import json

from django import forms, http
from django.conf import settings
from django.contrib.admin.actions import delete_selected
from django.contrib.admin.options import ModelAdmin, IncorrectLookupParameters, get_content_type_for_model
from django.contrib.admin.models import LogEntry, CHANGE
from django.contrib import messages
from django.db import IntegrityError, transaction
from django.utils.encoding import force_str, smart_str
from django.utils.html import format_html, mark_safe
from django.utils.translation import gettext as _, gettext_lazy
from django.contrib.admin import RelatedFieldListFilter
from django.contrib.admin.utils import get_model_from_relation
from django.core.exceptions import ValidationError
from django.core.serializers.json import DjangoJSONEncoder
from django.utils.translation import get_language_bidi
from django.db.models.fields.related import ForeignObjectRel, ManyToManyField

from js_asset import JS

from mptt.exceptions import InvalidMove
from mptt.forms import MPTTAdminForm, TreeNodeChoiceField
from mptt.models import MPTTModel, TreeForeignKey

__all__ = ('MPTTModelAdmin', 'MPTTAdminForm', 'DraggableMPTTAdmin')
IS_GRAPPELLI_INSTALLED = 'grappelli' in settings.INSTALLED_APPS


class MPTTModelAdmin(ModelAdmin):
    """
    A basic admin class that displays tree items according to their position in
    the tree.  No extra editing functionality beyond what Django admin normally
    offers.
    """

    if IS_GRAPPELLI_INSTALLED:
        change_list_template = 'admin/grappelli_mptt_change_list.html'
    else:
        change_list_template = 'admin/mptt_change_list.html'

    form = MPTTAdminForm

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if issubclass(db_field.remote_field.model, MPTTModel) \
                and not isinstance(db_field, TreeForeignKey) \
                and db_field.name not in self.raw_id_fields:
            db = kwargs.get('using')

            limit_choices_to = db_field.get_limit_choices_to()
            defaults = dict(
                form_class=TreeNodeChoiceField,
                queryset=db_field.remote_field.model._default_manager.using(
                    db).complex_filter(limit_choices_to),
                required=False)
            defaults.update(kwargs)
            kwargs = defaults
        return super(MPTTModelAdmin, self).formfield_for_foreignkey(
            db_field, request, **kwargs)

    def get_ordering(self, request):
        """
        Changes the default ordering for changelists to tree-order.
        """
        mptt_opts = self.model._mptt_meta
        return self.ordering or (mptt_opts.tree_id_attr, mptt_opts.left_attr)

    def delete_selected_tree(self, modeladmin, request, queryset):
        """
        Deletes multiple instances and makes sure the MPTT fields get
        recalculated properly. (Because merely doing a bulk delete doesn't
        trigger the post_delete hooks.)
        """
        # If this is True, the confirmation page has been displayed
        if request.POST.get('post'):
            n = 0
            with queryset.model._tree_manager.delay_mptt_updates():
                for obj in queryset:
                    if self.has_delete_permission(request, obj):
                        obj_display = force_str(obj)
                        self.log_deletion(request, obj, obj_display)
                        obj.delete()
                        n += 1
            self.message_user(
                request,
                _('Successfully deleted %(count)d items.') % {'count': n})
            # Return None to display the change list page again
            return None
        else:
            # (ab)using the built-in action to display the confirmation page
            return delete_selected(self, request, queryset)

    def get_actions(self, request):
        actions = super(MPTTModelAdmin, self).get_actions(request)
        if actions is not None and 'delete_selected' in actions:
            actions['delete_selected'] = (
                self.delete_selected_tree,
                'delete_selected',
                _('Delete selected %(verbose_name_plural)s'))
        return actions


class DraggableMPTTAdmin(MPTTModelAdmin):
    """
    The ``DraggableMPTTAdmin`` modifies the standard Django administration
    change list to a drag-drop enabled interface.
    """

    change_list_template = None  # Back to default
    list_per_page = 2000  # This will take a really long time to load.
    list_display = ('tree_actions', 'indented_title')  # Sane defaults.
    list_display_links = ('indented_title',)  # Sane defaults.
    mptt_level_indent = 20
    expand_tree_by_default = False

    def tree_actions(self, item):
        try:
            url = item.get_absolute_url()
        except Exception:  # Nevermind.
            url = ''

        return format_html(
            '<div class="drag-handle"></div>'
            '<div class="tree-node" data-pk="{}" data-level="{}"'
            ' data-url="{}"></div>',
            item.pk,
            item._mpttfield('level'),
            url,
        )
    tree_actions.short_description = ''

