feat: Add standalone outgoing messages count API endpoint (#13419)

This PR adds a new standalone `GET
/api/v2/accounts/:id/reports/outgoing_messages_count` endpoint that
returns outgoing message counts grouped by agent, team, inbox, or label.

app/builders/v2/reports/outgoing_messages_count_builder.rb

@@ -0,0 +1,79 @@
+class V2::Reports::OutgoingMessagesCountBuilder
+  include DateRangeHelper
+  attr_reader :account, :params
+
+  def initialize(account, params)
+    @account = account
+    @params = params
+  end
+
+  def build
+    send("build_by_#{params[:group_by]}")
+  end
+
+  private
+
+  def base_messages
+    account.messages.outgoing.unscope(:order).where(created_at: range)
+  end
+
+  def build_by_agent
+    counts = base_messages
+             .where(sender_type: 'User')
+             .where.not(sender_id: nil)
+             .group(:sender_id)
+             .count
+
+    user_names = account.users.where(id: counts.keys).index_by(&:id)
+
+    counts.map do |user_id, count|
+      user = user_names[user_id]
+      { id: user_id, name: user&.name, outgoing_messages_count: count }
+    end
+  end
+
+  def build_by_team
+    counts = base_messages
+             .joins('INNER JOIN conversations ON messages.conversation_id = conversations.id')
+             .where.not(conversations: { team_id: nil })
+             .group('conversations.team_id')
+             .count
+
+    team_names = account.teams.where(id: counts.keys).index_by(&:id)
+
+    counts.map do |team_id, count|
+      team = team_names[team_id]
+      { id: team_id, name: team&.name, outgoing_messages_count: count }
+    end
+  end
+
+  def build_by_inbox
+    counts = base_messages
+             .group(:inbox_id)
+             .count
+
+    inbox_names = account.inboxes.where(id: counts.keys).index_by(&:id)
+
+    counts.map do |inbox_id, count|
+      inbox = inbox_names[inbox_id]
+      { id: inbox_id, name: inbox&.name, outgoing_messages_count: count }
+    end
+  end
+
+  def build_by_label
+    counts = base_messages
+             .joins('INNER JOIN conversations ON messages.conversation_id = conversations.id')
+             .joins("INNER JOIN taggings ON taggings.taggable_id = conversations.id
+                     AND taggings.taggable_type = 'Conversation' AND taggings.context = 'labels'")
+             .joins('INNER JOIN tags ON tags.id = taggings.tag_id')
+             .group('tags.name')
+             .count
+
+    label_ids = account.labels.where(title: counts.keys).index_by(&:title)
+
+    counts.map do |label_name, count|
+      label = label_ids[label_name]
+      { id: label&.id, name: label_name, outgoing_messages_count: count }
+    end
+  end
+end

app/controllers/api/v2/accounts/reports_controller.rb

@@ -78,6 +78,15 @@ class Api::V2::Accounts::ReportsController < Api::V1::Accounts::BaseController
     render json: builder.build
   end
 
+  OUTGOING_MESSAGES_ALLOWED_GROUP_BY = %w[agent team inbox label].freeze
+
+  def outgoing_messages_count
+    return head :unprocessable_entity unless OUTGOING_MESSAGES_ALLOWED_GROUP_BY.include?(params[:group_by])
+
+    builder = V2::Reports::OutgoingMessagesCountBuilder.new(Current.account, outgoing_messages_count_params)
+    render json: builder.build
+  end
+
   private
 
   def generate_csv(filename, template)
@@ -171,4 +180,12 @@ class Api::V2::Accounts::ReportsController < Api::V1::Accounts::BaseController
       until: params[:until]
     }
   end
+
+  def outgoing_messages_count_params
+    {
+      group_by: params[:group_by],
+      since: params[:since],
+      until: params[:until]
+    }
+  end
 end