from django.contrib.admin.views.decorators import staff_member_required

from django.core import validators

from django import template, oldforms

from django.template import loader

from django.shortcuts import render_to_response

from django.contrib.sites.models import Site

from django.conf import settings

def template_validator(request):

    """

    Displays the template validator form, which finds and displays template

    syntax errors.

    """

    # get a dict of {site_id : settings_module} for the validator

    settings_modules = {}

    for mod in settings.ADMIN_FOR:

        settings_module = __import__(mod, {}, {}, [''])

        settings_modules[settings_module.SITE_ID] = settings_module

    manipulator = TemplateValidator(settings_modules)

    new_data, errors = {}, {}

    if request.POST:

        new_data = request.POST.copy()

        errors = manipulator.get_validation_errors(new_data)

        if not errors:

            request.user.message_set.create(message='The template is valid.')

    return render_to_response('admin/template_validator.html', {

        'title': 'Template validator',

        'form': oldforms.FormWrapper(manipulator, new_data, errors),

    }, context_instance=template.RequestContext(request))

template_validator = staff_member_required(template_validator)

class TemplateValidator(oldforms.Manipulator):

    def __init__(self, settings_modules):

        self.settings_modules = settings_modules

        site_list = Site.objects.in_bulk(settings_modules.keys()).values()

        self.fields = (

            oldforms.SelectField('site', is_required=True, choices=[(s.id, s.name) for s in site_list]),

            oldforms.LargeTextField('template', is_required=True, rows=25, validator_list=[self.isValidTemplate]),

        )

    def isValidTemplate(self, field_data, all_data):

        # get the settings module

        # if the site isn't set, we don't raise an error since the site field will

        try:

            site_id = int(all_data.get('site', None))

        except (ValueError, TypeError):

            return

        settings_module = self.settings_modules.get(site_id, None)

        if settings_module is None:

            return

        # so that inheritance works in the site's context, register a new function

        # for "extends" that uses the site's TEMPLATE_DIRS instead.

        def new_do_extends(parser, token):

            node = loader.do_extends(parser, token)

            node.template_dirs = settings_module.TEMPLATE_DIRS

            return node

        register = template.Library()

        register.tag('extends', new_do_extends)

        template.builtins.append(register)

        # Now validate the template using the new template dirs

        # making sure to reset the extends function in any case.

        error = None

        try:

            tmpl = loader.get_template_from_string(field_data)

            tmpl.render(template.Context({}))

        except template.TemplateSyntaxError, e:

            error = e

        template.builtins.remove(register)

        if error:

            raise validators.ValidationError, e.args