import itertools
import json

from urllib.parse import urljoin

from django import template
from django.conf import settings
from django.contrib.admin.utils import quote
from django.contrib.humanize.templatetags.humanize import intcomma
from django.contrib.messages.constants import DEFAULT_TAGS as MESSAGE_TAGS
from django.template.defaultfilters import stringfilter
from django.template.loader import render_to_string
from django.templatetags.static import static
from django.utils.html import format_html, format_html_join
from django.utils.safestring import mark_safe
from django.utils.translation import ugettext_lazy as _

from wagtail.admin.localization import get_js_translation_strings
from wagtail.admin.menu import admin_menu
from wagtail.admin.navigation import get_explorable_root_page
from wagtail.admin.search import admin_search_areas
from wagtail.admin.staticfiles import versioned_static as versioned_static_func
from wagtail.core import hooks
from wagtail.core.models import (
    CollectionViewRestriction, Page, PageViewRestriction, UserPagePermissionsProxy)
from wagtail.core.utils import cautious_slugify as _cautious_slugify
from wagtail.core.utils import camelcase_to_underscore, escape_script
from wagtail.users.utils import get_gravatar_url

register = template.Library()

register.filter('intcomma', intcomma)


@register.simple_tag(takes_context=True)
def menu_search(context):
    request = context['request']

    search_areas = admin_search_areas.search_items_for_request(request)
    if not search_areas:
        return ''
    search_area = search_areas[0]

    return render_to_string('wagtailadmin/shared/menu_search.html', {
        'search_url': search_area.url,
    })


@register.inclusion_tag('wagtailadmin/shared/main_nav.html', takes_context=True)
def main_nav(context):
    request = context['request']

    return {
        'menu_html': admin_menu.render_html(request),
        'request': request,
    }


@register.inclusion_tag('wagtailadmin/shared/breadcrumb.html', takes_context=True)
def explorer_breadcrumb(context, page, include_self=False):
    user = context['request'].user

    # find the closest common ancestor of the pages that this user has direct explore permission
    # (i.e. add/edit/publish/lock) over; this will be the root of the breadcrumb
    cca = get_explorable_root_page(user)
    if not cca:
        return {'pages': Page.objects.none()}

    return {
        'pages': page.get_ancestors(inclusive=include_self).descendant_of(cca, inclusive=True).specific()
    }


@register.inclusion_tag('wagtailadmin/shared/search_other.html', takes_context=True)
def search_other(context, current=None):
    request = context['request']

    return {
        'options_html': admin_search_areas.render_html(request, current),
        'request': request,
    }


@register.simple_tag
def main_nav_js():
    return admin_menu.media['js']


@register.filter("ellipsistrim")
def ellipsistrim(value, max_length):
    if len(value) > max_length:
        truncd_val = value[:max_length]
        if not len(value) == (max_length + 1) and value[max_length + 1] != " ":
            truncd_val = truncd_val[:truncd_val.rfind(" ")]
        return truncd_val + "…"
    return value


@register.filter
def fieldtype(bound_field):
    try:
        return camelcase_to_underscore(bound_field.field.__class__.__name__)
    except AttributeError:
        try:
            return camelcase_to_underscore(bound_field.__class__.__name__)
        except AttributeError:
            return ""


@register.filter
def widgettype(bound_field):
    try:
        return camelcase_to_underscore(bound_field.field.widget.__class__.__name__)
    except AttributeError:
        try:
            return camelcase_to_underscore(bound_field.widget.__class__.__name__)
        except AttributeError:
            return ""


def _get_user_page_permissions(context):
    # Create a UserPagePermissionsProxy object to represent the user's global permissions, and
    # cache it in the context for the duration of the page request, if one does not exist already
    if 'user_page_permissions' not in context:
        context['user_page_permissions'] = UserPagePermissionsProxy(context['request'].user)

    return context['user_page_permissions']


@register.simple_tag(takes_context=True)
def page_permissions(context, page):
    """
    Usage: {% page_permissions page as page_perms %}
    Sets the variable 'page_perms' to a PagePermissionTester object that can be queried to find out
    what actions the current logged-in user can perform on the given page.
    """
    return _get_user_page_permissions(context).for_page(page)


@register.simple_tag(takes_context=True)
def test_collection_is_public(context, collection):
    """
    Usage: {% test_collection_is_public collection as is_public %}
    Sets 'is_public' to True iff there are no collection view restrictions in place
    on this collection.
    Caches the list of collection view restrictions in the context, to avoid repeated
    DB queries on repeated calls.
    """
    if 'all_collection_view_restrictions' not in context:
        context['all_collection_view_restrictions'] = CollectionViewRestriction.objects.select_related('collection').values_list(
            'collection__name', flat=True
        )

    is_private = collection.name in context['all_collection_view_restrictions']

    return not is_private


@register.simple_tag(takes_context=True)
def test_page_is_public(context, page):
    """
    Usage: {% test_page_is_public page as is_public %}
    Sets 'is_public' to True iff there are no page view restrictions in place on
    this page.
    Caches the list of page view restrictions in the context, to avoid repeated
    DB queries on repeated calls.
    """
    if 'all_page_view_restriction_paths' not in context:
        context['all_page_view_restriction_paths'] = PageViewRestriction.objects.select_related('page').values_list(
            'page__path', flat=True
        )

