# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::Metrics::Subscribers::ActionCable, :request_store, feature_category: :application_performance do
  let(:subscriber) { described_class.new }
  let(:counter) { double(:counter) }
  let(:transmitted_bytes_counter) { double(:counter) }
  let(:channel_class) { 'IssuesChannel' }
  let(:event) { double(:event, name: name, payload: payload) }

  before do
    allow(::Gitlab::Metrics).to receive(:counter).with(
      :action_cable_single_client_transmissions_total, /transmit/
    ).and_return(counter)
    allow(::Gitlab::Metrics).to receive(:counter).with(
      :action_cable_transmitted_bytes_total, /transmit/
    ).and_return(transmitted_bytes_counter)
  end

  describe '#transmit' do
    let(:name) { 'transmit.action_cable' }
    let(:via) { nil }
    let(:payload) do
      {
        channel_class: channel_class,
        via: via,
        data: data
      }
    end

    let(:message_size) { ::Gitlab::Json.generate(data).bytesize }

    context 'for transmissions initiated by Channel instance' do
      let(:data) { {} }
      let(:expected_labels) do
        {
          channel: channel_class,
          broadcasting: nil,
          caller: 'channel'
        }
      end

      it 'tracks the event with "caller" set to "channel"' do
        expect(counter).to receive(:increment).with(expected_labels)
        expect(transmitted_bytes_counter).to receive(:increment).with(expected_labels, message_size)

        subscriber.transmit(event)
      end
    end

    context 'for transmissions initiated by GraphQL event subscriber' do
      let(:via) { 'streamed from graphql-subscription:09ae595a-45c4-4ae0-b765-4e503203211d' }
      let(:data) { { result: { 'data' => { 'issuableEpicUpdated' => '<GQL query result>' } } } }
      let(:expected_labels) do
        {
          channel: channel_class,
          broadcasting: 'graphql-event:issuableEpicUpdated',
          caller: 'graphql-subscription'
        }
      end

      it 'tracks the event with correct "caller" and "broadcasting"' do
        expect(counter).to receive(:increment).with(expected_labels)
        expect(transmitted_bytes_counter).to receive(:increment).with(expected_labels, message_size)

        subscriber.transmit(event)
      end

      it 'is indifferent to keys being symbols or strings in result payload' do
        expect(counter).to receive(:increment).with(expected_labels)
        expect(transmitted_bytes_counter).to receive(:increment).with(expected_labels, message_size)

        event.payload[:data].deep_stringify_keys!

        subscriber.transmit(event)
      end
    end

    context 'when transmission is coming from unknown source' do
      let(:via) { 'streamed from something else' }
      let(:data) { {} }
      let(:expected_labels) do
        {
          channel: channel_class,
          broadcasting: nil,
          caller: 'unknown'
        }
      end

      it 'tracks the event with "caller" set to "unknown"' do
        expect(counter).to receive(:increment).with(expected_labels)
        expect(transmitted_bytes_counter).to receive(:increment).with(expected_labels, message_size)

        subscriber.transmit(event)
      end
    end
  end

  describe '#broadcast' do
    let(:name) { 'broadcast.action_cable' }
    let(:coder) { ActiveSupport::JSON }
    let(:message) do
      { event: :updated }
    end

    let(:payload) do
      {
        broadcasting: broadcasting,
        message: message,
        coder: coder
      }
    end

    before do
      allow(::Gitlab::Metrics).to receive(:counter).with(
        :action_cable_broadcasts_total, /broadcast/
      ).and_return(counter)
    end

    context 'when broadcast is for a GraphQL event' do
      let(:broadcasting) { 'graphql-event::issuableEpicUpdated:issuableId:Z2lkOi8vZ2l0bGFiL0lzc3VlLzM' }

      it 'tracks the event with broadcasting set to event topic' do
        expect(counter).to receive(:increment).with({ broadcasting: 'graphql-event:issuableEpicUpdated' })

        subscriber.broadcast(event)
      end
    end

    context 'when broadcast is for a GraphQL channel subscription' do
      let(:broadcasting) { 'graphql-subscription:09ae595a-45c4-4ae0-b765-4e503203211d' }

      it 'strips out subscription ID from broadcasting' do
        expect(counter).to receive(:increment).with({ broadcasting: 'graphql-subscription' })

        subscriber.broadcast(event)
      end
    end

    context 'when broadcast is something else' do
      let(:broadcasting) { 'unknown-topic' }

      it 'tracks the event as "unknown"' do
        expect(counter).to receive(:increment).with({ broadcasting: 'unknown' })

        subscriber.broadcast(event)
      end
    end
  end

  describe '#transmit_subscription_confirmation' do
    let(:name) { 'transmit_subscription_confirmation.action_cable' }
    let(:channel_class) { 'IssuesChannel' }
    let(:payload) do
      {
        channel_class: channel_class
      }
    end

    it 'tracks the subscription confirmation event' do
      allow(::Gitlab::Metrics).to receive(:counter).with(
        :action_cable_subscription_confirmations_total, /confirm/
      ).and_return(counter)

      expect(counter).to receive(:increment)

      subscriber.transmit_subscription_confirmation(event)
    end
  end

  describe '#transmit_subscription_rejection' do
    let(:name) { 'transmit_subscription_rejection.action_cable' }
    let(:channel_class) { 'IssuesChannel' }
    let(:payload) do
      {
          channel_class: channel_class
      }
    end

    it 'tracks the subscription rejection event' do
      allow(::Gitlab::Metrics).to receive(:counter).with(
        :action_cable_subscription_rejections_total, /reject/
      ).and_return(counter)

      expect(counter).to receive(:increment)

      subscriber.transmit_subscription_rejection(event)
    end
  end
end