# -*- coding: utf-8 -*-
#
# Copyright (C) 2005-2009 Edgewall Software
# Copyright (C) 2005-2006 Christopher Lenz <cmlenz@gmx.de>
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://trac.edgewall.org/wiki/TracLicense.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://trac.edgewall.org/log/.
#
# Author: Christopher Lenz <cmlenz@gmx.de>

import datetime
import itertools
import os.path
import pkg_resources
import pprint
import re
try: 
    from cStringIO import StringIO as cStringIO 
except ImportError: 
    cStringIO = StringIO 

from genshi import Markup
from genshi.builder import tag, Element
from genshi.input import HTML, ParseError
from genshi.core import Attrs, START
from genshi.output import DocType
from genshi.template import TemplateLoader, MarkupTemplate, TextTemplate

from trac import __version__ as VERSION
from trac.config import *
from trac.core import *
from trac.env import IEnvironmentSetupParticipant
from trac.mimeview import get_mimetype, Context
from trac.resource import *
from trac.util import compat, get_reporter_id, presentation, get_pkginfo, \
                      get_module_path, translation
from trac.util.compat import partial, set
from trac.util.html import plaintext
from trac.util.text import pretty_size, obfuscate_email_address, \
                           shorten_line, unicode_quote_plus, to_unicode, \
                           javascript_quote
from trac.util.datefmt import pretty_timedelta, format_datetime, format_date, \
                              format_time, http_date, utc
from trac.util.translation import _
from trac.web.api import IRequestHandler, ITemplateStreamFilter, HTTPNotFound
from trac.web.href import Href
from trac.wiki import IWikiSyntaxProvider
from trac.wiki.formatter import format_to, format_to_html, format_to_oneliner

def add_link(req, rel, href, title=None, mimetype=None, classname=None):
    """Add a link to the chrome info that will be inserted as <link> element in
    the <head> of the generated HTML
    """
    linkid = '%s:%s' % (rel, href)
    linkset = req.chrome.setdefault('linkset', set())
    if linkid in linkset:
        return # Already added that link

    link = {'href': href, 'title': title, 'type': mimetype, 'class': classname}
    links = req.chrome.setdefault('links', {})
    links.setdefault(rel, []).append(link)
    linkset.add(linkid)

def add_stylesheet(req, filename, mimetype='text/css'):
    """Add a link to a style sheet to the chrome info so that it gets included
    in the generated HTML page.
    
    If the filename is absolute (i.e. starts with a slash), the generated link
    will be based off the application root path. If it is relative, the link
    will be based off the `/chrome/` path.
    """
    if filename.startswith('common/') and 'htdocs_location' in req.chrome:
        href = Href(req.chrome['htdocs_location'])
        filename = filename[7:]
    else:
        href = req.href
        if not filename.startswith('/'):
            href = href.chrome
    add_link(req, 'stylesheet', href(filename), mimetype=mimetype)

def add_script(req, filename, mimetype='text/javascript'):
    """Add a reference to an external javascript file to the template.
    
    If the filename is absolute (i.e. starts with a slash), the generated link
    will be based off the application root path. If it is relative, the link
    will be based off the `/chrome/` path.
    """
    scriptset = req.chrome.setdefault('scriptset', set())
    if filename in scriptset:
        return False # Already added that script

    if filename.startswith('common/') and 'htdocs_location' in req.chrome:
        href = Href(req.chrome['htdocs_location'])
        path = filename[7:]
    else:
        href = req.href
        if not filename.startswith('/'):
            href = href.chrome
        path = filename
    script = {'href': href(path), 'type': mimetype}

    req.chrome.setdefault('scripts', []).append(script)
    scriptset.add(filename)

def add_javascript(req, filename):
    """Deprecated: use `add_script()` instead."""
    add_script(req, filename, mimetype='text/javascript')

def add_warning(req, msg, *args):
    """Add a non-fatal warning to the request object.
    When rendering pages, any warnings will be rendered to the user."""
    if args:
        msg %= args
    req.chrome['warnings'].append(msg)

def add_notice(req, msg, *args):
    """Add an informational notice to the request object.
    When rendering pages, any notice will be rendered to the user."""
    if args:
        msg %= args
    req.chrome['notices'].append(msg)

def add_ctxtnav(req, elm_or_label, href=None, title=None):
    """Add an entry to the current page's ctxtnav bar.
    """
    if href:
        elm = tag.a(elm_or_label, href=href, title=title)
    else:
        elm = elm_or_label
    req.chrome.setdefault('ctxtnav', []).append(elm)

