from cgi import escape
import sys
from webob import Request as WebObRequest
from webob import Response

from zope.component.event import dispatch
from zope.component import queryUtility

from zope.interface import implements

from repoze.bfg.authorization import ACLAuthorizationPolicy

from repoze.bfg.events import NewRequest
from repoze.bfg.events import NewResponse
from repoze.bfg.events import WSGIApplicationCreatedEvent

from repoze.bfg.interfaces import ILogger
from repoze.bfg.interfaces import ISecurityPolicy
from repoze.bfg.interfaces import INotFoundAppFactory
from repoze.bfg.interfaces import IRequestFactory
from repoze.bfg.interfaces import IResponseFactory
from repoze.bfg.interfaces import IRootFactory
from repoze.bfg.interfaces import IRouter
from repoze.bfg.interfaces import IRoutesMapper
from repoze.bfg.interfaces import ISettings
from repoze.bfg.interfaces import IForbiddenResponseFactory
from repoze.bfg.interfaces import IUnauthorizedAppFactory
from repoze.bfg.interfaces import IView
from repoze.bfg.interfaces import IViewPermission
from repoze.bfg.interfaces import IAuthorizationPolicy
from repoze.bfg.interfaces import IAuthenticationPolicy

from repoze.bfg.log import make_stream_logger

from repoze.bfg.registry import Registry
from repoze.bfg.registry import populateRegistry

from repoze.bfg.request import HTTP_METHOD_FACTORIES
from repoze.bfg.request import Request

from repoze.bfg.secpols import registerBBBAuthn

from repoze.bfg.security import Allowed

from repoze.bfg.settings import Settings

from repoze.bfg.threadlocal import manager

from repoze.bfg.traversal import _traverse

from repoze.bfg.urldispatch import RoutesRootFactory

from repoze.bfg.wsgi import NotFound

_marker = object()

class Router(object):
    """ The main repoze.bfg WSGI application. """
    implements(IRouter)

    debug_authorization = False
    debug_notfound = False
    threadlocal_manager = manager

    def __init__(self, registry):
        self.registry = registry
        self.logger = registry.queryUtility(ILogger, 'repoze.bfg.debug')

        self.request_factory = registry.queryUtility(IRequestFactory)

        unauthorized_app_factory = registry.queryUtility(
            IUnauthorizedAppFactory)

        forbidden = None

        if unauthorized_app_factory is not None:
            warning = (
                'Instead of registering a utility against the '
                'repoze.bfg.interfaces.IUnauthorizedAppFactory interface '
                'to return a custom forbidden response, you should now '
                'register a "repoze.interfaces.IForbiddenResponseFactory".  '
                'The IUnauthorizedAppFactory interface was deprecated in '
                'repoze.bfg 0.9 and will be removed in a subsequent version '
                'of repoze.bfg.  See the "Hooks" chapter of the repoze.bfg '
                'documentation for more information about '
                'IForbiddenResponseFactory.')
            self.logger and self.logger.warn(warning)
            def forbidden(context, request):
                app = unauthorized_app_factory()
                response = request.get_response(app)
                return response

        forbidden = registry.queryUtility(IForbiddenResponseFactory,
                                          default=forbidden)

        self.forbidden_resp_factory = forbidden or default_forbidden_view

        self.notfound_app_factory = registry.queryUtility(INotFoundAppFactory,
                                                          default=NotFound)
        
        settings = registry.queryUtility(ISettings)
        if settings is not None:
            self.debug_authorization = settings.debug_authorization
            self.debug_notfound = settings.debug_notfound

        self.secured = not not registry.queryUtility(IAuthenticationPolicy)
            
        self.root_factory = registry.getUtility(IRootFactory)
        self.root_policy = self.root_factory # b/w compat
        self.traverser_warned = {}

    def __call__(self, environ, start_response):
        """
        Accept ``environ`` and ``start_response``; route requests to
        ``repoze.bfg`` views based on registrations within the
        application registry; call ``start_response`` and return an
        iterable.
        """
        registry = self.registry
        threadlocals = {'registry':registry, 'request':None}
        self.threadlocal_manager.push(threadlocals)

