import datetime
import re
import secrets
import ssl
import time
from datetime import date
from functools import cached_property, partial
from typing import TYPE_CHECKING, Literal, Optional
from urllib.parse import urlparse

import httpx
import urlman
from cachetools import TTLCache, cached
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding, rsa
from django.conf import settings
from django.contrib.auth.models import AbstractBaseUser, BaseUserManager
from django.db import models, transaction
from django.template.defaultfilters import linebreaks_filter
from django.utils import timezone
from django.utils.safestring import mark_safe
from loguru import logger
from lxml import etree

from .html import FediverseHtmlParser
from .uris import *

if TYPE_CHECKING:
    from django.db.models.manager import RelatedManager


class Snowflake:
    """
    Snowflake ID generator and parser.
    """

    # Epoch is 2022/1/1 at midnight, as these are used for _created_ times in our
    # own database, not original publish times (which would need an earlier one)
    EPOCH = 1641020400

    TYPE_POST = 0b000
    TYPE_POST_INTERACTION = 0b001
    TYPE_IDENTITY = 0b010
    TYPE_REPORT = 0b011
    TYPE_FOLLOW = 0b100

    @classmethod
    def generate(cls, type_id: int) -> int:
        """
        Generates a snowflake-style ID for the given "type". They are designed
        to fit inside 63 bits (a signed bigint)

        ID layout is:
        * 41 bits of millisecond-level timestamp (enough for EPOCH + 69 years)
        * 19 bits of random data (1% chance of clash at 10000 per millisecond)
        * 3 bits of type information

        We use random data rather than a sequence ID to try and avoid pushing
        this job onto the DB - we may do that in future. If a clash does
        occur, the insert will fail and Stator will retry the work for anything
        that's coming in remotely, leaving us to just handle that scenario for
        our own posts, likes, etc.
        """
        # Get the current time in milliseconds
        now: int = int((time.time() - cls.EPOCH) * 1000)
        # Generate random data
        rand_seq: int = secrets.randbits(19)
        # Compose them together
        return (now << 22) | (rand_seq << 3) | type_id

    @classmethod
    def get_type(cls, snowflake: int) -> int:
        """
        Returns the type of a given snowflake ID
        """
        if snowflake < (1 << 22):
            raise ValueError("Not a valid Snowflake ID")
        return snowflake & 0b111

    @classmethod
    def get_time(cls, snowflake: int) -> float:
        """
        Returns the generation time (in UNIX timestamp seconds) of the ID
        """
        if snowflake < (1 << 22):
            raise ValueError("Not a valid Snowflake ID")
        return ((snowflake >> 22) / 1000) + cls.EPOCH

    # Handy pre-baked methods for django model defaults
    @classmethod
    def generate_post(cls) -> int:
        return cls.generate(cls.TYPE_POST)

    @classmethod
    def generate_post_interaction(cls) -> int:
        return cls.generate(cls.TYPE_POST_INTERACTION)

    @classmethod
    def generate_identity(cls) -> int:
        return cls.generate(cls.TYPE_IDENTITY)

    @classmethod
    def generate_report(cls) -> int:
        return cls.generate(cls.TYPE_REPORT)

    @classmethod
    def generate_follow(cls) -> int:
        return cls.generate(cls.TYPE_FOLLOW)


class RsaKeys:
    @classmethod
    def generate_keypair(cls) -> tuple[str, str]:
        """
        Generates a new RSA keypair
        """
        private_key = rsa.generate_private_key(
            public_exponent=65537,
            key_size=2048,
        )
        private_key_serialized = private_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.PKCS8,
            encryption_algorithm=serialization.NoEncryption(),
        ).decode("ascii")
        public_key_serialized = (
            private_key.public_key()
            .public_bytes(
                encoding=serialization.Encoding.PEM,
                format=serialization.PublicFormat.SubjectPublicKeyInfo,
            )
            .decode("ascii")
        )
        return private_key_serialized, public_key_serialized


class User(AbstractBaseUser):
    identities: "RelatedManager[Identity]"

    class Meta:
        # managed = False
        db_table = "users_user"

    email = models.EmailField(unique=True)
    admin = models.BooleanField(default=False)
    moderator = models.BooleanField(default=False)
    banned = models.BooleanField(default=False)
    deleted = models.BooleanField(default=False)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    last_seen = models.DateTimeField(auto_now_add=True)
    USERNAME_FIELD = "email"
    EMAIL_FIELD = "email"
    REQUIRED_FIELDS: list[str] = []

    @property
    def is_active(self):
        return not (self.deleted or self.banned)

    @property
    def is_superuser(self):
        return self.admin

    @property
    def is_staff(self):
        return self.admin

    def has_module_perms(self, module):
        return self.admin

    def has_perm(self, perm):
        return self.admin

    # @cached_property
    # def config_user(self) -> Config.UserOptions:
    #     return Config.load_user(self)


class Domain(models.Model):
    """
    Represents a domain that a user can have an account on.

