Add ability to follow hashtags

activities/models/hashtag.py

@@ -114,6 +114,8 @@ class Hashtag(StatorModel):
 
     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/"
@@ -166,9 +168,14 @@ class Hashtag(StatorModel):
                 results[date(year, month, day)] = val
         return dict(sorted(results.items(), reverse=True)[:num])
 
-    def to_mastodon_json(self):
+    def to_mastodon_json(self, followed: bool | None = None):
-        return {
+        value = {
             "name": self.hashtag,
-            "url": self.urls.view.full(),
+            "url": self.urls.view.full(),  # type: ignore
             "history": [],
         }
+
+        if followed is not None:
+            value["followed"] = followed
+
+        return value

activities/models/post.py

@@ -38,6 +38,7 @@ from core.snowflake import Snowflake
 from stator.exceptions import TryAgainLater
 from stator.models import State, StateField, StateGraph, StatorModel
 from users.models.follow import FollowStates
+from users.models.hashtag_follow import HashtagFollow
 from users.models.identity import Identity, IdentityStates
 from users.models.inbox_message import InboxMessage
 from users.models.system_actor import SystemActor
@@ -726,12 +727,18 @@ class Post(StatorModel):
         targets = set()
         async for mention in self.mentions.all():
             targets.add(mention)
-        # Then, if it's not mentions only, also deliver to followers
+        # Then, if it's not mentions only, also deliver to followers and all hashtag followers
         if self.visibility != Post.Visibilities.mentioned:
             async for follower in self.author.inbound_follows.filter(
                 state__in=FollowStates.group_active()
             ).select_related("source"):
                 targets.add(follower.source)
+            if self.hashtags:
+                async for follow in HashtagFollow.objects.by_hashtags(
+                    self.hashtags
+                ).prefetch_related("identity"):
+                    targets.add(follow.identity)
+
         # If it's a reply, always include the original author if we know them
         reply_post = await self.ain_reply_to_post()
         if reply_post:

activities/views/hashtags.py

@@ -0,0 +1,38 @@
+from django.http import HttpRequest
+from django.shortcuts import get_object_or_404, redirect, render
+from django.utils.decorators import method_decorator
+from django.views.generic import View
+
+from activities.models.hashtag import Hashtag
+from users.decorators import identity_required
+
+
+@method_decorator(identity_required, name="dispatch")
+class HashtagFollow(View):
+    """
+    Follows/unfollows a hashtag with the current identity
+    """
+
+    undo = False
+
+    def post(self, request: HttpRequest, hashtag):
+        hashtag = get_object_or_404(
+            Hashtag,
+            pk=hashtag,
+        )
+        follow = None
+        if self.undo:
+            request.identity.hashtag_follows.filter(hashtag=hashtag).delete()
+        else:
+            follow = request.identity.hashtag_follows.get_or_create(hashtag=hashtag)
+        # Return either a redirect or a HTMX snippet
+        if request.htmx:
+            return render(
+                request,
+                "activities/_hashtag_follow.html",
+                {
+                    "hashtag": hashtag,
+                    "follow": follow,
+                },
+            )
+        return redirect(hashtag.urls.view)

activities/views/timelines.py

@@ -7,7 +7,7 @@ from activities.models import Hashtag, PostInteraction, TimelineEvent
 from activities.services import TimelineService
 from core.decorators import cache_page
 from users.decorators import identity_required
-from users.models import Bookmark
+from users.models import Bookmark, HashtagFollow
 
 from .compose import Compose
 
@@ -75,6 +75,10 @@ class Tag(ListView):
         context["bookmarks"] = Bookmark.for_identity(
             self.request.identity, context["page_obj"]
         )
+        context["follow"] = HashtagFollow.maybe_get(
+            self.request.identity,
+            self.hashtag,
+        )
         return context
 
 

api/schemas.py

@@ -276,13 +276,33 @@ class Tag(Schema):
     name: str
     url: str
     history: dict
+    followed: bool | None
 
     @classmethod
     def from_hashtag(
         cls,
         hashtag: activities_models.Hashtag,
+        followed: bool | None = None,
     ) -> "Tag":
-        return cls(**hashtag.to_mastodon_json())
+        return cls(**hashtag.to_mastodon_json(followed=followed))
+
+
+class FollowedTag(Tag):
+    id: str
+
+    @classmethod
+    def from_follow(
+        cls,
+        follow: users_models.HashtagFollow,
+    ) -> "FollowedTag":
+        return cls(id=follow.id, **follow.hashtag.to_mastodon_json(followed=True))
+
+    @classmethod
+    def map_from_follows(
+        cls,
+        hashtag_follows: list[users_models.HashtagFollow],
+    ) -> list["Tag"]:
+        return [cls.from_follow(follow) for follow in hashtag_follows]
 