# ???: Does this belong in trac.util somewhere? <NPK>
def prevnext_nav(req, label, uplabel=None):
    """Add Previous/Up/Next navigation links
       
       `req` a Request object
       `label` the label to use after the Previous/Next words
       `uplabel` the label to use for the Up link
    """
    links = req.chrome['links']
    
    if 'prev' not in links and \
       'up' not in links and \
       'next' not in links:
        # Short circuit
        return
    
    if 'prev' in links:
        link = links['prev'][0]
        add_ctxtnav(req, 
            tag.span(Markup('&larr; '),
                     tag.a(_('Previous %(label)s', label=label),
                            href=link['href'],
                            title=link['title'],
                            class_='prev'
                           )))
    else:
        add_ctxtnav(req, 
            tag.span(Markup('&larr; '),
                     _('Previous %(label)s', label=label), 
                     class_='missing'))

    if uplabel and 'up' in links:
        link = links['up'][0]
        add_ctxtnav(req, tag.a(uplabel, 
                               href=link['href'], 
                               title=link['title']))

    if 'next' in links:
        link = links['next'][0]
        add_ctxtnav(req, 
            tag.span(tag.a(_('Next %(label)s', label=label),
                           href=link['href'],
                           title=link['title'],
                           class_='next'),
                     Markup(' &rarr;')))
    else:
        add_ctxtnav(req, 
            tag.span(_('Next %(label)s', label=label),
                     Markup(' &rarr;'), class_='missing'))


def _save_messages(req, url, permanent):
    """Save warnings and notices in case of redirect, so that they can
    be displayed after the redirect."""
    for type_ in ['warnings', 'notices']:
        for (i, message) in enumerate(req.chrome[type_]):
            req.session['chrome.%s.%d' % (type_, i)] = message


class INavigationContributor(Interface):
    """Extension point interface for components that contribute items to the
    navigation.
    """

    def get_active_navigation_item(req):
        """This method is only called for the `IRequestHandler` processing the
        request.
        
        It should return the name of the navigation item that should be
        highlighted as active/current.
        """

    def get_navigation_items(req):
        """Should return an iterable object over the list of navigation items to
        add, each being a tuple in the form (category, name, text).
        """


class ITemplateProvider(Interface):
    """Extension point interface for components that provide their own
    ClearSilver templates and accompanying static resources.
    """

    def get_htdocs_dirs():
        """Return a list of directories with static resources (such as style
        sheets, images, etc.)

        Each item in the list must be a `(prefix, abspath)` tuple. The
        `prefix` part defines the path in the URL that requests to these
        resources are prefixed with.
        
        The `abspath` is the absolute path to the directory containing the
        resources on the local file system.
        """

    def get_templates_dirs():
        """Return a list of directories containing the provided template
        files.
        """


# Mappings for removal of control characters
_translate_nop = "".join([chr(i) for i in range(256)])
_invalid_control_chars = "".join([chr(i) for i in range(32)
                                  if i not in [0x09, 0x0a, 0x0d]])

    
class Chrome(Component):
    """Responsible for assembling the web site chrome, i.e. everything that
    is not actual page content.
    """
    implements(IEnvironmentSetupParticipant, IRequestHandler, ITemplateProvider,
               IWikiSyntaxProvider)

    navigation_contributors = ExtensionPoint(INavigationContributor)
    template_providers = ExtensionPoint(ITemplateProvider)
    stream_filters = ExtensionPoint(ITemplateStreamFilter)

    shared_templates_dir = PathOption('inherit', 'templates_dir', '',
        """Path to the shared templates directory.
        
