from django.db import models
from django.utils.html import conditional_escape, mark_safe
from django.utils.translation import ugettext_lazy as _

from mptt.forms import *  # noqa

from misago.core import forms
from misago.core.validators import validate_sluggable

from misago.forums.models import Forum, ForumRole


"""
Fields
"""
class ForumListLazyQueryset(object):
    def __init__(self, parent, acl):
        self._cache = None
        self.parent = parent
        self.acl = acl

    def get_parent(self):
        if not self.parent:
            self.parent = Forum.objects.root_category()
        return self.parent

    def _all(self):
        queryset = self.get_parent().get_descendants()
        if self.acl:
            allowed_ids = [0]
            for forum_id, perms in self.acl.get('forums', {}).items():
                if perms.get('can_see') and perms.get('can_browse'):
                    allowed_ids.append(forum_id)
            queryset = queryset.filter(id__in=allowed_ids)
        return queryset.all()

    def all(self):
        if not self._cache:
            self._cache = self._all()
        return self._cache

    def filter(self, *args, **kwargs):
        return self.all().filter(*args, **kwargs)

    def exclude(self, *args, **kwargs):
        return self.all().exclude(*args, **kwargs)

    def __len__(self):
        return len(self.all())


class MisagoForumMixin(object):
    def get_queryset(self, acl=None):
        queryset = self.parent.get_descendants()
        if acl:
            allowed_ids = [0]
            for forum_id, perms in acl.get('forums', {}).items():
                if perms.get('can_see') and perms.get('can_browse'):
                    allowed_ids.append(forum_id)
            queryset = queryset.filter(id__in=allowed_ids)
        return queryset

    def _get_level_indicator(self, obj):
        level = obj.level - self.queryset.get_parent().level - 1
        return mark_safe(conditional_escape('- - ') * level)


class ForumChoiceField(MisagoForumMixin, TreeNodeChoiceField):
    def __init__(self, parent=None, acl=None, *args, **kwargs):
        if not 'queryset' in kwargs:
            kwargs['queryset'] = ForumListLazyQueryset(parent, acl)
        super(ForumChoiceField, self).__init__(*args, **kwargs)


class ForumsMultipleChoiceField(MisagoForumMixin, TreeNodeMultipleChoiceField):
    def __init__(self, parent=None, acl=None, *args, **kwargs):
        if not 'queryset' in kwargs:
            kwargs['queryset'] = ForumListLazyQueryset(parent, acl)
        super(ForumsMultipleChoiceField, self).__init__(*args, **kwargs)


"""
Forms
"""
FORUM_ROLES = (
    ('category', _('Category')),
    ('forum', _('Forum')),
    ('redirect', _('Redirect')),
)


class AdminForumChoiceField(TreeNodeChoiceField):
    def __init__(self, *args, **kwargs):
        self.base_level = kwargs.pop('base_level', 1)
        kwargs['level_indicator'] = kwargs.get('level_indicator', '- - ')
        super(AdminForumChoiceField, self).__init__(*args, **kwargs)

    def _get_level_indicator(self, obj):
        level = getattr(obj, obj._mptt_meta.level_attr) - self.base_level
        if level > 0:
            return mark_safe(conditional_escape(self.level_indicator) * level)
        else:
            return ''


class ForumFormBase(forms.ModelForm):
    role = forms.ChoiceField(label=_("Type"), choices=FORUM_ROLES)
    name = forms.CharField(
        label=_("Name"),
        validators=[validate_sluggable()])
    description = forms.CharField(
        label=_("Description"), max_length=2048, required=False,
        widget=forms.Textarea(attrs={'rows': 3}),
        help_text=_("Optional description explaining forum intented "
                    "purpose."))
    redirect_url = forms.URLField(
        label=_("Redirect URL"),
        validators=[validate_sluggable()],
        help_text=_('If forum type is redirect, enter here its URL.'),
        required=False)
    css_class = forms.CharField(
        label=_("CSS class"), required=False,
        help_text=_("Optional CSS class used to customize this forum "
                    "appearance from templates."))
    is_closed = forms.YesNoSwitch(
        label=_("Closed forum"), required=False,
        help_text=_("Only members with valid permissions can post in "
                    "closed forums."))
    css_class = forms.CharField(
        label=_("CSS class"), required=False,
        help_text=_("Optional CSS class used to customize this forum "
                    "appearance from templates."))
    prune_started_after = forms.IntegerField(
        label=_("Thread age"), min_value=0,
        help_text=_("Prune thread if number of days since its creation is "
                    "greater than specified. Enter 0 to disable this "
                    "pruning criteria."))
    prune_replied_after = forms.IntegerField(
        label=_("Last reply"), min_value=0,
        help_text=_("Prune thread if number of days since last reply is "
                    "greater than specified. Enter 0 to disable this "
                    "pruning criteria."))