 
 class FeaturedTag(Schema):

api/urls.py

@@ -95,6 +95,8 @@ urlpatterns = [
     path("v1/statuses/<id>/unbookmark", statuses.unbookmark_status),
     # Tags
     path("v1/followed_tags", tags.followed_tags),
+    path("v1/tags/<id>/follow", tags.follow),
+    path("v1/tags/<id>/unfollow", tags.unfollow),
     # Timelines
     path("v1/timelines/home", timelines.home),
     path("v1/timelines/public", timelines.public),

api/views/tags.py

@@ -1,8 +1,12 @@
 from django.http import HttpRequest
+from django.shortcuts import get_object_or_404
 from hatchway import api_view
 
+from activities.models import Hashtag
 from api import schemas
 from api.decorators import scope_required
+from api.pagination import MastodonPaginator, PaginatingApiResponse, PaginationResult
+from users.models import HashtagFollow
 
 
 @scope_required("read:follows")
@@ -14,5 +18,51 @@ def followed_tags(
     min_id: str | None = None,
     limit: int = 100,
 ) -> list[schemas.Tag]:
-    # We don't implement this yet
+    queryset = HashtagFollow.objects.by_identity(request.identity)
-    return []
+    paginator = MastodonPaginator()
+    pager: PaginationResult[HashtagFollow] = paginator.paginate(
+        queryset,
+        min_id=min_id,
+        max_id=max_id,
+        since_id=since_id,
+        limit=limit,
+    )
+    return PaginatingApiResponse(
+        schemas.FollowedTag.map_from_follows(pager.results),
+        request=request,
+        include_params=["limit"],
+    )
+
+
+@scope_required("write:follows")
+@api_view.post
+def follow(
+    request: HttpRequest,
+    id: str,
+) -> schemas.Tag:
+    hashtag = get_object_or_404(
+        Hashtag,
+        pk=id,
+    )
+    request.identity.hashtag_follows.get_or_create(hashtag=hashtag)
+    return schemas.Tag.from_hashtag(
+        hashtag,
+        followed=True,
+    )
+
+
+@scope_required("write:follows")
+@api_view.post
+def unfollow(
+    request: HttpRequest,
+    id: str,
+) -> schemas.Tag:
+    hashtag = get_object_or_404(
+        Hashtag,
+        pk=id,
+    )
+    request.identity.hashtag_follows.filter(hashtag=hashtag).delete()
+    return schemas.Tag.from_hashtag(
+        hashtag,
+        followed=False,
+    )

static/css/style.css

@@ -714,28 +714,32 @@ form.inline {
     display: inline;
 }
 
-div.follow-profile {
+div.follow {
     float: right;
     margin: 20px 0 0 0;
     font-size: 16px;
     text-align: center;
 }
 
-.follow-profile.has-reverse {
+div.follow-hashtag {
+    margin: 0;
+}
+
+.follow.has-reverse {
     margin-top: 0;
 }
 
-.follow-profile .reverse-follow {
+.follow .reverse-follow {
     display: block;
     margin: 0 0 5px 0;
 }
 
-div.follow-profile button,
+div.follow button,
-div.follow-profile .button {
+div.follow .button {
     margin: 0;
 }
 
-div.follow-profile .actions {
+div.follow .actions {
     /* display: flex; */
     position: relative;
     justify-content: space-between;
@@ -744,14 +748,14 @@ div.follow-profile .actions {
     align-content: center;
 }
 
-div.follow-profile .actions a {
+div.follow .actions a {
     border-radius: 4px;
     min-width: 40px;
     text-align: center;
     cursor: pointer;
 }
 
-div.follow-profile .actions menu {
+div.follow .actions menu {
     display: none;
     background-color: var(--color-bg-menu);
     border-radius: 5px;
@@ -762,13 +766,13 @@ div.follow-profile .actions menu {
 }
 
 
-div.follow-profile .actions menu.enabled {
+div.follow .actions menu.enabled {
     display: block;
     min-width: 160px;
     z-index: 10;
 }
 
-div.follow-profile .actions menu a {
+div.follow .actions menu a {
     text-align: left;
     display: block;
     font-size: 15px;
@@ -776,7 +780,7 @@ div.follow-profile .actions menu a {
     color: var(--color-text-dull);
 }
 
-.follow-profile .actions menu button {
+.follow .actions menu button {
     background: none !important;
     border: none;
     cursor: pointer;
@@ -787,25 +791,25 @@ div.follow-profile .actions menu a {
     color: var(--color-text-dull);
 }
 
-.follow-profile .actions menu button i {
+.follow .actions menu button i {
     margin-right: 4px;
     width: 16px;
 }
 
