from __future__ import unicode_literals

import inspect
import logging
import urllib
import urlparse

from django.apps import apps
from django.conf import settings
from django.core.exceptions import PermissionDenied
from django.core.urlresolvers import resolve, reverse
from django.template import VariableDoesNotExist, Variable
from django.template.defaulttags import URLNode
from django.utils.encoding import force_text
from django.utils.http import urlencode, urlquote

from common.utils import return_attrib
from permissions import Permission

logger = logging.getLogger(__name__)


class ResolvedLink(object):
    def __init__(self, link, current_view):
        self.current_view = current_view
        self.disabled = False
        self.link = link
        self.url = '#'
        self.context = None
        self.request = None

    @property
    def active(self):
        return self.link.view == self.current_view

    @property
    def description(self):
        return self.link.description

    @property
    def icon(self):
        return self.link.icon

    @property
    def tags(self):
        return self.link.tags

    @property
    def text(self):
        try:
            return self.link.text(context=self.context)
        except TypeError:
            return self.link.text


class Menu(object):
    _registry = {}

    @classmethod
    def get(cls, name):
        return cls._registry[name]

    def __init__(self, name, icon=None, label=None):
        if name in self.__class__._registry:
            raise Exception('A menu with this name already exists')

        self.icon = icon
        self.name = name
        self.label = label
        self.bound_links = {}
        self.unbound_links = {}
        self.link_positions = {}
        self.__class__._registry[name] = self

    def _map_links_to_source(self, links, source, map_variable='bound_links', position=None):
        source_links = getattr(self, map_variable).setdefault(source, [])

        for link in links:
            source_links.append(link)
            self.link_positions[link] = position

    def bind_links(self, links, sources=None, position=None):
        """
        Associate a link to a model, a view inside this menu
        """

        try:
            for source in sources:
                self._map_links_to_source(
                    links=links, position=position, source=source
                )
        except TypeError:
            # Unsourced links display always
            self._map_links_to_source(
                links=links, position=position, source=sources
            )

    def get_resolved_navigation_object_list(self, context, source):
        resolved_navigation_object_list = []

        if source:
            resolved_navigation_object_list = [source]
        else:
            navigation_object_list = context.get(
                'navigation_object_list', ('object',)
            )

            logger.debug('navigation_object_list: %s', navigation_object_list)

            # Multiple objects
            for navigation_object in navigation_object_list:
                try:
                    resolved_navigation_object_list.append(
                        Variable(navigation_object).resolve(context)
                    )
                except VariableDoesNotExist:
                    pass

        logger.debug(
            'resolved_navigation_object_list: %s',
            force_text(resolved_navigation_object_list)
        )
        return resolved_navigation_object_list

    def resolve(self, context, source=None):
        result = []

        try:
            request = Variable('request').resolve(context)
        except VariableDoesNotExist:
            # There is no request variable, most probable a 500 in a test view
            # Don't return any resolved links then.
            logger.warning('No request variable, aborting menu resolution')
            return ()

        current_path = request.META['PATH_INFO']

        # Get sources: view name, view objects
        current_view = resolve(current_path).view_name

        resolved_navigation_object_list = self.get_resolved_navigation_object_list(
            context=context, source=source
        )

        for resolved_navigation_object in resolved_navigation_object_list:
            resolved_links = []

            for bound_source, links in self.bound_links.iteritems():
                try:
                    if inspect.isclass(bound_source):
                        if type(resolved_navigation_object) == bound_source:
                            for link in links:
                                resolved_link = link.resolve(
                                    context=context,
                                    resolved_object=resolved_navigation_object
                                )
                                if resolved_link:
                                    if resolved_link.link not in self.unbound_links.get(bound_source, ()):
                                        resolved_links.append(resolved_link)
                            # No need for further content object match testing
                            break
                        elif hasattr(resolved_navigation_object, 'get_deferred_fields') and resolved_navigation_object.get_deferred_fields() and isinstance(resolved_navigation_object, bound_source):
                            # Second try for objects using .defer() or .only()
                            for link in links:
                                resolved_link = link.resolve(
                                    context=context,
                                    resolved_object=resolved_navigation_object
                                )
                                if resolved_link:
                                    if resolved_link.link not in self.unbound_links.get(bound_source, ()):
                                        resolved_links.append(resolved_link)
                            # No need for further content object match testing
                            break
                except TypeError:
                    # When source is a dictionary
                    pass

            if resolved_links:
                result.append(resolved_links)

        resolved_links = []
        # View links
        for link in self.bound_links.get(current_view, []):
            resolved_link = link.resolve(context=context)
            if resolved_link:
                if resolved_link.link not in self.unbound_links.get(bound_source, ()):
                    resolved_links.append(resolved_link)

        if resolved_links:
            result.append(resolved_links)

        resolved_links = []

        # Main menu links
        for link in self.bound_links.get(None, []):
            if isinstance(link, Menu):
                resolved_link = link
                resolved_links.append(resolved_link)
            else:
                # "Always show" links
                resolved_link = link.resolve(context=context)
                if resolved_link.link not in self.unbound_links.get(None, ()):
                    resolved_links.append(resolved_link)

        if resolved_links:
            result.append(resolved_links)

        if result:
            # Sort links by position value passed during bind
            result[0] = sorted(
                result[0], key=lambda item: self.link_positions.get(item.link) if isinstance(item, ResolvedLink) else self.link_positions.get(item)
            )

        return result

    def unbind_links(self, links, sources=None):
        """
        Allow unbinding links from sources, used to allow 3rd party apps to
        change the link binding of core apps
        """

        try:
            for source in sources:
                self._map_links_to_source(
                    links=links, source=source, map_variable='unbound_links'
                )
        except TypeError:
            # Unsourced links display always
            self._map_links_to_source(
                links=links, source=sources, map_variable='unbound_links'
            )