    is_private = any([
        page.path.startswith(restricted_path)
        for restricted_path in context['all_page_view_restriction_paths']
    ])

    return not is_private


@register.simple_tag
def hook_output(hook_name):
    """
    Example: {% hook_output 'insert_editor_css' %}
    Whenever we have a hook whose functions take no parameters and return a string, this tag can be used
    to output the concatenation of all of those return values onto the page.
    Note that the output is not escaped - it is the hook function's responsibility to escape unsafe content.
    """
    snippets = [fn() for fn in hooks.get_hooks(hook_name)]
    return mark_safe(''.join(snippets))


@register.simple_tag
def usage_count_enabled():
    return getattr(settings, 'WAGTAIL_USAGE_COUNT_ENABLED', False)


@register.simple_tag
def base_url_setting():
    return getattr(settings, 'BASE_URL', None)


@register.simple_tag
def allow_unicode_slugs():
    return getattr(settings, 'WAGTAIL_ALLOW_UNICODE_SLUGS', True)


@register.simple_tag
def auto_update_preview():
    return getattr(settings, 'WAGTAIL_AUTO_UPDATE_PREVIEW', False)


class EscapeScriptNode(template.Node):
    TAG_NAME = 'escapescript'

    def __init__(self, nodelist):
        super().__init__()
        self.nodelist = nodelist

    def render(self, context):
        out = self.nodelist.render(context)
        return escape_script(out)

    @classmethod
    def handle(cls, parser, token):
        nodelist = parser.parse(('end' + EscapeScriptNode.TAG_NAME,))
        parser.delete_first_token()
        return cls(nodelist)


register.tag(EscapeScriptNode.TAG_NAME, EscapeScriptNode.handle)


# Helpers for Widget.render_with_errors, our extension to the Django widget API that allows widgets to
# take on the responsibility of rendering their own error messages
@register.filter
def render_with_errors(bound_field):
    """
    Usage: {{ field|render_with_errors }} as opposed to {{ field }}.
    If the field (a BoundField instance) has errors on it, and the associated widget implements
    a render_with_errors method, call that; otherwise, call the regular widget rendering mechanism.
    """
    widget = bound_field.field.widget
    if bound_field.errors and hasattr(widget, 'render_with_errors'):
        return widget.render_with_errors(
            bound_field.html_name,
            bound_field.value(),
            attrs={'id': bound_field.auto_id},
            errors=bound_field.errors
        )
    else:
        return bound_field.as_widget()


@register.filter
def has_unrendered_errors(bound_field):
    """
    Return true if this field has errors that were not accounted for by render_with_errors, because
    the widget does not support the render_with_errors method
    """
    return bound_field.errors and not hasattr(bound_field.field.widget, 'render_with_errors')


@register.filter(is_safe=True)
@stringfilter
def cautious_slugify(value):
    return _cautious_slugify(value)


@register.simple_tag(takes_context=True)
def querystring(context, **kwargs):
    """
    Print out the current querystring. Any keyword arguments to this template
    tag will be added to the querystring before it is printed out.

        <a href="/page/{% querystring key='value' %}">

    Will result in something like:

        <a href="/page/?foo=bar&key=value">
    """
    request = context['request']
    querydict = request.GET.copy()
    # Can't do querydict.update(kwargs), because QueryDict.update() appends to
    # the list of values, instead of replacing the values.
    for key, value in kwargs.items():
        if value is None:
            # Remove the key if the value is None
            querydict.pop(key, None)
        else:
            # Set the key otherwise
            querydict[key] = str(value)

    return '?' + querydict.urlencode()


@register.simple_tag(takes_context=True)
def page_table_header_label(context, label=None, parent_page_title=None, **kwargs):
    """
    Wraps table_header_label to add a title attribute based on the parent page title and the column label
    """
    if label:
        translation_context = {'parent': parent_page_title, 'label': label}
        ascending_title_text = _("Sort the order of child pages within '%(parent)s' by '%(label)s' in ascending order.") % translation_context
        descending_title_text = _("Sort the order of child pages within '%(parent)s' by '%(label)s' in descending order.") % translation_context
    else:
        ascending_title_text = None
        descending_title_text = None

    return table_header_label(context, label=label, ascending_title_text=ascending_title_text, descending_title_text=descending_title_text, **kwargs)


@register.simple_tag(takes_context=True)
def table_header_label(
    context, label=None, sortable=True, ordering=None,
    sort_context_var='ordering', sort_param='ordering', sort_field=None,
    ascending_title_text=None, descending_title_text=None
):
    """
    A label to go in a table header cell, optionally with a 'sort' link that alternates between
    forward and reverse sorting

    label = label text
    ordering = current active ordering. If not specified, we will fetch it from the template context variable
        given by sort_context_var. (We don't fetch it from the URL because that wouldn't give the view method
        the opportunity to set a default)
    sort_param = URL parameter that indicates the current active ordering
    sort_field = the value for sort_param that indicates that sorting is currently on this column.
        For example, if sort_param='ordering' and sort_field='title', then a URL parameter of
        ordering=title indicates that the listing is ordered forwards on this column, and a URL parameter
        of ordering=-title indicated that the listing is ordered in reverse on this column
    ascending_title_text = title attribute to use on the link when the link action will sort in ascending order
    descending_title_text = title attribute to use on the link when the link action will sort in descending order