        logger = self.logger
        request = None

        try:
            if self.request_factory is None:
                method = environ['REQUEST_METHOD']
                try:
                    # for speed we disuse HTTP_METHOD_FACTORIES.get
                    request_factory = HTTP_METHOD_FACTORIES[method]
                except KeyError:
                    request_factory = Request
            else:
                request_factory = self.request_factory

            request = request_factory(environ)
            threadlocals['request'] = request
            
            registry.has_listeners and registry.notify(NewRequest(request))
            root = self.root_factory(environ)
            tdict = _traverse(root, environ)
            if '_deprecation_warning' in tdict:
                warning = tdict.pop('_deprecation_warning')
                if not warning in self.traverser_warned:
                    self.logger and self.logger.warn(warning)
            context, view_name, subpath, traversed, vroot, vroot_path = (
                tdict['context'], tdict['view_name'], tdict['subpath'],
                tdict['traversed'], tdict['virtual_root'],
                tdict['virtual_root_path'])

            if isinstance(request, WebObRequest):
                # webob.Request's __setattr__ (as of 0.9.5 and lower)
                # is a bottleneck; if we're sure we're using a
                # webob.Request, go around its back and set stuff into
                # the environ directly
                attrs = environ.setdefault('webob.adhoc_attrs', {})
                attrs.update(tdict)
            else:
                request.root = root
                request.context = context
                request.view_name = view_name
                request.subpath = subpath
                request.traversed = traversed
                request.virtual_root = vroot
                request.virtual_root_path = vroot_path

            if self.secured:

                permitted = registry.queryMultiAdapter((context, request),
                                                       IViewPermission,
                                                       name=view_name)

                if permitted is None:
                    if self.debug_authorization:
                        permitted =  Allowed(
                            'Allowed: view name %r in context %r (no '
                            'permission registered).' %
                            (view_name, context))
                    else:
                        permitted = True

                
            else:
                if self.debug_authorization:
                    permitted =  Allowed(
                        'Allowed: view name %r in context %r (no '
                        'authentication policy in use).' % (view_name, context))
                else:
                    permitted = True

            if self.debug_authorization:
                logger and logger.debug(
                    'debug_authorization of url %s (view name %r against '
                    'context %r): %s' % (
                    request.url, view_name, context, permitted)
                    )

            if not permitted:
                if self.debug_authorization:
                    msg = str(permitted)
                else:
                    msg = 'Unauthorized: failed security policy check'

                environ['repoze.bfg.message'] = msg

                response = self.forbidden_resp_factory(context, request)
                start_response(response.status, response.headerlist)
                return response.app_iter

            response = registry.queryMultiAdapter(
                (context, request), IView, name=view_name)

            if response is None:
                if self.debug_notfound:
                    msg = (
                        'debug_notfound of url %s; path_info: %r, context: %r, '
                        'view_name: %r, subpath: %r, traversed: %r, '
                        'root: %r, vroot: %r,  vroot_path: %r' % (
                        request.url, request.path_info, context, view_name,
                        subpath, traversed, root, vroot, vroot_path)
                        )
                    logger and logger.debug(msg)
                else:
                    msg = request.url
                environ['repoze.bfg.message'] = msg
                notfound_app = self.notfound_app_factory()
                return notfound_app(environ, start_response)

            registry.has_listeners and registry.notify(NewResponse(response))

            try:
                start_response(response.status, response.headerlist)
                return response.app_iter
            except AttributeError:
                raise ValueError(
                    'Non-response object returned from view: %r' % response)

        finally:
            self.threadlocal_manager.pop()

def default_forbidden_view(context, request):
    status = '401 Unauthorized'
    try:
        msg = escape(request.environ['repoze.bfg.message'])
    except KeyError:
        msg = ''
    html = """
    <html>
    <title>%s</title>
    <body>
    <h1>%s</h1>
    <code>%s</code>
    </body>
    </html>
    """ % (status, status, msg)
    headers = [('Content-Length', str(len(html))),
               ('Content-Type', 'text/html')]
    response_factory = queryUtility(IResponseFactory, default=Response)
    return response_factory(status = status,
                            headerlist = headers,
                            app_iter = [html])

def make_app(root_factory, package=None, filename='configure.zcml',
             authentication_policy=None, authorization_policy=None,
             options=None, registry=None, debug_logger=None):
    # registry and debug_logger *only* for unittests
    """ Return a Router object, representing a fully configured
    ``repoze.bfg`` WSGI application.