class Link(object):
    def __init__(self, text, view=None, args=None, condition=None,
                 conditional_disable=None, description=None, icon=None,
                 keep_query=False, kwargs=None, permissions=None,
                 permissions_related=None, remove_from_query=None, tags=None,
                 url=None):

        self.args = args or []
        self.condition = condition
        self.conditional_disable = conditional_disable
        self.description = description
        self.icon = icon
        self.keep_query = keep_query
        self.kwargs = kwargs or {}
        self.permissions = permissions or []
        self.permissions_related = permissions_related
        self.remove_from_query = remove_from_query or []
        self.tags = tags
        self.text = text
        self.view = view
        self.url = url

    def resolve(self, context, resolved_object=None):
        AccessControlList = apps.get_model(
            app_label='acls', model_name='AccessControlList'
        )

        request = Variable('request').resolve(context)
        current_path = request.META['PATH_INFO']
        current_view = resolve(current_path).view_name

        # ACL is tested agains the resolved_object or just {{ object }} if not
        if not resolved_object:
            try:
                resolved_object = Variable('object').resolve(context=context)
            except VariableDoesNotExist:
                pass

        # If this link has a required permission check that the user has it
        # too
        if self.permissions:
            if resolved_object:
                try:
                    AccessControlList.objects.check_access(
                        permissions=self.permissions, user=request.user,
                        obj=resolved_object, related=self.permissions_related
                    )
                except PermissionDenied:
                    return None
            else:
                try:
                    Permission.check_permissions(
                        requester=request.user, permissions=self.permissions
                    )
                except PermissionDenied:
                    return None

        # Check to see if link has conditional display function and only
        # display it if the result of the conditional display function is
        # True
        if self.condition:
            if not self.condition(context):
                return None

        resolved_link = ResolvedLink(current_view=current_view, link=self)

        if self.view:
            view_name = Variable('"{}"'.format(self.view))
            if isinstance(self.args, list) or isinstance(self.args, tuple):
                # TODO: Don't check for instance check for iterable in try/except
                # block. This update required changing all 'args' argument in
                # links.py files to be iterables and not just strings.
                args = [Variable(arg) for arg in self.args]
            else:
                args = [Variable(self.args)]

            # If we were passed an instance of the view context object we are
            # resolving, inject it into the context. This help resolve links for
            # object lists.
            if resolved_object:
                context['resolved_object'] = resolved_object

            try:
                kwargs = self.kwargs(context)
            except TypeError:
                # Is not a callable
                kwargs = self.kwargs

            kwargs = {key: Variable(value) for key, value in kwargs.iteritems()}

            # Use Django's exact {% url %} code to resolve the link
            node = URLNode(
                view_name=view_name, args=args, kwargs=kwargs, asvar=None
            )
            try:
                resolved_link.url = node.render(context)
            except Exception as exception:
                logger.error(
                    'Error resolving link "%s" URL; %s', self.text, exception
                )
        elif self.url:
            resolved_link.url = self.url

        # This is for links that should be displayed but that are not clickable
        if self.conditional_disable:
            resolved_link.disabled = self.conditional_disable(context)
        else:
            resolved_link.disabled = False

        # Lets a new link keep the same URL query string of the current URL
        if self.keep_query:
            # Sometimes we are required to remove a key from the URL QS
            previous_path = force_text(
                urllib.unquote_plus(
                    force_text(
                        request.get_full_path()
                    ) or force_text(
                        request.META.get(
                            'HTTP_REFERER',
                            reverse(settings.LOGIN_REDIRECT_URL)
                        )
                    )
                )
            )
            query_string = urlparse.urlparse(previous_path).query
            parsed_query_string = urlparse.parse_qs(query_string)

            for key in self.remove_from_query:
                try:
                    del parsed_query_string[key]
                except KeyError:
                    pass

            resolved_link.url = '%s?%s' % (
                urlquote(resolved_link.url),
                urlencode(parsed_query_string, doseq=True)
            )

        resolved_link.context = context
        return resolved_link


class Separator(Link):
    """
    Menu separator. Renders to an <hr> tag
    """
    def __init__(self, *args, **kwargs):
        self.icon = None
        self.text = None
        self.view = None

    def resolve(self, *args, **kwargs):
        result = ResolvedLink(current_view=None, link=self)
        result.separator = True
        return result


class SourceColumn(object):
    _registry = {}

    @classmethod
    def get_for_source(cls, source):
        try:
            return cls._registry[source]
        except KeyError:
            try:
                # Try it as a queryset
                return cls._registry[source.model]
            except AttributeError:
                try:
                    # It seems to be an instance, try its class
                    return cls._registry[source.__class__]
                except KeyError:
                    try:
                        # Special case for queryset items produced from
                        # .defer() or .only() optimizations
                        return cls._registry[source._meta.parents.items()[0][0]]
                    except (AttributeError, KeyError, IndexError):
                        return ()
        except TypeError:
            # unhashable type: list
            return ()

    def __init__(self, source, label, attribute=None, func=None):
        self.source = source
        self.label = label
        self.attribute = attribute
        self.func = func
        self.__class__._registry.setdefault(source, [])
        self.__class__._registry[source].append(self)

    def resolve(self, context):
        if self.attribute:
            result = return_attrib(context['object'], self.attribute)
        elif self.func:
            result = self.func(context=context)

        return result


class Text(Link):
    """
    Menu text. Renders to a plain <li> tag
    """
    def __init__(self, *args, **kwargs):
        self.icon = None
        self.text = kwargs.get('text')
        self.view = None

    def resolve(self, *args, **kwargs):
        result = ResolvedLink(current_view=None, link=self)
        result.context = kwargs.get('context')
        result.text_span = True
        return result