        Templates in that directory are loaded in addition to those in the
        environments `templates` directory, but the latter take precedence.
        
        (''since 0.11'')""")

    auto_reload = Option('trac', 'auto_reload', False,
        """Automatically reload template files after modification.""")

    htdocs_location = Option('trac', 'htdocs_location', '',
        """Base URL of the core static resources.""")

    metanav_order = ListOption('trac', 'metanav',
                               'login,logout,prefs,help,about', doc=
        """Order of the items to display in the `metanav` navigation bar,
           listed by IDs. See also TracNavigation.""")

    mainnav_order = ListOption('trac', 'mainnav',
                               'wiki,timeline,roadmap,browser,tickets,'
                               'newticket,search', doc=
        """Order of the items to display in the `mainnav` navigation bar, 
           listed by IDs. See also TracNavigation.""")

    logo_link = Option('header_logo', 'link', '',
        """URL to link to from header logo.""")

    logo_src = Option('header_logo', 'src', 'site/your_project_logo.png',
        """URL of the image to use as header logo.""")

    logo_alt = Option('header_logo', 'alt', 
        "(please configure the [header_logo] section in trac.ini)",
        """Alternative text for the header logo.""")

    logo_width = IntOption('header_logo', 'width', -1,
        """Width of the header logo image in pixels.""")

    logo_height = IntOption('header_logo', 'height', -1,
        """Height of the header logo image in pixels.""")

    show_email_addresses = BoolOption('trac', 'show_email_addresses', 'false',
        """Show email addresses instead of usernames. If false, we obfuscate
        email addresses (''since 0.11'').""")

    show_ip_addresses = BoolOption('trac', 'show_ip_addresses', 'false',
        """Show IP addresses for resource edits (e.g. wiki).
        (''since 0.11.3'').""")

    templates = None

    # A dictionary of default context data for templates
    _default_context_data = {
        '_': translation._,
        'all': compat.all,
        'any': compat.any,
        'attrgetter': compat.attrgetter,
        'classes': presentation.classes,
        'date': datetime.date,
        'datetime': datetime.datetime,
        'first_last': presentation.first_last,
        'get_reporter_id': get_reporter_id,
        'gettext': translation.gettext,
        'group': presentation.group,
        'groupby': compat.py_groupby,
        'http_date': http_date,
        'istext': presentation.istext,
        'itemgetter': compat.itemgetter,
        'javascript_quote': javascript_quote,
        'ngettext': translation.ngettext,
        'paginate': presentation.paginate,
        'partial': partial,
        'plaintext': plaintext,
        'pprint': pprint.pformat,
        'pretty_size': pretty_size,
        'pretty_timedelta': pretty_timedelta,
        'quote_plus': unicode_quote_plus,
        'reversed': compat.reversed,
        'separated': presentation.separated,
        'shorten_line': shorten_line,
        'sorted': compat.sorted,
        'time': datetime.time,
        'timedelta': datetime.timedelta,
        'to_unicode': to_unicode,
        'utc': utc,
    }

    def __init__(self):
        import genshi
        self.env.systeminfo.append(('Genshi',
                                    get_pkginfo(genshi).get('version')))

    # IEnvironmentSetupParticipant methods

    def environment_created(self):
        """Create the environment templates directory."""
        if self.env.path:
            templates_dir = os.path.join(self.env.path, 'templates')
            if not os.path.exists(templates_dir):
                os.mkdir(templates_dir)

            if not self.shared_templates_dir or not os.path.exists(
                        os.path.join(self.shared_templates_dir, "site.html")):
                fileobj = open(os.path.join(templates_dir, 'site.html'), 'w')
                try:
                    fileobj.write("""\
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:py="http://genshi.edgewall.org/" py:strip="">
  <!--! Custom match templates go here -->
</html>""")
                finally:
                    fileobj.close()

