# frozen_string_literal: true

class QueryCounter
  QUERY_TYPES = [:delete, :insert, :select, :update].freeze

  attr_reader :queries

  def initialize
    @queries = {}
    @subscriber = ActiveSupport::Notifications.
      subscribe("sql.active_record") do |_name, _started, _finished, _unique_id, payload|
      type = get_type(payload[:sql])
      next if QUERY_TYPES.exclude?(type) || pg_query?(payload[:sql])

      table = get_table(payload[:sql])
      @queries[type] ||= {}
      @queries[type][table] ||= 0
      @queries[type][table] += 1
    end
  end

  def stop
    ActiveSupport::Notifications.unsubscribe("sql.active_record")
  end

  private

  def get_table(sql)
    sql_parts = sql.split(" ")
    case get_type(sql)
    when :insert
      sql_parts[3]
    when :update
      sql_parts[1]
    else
      table_index = sql_parts.index("FROM")
      sql_parts[table_index + 1]
    end.gsub(/(\\|")/, "").to_sym
  end

  def get_type(sql)
    sql.split(" ")[0].downcase.to_sym
  end

  def pg_query?(sql)
    sql.include?("SELECT a.attname") || sql.include?("pg_attribute")
  end
end