#!/usr/bin/env python

# trac-revprop-hook
# ----------------------------------------------------------------------------
# Copyright (c) 2007-2008 Emmanuel Blot
# ----------------------------------------------------------------------------

# This Subversion unified pre/post-revprop-change hook script is meant to 
# interface to the Trac (http://www.edgewall.com/products/trac/) issue 
# tracking/wiki/etc system.
#
# It should be called from the 'pre-revprop-change' and 'post-revprop-change'
# scripts in Subversion, such as via:
#
#  REPOS="$1"
#  REV="$2"
#  AUTHOR="$3"
#  PROPNAME="$4"  
#  TRAC_ENV="/somewhere/trac/project/"
#
#  cat | trac-revprop-hook -d "$REPOS" -p "$TRAC_ENV" -a "$AUTHOR" -r "$REV" \
#                          -p "$PROPNAME" <pre>|<post> "$"
# 

import re
import os
import sys

from optparse import OptionParser
from trac.env import open_environment
from ConfigParser import ConfigParser
from repproxy import RepositoryProxy

OK = 0
ERROR = 1

configpath = '/local/var/svn/config/access.conf'

changeset_cmd_pattern = r'^(?P<action>delivers|brings)(?P<force>\!)?\s+((\[(?P<first>\d+)\])(:\[(?P<second>\d+)\])?)?'

class RevpropHook(object):
    '''Hook script for revision property changes'''
    
    def __init__(self, post, project, rev, name, value, 
                 action=None, author=None, repos=None):
        if not os.path.isdir(os.environ['PYTHON_EGG_CACHE']):
            raise AssertionError("Invalid egg cache directory: %s" % os.environ['PYTHON_EGG_CACHE']);
        self.env = open_environment(project)
        self.repospath = self.env.config.get('trac', 'repository_dir')
        self.rev = int(rev)
        self.name = name
        self.value = value
        self.author = author
        self.action = action

        # sanity check: hook script repository match Trac repository
        if repos and self.repospath != repos:
            print >> sys.stderr, 'Invalid/incoherent repository %s %s' % \
                (self.repospath, repos)
            sys.exit(-ERROR)

        (type, prop) = name.split(':')

        if post:
            if type == 'svn':
                # on post-revprop-change, update Trac w/ SVN properties
                # custom properties are not cached anyway ;-(
                self._update_trac()
            sys.exit(0)

        if type == 'svn':
            if prop == 'log':
                self._verify_log_msg()
                sys.exit(0)
        elif type == 'rth':
            try:
                func = getattr(self, '_verify_rth_%s' % prop)
                # if the property is a valid one and the request is about deletion
                if func and self.action == 'D':
                    sys.exit(OK)
                func() and sys.exit(OK)
                print >> sys.stderr, 'Invalid value for property %s: %s' % \
                                     (self.name, self.value)
                sys.exit(-ERROR)
            except AttributeError:
                # unexpected property, will be catched later
                pass
        print >> sys.stderr, 'This property (%s) cannot be modified' % name
        sys.exit(-ERROR) 

    def _verify_log_msg(self):
        regex = re.compile(changeset_cmd_pattern, re.IGNORECASE)
        self.proxy = RepositoryProxy(self.repospath)
        oldlog = self.proxy.get_revision_log_message(self.rev)
        oldmo = regex.search(oldlog)
        if oldmo:
            newmo = regex.search(self.value)
            if (not newmo):
                print >> sys.stderr, \
                    'Missing message:\n  was: "%s"' % oldlog.split('\n')[0]
                sys.exit(-ERROR) 
            if (oldmo.group('first') != newmo.group('first')) or \
               (oldmo.group('second') != newmo.group('second')):
                if not self._is_admin(self.author) or not newmo.group('force'):
                    print >> sys.stderr, \
                        'Original parameters should be kept unaltered:\n' \
                        '  "%s"' % oldlog.split('\n')[0]
                    sys.exit(-ERROR) 

    def _verify_rth_deliver(self):
        # check that source revision are ordered integers
        try:
            prev = 1
            for src in self.value.split(','):
                rev = int(src)
                if rev < prev:
                    return None
                prev = rev
            return True
        except ValueError:
            return None

    def _verify_rth_bring(self):
        # check that source revision are ordered integers
        try:
            prev = 1
            for src in self.value.split(','):
                rev = int(src)
                if rev < prev:
                    return None
                prev = rev
            return True
        except ValueError:
            return None

    def _update_trac(self):
        # update Trac cache with the updated value
        repos = self.env.get_repository()
        repos.sync_changeset(self.rev)

    def _is_admin(self, author):
        '''
        Verify whether the author has administrator priviledges
        '''
        config = ConfigParser()
        if not os.path.isfile(configpath):
            raise AssertionError('Unable to find Subversion ACL for admins')
        config.read(configpath)
        admins = config.get('groups','admins')
        if not admins:
            raise AssertionError('Unable to retrieve Subversion ACL for admins')
        if not author.lower() in [s.strip() for s in admins.lower().split(',')]:
            return False
        return True


if __name__ == "__main__":
    usage = "usage: %prog [options] <pre|post>"
    parser = OptionParser(usage)
    parser.add_option('-p', '--project', dest='project', help='path to the Trac project')
    parser.add_option('-r', '--revision', dest='rev', help='repository revision number')
    parser.add_option('-u', '--user', dest='author', help='author of the change')
    parser.add_option('-d', '--repos', dest='rep', help='subversion repository path')
    parser.add_option('-n', '--name', dest='prop', help='property name')
    parser.add_option('-a', '--action', dest='action', help='subversion action code (A|D|M)')
    
    (options, args) = parser.parse_args(sys.argv[1:])
    if options.project is None:
        print "Unspecified project"
        sys.exit(-ERROR)       
    if options.rev is None:
        print "Unspecified revision"
        sys.exit(-ERROR)
    if options.prop is None:
        print "Unspecified name"
        sys.exit(-ERROR)
    if len(args) < 1:
        print "Missing argument"
        sys.exit(-ERROR)

    # grab the first line from stdin (we don't care about other lines for new)
    value = sys.stdin.readline()

    # consider that the defaut hook is 'pre' so that changes are always
    # validated if an invalid command line is provided
    hook = RevpropHook(args[0] != 'pre', options.project, options.rev, 
                       options.prop, value, options.action, options.author, 
                       options.rep)