    def environment_needs_upgrade(self, db):
        return False

    def upgrade_environment(self, db):
        pass

    # IRequestHandler methods

    def match_request(self, req):
        match = re.match(r'/chrome/(?P<prefix>[^/]+)/+(?P<filename>.+)',
                         req.path_info)
        if match:
            req.args['prefix'] = match.group('prefix')
            req.args['filename'] = match.group('filename')
            return True

    def process_request(self, req):
        prefix = req.args['prefix']
        filename = req.args['filename']

        dirs = []
        for provider in self.template_providers:
            for dir in [os.path.normpath(dir[1]) for dir
                        in provider.get_htdocs_dirs() if dir[0] == prefix]:
                dirs.append(dir)
                path = os.path.normpath(os.path.join(dir, filename))
                assert os.path.commonprefix([dir, path]) == dir
                if os.path.isfile(path):
                    req.send_file(path, get_mimetype(path))

        self.log.warning('File %s not found in any of %s', filename, dirs)
        raise HTTPNotFound('File %s not found', filename)

    # ITemplateProvider methods

    def get_htdocs_dirs(self):
        return [('common', pkg_resources.resource_filename('trac', 'htdocs')),
                ('site', self.env.get_htdocs_dir())]

    def get_templates_dirs(self):
        return filter(None, [
            self.env.get_templates_dir(),
            self.shared_templates_dir,
            pkg_resources.resource_filename('trac', 'templates'),
        ])

    # IWikiSyntaxProvider methods
    
    def get_wiki_syntax(self):
        return []
    
    def get_link_resolvers(self):
        yield ('htdocs', self._format_link)

    def _format_link(self, formatter, ns, file, label):
        file, query, fragment = formatter.split_link(file)
        href = formatter.href.chrome('site', file) + query + fragment
        return tag.a(label, href=href)

    # Public API methods

    def get_all_templates_dirs(self):
        """Return a list of the names of all known templates directories."""
        dirs = []
        for provider in self.template_providers:
            dirs += provider.get_templates_dirs()
        return dirs

    def prepare_request(self, req, handler=None):
        """Prepare the basic chrome data for the request.
        
        @param req: the request object
        @param handler: the `IRequestHandler` instance that is processing the
            request
        """
        self.log.debug('Prepare chrome data for request')

        chrome = {'links': {}, 'scripts': [], 'ctxtnav': [], 'warnings': [],
                  'notices': []}
        req.add_redirect_listener(_save_messages)

        # This is ugly... we can't pass the real Request object to the
        # add_xxx methods, because it doesn't yet have the chrome attribute
        class FakeRequest(object):
            def __init__(self, req):
                self.base_path = req.base_path
                self.chrome = chrome
        fakereq = FakeRequest(req)

        htdocs_location = self.htdocs_location or req.href.chrome('common')
        chrome['htdocs_location'] = htdocs_location.rstrip('/') + '/'

        # HTML <head> links
        add_link(fakereq, 'start', req.href.wiki())
        add_link(fakereq, 'search', req.href.search())
        add_link(fakereq, 'help', req.href.wiki('TracGuide'))
        add_stylesheet(fakereq, 'common/css/trac.css')
        add_script(fakereq, 'common/js/jquery.js')
        # Only activate noConflict mode if requested to by the handler
        if handler is not None and \
           getattr(handler.__class__, 'jquery_noconflict', False):
            add_script(fakereq, 'common/js/noconflict.js')
        add_script(fakereq, 'common/js/trac.js')
        add_script(fakereq, 'common/js/search.js')

        # Shortcut icon
        chrome['icon'] = self.get_icon_data(req)
        if chrome['icon']:
            src = chrome['icon']['src']
            mimetype = chrome['icon']['mimetype']
            add_link(fakereq, 'icon', src, mimetype=mimetype)
            add_link(fakereq, 'shortcut icon', src, mimetype=mimetype)