    ``root_factory`` must be a callable that accepts a WSGI
    environment and returns a traversal root object.  It may be
    ``None``, in which case traversal is not performed at all.
    Instead, all URL-to-code mapping is done via URL dispatch (aka
    Routes).

    ``package`` is a Python module representing the application's
    package.  It is optional, defaulting to ``None``.  If ``package``
    is ``None``, the ``filename`` passed must be an absolute pathname
    to a ZCML file that represents the application's configuration.

    ``filename`` is the filesystem path to a ZCML file (optionally
    relative to the package path) that should be parsed to create the
    application registry.  It defaults to ``configure.zcml``.

    ``authentication_policy`` should be an object that implements the
    ``repoze.bfg.interfaces.IAuthenticationPolicy`` interface (e.g.
    it might be an instance of
    ``repoze.bfg.authentication.RemoteUserAuthenticationPolicy``) or
    ``None``.  If ``authentication_policy`` is ``None``, no
    authentication or authorization will be performed.  Instead, BFG
    will ignore any view permission assertions in your application and
    imperative security checks performed by your application will
    always return ``True``.

    ``authorization_policy`` is an object that implements the
    ``repoze.bfg.interfaces.IAuthorizationPoicy`` interface
    (notionally) or ``None``.  If the ``authentication_policy``
    argument is ``None``, this argument is ignored entirely because
    being able to authorize access to a user depends on being able to
    authenticate that user.  If the ``authentication_policy`` argument
    is *not* ``None``, and the ``authorization_policy`` argument *is*
    ``None``, the authorization policy defaults to an authorization
    implementation that uses ACLs.

    ``options``, if used, should be a dictionary containing runtime
    options (e.g. the key/value pairs in an app section of a
    PasteDeploy file), with each key representing the option and the
    key's value representing the specific option value,
    e.g. ``{'reload_templates':True}``"""
    if options is None:
        options = {}

    regname = filename

    if package:
        regname = package.__name__
    if registry is None:
        registry = Registry(regname)

    if debug_logger is None:
        debug_logger = make_stream_logger('repoze.bfg.debug', sys.stderr)
    registry.registerUtility(debug_logger, ILogger, 'repoze.bfg.debug')
    settings = Settings(options)
    registry.registerUtility(settings, ISettings)
    mapper = RoutesRootFactory(root_factory)
    registry.registerUtility(mapper, IRoutesMapper)
    populateRegistry(registry, filename, package)
    if mapper.has_routes():
        # if the user had any <route/> statements in his configuration,
        # use the RoutesRootFactory as the root factory
        root_factory = mapper
    else:
        # otherwise, use only the supplied root_factory (unless it's None)
        if root_factory is None:
            raise ValueError(
                'root_factory (aka get_root) was None and no routes connected')

    registry.registerUtility(root_factory, IRootFactory)

    if authentication_policy:
        registry.registerUtility(authentication_policy, IAuthenticationPolicy)
        if authorization_policy is None:
            authorization_policy = ACLAuthorizationPolicy()
        registry.registerUtility(authorization_policy, IAuthorizationPolicy)
    else:
        # deal with bw compat of <= 0.8 security policies (deprecated)
        secpol = registry.queryUtility(ISecurityPolicy)
        if secpol is not None:
            debug_logger.warn(
                'Your application is using a repoze.bfg ``ISecurityPolicy`` '
                '(probably registered via ZCML).  This form of security policy '
                'has been deprecated in BFG 0.9.  See the "Security" chapter '
                'of the repoze.bfg documentation to see how to register a more '
                'up to date set of security policies (an authentication '
                'policy and an authorization policy).  ISecurityPolicy-based '
                'security policies will cease to work in a later BFG '
                'release.')
            registerBBBAuthn(secpol, registry)

    app = Router(registry)

    # We push the registry on to the stack here in case any ZCA API is
    # used in listeners subscribed to the WSGIApplicationCreatedEvent
    # we send.
    manager.push({'registry':registry, 'request':None})
    try:
        # use dispatch here instead of registry.notify to make unit
        # tests possible
        dispatch(WSGIApplicationCreatedEvent(app))
    finally:
        manager.pop()

    return app