# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::SQL::RecursiveCTE, feature_category: :shared do
  let(:cte) { described_class.new(:cte_name) }

  describe '#to_arel' do
    it 'generates an Arel relation for the CTE body' do
      rel1 = User.where(id: 1)
      rel2 = User.where(id: 2)

      cte << rel1
      cte << rel2

      sql = cte.to_arel.to_sql
      name = ApplicationRecord.connection.quote_table_name(:cte_name)

      sql1, sql2 = ApplicationRecord.connection.unprepared_statement do
        [rel1.except(:order).to_sql, rel2.except(:order).to_sql]
      end

      expect(sql).to eq("#{name} AS ((#{sql1})\nUNION\n(#{sql2}))")
    end
  end

  describe '#alias_to' do
    it 'returns an alias for the CTE' do
      table = Arel::Table.new(:kittens)

      source_name = ApplicationRecord.connection.quote_table_name(:cte_name)
      alias_name = ApplicationRecord.connection.quote_table_name(:kittens)

      expect(cte.alias_to(table).to_sql).to eq("#{source_name} AS #{alias_name}")
    end

    it 'replaces dots with an underscore' do
      table = Arel::Table.new('gitlab.kittens')

      source_name = ApplicationRecord.connection.quote_table_name(:cte_name)
      alias_name = ApplicationRecord.connection.quote_table_name(:gitlab_kittens)

      expect(cte.alias_to(table).to_sql).to eq("#{source_name} AS #{alias_name}")
    end
  end

  describe '#apply_to' do
    it 'applies a CTE to an ActiveRecord::Relation' do
      user = create(:user)
      cte = described_class.new(:cte_name)

      cte << User.where(id: user.id)

      relation = cte.apply_to(User.all)

      expect(relation.to_sql).to match(/WITH RECURSIVE.+cte_name/)
      expect(relation.to_a).to eq(User.where(id: user.id).to_a)
    end
  end

  it_behaves_like 'CTE with MATERIALIZED keyword examples' do
    # MATERIALIZED keyword is not needed for recursive queries
    let(:expected_query_block_with_materialized) { 'WITH RECURSIVE "some_cte" AS (' }
    let(:expected_query_block_without_materialized) { 'WITH RECURSIVE "some_cte" AS (' }

    let(:query) do
      recursive_cte = described_class.new(:some_cte)
      recursive_cte << User.active

      User.with.recursive(recursive_cte.to_arel).to_sql
    end
  end
end