        # Logo image
        chrome['logo'] = self.get_logo_data(req.href, req.abs_href)

        # Navigation links
        allitems = {}
        active = None
        for contributor in self.navigation_contributors:
            for category, name, text in contributor.get_navigation_items(req):
                category_section = self.config[category]
                if category_section.getbool(name, True):
                    # the navigation item is enabled (this is the default)
                    item = None
                    if isinstance(text, Element) and text.tag.localname == 'a':
                        item = text
                    label = category_section.get(name + '.label')
                    href = category_section.get(name + '.href')
                    if href:
                        if href.startswith('/'):
                            href = req.href() + href
                        if label:
                            item = tag.a(label) # create new label
                        elif not item:
                            item = tag.a(text) # wrap old text
                        item = item(href=href) # use new href
                    elif label and item: # create new label, use old href
                        item = tag.a(label, href=item.attrib.get('href'))
                    elif not item: # use old text
                        item = text
                    allitems.setdefault(category, {})[name] = item
            if contributor is handler:
                active = contributor.get_active_navigation_item(req)

        nav = {}
        for category, items in [(k, v.items()) for k, v in allitems.items()]:
            category_order = category + '_order'
            if hasattr(self, category_order):
                order = getattr(self, category_order)
                def navcmp(x, y):
                    if x[0] not in order:
                        return int(y[0] in order)
                    if y[0] not in order:
                        return -int(x[0] in order)
                    return cmp(order.index(x[0]), order.index(y[0]))
                items.sort(navcmp)

            nav[category] = []
            for name, label in items:
                nav[category].append({
                    'name': name,
                    'label': label,
                    'active': name == active
                })

        chrome['nav'] = nav
        
        # Default theme file
        chrome['theme'] = 'theme.html'

        return chrome

    def get_icon_data(self, req):
        icon = {}
        icon_src = icon_abs_src = self.env.project_icon
        if icon_src:
            if not icon_src.startswith('/') and icon_src.find('://') == -1:
                if '/' in icon_src:
                    icon_abs_src = req.abs_href.chrome(icon_src)
                    icon_src = req.href.chrome(icon_src)
                else:
                    icon_abs_src = req.abs_href.chrome('common', icon_src)
                    icon_src = req.href.chrome('common', icon_src)
            mimetype = get_mimetype(icon_src)
            icon = {'src': icon_src, 'abs_src': icon_abs_src,
                    'mimetype': mimetype}
        return icon

    def get_logo_data(self, href, abs_href=None):
        # TODO: Possibly, links to 'common/' could use chrome.htdocs_location
        logo = {}
        logo_src = self.logo_src
        if logo_src:
            abs_href = abs_href or href
            if logo_src.startswith('http://') or \
                    logo_src.startswith('https://') or \
                    logo_src.startswith('/'):
                # Nothing further can be calculated
                logo_src_abs = logo_src
            elif '/' in logo_src:
                # Like 'common/trac_banner.png' or 'site/my_banner.png'
                logo_src_abs = abs_href.chrome(logo_src)
                logo_src = href.chrome(logo_src)
            else:
                # Like 'trac_banner.png'
                logo_src_abs = abs_href.chrome('common', logo_src)
                logo_src = href.chrome('common', logo_src)
            width = self.logo_width > -1 and self.logo_width or None
            height = self.logo_height > -1 and self.logo_height or None
            logo = {
                'link': self.logo_link, 'src': logo_src,
                'src_abs': logo_src_abs, 'alt': self.logo_alt,
                'width': width, 'height': height
            }
        else:
            logo = {'link': self.logo_link, 'alt': self.logo_alt}
        return logo

    def populate_hdf(self, req):
        """Add chrome-related data to the HDF (deprecated)."""
        req.hdf['HTTP.PathInfo'] = req.path_info
        req.hdf['htdocs_location'] = req.chrome['htdocs_location']

        req.hdf['chrome.href'] = req.href.chrome()
        req.hdf['chrome.links'] = req.chrome['links']
        req.hdf['chrome.scripts'] = req.chrome['scripts']
        req.hdf['chrome.logo'] = req.chrome['logo']

        for category, items in req.chrome['nav'].items():
            for item in items:
                prefix = 'chrome.nav.%s.%s' % (category, item['name'])
                req.hdf[prefix] = item['label']

