import cPickle
import os
from os.path import realpath
import time
import types

from zope.configuration import xmlconfig

from zope.component import getSiteManager
from zope.component import adaptedBy
import zope.configuration.config

from zope.component.interface import provideInterface
from zope.configuration.exceptions import ConfigurationError
from zope.configuration.fields import GlobalObject

from zope.interface import Interface

from zope.schema import TextLine

from repoze.bfg.interfaces import IRequest
from repoze.bfg.interfaces import IViewPermission
from repoze.bfg.interfaces import IView
from repoze.bfg.path import package_path

from repoze.bfg.security import ViewPermissionFactory

def handler(methodName, *args, **kwargs):
    method = getattr(getSiteManager(), methodName)
    method(*args, **kwargs)

class Uncacheable(object):
    """ Include in discriminators of actions which are not cacheable """
    pass

def view(_context,
         permission=None,
         for_=None,
         view=None,
         name="",
         request_type=None,
         cacheable=True,
         ):

    if not view:
        raise ConfigurationError('"view" attribute was not specified')

    if for_ is not None:
        _context.action(
            discriminator = None,
            callable = provideInterface,
            args = ('', for_)
            )

    # views may be either functions or class instances
    if isinstance(view, types.FunctionType):
        adapted_by = adaptedBy(view)
    else:
        adapted_by = adaptedBy(type(view))

    if adapted_by is not None:
        try:
            if for_ is None:
                for_, _ = adapted_by
            if request_type is None:
                _, request_type = adapted_by
        except ValueError:
            # the component adaptation annotation does not conform to
            # the view specification; we ignore it.
            pass

    if request_type is None:
        request_type = IRequest

    if permission:
        pfactory = ViewPermissionFactory(permission)
        _context.action(
            discriminator = ('permission', for_, name, request_type,
                             IViewPermission),
            callable = handler,
            args = ('registerAdapter',
                    pfactory, (for_, request_type), IViewPermission, name,
                    _context.info),
            )

    cacheable = cacheable or Uncacheable

    _context.action(
        discriminator = ('view', for_, name, request_type, IView, cacheable),
        callable = handler,
        args = ('registerAdapter',
                view, (for_, request_type), IView, name,
                _context.info),
        )

class IViewDirective(Interface):
    for_ = GlobalObject(
        title=u"The interface or class this view is for.",
        required=False
        )

    permission = TextLine(
        title=u"Permission",
        description=u"The permission needed to use the view.",
        required=False
        )

    view = GlobalObject(
        title=u"",
        description=u"The view function",
        required=False,
        )

    name = TextLine(
        title=u"The name of the view",
        description=u"""
        The name shows up in URLs/paths. For example 'foo' or
        'foo.html'.""",
        required=False,
        )

    request_type = GlobalObject(
        title=u"""The request type interface for the view""",
        description=(u"The view will be called if the interface represented by "
                     u"'request_type' is implemented by the request.  The "
                     u"default request type is repoze.bfg.interfaces.IRequest"),
        required=False
        )

PVERSION = 1

def pickle_name(name, package):
    path = package_path(package)
    basename = os.path.join(path, name)
    return os.path.join(path, basename + '.cache')

def zcml_configure(name, package, load=cPickle.load):
    """ Execute pickled zcml actions or fall back to parsing from file
    """
    pckname = pickle_name(name, package)

    if not (os.path.isfile(pckname) or os.path.islink(pckname)):
        return file_configure(name, package)

    try:
        vers, ptime, actions = load(open(pckname, 'rb'))
    except (IOError, cPickle.UnpicklingError, EOFError, TypeError, ValueError,
            AttributeError, NameError, ImportError):
        return file_configure(name, package)

    if vers != PVERSION:
        return file_configure(name, package)

    try:
        ptime = int(ptime)
    except:
        return file_configure(name, package)

    if not hasattr(actions, '__iter__'):
        return file_configure(name, package)

    files = set()
    for action in actions:
        try:
            fileset = action[4]
            files.update(fileset)
        except (TypeError, IndexError):
            return file_configure(name, package)

    for file in files:
        if not(os.path.isfile(file) or os.path.islink(file)):
            return file_configure(name, package)

        mtime = os.stat(realpath(file)).st_mtime
        
        if  mtime >= ptime:
            return file_configure(name, package)

    context = zope.configuration.config.ConfigurationMachine()
    xmlconfig.registerCommonDirectives(context)
    context.actions = actions
    context.cached_execution = True
    context.execute_actions()
    return True

def file_configure(name, package, dump=cPickle.dump):
    context = zope.configuration.config.ConfigurationMachine()
    xmlconfig.registerCommonDirectives(context)
    context.package = package

    xmlconfig.include(context, name, package)
    context.execute_actions(clear=False)

    actions = context.actions
    pckname = pickle_name(name, package)

    for action in actions:
        
        discriminator = action[0]
        if discriminator and Uncacheable in discriminator:
            try:
                os.remove(pckname)
            except:
                pass
            return False

    try:
        data = (PVERSION, time.time(), actions)
        dump(data, open(pckname, 'wb'), -1)
    except (OSError, IOError, TypeError, cPickle.PickleError):
        try:
            os.remove(pckname)
        except:
            pass

    return False