# frozen_string_literal: true

module Local
  class RequestProfiling
    IGNORED_SQL_NAMES = %w[SCHEMA CACHE].freeze
    IGNORED_SQL = /\A(?:BEGIN|COMMIT|ROLLBACK|SAVEPOINT|RELEASE)/i

    def initialize(enabled: false)
      @enabled = enabled
      @measurements = []
    end

    def measure(name)
      return yield unless @enabled

      query_count = 0
      subscriber = lambda do |_event_name, _start, _finish, _id, payload|
        sql = payload[:sql].to_s
        next if IGNORED_SQL_NAMES.include?(payload[:name])
        next if sql.match?(IGNORED_SQL)

        query_count += 1
      end

      started_at = Process.clock_gettime(Process::CLOCK_MONOTONIC)
      result = nil
      ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') do
        result = yield
      end
      duration = (Process.clock_gettime(Process::CLOCK_MONOTONIC) - started_at) * 1000.0
      @measurements << { name:, duration: duration.round(1), query_count: }
      result
    end

    def apply_to(response, label:)
      return unless @enabled

      response.set_header('Server-Timing', @measurements.map { |m| "#{m[:name]};dur=#{m[:duration]}" }.join(', '))
      response.set_header(
        'X-Turniere-Profile',
        "#{label}: #{@measurements.map { |m| "#{m[:name]}=#{m[:duration]}ms/#{m[:query_count]}sql" }.join(', ')}"
      )
    end
  end
end