feat: Add inbox-label matrix report endpoint (#13394)

This PR added new API endpoint GET
/api/v2/accounts/:account_id/reports/inbox_label_matrix that returns
conversation counts grouped by inbox and label in a matrix format.
Supports optional filtering by date range, inbox_ids, and label_ids.

---------

Co-authored-by: Pranav <pranav@chatwoot.com>

spec/builders/v2/reports/inbox_label_matrix_builder_spec.rb

@@ -0,0 +1,135 @@
+require 'rails_helper'
+
+RSpec.describe V2::Reports::InboxLabelMatrixBuilder do
+  let!(:account) { create(:account) }
+  let!(:inbox_one) { create(:inbox, account: account, name: 'Email Support') }
+  let!(:inbox_two) { create(:inbox, account: account, name: 'Web Chat') }
+  let!(:label_one) { create(:label, account: account, title: 'bug') }
+  let!(:label_two) { create(:label, account: account, title: 'feature') }
+  let(:params) do
+    {
+      since: 1.week.ago.beginning_of_day.to_i.to_s,
+      until: Time.current.end_of_day.to_i.to_s
+    }
+  end
+  let(:builder) { described_class.new(account: account, params: params) }
+
+  describe '#build' do
+    subject(:report) { builder.build }
+
+    context 'when there are conversations with labels across inboxes' do
+      before do
+        c1 = create(:conversation, account: account, inbox: inbox_one, created_at: 2.days.ago)
+        c1.update(label_list: [label_one.title])
+
+        c2 = create(:conversation, account: account, inbox: inbox_one, created_at: 3.days.ago)
+        c2.update(label_list: [label_one.title, label_two.title])
+
+        c3 = create(:conversation, account: account, inbox: inbox_two, created_at: 1.day.ago)
+        c3.update(label_list: [label_two.title])
+      end
+
+      it 'returns inboxes ordered by name' do
+        expect(report[:inboxes]).to eq([
+                                         { id: inbox_one.id, name: 'Email Support' },
+                                         { id: inbox_two.id, name: 'Web Chat' }
+                                       ])
+      end
+
+      it 'returns labels ordered by title' do
+        expect(report[:labels]).to eq([
+                                        { id: label_one.id, title: 'bug' },
+                                        { id: label_two.id, title: 'feature' }
+                                      ])
+      end
+
+      it 'returns correct conversation counts in the matrix' do
+        # Email Support: bug=2, feature=1
+        # Web Chat: bug=0, feature=1
+        expect(report[:matrix]).to eq([[2, 1], [0, 1]])
+      end
+    end
+
+    context 'when filtering by inbox_ids' do
+      let(:params) do
+        {
+          since: 1.week.ago.beginning_of_day.to_i.to_s,
+          until: Time.current.end_of_day.to_i.to_s,
+          inbox_ids: [inbox_one.id]
+        }
+      end
+
+      before do
+        c1 = create(:conversation, account: account, inbox: inbox_one, created_at: 2.days.ago)
+        c1.update(label_list: [label_one.title])
+
+        c2 = create(:conversation, account: account, inbox: inbox_two, created_at: 1.day.ago)
+        c2.update(label_list: [label_one.title])
+      end
+
+      it 'only includes the specified inboxes and their counts' do
+        expect(report[:inboxes]).to eq([{ id: inbox_one.id, name: 'Email Support' }])
+        expect(report[:matrix]).to eq([[1, 0]])
+      end
+    end
+
+    context 'when filtering by label_ids' do
+      let(:params) do
+        {
+          since: 1.week.ago.beginning_of_day.to_i.to_s,
+          until: Time.current.end_of_day.to_i.to_s,
+          label_ids: [label_one.id]
+        }
+      end
+
+      before do
+        c1 = create(:conversation, account: account, inbox: inbox_one, created_at: 2.days.ago)
+        c1.update(label_list: [label_one.title, label_two.title])
+      end
+
+      it 'only includes the specified labels and their counts' do
+        expect(report[:labels]).to eq([{ id: label_one.id, title: 'bug' }])
+        expect(report[:matrix]).to eq([[1], [0]])
+      end
+    end
+
+    context 'when conversations are outside the date range' do
+      before do
+        c1 = create(:conversation, account: account, inbox: inbox_one, created_at: 2.days.ago)
+        c1.update(label_list: [label_one.title])
+
+        c2 = create(:conversation, account: account, inbox: inbox_one, created_at: 2.weeks.ago)
+        c2.update(label_list: [label_one.title])
+      end
+
+      it 'only counts conversations within the date range' do
+        expect(report[:matrix]).to eq([[1, 0], [0, 0]])
+      end
+    end
+
+    context 'when there are no conversations with labels' do
+      before do
+        create(:conversation, account: account, inbox: inbox_one, created_at: 2.days.ago)
+      end
+
+      it 'returns a matrix of zeros' do
+        expect(report[:matrix]).to eq([[0, 0], [0, 0]])
+      end
+    end
+
+    context 'when conversations belong to another account' do
+      let(:other_account) { create(:account) }
+      let(:other_inbox) { create(:inbox, account: other_account) }
+
+      before do
+        c1 = create(:conversation, account: other_account, inbox: other_inbox, created_at: 2.days.ago)
+        other_label = create(:label, account: other_account, title: 'bug')
+        c1.update(label_list: [other_label.title])
+      end
+
+      it 'does not include conversations from other accounts' do
+        expect(report[:matrix]).to eq([[0, 0], [0, 0]])
+      end
+    end
+  end
+end