Limit Exemplary comment label to one/day/user

This is a bit of a hacky way of doing it in a few aspects and definitely
still needs some work, but it's a reasonable start. Specifically, a
major miss is that there's no way to remove an Exemplary label unless
you currently have one available. This should definitely be fixed, but
I'm not sure what might be the best approach yet.

tildes/alembic/versions/8e54f422541c_user_track_last_usage_of_exemplary_label.py

@@ -0,0 +1,56 @@
+"""User: track last usage of exemplary label
+
+Revision ID: 8e54f422541c
+Revises: 5cd2db18b722
+Create Date: 2018-09-26 00:22:02.728425
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = "8e54f422541c"
+down_revision = "5cd2db18b722"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.add_column(
+        "users",
+        sa.Column(
+            "last_exemplary_label_time", sa.TIMESTAMP(timezone=True), nullable=True
+        ),
+    )
+
+    op.execute(
+        """
+        CREATE OR REPLACE FUNCTION update_user_last_exemplary_label_time() RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE users
+                SET last_exemplary_label_time = NOW()
+                WHERE user_id = NEW.user_id;
+
+            RETURN NULL;
+        END
+        $$ LANGUAGE plpgsql;
+    """
+    )
+
+    op.execute(
+        """
+        CREATE TRIGGER update_user_last_exemplary_label_time
+            AFTER INSERT ON comment_labels
+            FOR EACH ROW
+            WHEN (NEW.label = 'EXEMPLARY')
+            EXECUTE PROCEDURE update_user_last_exemplary_label_time();
+    """
+    )
+
+
+def downgrade():
+    op.execute("DROP TRIGGER update_user_last_exemplary_label_time ON comment_labels")
+    op.execute("DROP FUNCTION update_user_last_exemplary_label_time()")
+
+    op.drop_column("users", "last_exemplary_label_time")

tildes/scss/modules/_btn.scss

@@ -69,7 +69,8 @@
 .btn-comment-label {
   display: inline-flex;
   align-items: center;
-  margin: 0.4rem;
+  margin: 0 0.4rem;
+  padding: 0.2rem;
 
   font-size: 0.6rem;
   font-weight: bold;

tildes/scss/modules/_comment.scss

@@ -102,7 +102,6 @@
   margin: 0;
   padding: 0 1rem;
   justify-content: space-between;
-  align-items: center;
 
   @media (min-width: $size-md) {
     justify-content: left;
@@ -113,6 +112,12 @@
   font-size: 0.6rem;
 }
 
+.comment-label-note {
+  font-size: 0.5rem;
+  font-style: italic;
+  text-align: center;
+}
+
 .comment-text {
   padding: 0.2rem;
   padding-left: 0.4rem;

tildes/sql/init/triggers/comment_labels/users.sql

@@ -0,0 +1,19 @@
+-- Copyright (c) 2018 Tildes contributors <code@tildes.net>
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+CREATE OR REPLACE FUNCTION update_user_last_exemplary_label_time() RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE users
+        SET last_exemplary_label_time = NOW()
+        WHERE user_id = NEW.user_id;
+
+    RETURN NULL;
+END
+$$ LANGUAGE plpgsql;
+
+
+CREATE TRIGGER update_user_last_exemplary_label_time
+    AFTER INSERT ON comment_labels
+    FOR EACH ROW
+    WHEN (NEW.label = 'EXEMPLARY')
+    EXECUTE PROCEDURE update_user_last_exemplary_label_time();

tildes/static/js/behaviors/comment-label-button.js

@@ -55,7 +55,17 @@ $.onmount('[data-js-comment-label-button]', function() {
                 }
 
