btrc-hub/backend/spec/requests/list_limits_spec.rb

require 'rails_helper'

RSpec.describe 'List API limits', type: :request do
  shared_examples 'a capped list' do |default_count, minimum_count, paginated|
    def response_rows
      body = json
      body.is_a?(Array) ? body : body.fetch(collection_key)
    end

    it 'caps oversized limits at 100 and preserves the 100 boundary' do
      get path, params: { locale: 'ja', limit: 100 }
      expect(response).to have_http_status(:ok)
      expect(response_rows.size).to eq(100)
      boundary_rows = response_rows

      [101, 10_000].each do |limit|
        get path, params: { locale: 'ja', limit: }
        expect(response).to have_http_status(:ok)
        expect(response_rows).to eq(boundary_rows)
      end
    end

    it 'preserves the default, nonpositive and small positive limits' do
      get path, params: { locale: 'ja' }
      expect(response).to have_http_status(:ok)
      expect(response_rows.size).to eq(default_count)

      [0, -1].each do |limit|
        get path, params: { locale: 'ja', limit: }
        expect(response).to have_http_status(:ok)
        expect(response_rows.size).to eq(minimum_count)
      end

      get path, params: { locale: 'ja', limit: 2 }
      expect(response).to have_http_status(:ok)
      expect(response_rows.size).to eq(2)
    end

    if paginated
      it 'uses the capped limit for page offsets and preserves total count' do
        get path, params: { locale: 'ja', limit: 100 }
        first_page = response_rows
        expect(response).to have_http_status(:ok)
        expect(json.fetch('count')).to eq(101)

        get path, params: { locale: 'ja', limit: 100, page: 2 }
        expect(response).to have_http_status(:ok)
        expect(response_rows.size).to eq(1)
        second_page = response_rows
        expect(first_page & second_page).to be_empty

        get path, params: { locale: 'ja', limit: 101, page: 2 }
        expect(response).to have_http_status(:ok)
        expect(response_rows).to eq(second_page)
        expect(json.fetch('count')).to eq(101)
      end
    end
  end

  context 'posts' do
    let(:path) { '/posts' }
    let(:collection_key) { 'posts' }
    before { create_list(:post, 101) }

    include_examples 'a capped list', 20, 1, true
  end

  context 'tags' do
    let(:path) { '/tags' }
    let(:collection_key) { 'tags' }
    before { create_list(:tag, 101) }

    include_examples 'a capped list', 20, 1, true
  end

  context 'nico tags' do
    let(:path) { '/tags/nico' }
    let(:collection_key) { 'tags' }
    before { create_list(:external_tag, 101) }

    include_examples 'a capped list', 20, 1, true
  end

  context 'materials' do
    let(:path) { '/materials' }
    let(:collection_key) { 'materials' }
    before do
      101.times { |index| Material.create!(url: "https://example.com/material-#{ index }") }
    end

    include_examples 'a capped list', 20, 1, true
  end

  context 'post versions' do
    let(:path) { '/posts/versions' }
    let(:collection_key) { 'versions' }
    let(:post) { create(:post) }
    before do
      101.times do |index|
        PostVersion.create!(post:, version_no: index + 1, event_type: 'update',
                            url: post.url, tags: '', tags_json: [], parent_post_ids: '')
      end
    end

    include_examples 'a capped list', 20, 1, true
  end

  context 'tag versions' do
    let(:path) { '/tags/versions' }
    let(:collection_key) { 'versions' }
    let(:tag) { create(:tag) }
    before do
      101.times do |index|
        TagVersion.create!(tag:, version_no: index + 1, event_type: 'update',
                           name: 'limit tag', category: 'general', aliases: '',
                           parent_tag_ids: '', names: {
                               ja: { name: 'limit tag', script_code: 'Jpan',
                                     auto_generated: false, aliases: [] } })
      end
    end

    include_examples 'a capped list', 20, 1, true
  end

  context 'material versions' do
    let(:path) { '/materials/versions' }
    let(:collection_key) { 'versions' }
    let(:material) { Material.create!(url: 'https://example.com/material') }
    before do
      101.times do |index|
        MaterialVersion.create!(material:, version_no: index + 1,
                                event_type: 'update', url: material.url)
      end
    end

    include_examples 'a capped list', 20, 1, true
  end

  context 'theatre lists' do
    let(:theatre) { create(:theatre) }
    let(:post) { create(:post) }

    context 'comments' do
      let(:path) { "/theatres/#{ theatre.id }/comments" }
      before { create_list(:theatre_comment, 101, theatre:, user: theatre.created_by_user) }

      include_examples 'a capped list', 20, 20, false
    end

    context 'programmes' do
      let(:path) { "/theatres/#{ theatre.id }/programmes" }
      before do
        101.times do |index|
          TheatreProgramme.create!(theatre:, post:, position: index + 1)
        end
      end

      include_examples 'a capped list', 100, 100, false
    end

    context 'skip events' do
      let(:path) { "/theatres/#{ theatre.id }/skip_events" }
      before do
        101.times do |index|
          TheatreSkipEvent.create!(theatre:, post:,
                                   skipped_by_user: theatre.created_by_user,
                                   created_at: Time.utc(2026, 1, 1) + index.seconds)
        end
      end

      include_examples 'a capped list', 50, 50, false
    end
  end
end