_tag(self, name, user, message=None, date=None):

    @LazyProperty

    def revisions(self):

        """

        Returns list of revisions' ids, in ascending order.  Being lazy

        attribute allows external tools to inject shas from cache.

        """

        return self._get_all_revisions()

    @LazyProperty

    def name(self):

        return os.path.basename(self.path)

    @LazyProperty

    def branches(self):

        return self._get_branches()

    @LazyProperty

    def closed_branches(self):

        return self._get_branches(normal=False, closed=True)

    @LazyProperty

    def allbranches(self):

        """

        List all branches, including closed branches.

        """

        return self._get_branches(closed=True)

    def _get_branches(self, normal=True, closed=False):

        """

        Gets branches for this repository

        Returns only not closed branches by default

        :param closed: return also closed branches for mercurial

        :param normal: return also normal branches

        """

        if self._empty:

            return {}

        bt = OrderedDict()

        for bn, _heads, node, isclosed in sorted(self._repo.branchmap().iterbranches()):

            if isclosed:

                if closed:

                    bt[safe_str(bn)] = ascii_str(mercurial.node.hex(node))

            else:

                if normal:

                    bt[safe_str(bn)] = ascii_str(mercurial.node.hex(node))

        return bt

    @LazyProperty

    def tags(self):

        """

        Gets tags for this repository

        """

        return self._get_tags()

    def _get_tags(self):

        if self._empty:

            return {}

        return OrderedDict(sorted(

            ((safe_str(n), ascii_str(mercurial.node.hex(h))) for n, h in self._repo.tags().items()),

            reverse=True,

            key=lambda x: x[0],  # sort by name

        ))

    def tag(self, name, user, revision=None, message=None, date=None,

            **kwargs):

        """

        Creates and returns a tag for the given ``revision``.

        :param name: name for new tag

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param revision: changeset id for which new tag would be created

        :param message: message of the tag's commit

        :param date: date of tag's commit

        :raises TagAlreadyExistError: if tag with same name already exists

        """

        if name in self.tags:

            raise TagAlreadyExistError("Tag %s already exists" % name)

        changeset = self.get_changeset(revision)

        local = kwargs.setdefault('local', False)

        if message is None:

            message = "Added tag %s for changeset %s" % (name,

                changeset.short_id)

        if date is None:

            date = safe_bytes(datetime.datetime.now().strftime('%a, %d %b %Y %H:%M:%S'))

        try:

            mercurial.tags.tag(self._repo, safe_bytes(name), changeset._ctx.node(), safe_bytes(message), local, safe_bytes(user), date)

        except mercurial.error.Abort as e:

            raise RepositoryError(e.args[0])

        # Reinitialize tags

        self.tags = self._get_tags()

        tag_id = self.tags[name]

        return self.get_changeset(revision=tag_id)

    def remove_tag(self, name, user, message=None, date=None):

        """

        Removes tag with the given ``name``.

        :param name: name of the tag to be removed

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param message: message of the tag's removal commit

        :param date: date of tag's removal commit

        :raises TagDoesNotExistError: if tag with given name does not exists

        """

        if name not in self.tags:

            raise TagDoesNotExistError("Tag %s does not exist" % name)

        if message is None:

            message = "Removed tag %s" % name

        if date is None:

            date = safe_bytes(datetime.datetime.now().strftime('%a, %d %b %Y %H:%M:%S'))

        local = False

        try:

            mercurial.tags.tag(self._repo, safe_bytes(name), mercurial.commands.nullid, safe_bytes(message), local, safe_bytes(user), date)

            self.tags = self._get_tags()

        except mercurial.error.Abort as e:

            raise RepositoryError(e.args[0])

    @LazyProperty

    def bookmarks(self):

        """

        Gets bookmarks for this repository

        """

        return self._get_bookmarks()

    def _get_bookmarks(self):

        if self._empty:

            return {}

        return OrderedDict(sorted(

            ((safe_str(n), ascii_str(mercurial.node.hex(h))) for n, h in self._repo._bookmarks.items()),

            reverse=True,

            key=lambda x: x[0],  # sort by name

        ))

    def _get_all_revisions(self):

        return [ascii_str(self._repo[x].hex()) for x in self._repo.filtered(b'visible').changelog.revs()]

    def get_diff(self, rev1, rev2, path='', ignore_whitespace=False,

                  context=3):

        """

        Returns (git like) *diff*, as plain text. Shows changes introduced by

        ``rev2`` since ``rev1``.

        :param rev1: Entry point from which diff is shown. Can be

          ``self.EMPTY_CHANGESET`` - in this case, patch showing all

          the changes since empty state of the repository until ``rev2``

        :param rev2: Until which revision changes should be shown.

        :param ignore_whitespace: If set to ``True``, would not show whitespace

          changes. Defaults to ``False``.

        :param context: How many lines before/after changed lines should be

          shown. Defaults to ``3``. If negative value is passed-in, it will be

          set to ``0`` instead.