-.follow-profile .actions button:hover {
+.follow .actions button:hover {
     color: var(--color-text-main);
 }
 
-.follow-profile .actions menu a i {
+.follow .actions menu a i {
     margin-right: 4px;
     width: 16px;
 }
 
-div.follow-profile .actions a:hover {
+div.follow .actions a:hover {
     color: var(--color-text-main);
 }
 
-div.follow-profile .actions a.active {
+div.follow .actions a.active {
     color: var(--color-text-link);
 }
 
@@ -1305,6 +1309,11 @@ table.metadata td .emoji {
     margin: 0 0 10px 0;
     color: var(--color-text-main);
     font-size: 130%;
+    display: flow-root;
+}
+
+.left-column .timeline-name .hashtag {
+    margin-top: 5px;
 }
 
 .left-column .timeline-name i {

takahe/urls.py

@@ -2,7 +2,16 @@ from django.conf import settings as djsettings
 from django.contrib import admin as djadmin
 from django.urls import include, path, re_path
 
-from activities.views import compose, debug, explore, follows, posts, search, timelines
+from activities.views import (
+    compose,
+    debug,
+    explore,
+    follows,
+    hashtags,
+    posts,
+    search,
+    timelines,
+)
 from api.views import oauth
 from core import views as core
 from mediaproxy import views as mediaproxy
@@ -27,6 +36,8 @@ urlpatterns = [
     path("federated/", timelines.Federated.as_view(), name="federated"),
     path("search/", search.Search.as_view(), name="search"),
     path("tags/<hashtag>/", timelines.Tag.as_view(), name="tag"),
+    path("tags/<hashtag>/follow/", hashtags.HashtagFollow.as_view()),
+    path("tags/<hashtag>/unfollow/", hashtags.HashtagFollow.as_view(undo=True)),
     path("explore/", explore.Explore.as_view(), name="explore"),
     path("explore/tags/", explore.ExploreTag.as_view(), name="explore-tag"),
     path(

templates/activities/_hashtag_follow.html

@@ -0,0 +1,9 @@
+{% if follow %}
+    <button title="Unfollow" class="active" hx-trigger="click, keyup[key=='Enter']" hx-post="{{ hashtag.urls.unfollow }}" hx-swap="outerHTML" tabindex="0">
+        Unfollow
+    </button>
+{% else %}
+    <button title="Follow" hx-trigger="click, keyup[key=='Enter']" hx-post="{{ hashtag.urls.follow }}" hx-swap="outerHTML" tabindex="0">
+        Follow
+    </button>
+{% endif %}

templates/activities/tag.html

@@ -3,7 +3,14 @@
 {% block title %}#{{ hashtag.display_name }} Timeline{% endblock %}
 
 {% block content %}
-    <div class="timeline-name"><i class="fa-solid fa-hashtag"></i>{{ hashtag.display_name }}</div>
+    <div class="timeline-name">
+        <div class="inline follow follow-hashtag">
+            {% include "activities/_hashtag_follow.html" %}
+        </div>
+        <div class="hashtag">
+            <i class="fa-solid fa-hashtag"></i>{{ hashtag.display_name }}
+        </div>
+    </div>
     {% for post in page_obj %}
         {% include "activities/_post.html" %}
     {% empty %}

templates/identity/_view_menu.html

@@ -1,4 +1,4 @@
-<div class="inline follow-profile {% if inbound_follow %}has-reverse{% endif %}">
+<div class="inline follow {% if inbound_follow %}has-reverse{% endif %}">
     <div class="actions" role="menubar">
         {% if request.identity == identity %}
             <a href="{% url "settings_profile" %}" class="button" title="Edit Profile">