    For protocol reasons, if we want to allow custom usernames
    per domain, each "display" domain (the one in the handle) must either let
    us serve on it directly, or have a "service" domain that maps
    to it uniquely that we can serve on that.

    That way, someone coming in with just an Actor URI as their
    entrypoint can still try to webfinger preferredUsername@actorDomain
    and we can return an appropriate response.

    It's possible to just have one domain do both jobs, of course.
    This model also represents _other_ servers' domains, which we treat as
    display domains for now, until we start doing better probing.
    """

    domain = models.CharField(max_length=250, primary_key=True)
    service_domain = models.CharField(
        max_length=250,
        null=True,
        blank=True,
        db_index=True,
        unique=True,
    )

    # state = StateField(DomainStates)
    state = models.CharField(max_length=100, default="outdated")
    state_changed = models.DateTimeField(auto_now_add=True)

    # nodeinfo 2.0 detail about the remote server
    nodeinfo = models.JSONField(null=True, blank=True)

    # If we own this domain
    local = models.BooleanField()

    # If we have blocked this domain from interacting with us
    blocked = models.BooleanField(default=False)

    # Domains can be joinable by any user of the instance (as the default one
    # should)
    public = models.BooleanField(default=False)

    # If this is the default domain (shown as the default entry for new users)
    default = models.BooleanField(default=False)

    # Domains can also be linked to one or more users for their private use
    # This should be display domains ONLY
    users = models.ManyToManyField("takahe.User", related_name="domains", blank=True)

    # Free-form notes field for admins
    notes = models.TextField(blank=True, null=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class urls(urlman.Urls):
        root = "/admin/domains/"
        create = "/admin/domains/create/"
        edit = "/admin/domains/{self.domain}/"
        delete = "{edit}delete/"
        root_federation = "/admin/federation/"
        edit_federation = "/admin/federation/{self.domain}/"

    class Meta:
        # managed = False
        db_table = "users_domain"
        indexes: list = []

    @classmethod
    def get_remote_domain(cls, domain: str) -> "Domain":
        return cls.objects.get_or_create(domain=domain.lower(), local=False)[0]

    @classmethod
    def get_domain(cls, domain: str) -> Optional["Domain"]:
        try:
            return cls.objects.get(
                models.Q(domain=domain.lower())
                | models.Q(service_domain=domain.lower())
            )
        except cls.DoesNotExist:
            return None

    @property
    def uri_domain(self) -> str:
        if self.service_domain:
            return self.service_domain
        return self.domain

    @classmethod
    def available_for_user(cls, user):
        """
        Returns domains that are available for the user to put an identity on
        """
        return cls.objects.filter(
            models.Q(public=True) | models.Q(users__id=user.id),
            local=True,
        ).order_by("-default", "domain")

    def __str__(self):
        return self.domain


class Identity(models.Model):
    """
    Represents both local and remote Fediverse identities (actors)
    """

    domain_id: int

    class Restriction(models.IntegerChoices):
        none = 0
        limited = 1
        blocked = 2

    ACTOR_TYPES = ["person", "service", "application", "group", "organization"]

    id = models.BigIntegerField(primary_key=True, default=Snowflake.generate_identity)

    # The Actor URI is essentially also a PK - we keep the default numeric
    # one around as well for making nice URLs etc.
    actor_uri = models.CharField(max_length=500, unique=True)

    # state = StateField(IdentityStates)
    state = models.CharField(max_length=100, default="outdated")
    state_changed = models.DateTimeField(auto_now_add=True)

    local = models.BooleanField(db_index=True)
    users = models.ManyToManyField(
        "takahe.User",
        related_name="identities",
        blank=True,
    )

    username = models.CharField(max_length=500, blank=True, null=True)
    # Must be a display domain if present
    domain = models.ForeignKey(
        Domain,
        blank=True,
        null=True,
        on_delete=models.PROTECT,
        related_name="identities",
    )

    name = models.CharField(max_length=500, blank=True, null=True)
    summary = models.TextField(blank=True, null=True)
    manually_approves_followers = models.BooleanField(blank=True, null=True)
    discoverable = models.BooleanField(default=True)

    profile_uri = models.CharField(max_length=500, blank=True, null=True)
    inbox_uri = models.CharField(max_length=500, blank=True, null=True)
    shared_inbox_uri = models.CharField(max_length=500, blank=True, null=True)
    outbox_uri = models.CharField(max_length=500, blank=True, null=True)
    icon_uri = models.CharField(max_length=500, blank=True, null=True)
    image_uri = models.CharField(max_length=500, blank=True, null=True)
    followers_uri = models.CharField(max_length=500, blank=True, null=True)
    following_uri = models.CharField(max_length=500, blank=True, null=True)
    featured_collection_uri = models.CharField(max_length=500, blank=True, null=True)
    actor_type = models.CharField(max_length=100, default="person")