        """

        # Negative context values make no sense, and will result in

        # errors. Ensure this does not happen.

        if context < 0:

            context = 0

        if hasattr(rev1, 'raw_id'):

            rev1 = getattr(rev1, 'raw_id')

        if hasattr(rev2, 'raw_id'):

            rev2 = getattr(rev2, 'raw_id')

        # Check if given revisions are present at repository (may raise

        # ChangesetDoesNotExistError)

        if rev1 != self.EMPTY_CHANGESET:

            self.get_changeset(rev1)

        self.get_changeset(rev2)

        if path:

            file_filter = mercurial.match.exact([safe_bytes(path)])

        else:

            file_filter = None

        return b''.join(mercurial.patch.diff(self._repo, rev1, rev2, match=file_filter,

                          opts=mercurial.mdiff.diffopts(git=True,

                                        showfunc=True,

                                        ignorews=ignore_whitespace,

                                        context=context)))

        On failures it'll raise urllib2.HTTPError, exception is also thrown

        when the return code is non 200

        """

        # check first if it's not an local url

        url = safe_bytes(url)

        if os.path.isdir(url) or url.startswith(b'file:'):

        if url.startswith(b'ssh:'):

            # in case of invalid uri or authentication issues, sshpeer will

            # throw an exception.

            mercurial.sshpeer.instance(repoui or mercurial.ui.ui(), url, False).lookup(b'tip')

        url_prefix = None

        if b'+' in url[:url.find(b'://')]:

            url_prefix, url = url.split(b'+', 1)

        url_obj = mercurial.util.url(url)

        test_uri, handlers = get_urllib_request_handlers(url_obj)

        url_obj.passwd = b'*****'

        cleaned_uri = str(url_obj)

        o = urllib.request.build_opener(*handlers)

        o.addheaders = [('Content-Type', 'application/mercurial-0.1'),

                        ('Accept', 'application/mercurial-0.1')]

        req = urllib.request.Request(

            "%s?%s" % (

                safe_str(test_uri),

                urllib.parse.urlencode({

                    'cmd': 'between',

                    'pairs': "%s-%s" % ('0' * 40, '0' * 40),

                })

            ))

        try:

            resp = o.open(req)

            if resp.code != 200:

                raise Exception('Return Code is not 200')

        except Exception as e:

            # means it cannot be cloned

            raise urllib.error.URLError("[%s] org_exc: %s" % (cleaned_uri, e))

        if not url_prefix: # skip git+http://... etc

            # now check if it's a proper hg repo

            try:

                mercurial.httppeer.instance(repoui or mercurial.ui.ui(), url, False).lookup(b'tip')

            except Exception as e:

                raise urllib.error.URLError(

                    "url [%s] does not look like an hg repo org_exc: %s"

                    % (cleaned_uri, e))

    def _get_repo(self, create, src_url=None, update_after_clone=False):

        """

        Function will check for mercurial repository in given path and return

        a localrepo object. If there is no repository in that path it will

        raise an exception unless ``create`` parameter is set to True - in

        that case repository would be created and returned.

        If ``src_url`` is given, would try to clone repository from the

        location at given clone_point. Additionally it'll make update to

        working copy accordingly to ``update_after_clone`` flag

        """

        try:

            if src_url:

                url = safe_bytes(self._get_url(src_url))

                opts = {}

                if not update_after_clone:

                    opts.update({'noupdate': True})

                MercurialRepository._check_url(url, self.baseui)

                mercurial.commands.clone(self.baseui, url, safe_bytes(self.path), **opts)

                # Don't try to create if we've already cloned repo

                create = False

            return mercurial.localrepo.instance(self.baseui, safe_bytes(self.path), create=create)

        except (mercurial.error.Abort, mercurial.error.RepoError) as err:

            if create:

                msg = "Cannot create repository at %s. Original error was %s" \

                    % (self.name, err)

            else:

                msg = "Not valid repository at %s. Original error was %s" \

                    % (self.name, err)

            raise RepositoryError(msg)

    @LazyProperty

    def in_memory_changeset(self):

        return inmemory.MercurialInMemoryChangeset(self)

    @LazyProperty

    def description(self):

        _desc = self._repo.ui.config(b'web', b'description', None, untrusted=True)

        return safe_str(_desc or b'unknown')

    @LazyProperty

    def contact(self):

        return safe_str(mercurial.hgweb.common.get_contact(self._repo.ui.config)

                            or b'Unknown')

    @LazyProperty

    def last_change(self):

        """

        Returns last change made on this repository as datetime object

        """

        return date_fromtimestamp(self._get_mtime(), makedate()[1])

    def _get_mtime(self):

        try:

            return time.mktime(self.get_changeset().date.timetuple())

        except RepositoryError:

            # fallback to filesystem

            cl_path = os.path.join(self.path, '.hg', "00changelog.i")

            st_path = os.path.join(self.path, '.hg', "store")

            if os.path.exists(cl_path):

                return os.stat(cl_path).st_mtime

            else:

                return os.stat(st_path).st_mtime

    def _get_revision(self, revision):

        """

        Given any revision identifier, returns a 40 char string with revision hash.