    def indented_title(self, item):
        """
        Generate a short title for an object, indent it depending on
        the object's depth in the hierarchy.
        """
        return format_html(
            '<div style="text-indent:{}px">{}</div>',
            item._mpttfield('level') * self.mptt_level_indent,
            item,
        )
    indented_title.short_description = gettext_lazy('title')

    def changelist_view(self, request, *args, **kwargs):
        if request.is_ajax() and request.POST.get('cmd') == 'move_node':
            return self._move_node(request)

        response = super(DraggableMPTTAdmin, self).changelist_view(
            request, *args, **kwargs)

        try:
            response.context_data['media'] = response.context_data['media'] + forms.Media(
                css={
                    'all': ['mptt/draggable-admin.css'],
                },
                js=[
                    'admin/js/vendor/jquery/jquery.js',
                    'admin/js/jquery.init.js',
                    JS('mptt/draggable-admin.js', {
                        'id': 'draggable-admin-context',
                        'data-context': json.dumps(
                            self._tree_context(request), cls=DjangoJSONEncoder
                        ),
                    }),
                ],
            )
        except (AttributeError, KeyError):
            # Not meant for us if there is no context_data attribute (no
            # TemplateResponse) or no media in the context.
            pass

        return response

    def get_data_before_update(self, request, cut_item, pasted_on):
        mptt_opts = self.model._mptt_meta
        mptt_attr_fields = ("parent_attr", "left_attr", "right_attr", "tree_id_attr", "level_attr")
        mptt_fields = [getattr(mptt_opts, attr) for attr in mptt_attr_fields]
        return {k: getattr(cut_item, k) for k in mptt_fields}

    def get_move_node_change_message(self, request, cut_item, pasted_on, data_before_update):
        changed_fields = [k for k, v in data_before_update.items() if v != getattr(cut_item, k)]
        return [{'changed': {'fields': changed_fields}}]

    @transaction.atomic
    def _move_node(self, request):
        position = request.POST.get('position')
        if position not in ('last-child', 'left', 'right'):
            self.message_user(request, _('Did not understand moving instruction.'), level=messages.ERROR)
            return http.HttpResponse('FAIL, unknown instruction.')

        queryset = self.get_queryset(request)
        try:
            cut_item = queryset.get(pk=request.POST.get('cut_item'))
            pasted_on = queryset.get(pk=request.POST.get('pasted_on'))
        except (self.model.DoesNotExist, TypeError, ValueError):
            self.message_user(request, _('Objects have disappeared, try again.'), level=messages.ERROR)
            return http.HttpResponse('FAIL, invalid objects.')

        if not self.has_change_permission(request, cut_item):
            self.message_user(request, _('No permission'), level=messages.ERROR)
            return http.HttpResponse('FAIL, no permission.')

        data_before_update = self.get_data_before_update(request, cut_item, pasted_on)

        try:
            self.model._tree_manager.move_node(cut_item, pasted_on, position)
        except InvalidMove as e:
            self.message_user(request, '%s' % e, level=messages.ERROR)
            return http.HttpResponse('FAIL, invalid move.')
        except IntegrityError as e:
            self.message_user(request, _('Database error: %s') % e, level=messages.ERROR)
            raise

        change_message = self.get_move_node_change_message(request, cut_item, pasted_on, data_before_update)

        LogEntry.objects.log_action(
            user_id=request.user.id,
            content_type_id=get_content_type_for_model(cut_item).pk,
            object_id=cut_item.pk,
            object_repr=str(cut_item),
            action_flag=CHANGE,
            change_message=change_message
        )

        self.message_user(
            request,
            _('%s has been successfully moved.') % cut_item)
        return http.HttpResponse('OK, moved.')

    def _tree_context(self, request):
        opts = self.model._meta

        return {
            'storageName': 'tree_%s_%s_collapsed' % (opts.app_label, opts.model_name),
            'treeStructure': self._build_tree_structure(self.get_queryset(request)),
            'levelIndent': self.mptt_level_indent,
            'messages': {
                'before': _('move node before node'),
                'child': _('move node to child position'),
                'after': _('move node after node'),
                'collapseTree': _('Collapse tree'),
                'expandTree': _('Expand tree'),
            },
            'expandTreeByDefault': self.expand_tree_by_default,
        }

    def _build_tree_structure(self, queryset):
        """
        Build an in-memory representation of the item tree, trying to keep
        database accesses down to a minimum. The returned dictionary looks like
        this (as json dump):

            {"6": [7, 8, 10]
             "7": [12],
             ...
             }

        Leaves are not included in the dictionary.
        """
        all_nodes = {}

        mptt_opts = self.model._mptt_meta
        items = queryset.values_list(
            'pk',
            '%s_id' % mptt_opts.parent_attr,
        )
        for p_id, parent_id in items:
            all_nodes.setdefault(
                str(parent_id) if parent_id else 0,
                [],
            ).append(p_id)
        return all_nodes


class TreeRelatedFieldListFilter(RelatedFieldListFilter):
    """
    Admin filter class which filters models related to parent model with all it's descendants.