    # icon = models.ImageField(
    #     upload_to=partial(upload_namer, "profile_images"), blank=True, null=True
    # )
    # image = models.ImageField(
    #     upload_to=partial(upload_namer, "background_images"), blank=True, null=True
    # )

    # Should be a list of {"name":..., "value":...} dicts
    metadata = models.JSONField(blank=True, null=True)

    # Should be a list of object URIs (we don't want a full M2M here)
    pinned = models.JSONField(blank=True, null=True)

    # Admin-only moderation fields
    sensitive = models.BooleanField(default=False)
    restriction = models.IntegerField(
        choices=Restriction.choices, default=Restriction.none, db_index=True
    )
    admin_notes = models.TextField(null=True, blank=True)

    private_key = models.TextField(null=True, blank=True)
    public_key = models.TextField(null=True, blank=True)
    public_key_id = models.TextField(null=True, blank=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    fetched = models.DateTimeField(null=True, blank=True)
    deleted = models.DateTimeField(null=True, blank=True)

    # objects = IdentityManager()

    ### Model attributes ###

    class Meta:
        # managed = False
        db_table = "users_identity"
        verbose_name_plural = "identities"
        unique_together = [("username", "domain")]
        indexes: list = []  # We need this so Stator can add its own

    class urls(urlman.Urls):
        view = "/@{self.username}@{self.domain_id}/"
        replies = "{view}replies/"
        settings = "{view}settings/"
        action = "{view}action/"
        followers = "{view}followers/"
        following = "{view}following/"
        search = "{view}search/"
        activate = "{view}activate/"
        admin = "/admin/identities/"
        admin_edit = "{admin}{self.pk}/"
        djadmin_edit = "/djadmin/users/identity/{self.id}/change/"

        def get_scheme(self, url):
            return "https"

        def get_hostname(self, url):
            return self.instance.domain.uri_domain

    def __str__(self):
        if self.username and self.domain:
            return self.handle
        return self.actor_uri

    def absolute_profile_uri(self):
        """
        Returns a profile URI that is always absolute, for sending out to
        other servers.
        """
        if self.local:
            return f"https://{self.domain.uri_domain}/@{self.username}/"
        else:
            return self.profile_uri

    @property
    def handle(self):
        if self.username is None:
            return "(unknown user)"
        if self.domain_id:
            return f"{self.username}@{self.domain_id}"
        return f"{self.username}@(unknown server)"

    @property
    def user_pk(self):
        user = self.users.first()
        return user.pk if user else None

    @classmethod
    def fetch_webfinger_url(cls, domain: str) -> str:
        """
        Given a domain (hostname), returns the correct webfinger URL to use
        based on probing host-meta.
        """
        with httpx.Client(
            timeout=settings.SETUP.REMOTE_TIMEOUT,
            headers={"User-Agent": settings.TAKAHE_USER_AGENT},
        ) as client:
            try:
                response = client.get(
                    f"https://{domain}/.well-known/host-meta",
                    follow_redirects=True,
                    headers={"Accept": "application/xml"},
                )

                # In the case of anything other than a success, we'll still try
                # hitting the webfinger URL on the domain we were given to handle
                # incorrectly setup servers.
                if response.status_code == 200 and response.content.strip():
                    tree = etree.fromstring(response.content)
                    template = tree.xpath(
                        "string(.//*[local-name() = 'Link' and @rel='lrdd' and (not(@type) or @type='application/jrd+json')]/@template)"
                    )
                    if template:
                        return template  # type: ignore
            except (httpx.RequestError, etree.ParseError):
                pass

        return f"https://{domain}/.well-known/webfinger?resource={{uri}}"

    @classmethod
    def fetch_webfinger(cls, handle: str) -> tuple[str | None, str | None]:
        """
        Given a username@domain handle, returns a tuple of
        (actor uri, canonical handle) or None, None if it does not resolve.
        """
        domain = handle.split("@")[1].lower()
        try:
            webfinger_url = cls.fetch_webfinger_url(domain)
        except ssl.SSLCertVerificationError:
            return None, None

        # Go make a Webfinger request
        with httpx.Client(
            timeout=settings.SETUP.REMOTE_TIMEOUT,
            headers={"User-Agent": settings.TAKAHE_USER_AGENT},
        ) as client:
            try:
                response = client.get(
                    webfinger_url.format(uri=f"acct:{handle}"),
                    follow_redirects=True,
                    headers={"Accept": "application/json"},
                )
                response.raise_for_status()
            except (httpx.HTTPError, ssl.SSLCertVerificationError) as ex:
                response = getattr(ex, "response", None)
                if (
                    response
                    and response.status_code < 500
                    and response.status_code not in [400, 401, 403, 404, 406, 410]
                ):
                    raise ValueError(
                        f"Client error fetching webfinger: {response.status_code}",
                        response.content,
                    )
                return None, None

        try:
            data = response.json()
        except ValueError:
            # Some servers return these with a 200 status code!
            if b"not found" in response.content.lower():
                return None, None
            raise ValueError(
                "JSON parse error fetching webfinger",
                response.content,
            )
        try:
            if data["subject"].startswith("acct:"):
                data["subject"] = data["subject"][5:]
            for link in data["links"]:
                if (
                    link.get("type") == "application/activity+json"
                    and link.get("rel") == "self"
                ):
                    return link["href"], data["subject"]
        except KeyError:
            # Server returning wrong payload structure
            pass
        return None, None

    @classmethod
    def by_username_and_domain(
        cls,
        username: str,
        domain: str | Domain,
        fetch: bool = False,
        local: bool = False,
    ):
        """
        Get an Identity by username and domain.

