ruby-analysis/delfos

# frozen_string_literal: true

require "delfos/neo4j/query_execution/transactional"

module Delfos
  module Neo4j
    module QueryExecution
      module Batch
        class Execution
          attr_reader :size, :current_transaction_url, :commit_url, :expires, :query_count

          def initialize(size:, clock: Time)
            @size               = size
            @clock              = clock
            reset!
          end

          def execute!(query, params: {})
            check_for_expiry!

            perform_query(query, params)
            flush_if_required!
          end

          def flush!
            return unless query_count.positive?
            return unless @commit_url
            QueryExecution::Transactional.commit!(@commit_url)

            reset!
          end

          private

          def perform_query(query, params)
            transactional_query = QueryExecution::Transactional.new(query, params, url)
            @total_query_length += transactional_query.query_length
            transaction_url, @commit_url, @expires = transactional_query.perform
            @current_transaction_url ||= transaction_url # the transaction_url is only returned with the first request
            @query_count += 1
          end

          def url
            return @commit_url if @commit_url && batch_full? || expires_soon?

            current_transaction_url || new_transaction_url
          end

          def new_transaction_url
            Delfos.config.neo4j.uri_for("/db/data/transaction")
          end

          def flush_if_required!
            check_for_expiry!

            if batch_full? || expires_soon? || large_query?
              flush!
              return true
            end

            false
          end

          def check_for_expiry!
            return if @expires.nil? || (@clock.now <= @expires)

            raise QueryExecution::ExpiredTransaction.new(@commit_url, "")
          end

          def batch_full?
            query_count >= size
          end

          def expires_soon?
            @expires && (@clock.now + 10 > @expires)
          end

          def large_query?
            @total_query_length >= Delfos.max_query_size
          end

          def reset!
            @query_count             = 0
            @total_query_length      = 0
            @current_transaction_url = nil
            @commit_url              = nil
            @expires                 = nil
          end
        end
      end
    end
  end
end