     Usage:

    from mptt.admin import TreeRelatedFieldListFilter

    @admin.register(models.MyModel)
    class MyModelAdmin(admin.ModelAdmin):
        model = models.MyModel
        list_filter =
        (
            ('my_related_model', TreeRelatedFieldListFilter),
        )
    """
    template = 'admin/mptt_filter.html'
    mptt_level_indent = 10

    def __init__(self, field, request, params, model, model_admin, field_path):
        self.other_model = get_model_from_relation(field)
        if field.remote_field is not None and hasattr(field.remote_field, 'get_related_field'):
            self.rel_name = field.remote_field.get_related_field().name
        else:
            self.rel_name = self.other_model._meta.pk.name
        self.changed_lookup_kwarg = '%s__%s__inhierarchy' % (field_path, self.rel_name)
        super(TreeRelatedFieldListFilter, self).__init__(field, request, params,
                                                         model, model_admin, field_path)
        self.lookup_val = request.GET.get(self.changed_lookup_kwarg)

    def expected_parameters(self):
        return [self.changed_lookup_kwarg, self.lookup_kwarg_isnull]

    # Ripped from contrib.admin.filters,FieldListFilter Django 1.8 to deal with
    # lookup name 'inhierarchy'
    def queryset(self, request, queryset):
        try:
            # #### MPTT ADDITION START
            if self.lookup_val:
                other_model = self.other_model.objects.get(pk=self.lookup_val)
                other_models = other_model.get_descendants(True)
                del self.used_parameters[self.changed_lookup_kwarg]
                self.used_parameters.update(
                    {'%s__%s__in' % (self.field_path, self.rel_name): other_models}
                )
            # #### MPTT ADDITION END
            return queryset.filter(**self.used_parameters)
        except ValidationError as e:
            raise IncorrectLookupParameters(e)

    # Adding padding_style to each choice tuple
    def field_choices(self, field, request, model_admin):
        mptt_level_indent = getattr(model_admin, 'mptt_level_indent', self.mptt_level_indent)
        language_bidi = get_language_bidi()
        initial_choices = field.get_choices(include_blank=False)
        pks = [pk for pk, val in initial_choices]
        models = field.related_model._default_manager.filter(pk__in=pks)
        levels_dict = {model.pk: getattr(model, model._mptt_meta.level_attr) for model in models}
        choices = []
        for pk, val in initial_choices:
            padding_style = ' style="padding-%s:%spx"' % (
                'right' if language_bidi else 'left',
                mptt_level_indent * levels_dict[pk])
            choices.append((pk, val, mark_safe(padding_style)))
        return choices

    # Ripped from contrib.admin.filters,RelatedFieldListFilter Django 1.8 to
    # yield padding_style
    def choices(self, cl):
        # #### MPTT ADDITION START
        EMPTY_CHANGELIST_VALUE = self.empty_value_display
        # #### MPTT ADDITION END
        yield {
            'selected': self.lookup_val is None and not self.lookup_val_isnull,
            'query_string': cl.get_query_string({}, [self.changed_lookup_kwarg, self.lookup_kwarg_isnull]),
            'display': _('All'),
        }
        for pk_val, val, padding_style in self.lookup_choices:
            yield {
                'selected': self.lookup_val == smart_str(pk_val),
                'query_string': cl.get_query_string({
                    self.changed_lookup_kwarg: pk_val,
                }, [self.lookup_kwarg_isnull]),
                'display': val,
                # #### MPTT ADDITION START
                'padding_style': padding_style,
                # #### MPTT ADDITION END
            }
        if (isinstance(self.field, ForeignObjectRel) and
                (self.field.field.null or isinstance(self.field.field, ManyToManyField)) or
                self.field.remote_field is not None and
                (self.field.null or isinstance(self.field, ManyToManyField))):
            yield {
                'selected': bool(self.lookup_val_isnull),
                'query_string': cl.get_query_string({
                    self.lookup_kwarg_isnull: 'True',
                }, [self.changed_lookup_kwarg]),
                'display': EMPTY_CHANGELIST_VALUE,
            }