        When fetch is True, a failed lookup will do a webfinger lookup to attempt to do
        a lookup by actor_uri, creating an Identity record if one does not exist. When
        local is True, lookups will be restricted to local domains.

        If domain is a Domain, domain.local is used instead of passsed local.

        """
        if username.startswith("@"):
            raise ValueError("Username must not start with @")

        domain_instance = None

        if isinstance(domain, Domain):
            domain_instance = domain
            local = domain.local
            domain = domain.domain
        else:
            domain = domain.lower()
        try:
            if local:
                return cls.objects.get(
                    username__iexact=username,
                    domain_id=domain,
                    local=True,
                )
            else:
                return cls.objects.get(
                    username__iexact=username,
                    domain_id=domain,
                )
        except cls.DoesNotExist:
            if fetch and not local:
                actor_uri, handle = cls.fetch_webfinger(f"{username}@{domain}")
                if handle is None:
                    return None
                # See if this actually does match an existing actor
                try:
                    return cls.objects.get(actor_uri=actor_uri)
                except cls.DoesNotExist:
                    pass
                # OK, make one
                username, domain = handle.split("@")
                if not domain_instance:
                    domain_instance = Domain.get_remote_domain(domain)
                return cls.objects.create(
                    actor_uri=actor_uri,
                    username=username,
                    domain_id=domain_instance,
                    local=False,
                )
            return None

    def generate_keypair(self):
        if not self.local:
            raise ValueError("Cannot generate keypair for remote user")
        self.private_key, self.public_key = RsaKeys.generate_keypair()
        self.public_key_id = self.actor_uri + "#main-key"
        self.save()


class Follow(models.Model):
    """
    When one user (the source) follows other (the target)
    """

    id = models.BigIntegerField(primary_key=True, default=Snowflake.generate_follow)

    source = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="outbound_follows",
    )
    target = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="inbound_follows",
    )

    boosts = models.BooleanField(
        default=True, help_text="Also follow boosts from this user"
    )

    uri = models.CharField(blank=True, null=True, max_length=500)
    note = models.TextField(blank=True, null=True)

    # state = StateField(FollowStates)
    state = models.CharField(max_length=100, default="unrequested")
    state_changed = models.DateTimeField(auto_now_add=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        # managed = False
        db_table = "users_follow"
        unique_together = [("source", "target")]
        indexes: list = []  # We need this so Stator can add its own

    def __str__(self):
        return f"#{self.id}: {self.source} → {self.target}"


class Post(models.Model):
    """
    A post (status, toot) that is either local or remote.
    """

    interactions: "models.QuerySet[PostInteraction]"

    class Visibilities(models.IntegerChoices):
        public = 0
        local_only = 4
        unlisted = 1
        followers = 2
        mentioned = 3

    class Types(models.TextChoices):
        article = "Article"
        audio = "Audio"
        event = "Event"
        image = "Image"
        note = "Note"
        page = "Page"
        question = "Question"
        video = "Video"

    id = models.BigIntegerField(primary_key=True, default=Snowflake.generate_post)

    # The author (attributedTo) of the post
    author = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="posts",
    )

    # The state the post is in
    # state = StateField(PostStates)
    state = models.CharField(max_length=100, default="new")
    state_changed = models.DateTimeField(auto_now_add=True)

    # If it is our post or not
    local = models.BooleanField()

    # The canonical object ID
    object_uri = models.CharField(max_length=2048, blank=True, null=True, unique=True)

    # Who should be able to see this Post
    visibility = models.IntegerField(
        choices=Visibilities.choices,
        default=Visibilities.public,
    )

    # The main (HTML) content
    content = models.TextField()

    type = models.CharField(
        max_length=20,
        choices=Types.choices,
        default=Types.note,
    )
    type_data = models.JSONField(
        blank=True,
        null=True,  # , encoder=PostTypeDataEncoder, decoder=PostTypeDataDecoder
    )

    # If the contents of the post are sensitive, and the summary (content
    # warning) to show if it is
    sensitive = models.BooleanField(default=False)
    summary = models.TextField(blank=True, null=True)

    # The public, web URL of this Post on the original server
    url = models.CharField(max_length=2048, blank=True, null=True)

