##############################################################################
#
# Copyright (c) 2004, 2005 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Machinery for making things viewable

$Id: viewable.py 61435 2005-11-08 15:46:36Z yuppie $
"""
import inspect
from zExceptions import NotFound
from zope.component import ComponentLookupError
from zope.interface import implements
from zope.publisher.interfaces.browser import IBrowserRequest
from zope.app.zapi import getDefaultViewName

from Products.Five.traversable import FakeRequest
from Products.Five.interfaces import IBrowserDefault

_marker = object

class Viewable:
    """A mixin to make an object viewable.
    """
    __five_viewable__ = True

    def __fallback_default__(self, request):
        """Try to dispatch to existing index_html or __call__"""
        if getattr(self, 'index_html', None):
            return self, ('index_html',)
        if getattr(self, 'fallback_call__', None):
            return self, ('fallback_call__',)
        # XXX Should never get this far. But if it does?

    # def fallback_call__(self, *args, **kw):
    #    """By default, return self"""
    #    return self

    # we have a default view, tell zpublisher to go there
    def __browser_default__(self, request):
        obj = self
        path = None
        if request['REQUEST_METHOD'] not in ('GET', 'POST'):
            return obj, [request['REQUEST_METHOD']]
        try:
            obj, path = IBrowserDefault(self).defaultView(request)
        except ComponentLookupError:
            pass
        if path:
            if len(path) == 1 and path[0] == '__call__':
                return obj, ('fallback_call__',)
            return obj, path
        return self.__fallback_default__(request)
    __browser_default__.__five_method__ = True

    # this is technically not needed because ZPublisher finds our
    # attribute through __browser_default__; but we also want to be
    # able to call pages from python modules, PythonScripts or ZPT
    # def __call__(self, *args, **kw):
    #    """ """
    #    request = kw.get('REQUEST')
    #    if not IBrowserRequest.providedBy(request):
    #        request = getattr(self, 'REQUEST', None)
    #        if not IBrowserRequest.providedBy(request):
    #            request = FakeRequest()
    #    obj, path = self.__browser_default__(request)
    #    if path and not simpleRecursion():
    #        meth = obj.unrestrictedTraverse(path)
    #        if meth is not None:
    #            return meth(*args, **kw)
    #    return self.fallback_call__(*args, **kw)
    # __call__.__five_method__ = True

# def simpleRecursion():
#     # This tests for simple recursion, which can easily happen
#     # in CMF, like the following:
#     # - Object has a method named 'view'
#     # - 'view' method calls '__call__'
#     # - five:viewable overrides call to use '__browser_default__'
#     #   to find a default view and call it
#     # - defaultView is set to 'view'
#     # Bang. Infinite recursion.
#     stack = inspect.stack()
#     try:
#         if len(stack) < 4:
#             return False
#         if stack[2][1:4] == stack[4][1:4]:
#             return True
#     finally:
#         del stack
#     return False

class BrowserDefault(object):
    implements(IBrowserDefault)

    def __init__(self, context):
        self.context = context

    def defaultView(self, request):
        context = self.context
        try:
            name = getDefaultViewName(context, request)
            return context, [name,]
        except ComponentLookupError:
            return context, None
