From 3cc487f94bff0eee45ee13f0528131af8052eb05 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Fri, 24 Sep 2021 18:04:27 -0700
Subject: [PATCH] Distinguish new posts from already-seen posts

---
 amanuensis/backend/post.py                  | 46 +++++++++++++++++++--
 amanuensis/db/models.py                     |  6 ++-
 amanuensis/resources/page.css               |  4 ++
 amanuensis/server/lexicon/posts/__init__.py | 16 +++++--
 amanuensis/server/lexicon/posts/posts.jinja | 17 +++++---
 5 files changed, 75 insertions(+), 14 deletions(-)

diff --git a/amanuensis/backend/post.py b/amanuensis/backend/post.py
index 8a170fb..38dbea4 100644
--- a/amanuensis/backend/post.py
+++ b/amanuensis/backend/post.py
@@ -2,12 +2,13 @@
 Post query interface
 """
 
-from typing import Optional
+from typing import Optional, Sequence, Tuple
 
-from sqlalchemy import select
+from sqlalchemy import select, update, func
+from sqlalchemy.sql.sqltypes import DateTime
 
 from amanuensis.db import DbContext, Post
-from amanuensis.db.models import Lexicon
+from amanuensis.db.models import Lexicon, Membership
 from amanuensis.errors import ArgumentError, BackendArgumentTypeError
 
 
@@ -47,3 +48,42 @@ def create(
     db.session.add(new_post)
     db.session.commit()
     return new_post
+
+
+def get_posts_for_membership(
+    db: DbContext, membership_id: int
+) -> Tuple[Sequence[Post], Sequence[Post]]:
+    """
+    Returns posts for the membership's lexicon, split into posts that
+    are new since the last view and posts that were previously seen.
+    """
+    # Save the current timestamp, so we don't miss posts created between now
+    # and when we finish looking stuff up
+    now: DateTime = db(select(func.now())).scalar_one()
+
+    # Save the previous last-seen timestamp for splitting new from old posts,
+    # then update the membership with the current time
+    last_seen: DateTime = db(
+        select(Membership.last_post_seen).where(Membership.id == membership_id)
+    ).scalar_one()
+    db(
+        update(Membership)
+        .where(Membership.id == membership_id)
+        .values(last_post_seen=now)
+    )
+    db.session.commit()
+
+    # Fetch posts in two groups, new ones after the last-seen time and old ones
+    # If last-seen is null, then just return everything as new
+    new_posts = db(
+        select(Post)
+        .where(last_seen is None or Post.created > last_seen)
+        .order_by(Post.created.desc())
+    ).scalars()
+    old_posts = db(
+        select(Post)
+        .where(last_seen is not None and Post.created <= last_seen)
+        .order_by(Post.created.desc())
+    ).scalars()
+
+    return new_posts, old_posts
diff --git a/amanuensis/db/models.py b/amanuensis/db/models.py
index cc5d2c1..4633e83 100644
--- a/amanuensis/db/models.py
+++ b/amanuensis/db/models.py
@@ -251,7 +251,9 @@ class Lexicon(ModelBase):
     indices = relationship("ArticleIndex", back_populates="lexicon")
     index_rules = relationship("ArticleIndexRule", back_populates="lexicon")
     content_rules = relationship("ArticleContentRule", back_populates="lexicon")
-    posts = relationship("Post", back_populates="lexicon", order_by="Post.created.desc()")
+    posts = relationship(
+        "Post", back_populates="lexicon", order_by="Post.created.desc()"
+    )
 
     #######################
     # Derived information #
@@ -654,7 +656,7 @@ class Post(ModelBase):
     ################
 
     # The timestamp the post was created
-    created = Column(DateTime, nullable=False, server_default=func.now())
+    created = Column(DateTime, nullable=False, server_default=func.utcnow())
 