    # The Post it is replying to as an AP ID URI
    # (as otherwise we'd have to pull entire threads to use IDs)
    in_reply_to = models.CharField(max_length=500, blank=True, null=True, db_index=True)

    # The identities the post is directly to (who can see it if not public)
    to = models.ManyToManyField(
        "takahe.Identity",
        related_name="posts_to",
        blank=True,
    )

    # The identities mentioned in the post
    mentions = models.ManyToManyField(
        "takahe.Identity",
        related_name="posts_mentioning",
        blank=True,
    )

    # Hashtags in the post
    hashtags = models.JSONField(blank=True, null=True)

    emojis = models.ManyToManyField(
        "takahe.Emoji",
        related_name="posts_using_emoji",
        blank=True,
    )

    # Like/Boost/etc counts
    stats = models.JSONField(blank=True, null=True)

    # When the post was originally created (as opposed to when we received it)
    published = models.DateTimeField(default=timezone.now)

    # If the post has been edited after initial publication
    edited = models.DateTimeField(blank=True, null=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        # managed = False
        db_table = "activities_post"

    class urls(urlman.Urls):
        view = "{self.author.urls.view}posts/{self.id}/"
        object_uri = "{self.author.actor_uri}posts/{self.id}/"
        action_like = "{view}like/"
        action_unlike = "{view}unlike/"
        action_boost = "{view}boost/"
        action_unboost = "{view}unboost/"
        action_bookmark = "{view}bookmark/"
        action_unbookmark = "{view}unbookmark/"
        action_delete = "{view}delete/"
        action_edit = "{view}edit/"
        action_report = "{view}report/"
        action_reply = "/compose/?reply_to={self.id}"
        admin_edit = "/djadmin/activities/post/{self.id}/change/"

        def get_scheme(self, url):
            return "https"

        def get_hostname(self, url):
            return self.instance.author.domain.uri_domain

    def __str__(self):
        return f"{self.author} #{self.id}"

    def get_absolute_url(self):
        return self.urls.view

    def absolute_object_uri(self):
        """
        Returns an object URI that is always absolute, for sending out to
        other servers.
        """
        if self.local:
            return self.author.absolute_profile_uri() + f"posts/{self.id}/"
        else:
            return self.object_uri

    def in_reply_to_post(self) -> Optional["Post"]:
        """
        Returns the actual Post object we're replying to, if we can find it
        """
        if self.in_reply_to is None:
            return None
        return (
            Post.objects.filter(object_uri=self.in_reply_to)
            .select_related("author")
            .first()
        )

    @classmethod
    def create_local(
        cls,
        author: Identity,
        raw_prepend_content: str,
        content: str,
        summary: str | None = None,
        sensitive: bool = False,
        visibility: int = Visibilities.public,
        reply_to: Optional["Post"] = None,
        attachments: list | None = None,
        type_data: dict | None = None,
        published: datetime.datetime | None = None,
    ) -> "Post":
        with transaction.atomic():
            # Find mentions in this post
            mentions = cls.mentions_from_content(content, author)
            # mentions = set()
            if reply_to:
                mentions.add(reply_to.author)
                # Maintain local-only for replies
                if reply_to.visibility == reply_to.Visibilities.local_only:
                    visibility = reply_to.Visibilities.local_only
            # Find emoji in this post
            emojis = Emoji.emojis_from_content(content, None)
            # Strip all unwanted HTML and apply linebreaks filter, grabbing hashtags on the way
            parser = FediverseHtmlParser(linebreaks_filter(content), find_hashtags=True)
            content = parser.html.replace("<p>", "<p>" + raw_prepend_content, 1)
            hashtags = (
                sorted([tag[: Hashtag.MAXIMUM_LENGTH] for tag in parser.hashtags])
                or None
            )
            # Make the Post object
            post = cls.objects.create(
                author=author,
                content=content,
                summary=summary or None,
                sensitive=bool(summary) or sensitive,
                local=True,
                visibility=visibility,
                hashtags=hashtags,
                in_reply_to=reply_to.object_uri if reply_to else None,
            )
            post.object_uri = post.urls.object_uri
            post.url = post.absolute_object_uri()
            post.mentions.set(mentions)
            post.emojis.set(emojis)
            if published and published < timezone.now():
                post.published = published
                if timezone.now() - published > datetime.timedelta(days=2):
                    post.state = "fanned_out"  # add post quietly if it's old
            # if attachments:# FIXME
            #     post.attachments.set(attachments)
            # if question: # FIXME
            #     post.type = question["type"]
            #     post.type_data = PostTypeData(__root__=question).__root__
            if type_data:
                post.type_data = type_data
            post.save()
            # Recalculate parent stats for replies
            if reply_to:
                reply_to.calculate_stats()
        return post