    def populate_data(self, req, data):
        d = self._default_context_data.copy()
        d['trac'] = {
            'version': VERSION,
            'homepage': 'http://trac.edgewall.org/', # FIXME: use setup data
            'systeminfo': self.env.systeminfo,
        }
        
        href = req and req.href
        abs_href = req and req.abs_href or self.env.abs_href
        admin_href = None
        if self.env.project_admin_trac_url == '.':
            admin_href = href
        elif self.env.project_admin_trac_url:
            admin_href = Href(self.env.project_admin_trac_url)
            
        d['project'] = {
            'name': self.env.project_name,
            'descr': self.env.project_description,
            'url': self.env.project_url,
            'admin': self.env.project_admin,
            'admin_href': admin_href,
            'admin_trac_url': self.env.project_admin_trac_url,
        }
        d['chrome'] = {
            'footer': Markup(self.env.project_footer)
        }
        if req:
            d['chrome'].update(req.chrome)
        else:
            d['chrome'].update({
                'htdocs_location': self.htdocs_location,
                'logo': self.get_logo_data(self.env.abs_href),
            })

        show_email_addresses = (self.show_email_addresses or not req or \
                                'EMAIL_VIEW' in req.perm)
        tzinfo = None
        if req:
            tzinfo = req.tz

        def dateinfo(date):
            return tag.span(pretty_timedelta(date),
                            title=format_datetime(date))

        def get_rel_url(resource, **kwargs):
            return get_resource_url(self.env, resource, href, **kwargs)

        def get_abs_url(resource, **kwargs):
            return get_resource_url(self.env, resource, abs_href, **kwargs)

        d.update({
            'context': req and Context.from_request(req) or None,
            'url_of': get_rel_url,
            'abs_url_of': get_abs_url,
            'name_of': partial(get_resource_name, self.env),
            'shortname_of': partial(get_resource_shortname, self.env),
            'summary_of': partial(get_resource_summary, self.env),
            'req': req,
            'abs_href': abs_href,
            'href': href,
            'perm': req and req.perm,
            'authname': req and req.authname or '<trac>',
            'show_email_addresses': show_email_addresses,
            'show_ip_addresses': self.show_ip_addresses,
            'format_author': partial(self.format_author, req),
            'format_emails': self.format_emails,

            # Date/time formatting
            'dateinfo': dateinfo,
            'format_datetime': partial(format_datetime, tzinfo=tzinfo),
            'format_date': partial(format_date, tzinfo=tzinfo),
            'format_time': partial(format_time, tzinfo=tzinfo),
            'fromtimestamp': partial(datetime.datetime.fromtimestamp,
                                     tz=tzinfo),

            # Wiki-formatting functions
            'wiki_to': partial(format_to, self.env),
            'wiki_to_html': partial(format_to_html, self.env),
            'wiki_to_oneliner': partial(format_to_oneliner, self.env),
        })

        # Finally merge in the page-specific data
        d.update(data)
        return d

    def load_template(self, filename, method=None):
        """Retrieve a Template and optionally preset the template data.

        Also, if the optional `method` argument is set to `'text'`, a
        TextTemplate instance will be created instead of a MarkupTemplate.
        """
        if not self.templates:
            self.templates = TemplateLoader(self.get_all_templates_dirs(),
                                            auto_reload=self.auto_reload,
                                            variable_lookup='lenient')
        if method == 'text':
            cls = TextTemplate
        else:
            cls = MarkupTemplate

        return self.templates.load(filename, cls=cls)

    def render_template(self, req, filename, data, content_type=None,
                        fragment=False):
        """Render the `filename` using the `data` for the context.