     # The body of the post
     body = Column(Text, nullable=False)
diff --git a/amanuensis/resources/page.css b/amanuensis/resources/page.css
index 8fb534b..0a9149d 100644
--- a/amanuensis/resources/page.css
+++ b/amanuensis/resources/page.css
@@ -215,6 +215,10 @@ details.setting-help {
 #index-definition-table td input[type=number] {
 	width: 4em;
 }
+section.new-post {
+	padding: 9px;
+	border: 1px dashed red;
+}
 p.post-byline {
 	color: #606060;
 	text-align: right;
diff --git a/amanuensis/server/lexicon/posts/__init__.py b/amanuensis/server/lexicon/posts/__init__.py
index 9dee642..3d0a7ec 100644
--- a/amanuensis/server/lexicon/posts/__init__.py
+++ b/amanuensis/server/lexicon/posts/__init__.py
@@ -7,7 +7,12 @@ from amanuensis.backend import postq
 from amanuensis.db import Post
 from amanuensis.parser import RenderableVisitor, parse_raw_markdown
 from amanuensis.parser.core import *
-from amanuensis.server.helpers import lexicon_param, player_required, current_lexicon
+from amanuensis.server.helpers import (
+    lexicon_param,
+    player_required,
+    current_lexicon,
+    current_membership,
+)
 
 from .forms import CreatePostForm
 
@@ -22,10 +27,10 @@ class PostFormatter(RenderableVisitor):
         return span.innertext
 
     def LineBreak(self, span: LineBreak):
-        return '<br>'
+        return "<br>"
 
     def ParsedArticle(self, span: ParsedArticle):
-        return '\n'.join(span.recurse(self))
+        return "\n".join(span.recurse(self))
 
     def BodyParagraph(self, span: BodyParagraph):
         return f'<p>{"".join(span.recurse(self))}</p>'
@@ -34,7 +39,7 @@ class PostFormatter(RenderableVisitor):
         return (
             '<hr><span class="signature"><p>'
             f'{"".join(span.recurse(self))}'
-            '</p></span>'
+            "</p></span>"
         )
 
     def BoldSpan(self, span: BoldSpan):
@@ -59,11 +64,14 @@ def render_post_body(post: Post) -> str:
 @player_required
 def list(lexicon_name):
     form = CreatePostForm()
+    new_posts, old_posts = postq.get_posts_for_membership(g.db, current_membership.id)
     return render_template(
         "posts.jinja",
         lexicon_name=lexicon_name,
         form=form,
         render_post_body=render_post_body,
+        new_posts=new_posts,
+        old_posts=old_posts,
     )
 
 
diff --git a/amanuensis/server/lexicon/posts/posts.jinja b/amanuensis/server/lexicon/posts/posts.jinja
index f68b132..6fca8c6 100644
--- a/amanuensis/server/lexicon/posts/posts.jinja
+++ b/amanuensis/server/lexicon/posts/posts.jinja
@@ -2,6 +2,13 @@
 {% set current_page = "characters" %}
 {% block title %}Character | {{ lexicon_title }}{% endblock %}
 
+{% macro make_post(post, is_new) %}
+<section{% if is_new %} class="new-post"{% endif %}>
+<p>{{ render_post_body(post) }}</p>
+<p class="post-byline">Posted {% if post.user_id %}by {{ post.user.display_name }} {% endif %}at {{ post.created }}</p>
+</section>
+{% endmacro %}
+
 {% block main %}
 <section>
 <form action="" method="post" novalidate>
@@ -11,10 +18,10 @@
 </form>
 </section>
 
-{% for post in current_lexicon.posts %}
-<section>
-<p>{{ render_post_body(post) }}</p>
-<p class="post-byline">Posted {% if post.user_id %}by {{ post.user.display_name }} {% endif %}at {{ post.created }}</p>
-</section>
+{% for post in new_posts %}
+{{ make_post(post, True) }}
+{% endfor %}
+{% for post in old_posts %}
+{{ make_post(post, False) }}
 {% endfor %}
 {% endblock %}