    def edit_local(
        self,
        raw_prepend_content: str,
        content: str,
        summary: str | None = None,
        sensitive: bool | None = None,
        visibility: int = Visibilities.public,
        attachments: list | None = None,
        attachment_attributes: list | None = None,
        type_data: dict | None = None,
    ):
        with transaction.atomic():
            # Strip all HTML and apply linebreaks filter
            parser = FediverseHtmlParser(linebreaks_filter(content), find_hashtags=True)
            self.content = parser.html.replace("<p>", "<p>" + raw_prepend_content, 1)
            self.hashtags = (
                sorted([tag[: Hashtag.MAXIMUM_LENGTH] for tag in parser.hashtags])
                or None
            )
            self.summary = summary or None
            self.sensitive = bool(summary) if sensitive is None else sensitive
            self.visibility = visibility
            self.edited = timezone.now()
            self.mentions.set(self.mentions_from_content(content, self.author))
            self.emojis.set(Emoji.emojis_from_content(content, None))
            # self.attachments.set(attachments or []) # fixme
            if type_data:
                self.type_data = type_data
            self.save()

            for attrs in attachment_attributes or []:
                attachment = next(
                    (a for a in attachments or [] if str(a.id) == attrs.id), None
                )
                if attachment is None:
                    continue
                attachment.name = attrs.description
                attachment.save()

            self.state = "edited"
            self.state_changed = timezone.now()
            self.state_next_attempt = None
            self.state_locked_until = None
            self.save()

    @classmethod
    def mentions_from_content(cls, content, author) -> set[Identity]:
        mention_hits = FediverseHtmlParser(content, find_mentions=True).mentions
        mentions = set()
        for handle in mention_hits:
            handle = handle.lower()
            if "@" in handle:
                username, domain = handle.split("@", 1)
            else:
                username = handle
                domain = author.domain_id
            identity = Identity.by_username_and_domain(
                username=username,
                domain=domain,
                fetch=True,
            )
            if identity is not None:
                mentions.add(identity)
        return mentions

    def ensure_hashtags(self) -> None:
        """
        Ensure any of the already parsed hashtags from this Post
        have a corresponding Hashtag record.
        """
        # Ensure hashtags
        if self.hashtags:
            for hashtag in self.hashtags:
                tag, _ = Hashtag.objects.get_or_create(
                    hashtag=hashtag[: Hashtag.MAXIMUM_LENGTH],
                )
                tag.transition_perform("outdated")

    def calculate_stats(self, save=True):
        """
        Recalculates our stats dict
        """
        from .models import PostInteraction

        self.stats = {
            "likes": self.interactions.filter(
                type=PostInteraction.Types.like,
                state__in=["new", "fanned_out"],
            ).count(),
            "boosts": self.interactions.filter(
                type=PostInteraction.Types.boost,
                state__in=["new", "fanned_out"],
            ).count(),
            "replies": Post.objects.filter(in_reply_to=self.object_uri).count(),
        }
        if save:
            self.save()


class EmojiQuerySet(models.QuerySet):
    def usable(self, domain: Domain | None = None):
        """
        Returns all usable emoji, optionally filtering by domain too.
        """
        visible_q = models.Q(local=True) | models.Q(public=True)
        if True:  # Config.system.emoji_unreviewed_are_public:
            visible_q |= models.Q(public__isnull=True)
        qs = self.filter(visible_q)

        if domain:
            if not domain.local:
                qs = qs.filter(domain=domain)

        return qs


class EmojiManager(models.Manager):
    def get_queryset(self):
        return EmojiQuerySet(self.model, using=self._db)

    def usable(self, domain: Domain | None = None):
        return self.get_queryset().usable(domain)


class Emoji(models.Model):
    class Meta:
        # managed = False
        db_table = "activities_emoji"

    # Normalized Emoji without the ':'
    shortcode = models.SlugField(max_length=100, db_index=True)

    domain = models.ForeignKey(
        "takahe.Domain", null=True, blank=True, on_delete=models.CASCADE
    )
    local = models.BooleanField(default=True)

    # Should this be shown in the public UI?
    public = models.BooleanField(null=True)

    object_uri = models.CharField(max_length=500, blank=True, null=True, unique=True)

    mimetype = models.CharField(max_length=200)

    # Files may not be populated if it's remote and not cached on our side yet
    file = models.ImageField(
        # upload_to=partial(upload_emoji_namer, "emoji"),
        null=True,
        blank=True,
    )

    # A link to the custom emoji
    remote_url = models.CharField(max_length=500, blank=True, null=True)

    # Used for sorting custom emoji in the picker
    category = models.CharField(max_length=100, blank=True, null=True)

    # State of this Emoji
    # state = StateField(EmojiStates)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    objects = EmojiManager()

    @classmethod
    def emojis_from_content(cls, content: str, domain: Domain | None) -> list["Emoji"]:
        """
        Return a parsed and sanitized of emoji found in content without
        the surrounding ':'.
        """
        emoji_hits = FediverseHtmlParser(
            content, find_emojis=True, emoji_domain=domain
        ).emojis
        emojis = sorted({emoji for emoji in emoji_hits})
        q = models.Q(local=True) | models.Q(public=True) | models.Q(public__isnull=True)
        if domain and not domain.local:
            q = q & models.Q(domain=domain)
        return list(
            cls.objects.filter(local=(domain is None) or domain.local)
            .filter(q)
            .filter(shortcode__in=emojis)
        )