    To disable sorting on this column, set sortable=False or leave sort_field unspecified.
    """
    if not sortable or not sort_field:
        # render label without a sort link
        return label

    if ordering is None:
        ordering = context.get(sort_context_var)
    reverse_sort_field = "-%s" % sort_field

    if ordering == sort_field:
        # currently ordering forwards on this column; link should change to reverse ordering
        attrs = {
            'href': querystring(context, **{sort_param: reverse_sort_field}),
            'class': "icon icon-arrow-down-after teal",
        }
        if descending_title_text is not None:
            attrs['title'] = descending_title_text

    elif ordering == reverse_sort_field:
        # currently ordering backwards on this column; link should change to forward ordering
        attrs = {
            'href': querystring(context, **{sort_param: sort_field}),
            'class': "icon icon-arrow-up-after teal",
        }
        if ascending_title_text is not None:
            attrs['title'] = ascending_title_text

    else:
        # not currently ordering on this column; link should change to forward ordering
        attrs = {
            'href': querystring(context, **{sort_param: sort_field}),
            'class': "icon icon-arrow-down-after",
        }
        if ascending_title_text is not None:
            attrs['title'] = ascending_title_text

    attrs_string = format_html_join(' ', '{}="{}"', attrs.items())

    return format_html(
        # need whitespace around label for correct positioning of arrow icon
        '<a {attrs}> {label} </a>',
        attrs=attrs_string, label=label
    )


@register.simple_tag(takes_context=True)
def pagination_querystring(context, page_number, page_key='p'):
    """
    Print out a querystring with an updated page number:

        {% if page.has_next_page %}
            <a href="{% pagination_link page.next_page_number %}">Next page</a>
        {% endif %}
    """
    return querystring(context, **{page_key: page_number})


@register.inclusion_tag("wagtailadmin/pages/listing/_pagination.html",
                        takes_context=True)
def paginate(context, page, base_url='', page_key='p',
             classnames=''):
    """
    Print pagination previous/next links, and the page count. Take the
    following arguments:

    page
        The current page of results. This should be a Django pagination `Page`
        instance

    base_url
        The base URL of the next/previous page, with no querystring.
        This is optional, and defaults to the current page by just printing the
        querystring for the next/previous page.

    page_key
        The name of the page variable in the query string. Defaults to 'p'.

    classnames
        Extra classes to add to the next/previous links.
    """
    request = context['request']
    return {
        'base_url': base_url,
        'classnames': classnames,
        'request': request,
        'page': page,
        'page_key': page_key,
        'paginator': page.paginator,
    }


@register.inclusion_tag("wagtailadmin/pages/listing/_buttons.html",
                        takes_context=True)
def page_listing_buttons(context, page, page_perms, is_parent=False):
    button_hooks = hooks.get_hooks('register_page_listing_buttons')
    buttons = sorted(itertools.chain.from_iterable(
        hook(page, page_perms, is_parent)
        for hook in button_hooks))

    for hook in hooks.get_hooks('construct_page_listing_buttons'):
        hook(buttons, page, page_perms, is_parent, context)

    return {'page': page, 'buttons': buttons}


@register.simple_tag
def message_tags(message):
    level_tag = MESSAGE_TAGS.get(message.level)
    if message.extra_tags and level_tag:
        return message.extra_tags + ' ' + level_tag
    elif message.extra_tags:
        return message.extra_tags
    elif level_tag:
        return level_tag
    else:
        return ''


@register.filter('abs')
def _abs(val):
    return abs(val)


@register.filter
def admin_urlquote(value):
    return quote(value)


@register.simple_tag
def avatar_url(user, size=50):
    """
    A template tag that receives a user and size and return
    the appropiate avatar url for that user.
    Example usage: {% avatar_url request.user 50 %}
    """

    if hasattr(user, 'wagtail_userprofile') and user.wagtail_userprofile.avatar:
        return user.wagtail_userprofile.avatar.url

    if hasattr(user, 'email'):
        gravatar_url = get_gravatar_url(user.email, size=size)
        if gravatar_url is not None:
            return gravatar_url

    return versioned_static_func('wagtailadmin/images/default-user-avatar.png')


@register.simple_tag
def js_translation_strings():
    return mark_safe(json.dumps(get_js_translation_strings()))


@register.simple_tag
def notification_static(path):
    """
    Variant of the {% static %}` tag for use in notification emails - tries to form
    a full URL using BASE_URL if the static URL isn't already a full URL.
    """
    return urljoin(base_url_setting(), static(path))


@register.simple_tag
def versioned_static(path):
    """
    Wrapper for Django's static file finder to append a cache-busting query parameter
    that updates on each Wagtail version
    """
    return versioned_static_func(path)