        :param revision: str or int or None

        """

        if self._empty:

            raise EmptyRepositoryError("There are no changesets yet")

        if revision in [-1, None]:

            revision = b'tip'

        elif isinstance(revision, str):

            revision = safe_bytes(revision)

        try:

            if isinstance(revision, int):

                return ascii_str(self._repo[revision].hex())

            return ascii_str(mercurial.scmutil.revsymbol(self._repo, revision).hex())

        except (IndexError, ValueError, mercurial.error.RepoLookupError, TypeError):

            msg = "Revision %r does not exist for %s" % (safe_str(revision), self.name)

            raise ChangesetDoesNotExistError(msg)

        except (LookupError, ):

            msg = "Ambiguous identifier `%s` for %s" % (safe_str(revision), self.name)

            raise ChangesetDoesNotExistError(msg)

    def get_ref_revision(self, ref_type, ref_name):

        """

        Returns revision number for the given reference.

        """

        if ref_type == 'rev' and not ref_name.strip('0'):

            return self.EMPTY_CHANGESET

        # lookup up the exact node id

        _revset_predicates = {

                'branch': 'branch',

                'book': 'bookmark',

                'tag': 'tag',

                'rev': 'id',

            }

        # avoid expensive branch(x) iteration over whole repo

        rev_spec = "%%s & %s(%%s)" % _revset_predicates[ref_type]

        try:

            revs = self._repo.revs(rev_spec, ref_name, ref_name)

        except LookupError:

            msg = "Ambiguous identifier %s:%s for %s" % (ref_type, ref_name, self.name)

            raise ChangesetDoesNotExistError(msg)

        except mercurial.error.RepoLookupError:

            msg = "Revision %s:%s does not exist for %s" % (ref_type, ref_name, self.name)

            raise ChangesetDoesNotExistError(msg)

        if revs:

            revision = revs.last()

        else:

            # TODO: just report 'not found'?

            revision = ref_name

        return self._get_revision(revision)

    def _get_archives(self, archive_name='tip'):

        allowed = self.baseui.configlist(b"web", b"allow_archive",

                                         untrusted=True)

        for name, ext in [(b'zip', '.zip'), (b'gz', '.tar.gz'), (b'bz2', '.tar.bz2')]:

            if name in allowed or self._repo.ui.configbool(b"web",

                                                           b"allow" + name,

                                                           untrusted=True):

                yield {"type": safe_str(name), "extension": ext, "node": archive_name}

    def _get_url(self, url):

        """

        Returns normalized url. If schema is not given, fall back to

        filesystem (``file:///``) schema.

        """

        if url != 'default' and '://' not in url:

            url = "file:" + urllib.request.pathname2url(url)

        return url

    def get_changeset(self, revision=None):

        """

        Returns ``MercurialChangeset`` object representing repository's

        changeset at the given ``revision``.

        """

        return changeset.MercurialChangeset(repository=self, revision=self._get_revision(revision))

    def get_changesets(self, start=None, end=None, start_date=None,

                       end_date=None, branch_name=None, reverse=False, max_revisions=None):

        """

        Returns iterator of ``MercurialChangeset`` objects from start to end

        (both are inclusive)

        :param start: None, str, int or mercurial lookup format

        :param end:  None, str, int or mercurial lookup format

        :param start_date:

        :param end_date:

        :param branch_name:

        :param reversed: return changesets in reversed order

        """

        start_raw_id = self._get_revision(start)

        start_pos = None if start is None else self.revisions.index(start_raw_id)

        end_raw_id = self._get_revision(end)

        end_pos = None if end is None else self.revisions.index(end_raw_id)

        if start_pos is not None and end_pos is not None and start_pos > end_pos:

            raise RepositoryError("Start revision '%s' cannot be "

                                  "after end revision '%s'" % (start, end))

        if branch_name and branch_name not in self.allbranches:

            msg = "Branch %r not found in %s" % (branch_name, self.name)

            raise BranchDoesNotExistError(msg)

        if end_pos is not None:

            end_pos += 1

        # filter branches

        filter_ = []

        if branch_name:

            filter_.append(b'branch("%s")' % safe_bytes(branch_name))

        if start_date:

            filter_.append(b'date(">%s")' % safe_bytes(str(start_date)))

        if end_date:

            filter_.append(b'date("<%s")' % safe_bytes(str(end_date)))

        if filter_ or max_revisions:

            if filter_:

                revspec = b' and '.join(filter_)

            else:

                revspec = b'all()'

            if max_revisions:

                revspec = b'limit(%s, %d)' % (revspec, max_revisions)

            revisions = mercurial.scmutil.revrange(self._repo, [revspec])

        else:

            revisions = self.revisions

        # this is very much a hack to turn this into a list; a better solution