tests/activities/models/test_timeline_event.py

@@ -1,7 +1,7 @@
 import pytest
 from django.utils import timezone
 
-from activities.models import Post, TimelineEvent
+from activities.models import Hashtag, Post, TimelineEvent
 from activities.services import PostService
 from core.ld import format_ld_date
 from users.models import Block, Follow, Identity, InboxMessage
@@ -257,3 +257,70 @@ def test_clear_timeline(
     assert TimelineEvent.objects.filter(
         type=TimelineEvent.Types.mentioned, identity=identity
     ).exists() == (not full)
+
+
+@pytest.mark.django_db
+@pytest.mark.parametrize("local", [True, False])
+@pytest.mark.parametrize("blocked", ["full", "mute", "no"])
+def test_hashtag_followed(
+    identity: Identity,
+    other_identity: Identity,
+    remote_identity: Identity,
+    stator,
+    local: bool,
+    blocked: bool,
+):
+    """
+    Ensure that a new or incoming post with a hashtag followed by a local entity
+    results in a timeline event, unless the author is blocked.
+    """
+    hashtag = Hashtag.objects.get_or_create(hashtag="takahe")[0]
+    identity.hashtag_follows.get_or_create(hashtag=hashtag)
+
+    if local:
+        Post.create_local(author=other_identity, content="Hello from #Takahe!")
+    else:
+        # Create an inbound new post message
+        message = {
+            "id": "test",
+            "type": "Create",
+            "actor": remote_identity.actor_uri,
+            "object": {
+                "id": "https://remote.test/test-post",
+                "type": "Note",
+                "published": format_ld_date(timezone.now()),
+                "attributedTo": remote_identity.actor_uri,
+                "to": "as:Public",
+                "content": '<p>Hello from <a href="https://remote.test/tags/takahe/" rel="tag">#Takahe</a>!',
+                "tag": {
+                    "type": "Hashtag",
+                    "href": "https://remote.test/tags/takahe/",
+                    "name": "#Takahe",
+                },
+            },
+        }
+        InboxMessage.objects.create(message=message)
+
+    # Implement any blocks
+    author = other_identity if local else remote_identity
+    if blocked == "full":
+        Block.create_local_block(identity, author)
+    elif blocked == "mute":
+        Block.create_local_mute(identity, author)
+
+    # Run stator twice - to make fanouts and then process them
+    stator.run_single_cycle_sync()
+    stator.run_single_cycle_sync()
+
+    if blocked in ["full", "mute"]:
+        # Verify post is not in timeline
+        assert not TimelineEvent.objects.filter(
+            type=TimelineEvent.Types.post, identity=identity
+        ).exists()
+    else:
+        # Verify post is in timeline
+        event = TimelineEvent.objects.filter(
+            type=TimelineEvent.Types.post, identity=identity
+        ).first()
+        assert event
+        assert "Hello from " in event.subject_post.content

users/migrations/0016_hashtagfollow.py

@@ -0,0 +1,49 @@
+# Generated by Django 4.1.7 on 2023-03-11 19:50
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("activities", "0012_in_reply_to_index"),
+        ("users", "0015_bookmark"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="HashtagFollow",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("created", models.DateTimeField(auto_now_add=True)),
+                (
+                    "hashtag",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="followers",
+                        to="activities.hashtag",
+                    ),
+                ),
+                (
+                    "identity",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="hashtag_follows",
+                        to="users.identity",
+                    ),
+                ),
+            ],
+            options={
+                "unique_together": {("identity", "hashtag")},
+            },
+        ),
+    ]

users/models/__init__.py

@@ -3,6 +3,7 @@ from .block import Block, BlockStates  # noqa
 from .bookmark import Bookmark  # noqa
 from .domain import Domain  # noqa
 from .follow import Follow, FollowStates  # noqa
+from .hashtag_follow import HashtagFollow  # noqa
 from .identity import Identity, IdentityStates  # noqa
 from .inbox_message import InboxMessage, InboxMessageStates  # noqa
 from .invite import Invite  # noqa

users/models/hashtag_follow.py

@@ -0,0 +1,58 @@
+from typing import Optional
+
+from django.db import models
+
+
+class HashtagFollowQuerySet(models.QuerySet):
+    def by_hashtags(self, hashtags: list[str]):
+        return self.filter(hashtag_id__in=hashtags)
+
+    def by_identity(self, identity):
+        return self.filter(identity=identity)
+
+
+class HashtagFollowManager(models.Manager):
+    def get_queryset(self):
+        return HashtagFollowQuerySet(self.model, using=self._db)
+
+    def by_hashtags(self, hashtags: list[str]):
+        return self.get_queryset().by_hashtags(hashtags)
+
+    def by_identity(self, identity):
+        return self.get_queryset().by_identity(identity)
+
+
+class HashtagFollow(models.Model):
+    identity = models.ForeignKey(
+        "users.Identity",
+        on_delete=models.CASCADE,
+        related_name="hashtag_follows",
+    )
+    hashtag = models.ForeignKey(
+        "activities.Hashtag",
+        on_delete=models.CASCADE,
+        related_name="followers",
+        db_index=True,
+    )
+
+    created = models.DateTimeField(auto_now_add=True)
+
+    objects = HashtagFollowManager()
+
+    class Meta:
+        unique_together = [("identity", "hashtag")]
+
+    def __str__(self):
+        return f"#{self.id}: {self.identity} → {self.hashtag_id}"
+
+    ### Alternate fetchers/constructors ###
+
+    @classmethod
+    def maybe_get(cls, identity, hashtag) -> Optional["HashtagFollow"]:
+        """
+        Returns a hashtag follow if it exists between identity and hashtag
+        """
+        try:
+            return HashtagFollow.objects.get(identity=identity, hashtag=hashtag)
+        except HashtagFollow.DoesNotExist:
+            return None