    class Meta:
        model = Forum
        fields = [
            'role',
            'name',
            'description',
            'redirect_url',
            'css_class',
            'is_closed',
            'prune_started_after',
            'prune_replied_after',
            'archive_pruned_in',
        ]

    def clean_copy_permissions(self):
        data = self.cleaned_data['copy_permissions']
        if data and data.pk == self.instance.pk:
            message = _("Permissions cannot be copied from forum into itself.")
            raise forms.ValidationError(message)
        return data

    def clean_archive_pruned_in(self):
        data = self.cleaned_data['archive_pruned_in']
        if data and data.pk == self.instance.pk:
            message = _("Forum cannot act as archive for itself.")
            raise forms.ValidationError(message)
        return data

    def clean(self):
        data = super(ForumFormBase, self).clean()

        self.instance.set_name(data.get('name'))

        if data['role'] != 'category':
            if not data['new_parent'].level:
                message = _("Only categories can have no parent category.")
                raise forms.ValidationError(message)

        if data['role'] == 'redirect':
            if not data.get('redirect_url'):
                message = _("This forum is redirect, yet you haven't "
                            "specified URL to which it should redirect "
                            "after click.")
                raise forms.ValidationError(message)

        return data


def ForumFormFactory(instance):
    parent_queryset = Forum.objects.all_forums(True).order_by('lft')
    if instance.pk:
        not_siblings = models.Q(lft__lt=instance.lft)
        not_siblings = not_siblings | models.Q(rght__gt=instance.rght)
        parent_queryset = parent_queryset.filter(not_siblings)

    return type('ForumFormFinal', (ForumFormBase,), {
        'new_parent': AdminForumChoiceField(
            label=_("Parent forum"),
            queryset=parent_queryset,
            initial=instance.parent,
            empty_label=None),
        'copy_permissions': AdminForumChoiceField(
            label=_("Copy permissions"),
            help_text=_("You can replace this forum permissions with "
                        "permissions copied from forum selected here."),
            queryset=Forum.objects.all_forums(),
            empty_label=_("Don't copy permissions"),
            required=False),
        'archive_pruned_in': AdminForumChoiceField(
            label=_("Archive"),
            help_text=_("Instead of being deleted, pruned threads can be "
                        "moved to designated forum."),
            queryset=Forum.objects.all_forums(),
            empty_label=_("Don't archive pruned threads"),
            required=False),
        })


class DeleteForumFormBase(forms.ModelForm):
    class Meta:
        model = Forum
        fields = []

    def clean(self):
        data = super(DeleteForumFormBase, self).clean()

        if data.get('move_threads_to'):
            if data['move_threads_to'].pk == self.instance.pk:
                message = _("You are trying to move this forum threads to "
                            "itself.")
                raise forms.ValidationError(message)

            if data['move_threads_to'].role == 'category':
                message = _("Threads can't be moved to category.")
                raise forms.ValidationError(message)

            if data['move_threads_to'].role == 'redirect':
                message = _("Threads can't be moved to redirect.")
                raise forms.ValidationError(message)

            moving_to_child = self.instance.has_child(data['move_threads_to'])
            if moving_to_child and not data.get('move_children_to'):
                message = _("You are trying to move this forum threads to a "
                            "child forum that will be deleted together with "
                            "this forum.")
                raise forms.ValidationError(message)

        if data.get('move_children_to'):
            if data['move_children_to'].special_role == 'root_category':
                for child in self.instance.get_children().iterator():
                    if child.role != 'category':
                        message = _("One or more child forums in forum are "
                                    "not categories and thus cannot be made "
                                    "root categories.")
                        raise forms.ValidationError(message)

        return data


def DeleteFormFactory(instance):
    content_queryset = Forum.objects.all_forums().order_by('lft')
    fields = {
        'move_threads_to': AdminForumChoiceField(
            label=_("Move forum threads to"),
            queryset=content_queryset,
            initial=instance.parent,
            empty_label=_('Delete with forum'),
            required=False),
    }

    not_siblings = models.Q(lft__lt=instance.lft)
    not_siblings = not_siblings | models.Q(rght__gt=instance.rght)
    children_queryset = Forum.objects.all_forums(True)
    children_queryset = children_queryset.filter(not_siblings).order_by('lft')

    if children_queryset.exists():
        fields['move_children_to'] = AdminForumChoiceField(
            label=_("Move child forums to"),
            queryset=children_queryset,
            empty_label=_('Delete with forum'),
            required=False)

    return type('DeleteForumFormFinal', (DeleteForumFormBase,), fields)


class ForumRoleForm(forms.ModelForm):
    name = forms.CharField(label=_("Role name"))

    class Meta:
        model = ForumRole
        fields = ['name']


def RoleForumACLFormFactory(forum, forum_roles, selected_role):
    attrs = {
        'forum': forum,
        'role': forms.ModelChoiceField(
            label=_("Role"),
            required=False,
            queryset=forum_roles,
            initial=selected_role,
            empty_label=_("No access"))
    }

    return type('RoleForumACLForm', (forms.Form,), attrs)


def ForumRolesACLFormFactory(role, forum_roles, selected_role):
    attrs = {
        'role': role,
        'forum_role': forms.ModelChoiceField(
            label=_("Role"),
            required=False,
            queryset=forum_roles,
            initial=selected_role,
            empty_label=_("No access"))
    }

    return type('ForumRolesACLForm', (forms.Form,), attrs)