Add JSON activities API endpoint (#2783)

* Add JSON events API endpoint

* Add regression test for event particulars defaults

* Move JSON events API to a dedicated ActivitiesController

The events endpoint served both the HTML day timeline and the JSON API
feed, but the two paths shared no data or behavior — the HTML side uses
DayTimelinesScoped while the JSON side built its own query. Splitting
into ActivitiesController gives the API its own home at
GET /:account/activities.json without dragging in the timeline
before_actions.

Also preloads comment creator in Event.preloaded to avoid an N+1 when
rendering comment eventables in the JSON feed.

app/controllers/activities_controller.rb

@@ -0,0 +1,30 @@
+class ActivitiesController < ApplicationController
+  ACTIONS = %w[
+    card_assigned
+    card_auto_postponed
+    card_board_changed
+    card_closed
+    card_postponed
+    card_published
+    card_reopened
+    card_sent_back_to_triage
+    card_title_changed
+    card_triaged
+    card_unassigned
+    comment_created
+  ].freeze
+
+  def index
+    set_page_and_extract_portion_from(activities)
+  end
+
+  private
+    def activities
+      Current.user.accessible_events
+        .preloaded
+        .where(action: ACTIONS)
+        .for_creators(params[:creator_ids])
+        .for_boards(params[:board_ids])
+        .reverse_chronologically
+    end
+end

app/models/event.rb

@@ -9,10 +9,13 @@ class Event < ApplicationRecord
   has_many :webhook_deliveries, class_name: "Webhook::Delivery", dependent: :delete_all
 
   scope :chronologically, -> { order created_at: :asc, id: :desc }
+  scope :reverse_chronologically, -> { order created_at: :desc, id: :desc }
+  scope :for_creators, ->(ids) { where(creator_id: ids) if ids.present? }
+  scope :for_boards, ->(ids) { where(board_id: ids) if ids.present? }
   scope :preloaded, -> {
     includes(:creator, :board, {
       eventable: [
-        :goldness, :closure, :image_attachment,
+        :creator, :goldness, :closure, :image_attachment,
         { rich_text_body: :embeds_attachments },
         { rich_text_description: :embeds_attachments },
         { card: [ :goldness, :closure, :image_attachment ] }

app/models/event/particulars.rb

@@ -8,4 +8,21 @@ module Event::Particulars
   def assignees
     @assignees ||= User.where id: assignee_ids
   end
+
+  def api_particulars
+    nested = particulars.dig("particulars") || {}
+
+    case action.to_s
+    when "card_assigned", "card_unassigned"
+      { "assignee_ids" => Array(assignee_ids) }
+    when "card_board_changed"
+      { "old_board" => nested["old_board"].to_s, "new_board" => nested["new_board"].to_s }
+    when "card_title_changed"
+      { "old_title" => nested["old_title"].to_s, "new_title" => nested["new_title"].to_s }
+    when "card_triaged"
+      { "column" => nested["column"].to_s }
+    else
+      {}
+    end
+  end
 end

app/views/activities/_activity.json.jbuilder

@@ -0,0 +1,21 @@
+json.(event, :id, :action)
+json.created_at event.created_at.utc
+json.description event.description_for(Current.user).to_plain_text
+json.particulars event.api_particulars
+json.url(
+  case event.eventable
+  when Comment then card_url(event.eventable.card, anchor: dom_id(event.eventable))
+  else polymorphic_url(event.eventable)
+  end
+)
+json.eventable_type event.eventable_type
+
+json.eventable do
+  case event.eventable
+  when Card    then json.partial! "cards/card", card: event.eventable
+  when Comment then json.partial! "cards/comments/comment", comment: event.eventable
+  end
+end
+
+json.board event.board, partial: "boards/board", as: :board
+json.creator event.creator, partial: "users/user", as: :user

app/views/activities/index.json.jbuilder

@@ -0,0 +1 @@
+json.array! @page.records, partial: "activities/activity", as: :event