from __future__ import unicode_literals

from django.contrib import messages
from django.db import models
from django.shortcuts import redirect, render

from modelcluster.contrib.taggit import ClusterTaggableManager
from modelcluster.fields import ParentalKey

from taggit.models import Tag, TaggedItemBase

from wagtail.contrib.wagtailroutablepage.models import RoutablePageMixin, route
from wagtail.wagtailadmin.edit_handlers import FieldPanel, InlinePanel
from wagtail.wagtailcore.models import Page, Orderable
from wagtail.wagtailimages.edit_handlers import ImageChooserPanel
from wagtail.wagtailsearch import index
from wagtail.wagtailsnippets.edit_handlers import SnippetChooserPanel

from bakerydemo.base.models import BasePageFieldsMixin


class BlogPeopleRelationship(Orderable, models.Model):
    """
    This defines the relationship between the `People` within the `base`
    app and the BlogPage below allowing us to add people to a BlogPage.
    """
    page = ParentalKey(
        'BlogPage', related_name='blog_person_relationship'
    )
    people = models.ForeignKey(
        'base.People', related_name='person_blog_relationship'
    )
    panels = [
        SnippetChooserPanel('people')
    ]


class BlogPageTag(TaggedItemBase):
    content_object = ParentalKey('BlogPage', related_name='tagged_items')


class BlogPage(BasePageFieldsMixin, Page):
    """
    A Blog Page (Post)
    """
    subtitle = models.CharField(blank=True, max_length=255)
    tags = ClusterTaggableManager(through=BlogPageTag, blank=True)
    date_published = models.DateField("Date article published", blank=True, null=True)

    content_panels = BasePageFieldsMixin.content_panels + [
        FieldPanel('date_published'),
        InlinePanel(
            'blog_person_relationship', label="Author(s)",
            panels=None, min_num=1),
        FieldPanel('tags'),
    ]
    # Inject subtitle panel after title field
    title_index = next((i for i, panel in enumerate(content_panels) if panel.field_name == 'title'), -1)  # noqa
    content_panels.insert(title_index + 1, FieldPanel('subtitle'))

    search_fields = Page.search_fields + [
        index.SearchField('title'),
        index.SearchField('body'),
    ]

    def authors(self):
        """
        Returns the BlogPage's related People
        """
        authors = [
            n.people for n in self.blog_person_relationship.all()
        ]

        return authors

    @property
    def get_tags(self):
        """
        Returns the BlogPage's related list of Tags.
        Each Tag is modified to include a url attribute
        """
        tags = self.tags.all()
        for tag in tags:
            tag.url = '/'+'/'.join(s.strip('/') for s in [
                self.get_parent().url,
                'tags',
                tag.slug
            ])
        return tags

    parent_page_types = ['BlogIndexPage']

    # Define what content types can exist as children of BlogPage.
    # Empty list means that no child content types are allowed.
    subpage_types = []


class BlogIndexPage(BasePageFieldsMixin, RoutablePageMixin, Page):
    """
    Index page for blogs.
    We need to alter the page model's context to return the child page objects - the
    BlogPage - so that it works as an index page

    RoutablePageMixin is used to allow for a custom sub-URL for tag views.
    """

    # What pages types can live under this page type?
    subpage_types = ['BlogPage']

    def get_context(self, request):
        context = super(BlogIndexPage, self).get_context(request)
        context['posts'] = BlogPage.objects.descendant_of(
            self).live().order_by(
            '-date_published')
        return context

    @route('^tags/$', name='tag_archive')
    @route('^tags/(\w+)/$', name='tag_archive')
    def tag_archive(self, request, tag=None):
        """
        A Custom view that utilizes Tags.
        This view will return all related BlogPages for a given Tag or
        redirect back to the BlogIndexPage.
        """

        try:
            tag = Tag.objects.get(slug=tag)
        except Tag.DoesNotExist:
            if tag:
                msg = 'There are no blog posts tagged with "{}"'.format(tag)
                messages.add_message(request, messages.INFO, msg)
            return redirect(self.url)

        posts = self.get_posts(tag=tag)

        context = {
            'tag': tag,
            'posts': posts
        }
        return render(request, 'blog/blog_index_page.html', context)

    def get_posts(self, tag=None):
        """
        Return the child BlogPage objects for this BlogPageIndex.
        Optional filter by tag.
        """

        posts = BlogPage.objects.live().descendant_of(self)
        if tag:
            posts = posts.filter(tags=tag)
        return posts

    def get_child_tags(self):
        """
        Returns the list of Tags for all child posts of this BlogPage.
        """

        tags = []
        for post in self.get_posts():
            tags += post.get_tags  # Not tags.append() because we don't want a list of lists
        tags = sorted(set(tags))
        return tags

    content_panels = Page.content_panels + [
        FieldPanel('introduction', classname="full"),
        ImageChooserPanel('image'),
    ]