    @classmethod
    @cached(cache=TTLCache(maxsize=1000, ttl=60))
    def get_by_domain(cls, shortcode, domain: Domain | None) -> "Emoji | None":
        """
        Given an emoji shortcode and optional domain, looks up the single
        emoji and returns it. Raises Emoji.DoesNotExist if there isn't one.
        """
        try:
            if domain is None or domain.local:
                return cls.objects.get(local=True, shortcode=shortcode)
            else:
                return cls.objects.get(domain=domain, shortcode=shortcode)
        except Emoji.DoesNotExist:
            return None

    @property
    def fullcode(self):
        return f":{self.shortcode}:"

    @property
    def is_usable(self) -> bool:
        """
        Return True if this Emoji is usable.
        """
        return self.public or self.public is None

    def full_url(self, always_show=False) -> RelativeAbsoluteUrl:
        if self.is_usable or always_show:
            if self.file:
                return AutoAbsoluteUrl(self.file.url)
            elif self.remote_url:
                return ProxyAbsoluteUrl(
                    f"/proxy/emoji/{self.pk}/",
                    remote_url=self.remote_url,
                )
        return StaticAbsoluteUrl("img/blank-emoji-128.png")

    def as_html(self):
        if self.is_usable:
            return mark_safe(
                f'<img src="{self.full_url().relative}" class="emoji" alt="Emoji {self.shortcode}">'
            )
        return self.fullcode


class HashtagQuerySet(models.QuerySet):
    def public(self):
        public_q = models.Q(public=True)
        if True:  # Config.system.hashtag_unreviewed_are_public:
            public_q |= models.Q(public__isnull=True)
        return self.filter(public_q)

    def hashtag_or_alias(self, hashtag: str):
        return self.filter(
            models.Q(hashtag=hashtag) | models.Q(aliases__contains=hashtag)
        )


class HashtagManager(models.Manager):
    def get_queryset(self):
        return HashtagQuerySet(self.model, using=self._db)

    def public(self):
        return self.get_queryset().public()

    def hashtag_or_alias(self, hashtag: str):
        return self.get_queryset().hashtag_or_alias(hashtag)


class Hashtag(models.Model):
    class Meta:
        # managed = False
        db_table = "activities_hashtag"

    MAXIMUM_LENGTH = 100

    # Normalized hashtag without the '#'
    hashtag = models.SlugField(primary_key=True, max_length=100)

    # Friendly display override
    name_override = models.CharField(max_length=100, null=True, blank=True)

    # Should this be shown in the public UI?
    public = models.BooleanField(null=True)

    # State of this Hashtag
    # state = StateField(HashtagStates)
    state = models.CharField(max_length=100, default="outdated")
    state_changed = models.DateTimeField(auto_now_add=True)

    # Metrics for this Hashtag
    stats = models.JSONField(null=True, blank=True)
    # Timestamp of last time the stats were updated
    stats_updated = models.DateTimeField(null=True, blank=True)

    # List of other hashtags that are considered similar
    aliases = models.JSONField(null=True, blank=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    objects = HashtagManager()

    class urls(urlman.Urls):
        view = "/tags/{self.hashtag}/"
        follow = "/tags/{self.hashtag}/follow/"
        unfollow = "/tags/{self.hashtag}/unfollow/"
        admin = "/admin/hashtags/"
        admin_edit = "{admin}{self.hashtag}/"
        admin_enable = "{admin_edit}enable/"
        admin_disable = "{admin_edit}disable/"
        timeline = "/tags/{self.hashtag}/"

    hashtag_regex = re.compile(r"\B#([a-zA-Z0-9(_)]+\b)(?!;)")

    def save(self, *args, **kwargs):
        self.hashtag = self.hashtag.lstrip("#")
        if self.name_override:
            self.name_override = self.name_override.lstrip("#")
        return super().save(*args, **kwargs)

    @property
    def display_name(self):
        return self.name_override or self.hashtag

    def __str__(self):
        return self.display_name

    def usage_months(self, num: int = 12) -> dict[date, int]:
        """
        Return the most recent num months of stats
        """
        if not self.stats:
            return {}
        results = {}
        for key, val in self.stats.items():
            parts = key.split("-")
            if len(parts) == 2:
                year = int(parts[0])
                month = int(parts[1])
                results[date(year, month, 1)] = val
        return dict(sorted(results.items(), reverse=True)[:num])

    def usage_days(self, num: int = 7) -> dict[date, int]:
        """
        Return the most recent num days of stats
        """
        if not self.stats:
            return {}
        results = {}
        for key, val in self.stats.items():
            parts = key.split("-")
            if len(parts) == 3:
                year = int(parts[0])
                month = int(parts[1])
                day = int(parts[2])
                results[date(year, month, day)] = val
        return dict(sorted(results.items(), reverse=True)[:num])

    def to_mastodon_json(self, following: bool | None = None):
        value = {
            "name": self.hashtag,
            "url": self.urls.view.full(),  # type: ignore
            "history": [],
        }

        if following is not None:
            value["following"] = following

        return value


class PostInteraction(models.Model):
    """
    Handles both boosts and likes
    """

    class Types(models.TextChoices):
        like = "like"
        boost = "boost"
        vote = "vote"
        pin = "pin"

    id = models.BigIntegerField(
        primary_key=True,
        default=Snowflake.generate_post_interaction,
    )

