# Copyright 2008 Paul Crowley <paul@lshift.net>

# Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

from mercurial.i18n import _

from mercurial.node import *

from mercurial import util

import os

import re

allowedchars = "A-Za-z0-9_-"

goodglobre = re.compile("[*/%s]+$" % allowedchars)

# Don't put anything except *A-Za-z0-9_- in rule globs or   

# it will match nothing.  No regexp metachars, not even .

# We may fix this later.

def globmatcher(pattern):

    if not goodglobre.match(pattern):

        #fail("Bad glob pattern in auth config: %s" % pattern)

        # FIXME: report it somehow

        return lambda x: False

    pattern = pattern.replace("*", "[]")

    pattern = pattern.replace("[][]", "[/%s]*" % allowedchars)

    pattern = pattern.replace("[]", "[%s]*" % allowedchars)

    rex = re.compile(pattern + "$")

    return lambda x: rex.match(x) is not None

def rule(pairs):

    matchers = [(k, globmatcher(v)) for k, v in pairs]

    def c(**kw):

        for k, m in matchers:

            if k not in kw or not m(kw[k]):

                return False

        return True

    return c

class Rulefile(object):

    '''Class representing the rules in a rule file'''

    self.levels = ["init", "write", "read", "deny"]

    def __init__(self):

        self.rules = []

    def add(self, action, conditions):

        self.rules.append((action, conditions))

    def matchrule(self, **kw):

        for a, c in self.rules:

            if c(**kw):

                return a

        return None

    def allow(self, level, **kw):

        a = matchrule(self, **kw)

        return a in self.levels and self.levels.index(a) <= self.levels.index(level)

def read_rules(fn):

    res = Rulefile()

    f = open(fn)

    try:

        for l in f:

            l = l.strip()

            if len(l) == 0 or l.startswith["#"]:

                continue

            res.add(l[0], rule([c.split("=", 1) for c in l[1:]]))

    finally:

        f.close()

class Checker(object):

    '''acl checker.'''

    def getuser(self):

        '''return name of hg-ssh user'''

        return os.environ['REMOTE_USER']

    def __init__(self, ui, repo):

        self.ui = ui

        self.repo = repo

        self.rules = read_rules(os.environ['HG_ACCESS_RULES_FILE'])

    def check(self, node):

        '''return if access allowed, raise exception if not.'''

        files = self.repo.changectx(node).files()

        for f in files:

            if not self.rules.allow("write", user=self.user, ):

                self.ui.debug(_('%s: user %s not allowed on %s\n') %

                              (__name__, self.getuser(), f))

                raise util.Abort(_('%s: access denied for changeset %s') %

                                 (__name__, short(node)))

        self.ui.debug(_('%s: allowing changeset %s\n') % (__name__, short(node)))

def hook(ui, repo, hooktype, node=None, source=None, **kwargs):

    if hooktype != 'pretxnchangegroup':

        raise util.Abort(_('config error - hook type "%s" cannot stop '

                           'incoming changesets') % hooktype)

    c = checker(ui, repo)

    start = repo.changelog.rev(bin(node))

    end = repo.changelog.count()

    for rev in xrange(start, end):

        c.check(repo.changelog.node(rev))