import re

from django.core.exceptions import ValidationError
from django.db import models
from django.urls import reverse
from django.utils import timezone
from django.utils.translation import gettext_lazy as _
from django.utils.functional import cached_property
from django.contrib.contenttypes.fields import GenericRelation
from mptt.fields import TreeForeignKey
from mptt.models import MPTTModel

from judge.models.profile import Organization, Profile
from judge.models.pagevote import PageVotable
from judge.models.bookmark import Bookmarkable
from judge.caching import cache_wrapper

__all__ = ["MiscConfig", "validate_regex", "NavigationBar", "BlogPost"]


class MiscConfig(models.Model):
    key = models.CharField(max_length=30, db_index=True)
    value = models.TextField(blank=True)

    def __str__(self):
        return self.key

    class Meta:
        verbose_name = _("configuration item")
        verbose_name_plural = _("miscellaneous configuration")


def validate_regex(regex):
    try:
        re.compile(regex, re.VERBOSE)
    except re.error as e:
        raise ValidationError("Invalid regex: %s" % e.message)


class NavigationBar(MPTTModel):
    class Meta:
        verbose_name = _("navigation item")
        verbose_name_plural = _("navigation bar")

    class MPTTMeta:
        order_insertion_by = ["order"]

    order = models.PositiveIntegerField(db_index=True, verbose_name=_("order"))
    key = models.CharField(max_length=10, unique=True, verbose_name=_("identifier"))
    label = models.CharField(max_length=20, verbose_name=_("label"))
    path = models.CharField(max_length=255, verbose_name=_("link path"))
    regex = models.TextField(
        verbose_name=_("highlight regex"), validators=[validate_regex]
    )
    parent = TreeForeignKey(
        "self",
        verbose_name=_("parent item"),
        null=True,
        blank=True,
        related_name="children",
        on_delete=models.CASCADE,
    )

    def __str__(self):
        return self.label

    @property
    def pattern(self, cache={}):
        # A cache with a bad policy is an alias for memory leak
        # Thankfully, there will never be too many regexes to cache.
        if self.regex in cache:
            return cache[self.regex]
        else:
            pattern = cache[self.regex] = re.compile(self.regex, re.VERBOSE)
            return pattern


class BlogPost(models.Model, PageVotable, Bookmarkable):
    title = models.CharField(verbose_name=_("post title"), max_length=100)
    authors = models.ManyToManyField(Profile, verbose_name=_("authors"), blank=True)
    slug = models.SlugField(verbose_name=_("slug"))
    visible = models.BooleanField(verbose_name=_("public visibility"), default=False)
    sticky = models.BooleanField(verbose_name=_("sticky"), default=False)
    publish_on = models.DateTimeField(verbose_name=_("publish after"))
    content = models.TextField(verbose_name=_("post content"))
    summary = models.TextField(verbose_name=_("post summary"), blank=True)
    og_image = models.CharField(
        verbose_name=_("openGraph image"), default="", max_length=150, blank=True
    )
    organizations = models.ManyToManyField(
        Organization,
        blank=True,
        verbose_name=_("organizations"),
        help_text=_("If private, only these organizations may see the blog post."),
    )
    is_organization_private = models.BooleanField(
        verbose_name=_("private to organizations"), default=False
    )
    comments = GenericRelation("Comment")
    pagevote = GenericRelation("PageVote")
    bookmark = GenericRelation("BookMark")

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse("blog_post", args=(self.id, self.slug))

    def is_accessible_by(self, user):
        if self.visible and self.publish_on <= timezone.now():
            if not self.is_organization_private:
                return True
            if (
                user.is_authenticated
                and self.organizations.filter(
                    id__in=user.profile.organizations.all()
                ).exists()
            ):
                return True
        if user.has_perm("judge.edit_all_post"):
            return True
        return (
            user.is_authenticated and self.authors.filter(id=user.profile.id).exists()
        )

    def is_editable_by(self, user):
        if not user.is_authenticated:
            return False
        if user.has_perm("judge.edit_all_post"):
            return True
        return (
            user.has_perm("judge.change_blogpost")
            and self.authors.filter(id=user.profile.id).exists()
        )

    @cache_wrapper(prefix="BPga")
    def get_authors(self):
        return self.authors.only("id")

    class Meta:
        permissions = (("edit_all_post", _("Edit all posts")),)
        verbose_name = _("blog post")
        verbose_name_plural = _("blog posts")