from __future__ import absolute_import

import errno

import os

import posixpath

import stat

from .i18n import _

from . import (

    encoding,

    error,

    util,

)

def _lowerclean(s):

    return encoding.hfsignoreclean(s.lower())

class pathauditor(object):

    '''ensure that a filesystem path contains no banned components.

    the following properties of a path are checked:

    - ends with a directory separator

    - under top-level .hg

    - starts at the root of a windows drive

    - contains ".."

    More check are also done about the file system states:

    - traverses a symlink (e.g. a/symlink_here/b)

    - inside a nested repository (a callback can be used to approve

      some nested repositories, e.g., subrepositories)

    The file system checks are only done when 'realfs' is set to True (the

    default). They should be disable then we are auditing path for operation on

    stored history.

    '''

    def __init__(self, root, callback=None, realfs=True):

        self.audited = set()

        self.auditeddir = set()

        self.root = root

        self._realfs = realfs

        self.callback = callback

        if os.path.lexists(root) and not util.fscasesensitive(root):

            self.normcase = util.normcase

        else:

            self.normcase = lambda x: x

    def __call__(self, path):

        '''Check the relative path.

        path may contain a pattern (e.g. foodir/**.txt)'''

        path = util.localpath(path)

        normpath = self.normcase(path)

        if normpath in self.audited:

            return

        # AIX ignores "/" at end of path, others raise EISDIR.

        if util.endswithsep(path):

            raise error.Abort(_("path ends in directory separator: %s") % path)

        parts = util.splitpath(path)

        if (os.path.splitdrive(path)[0]

            or _lowerclean(parts[0]) in ('.hg', '.hg.', '')

            or os.pardir in parts):

            raise error.Abort(_("path contains illegal component: %s") % path)

        # Windows shortname aliases

        for p in parts:

            if "~" in p:

                first, last = p.split("~", 1)

                if last.isdigit() and first.upper() in ["HG", "HG8B6C"]:

                    raise error.Abort(_("path contains illegal component: %s")

                                     % path)

        if '.hg' in _lowerclean(path):

            lparts = [_lowerclean(p.lower()) for p in parts]

            for p in '.hg', '.hg.':

                if p in lparts[1:]:

                    pos = lparts.index(p)

                    base = os.path.join(*parts[:pos])

                    raise error.Abort(_("path '%s' is inside nested repo %r")

                                     % (path, base))

        normparts = util.splitpath(normpath)

        assert len(parts) == len(normparts)

        parts.pop()

        normparts.pop()

        prefixes = []

        # It's important that we check the path parts starting from the root.

        # This means we won't accidentaly traverse a symlink into some other

        # filesystem (which is potentially expensive to access).

        for i in range(len(parts)):

            prefix = os.sep.join(parts[:i + 1])

            normprefix = os.sep.join(normparts[:i + 1])

            if normprefix in self.auditeddir:

                continue

            if self._realfs:

                self._checkfs(prefix, path)

            prefixes.append(normprefix)

        self.audited.add(normpath)

        # only add prefixes to the cache after checking everything: we don't

        # want to add "foo/bar/baz" before checking if there's a "foo/.hg"

        self.auditeddir.update(prefixes)

    def _checkfs(self, prefix, path):

        """raise exception if a file system backed check fails"""

        curpath = os.path.join(self.root, prefix)

        try:

            st = os.lstat(curpath)

        except OSError as err:

            # EINVAL can be raised as invalid path syntax under win32.

            # They must be ignored for patterns can be checked too.

            if err.errno not in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL):

                raise

        else:

            if stat.S_ISLNK(st.st_mode):

                msg = _('path %r traverses symbolic link %r') % (path, prefix)

                raise error.Abort(msg)

            elif (stat.S_ISDIR(st.st_mode) and

                  os.path.isdir(os.path.join(curpath, '.hg'))):

                if not self.callback or not self.callback(curpath):

                    msg = _("path '%s' is inside nested repo %r")

                    raise error.Abort(msg % (path, prefix))

    def check(self, path):

        try:

            self(path)

            return True

        except (OSError, error.Abort):

            return False

def canonpath(root, cwd, myname, auditor=None):

    '''return the canonical path of myname, given cwd and root'''

    if util.endswithsep(root):

        rootsep = root

    else:

        rootsep = root + os.sep

    name = myname

    if not os.path.isabs(name):

        name = os.path.join(root, cwd, name)

    name = os.path.normpath(name)

    if auditor is None:

        auditor = pathauditor(root)

    if name != rootsep and name.startswith(rootsep):

        name = name[len(rootsep):]

        auditor(name)

        return util.pconvert(name)

    elif name == root:

        return ''

    else:

        # Determine whether `name' is in the hierarchy at or beneath `root',

        # by iterating name=dirname(name) until that causes no change (can't

        # check name == '/', because that doesn't work on windows). The list

        # `rel' holds the reversed list of components making up the relative

        # file name we want.

        rel = []

        while True:

            try:

                s = util.samefile(name, root)

            except OSError:

                s = False

            if s:

                if not rel:

                    # name was actually the same as root (maybe a symlink)

                    return ''

                rel.reverse()

                name = os.path.join(*rel)

                auditor(name)

                return util.pconvert(name)

            dirname, basename = util.split(name)

            rel.append(basename)

            if dirname == name:

                break

            name = dirname

        # A common mistake is to use -R, but specify a file relative to the repo

        # instead of cwd.  Detect that case, and provide a hint to the user.

        hint = None

        try:

            if cwd != root:

                canonpath(root, root, myname, auditor)

                hint = (_("consider using '--cwd %s'")

                        % os.path.relpath(root, cwd))

        except error.Abort:

            pass

        raise error.Abort(_("%s not under root '%s'") % (myname, root),

                         hint=hint)

def normasprefix(path):

    '''normalize the specified path as path prefix

    Returned value can be used safely for "p.startswith(prefix)",

    "p[len(prefix):]", and so on.

    For efficiency, this expects "path" argument to be already

    normalized by "os.path.normpath", "os.path.realpath", and so on.

    See also issue3033 for detail about need of this function.

    >>> normasprefix('/foo/bar').replace(os.sep, '/')

    '/foo/bar/'

    >>> normasprefix('/').replace(os.sep, '/')

    '/'

    '''

    d, p = os.path.splitdrive(path)

    if len(p) != len(os.sep):

        return path + os.sep

    else:

        return path

# forward two methods from posixpath that do what we need, but we'd

# rather not let our internals know that we're thinking in posix terms

# - instead we'll let them be oblivious.

join = posixpath.join

dirname = posixpath.dirname