    # The state the boost is in
    # state = StateField(PostInteractionStates)
    state = models.CharField(max_length=100, default="new")
    state_changed = models.DateTimeField(auto_now_add=True)

    # The canonical object ID
    object_uri = models.CharField(max_length=500, blank=True, null=True, unique=True)

    # What type of interaction it is
    type = models.CharField(max_length=100, choices=Types.choices)

    # The user who boosted/liked/etc.
    identity = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="interactions",
    )

    # The post that was boosted/liked/etc
    post = models.ForeignKey(
        "takahe.Post",
        on_delete=models.CASCADE,
        related_name="interactions",
    )

    # Used to store any interaction extra text value like the vote
    # in the question/poll case
    value = models.CharField(max_length=50, blank=True, null=True)

    # When the activity was originally created (as opposed to when we received it)
    # Mastodon only seems to send this for boosts, not likes
    published = models.DateTimeField(default=timezone.now)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        # managed = False
        db_table = "activities_postinteraction"


class Block(models.Model):
    """
    When one user (the source) mutes or blocks another (the target)
    """

    # state = StateField(BlockStates)
    state = models.CharField(max_length=100, default="new")
    state_changed = models.DateTimeField(auto_now_add=True)

    source = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="outbound_blocks",
    )

    target = models.ForeignKey(
        "takahe.Identity",
        on_delete=models.CASCADE,
        related_name="inbound_blocks",
    )

    uri = models.CharField(blank=True, null=True, max_length=500)

    # If it is a mute, we will stop delivering any activities from target to
    # source, but we will still deliver activities from source to target.
    # A full block (mute=False) stops activities both ways.
    mute = models.BooleanField()
    include_notifications = models.BooleanField(default=False)

    expires = models.DateTimeField(blank=True, null=True)
    note = models.TextField(blank=True, null=True)

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        # managed = False
        db_table = "users_block"

    def __str__(self):
        return f"#{self.pk}: {self.source} blocks {self.target}"

    ### Alternate fetchers/constructors ###

    @classmethod
    def maybe_get(
        cls, source, target, mute=False, require_active=False
    ) -> Optional["Block"]:
        """
        Returns a Block if it exists between source and target
        """
        try:
            if require_active:
                return cls.objects.filter(
                    status__in=["new", "sent", "awaiting_expiry"]
                ).get(source=source, target=target, mute=mute)
            else:
                return cls.objects.get(source=source, target=target, mute=mute)
        except cls.DoesNotExist:
            return None

    @classmethod
    def create_local_block(cls, source, target) -> "Block":
        """
        Creates or updates a full Block from a local Identity to the target
        (which can be local or remote).
        """
        if not source.local:
            raise ValueError("You cannot block from a remote Identity")
        block = cls.maybe_get(source=source, target=target, mute=False)
        if block is not None:
            if not block.state in ["new", "sent", "awaiting_expiry"]:
                block.state = BlockStates.new  # type:ignore
            block.save()
        else:
            with transaction.atomic():
                block = cls.objects.create(
                    source=source,
                    target=target,
                    mute=False,
                )
                block.uri = source.actor_uri + f"block/{block.pk}/"
                block.save()
        return block

    @classmethod
    def create_local_mute(
        cls,
        source,
        target,
        duration=None,
        include_notifications=False,
    ) -> "Block":
        """
        Creates or updates a muting Block from a local Identity to the target
        (which can be local or remote).
        """
        if not source.local:
            raise ValueError("You cannot mute from a remote Identity")
        block = cls.maybe_get(source=source, target=target, mute=True)
        if block is not None:
            if not block in ["new", "sent", "awaiting_expiry"]:
                block.state = BlockStates.new  # type:ignore
            if duration:
                block.expires = timezone.now() + datetime.timedelta(seconds=duration)
            block.include_notifications = include_notifications
            block.save()
        else:
            with transaction.atomic():
                block = cls.objects.create(
                    source=source,
                    target=target,
                    mute=True,
                    include_notifications=include_notifications,
                    expires=(
                        timezone.now() + datetime.timedelta(seconds=duration)
                        if duration
                        else None
                    ),
                )
                block.uri = source.actor_uri + f"block/{block.pk}/"
                block.save()
        return block