        The `content_type` argument is used to choose the kind of template
        used (TextTemplate if `'text/plain'`, MarkupTemplate otherwise), and
        tweak the rendering process (use of XHTML Strict doctype if
        `'text/html'` is given).
        """
        if content_type is None:
            content_type = 'text/html'
        method = {'text/html': 'xhtml',
                  'text/plain': 'text'}.get(content_type, 'xml')

        if method == "xhtml":
            # Retrieve post-redirect messages saved in session
            for type_ in ['warnings', 'notices']:
                try:
                    for i in itertools.count():
                        req.chrome[type_].append(
                            req.session.pop('chrome.%s.%d' % (type_, i)))
                except KeyError:
                    pass

        template = self.load_template(filename, method=method)
        data = self.populate_data(req, data)

        stream = template.generate(**data)

        # Filter through ITemplateStreamFilter plugins
        if self.stream_filters:
            stream |= self._filter_stream(req, method, filename, stream, data)

        if fragment:
            return stream

        if method == 'text':
            buffer = cStringIO()
            stream.render('text', out=buffer)
            return buffer.getvalue()

        doctype = {'text/html': DocType.XHTML_STRICT}.get(content_type)
        if doctype:
            if req.form_token:
                stream |= self._add_form_token(req.form_token)
            if not int(req.session.get('accesskeys', 0)):
                stream |= self._strip_accesskeys

        links = req.chrome.get('links')
        scripts = req.chrome.get('scripts')
        req.chrome['links'] = {}
        req.chrome['scripts'] = []
        data.setdefault('chrome', {}).update({
            'late_links': req.chrome['links'],
            'late_scripts': req.chrome['scripts'],
        })

        try:
            buffer = cStringIO()
            stream.render(method, doctype=doctype, out=buffer)
            return buffer.getvalue().translate(_translate_nop,
                                               _invalid_control_chars)
        except Exception, e:
            # restore what may be needed by the error template
            req.chrome['links'] = links
            req.chrome['scripts'] = scripts
            # give some hints when hitting a Genshi unicode error
            if isinstance(e, UnicodeError):
                pos = self._stream_location(stream)
                if pos:
                    location = "'%s', line %s, char %s" % pos
                else:
                    location = _("(unknown template location)")
                raise TracError(_("Genshi %(error)s error while rendering "
                                  "template %(location)s", 
                                  error=e.__class__.__name__, 
                                  location=location))
            raise

    # E-mail formatting utilities

    def cc_list(self, cc_field):
        """Split a CC: value in a list of addresses."""
        if not cc_field:
            return []
        return [cc.strip() for cc in cc_field.split(',') if cc]

    def format_emails(self, context, value, sep=', '):
        """Normalize a list of e-mails and obfuscate them if needed.

        :param context: the context in which the check for obfuscation should
                        be done
        :param value: a string containing a comma-separated list of e-mails
        :param sep: the separator to use when rendering the list again
        """
        all_cc = self.cc_list(value)
        if not (self.show_email_addresses or 'EMAIL_VIEW' in context.perm):
            all_cc = [obfuscate_email_address(cc) for cc in all_cc]
        return sep.join(all_cc)
    
    def format_author(self, req, author):
        if self.show_email_addresses or not req or 'EMAIL_VIEW' in req.perm:
            return author
        else:
            return obfuscate_email_address(author)

    # Template filters

    def _add_form_token(self, token):
        elem = tag.div(
            tag.input(type='hidden', name='__FORM_TOKEN', value=token)
        )
        def _generate(stream, ctxt=None):
            for kind, data, pos in stream:
                if kind is START and data[0].localname == 'form' \
                                 and data[1].get('method', '').lower() == 'post':
                    yield kind, data, pos
                    for event in elem.generate():
                        yield event
                else:
                    yield kind, data, pos
        return _generate

    def _strip_accesskeys(self, stream, ctxt=None):
        for kind, data, pos in stream:
            if kind is START and 'accesskey' in data[1]:
                data = data[0], Attrs([(k,v) for k,v in data[1]
                                       if k != 'accesskey'])
            yield kind, data, pos

    def _filter_stream(self, req, method, filename, stream, data):
        def inner(stream, ctxt=None):
            for filter in self.stream_filters:
                stream = filter.filter_stream(req, method, filename, stream,
                                              data)
            return stream
        return inner

    def _stream_location(self, stream):
        for kind, data, pos in stream:
            return pos