                 $(label).on('after.success.ic', function(evt) {
-                    Tildes.addUserLabel(commentID, evt.target.textContent);
+                    var labelName = evt.target.textContent;
+                    Tildes.addUserLabel(commentID, labelName);
+
+                    // if the applied label was Exemplary, remove the button from the
+                    // template since they can't use it again anyway
+                    if (labelName === "exemplary") {
+                        var exemplaryButton = labeltemplate.content.querySelector('.btn-comment-label-exemplary');
+                        if (exemplaryButton) {
+                            exemplaryButton.parentElement.remove();
+                        }
+                    }
                 });
             }
 

tildes/tildes/models/comment/comment_label.py

@@ -18,7 +18,13 @@ from .comment import Comment
 
 
 class CommentLabel(DatabaseModel):
-    """Model for the labels attached to comments by users."""
+    """Model for the labels attached to comments by users.
+
+    Trigger behavior:
+      Outgoing:
+        - Inserting a row for an exemplary label will set last_exemplary_label_time for
+          the relevant user.
+    """
 
     __tablename__ = "comment_labels"
 

tildes/tildes/models/user/user.py

@@ -32,7 +32,7 @@ from sqlalchemy.orm import deferred
 from sqlalchemy.sql.expression import text
 from sqlalchemy_utils import Ltree
 
-from tildes.enums import TopicSortOption
+from tildes.enums import CommentLabelOption, TopicSortOption
 from tildes.lib.database import ArrayOfLtree, CIText
 from tildes.lib.datetime import utc_now
 from tildes.lib.hash import hash_string, is_match_for_hash
@@ -49,6 +49,8 @@ class User(DatabaseModel):
           deletions, and updates to is_unread in comment_notifications.
         - num_unread_messages will be incremented and decremented by insertions,
           deletions, and updates to unread_user_ids in message_conversations.
+        - last_exemplary_label_time will be set when a row for an exemplary label is
+          inserted into comment_labels.
     """
 
     schema_class = UserSchema
@@ -102,6 +104,7 @@ class User(DatabaseModel):
         "filtered_topic_tags", ArrayOfLtree, nullable=False, server_default="{}"
     )
     comment_label_weight: Optional[float] = Column(REAL)
+    last_exemplary_label_time: Optional[datetime] = Column(TIMESTAMP(timezone=True))
 
     @hybrid_property
     def filtered_topic_tags(self) -> List[str]:
@@ -238,3 +241,13 @@ class User(DatabaseModel):
     def is_admin(self) -> bool:
         """Return whether the user has admin permissions."""
         return "admin" in self.auth_principals
+
+    def is_label_available(self, label: CommentLabelOption) -> bool:
+        """Return whether the user has a particular label available."""
+        if label == CommentLabelOption.EXEMPLARY:
+            if not self.last_exemplary_label_time:
+                return True
+
+            return utc_now() - self.last_exemplary_label_time > timedelta(hours=24)
+
+        return True

tildes/tildes/templates/macros/comments.jinja2

@@ -254,13 +254,16 @@
 {% macro comment_label_options_template(options) %}
   <template id="comment-label-options">
     <menu class="comment-label-buttons">
-      {% for label in options %}
+      {% for label in options if request.user.is_label_available(label) %}
         <li>
           <a class="btn-comment-label btn-comment-label-{{ label.name|lower }}"
             {% if label.reason_prompt %}
               data-js-reason-prompt="{{ label.reason_prompt }}"
             {% endif %}
           >{{ label.name|lower }}</a>
+          {% if label.name == "EXEMPLARY" %}
+            <div class="comment-label-note">One per day</div>
+          {% endif %}
         </li>
       {% endfor %}
     </ul>

tildes/tildes/views/api/web/comment.py

@@ -4,6 +4,7 @@
 """Web API endpoints related to comments."""
 
 from marshmallow.fields import Boolean
+from pyramid.httpexceptions import HTTPUnprocessableEntity
 from pyramid.request import Request
 from pyramid.response import Response
 from sqlalchemy.dialects.postgresql import insert
@@ -265,6 +266,9 @@ def put_label_comment(
     """Add a label to a comment."""
     comment = request.context
 
+    if not request.user.is_label_available(name):
+        raise HTTPUnprocessableEntity("That label is not available.")
+
     savepoint = request.tm.savepoint()
 
     weight = request.user.comment_label_weight