# frozen_string_literal: true

class LogAnalyzer

  class LineParser

    # log_format log_discourse '[$time_local] "$http_host" $remote_addr "$request" "$http_user_agent" "$sent_http_x_discourse_route" $status $bytes_sent "$http_referer" $upstream_response_time $request_time "$sent_http_x_discourse_username"';

    attr_accessor :time, :ip_address, :url, :route, :user_agent, :rails_duration, :total_duration,
                  :username, :status, :bytes_sent, :referer

    PATTERN = /\[(.*)\](?: ".*")? (\S+) \"(.*)\" \"(.*)\" \"(.*)\" ([0-9]+) ([0-9]+) \"(.*)\" ([0-9.]+) ([0-9.]+) "(.*)"/

    TIME_FORMAT = "%d/%b/%Y:%H:%M:%S %Z"

    def self.parse(line)

      result = new
      _, result.time, result.ip_address, result.url, result.user_agent,
        result.route, result.status, result.bytes_sent, result.referer,
        result.rails_duration, result.total_duration, result.username = line.match(PATTERN).to_a

      result.rails_duration = result.rails_duration.to_f
      result.total_duration = result.total_duration.to_f

      verb = result.url[0..3] if result.url
      if verb && verb == "POST"
        result.route += " (POST)"
      end

      if verb && verb == "PUT"
        result.route += " (PUT)"
      end

      result.url = self.sanitize_url(result.url) if result.url

      result
    end

    def is_mobile?
      user_agent =~ /Mobile|Android|webOS/ && !(user_agent =~ /iPad|Nexus (7|10)/)
    end

    def parsed_time
      DateTime.strptime(time, TIME_FORMAT) if time
    end

    private

    def self.sanitize_url(url)
      url.gsub(/api_key=([\w.\-]+)/, 'api_key=[FILTERED]')
    end
  end

  attr_reader :total_requests, :message_bus_requests, :filenames,
              :ip_to_rails_duration, :username_to_rails_duration,
              :route_to_rails_duration, :url_to_rails_duration,
              :status_404_to_count, :from_time, :to_time

  def self.analyze(filenames, args)
    new(filenames, args).analyze
  end

  class Aggeregator

    attr_accessor :aggregate_type

    def initialize
      @data = {}
      @aggregate_type = :duration
    end

    def add(id, duration, aggregate = nil)
      ary = (@data[id] ||= [0, 0])
      ary[0] += duration
      ary[1] += 1
      unless aggregate.nil?
        ary[2] ||= Hash.new(0)
        if @aggregate_type == :duration
          ary[2][aggregate] += duration
        elsif @aggregate_type == :count
          ary[2][aggregate] += 1
        end
      end
    end

    def top(n, aggregator_formatter = nil)
      @data.sort { |a, b| b[1][0] <=> a[1][0] }.first(n).map do |metric, ary|
        metric = metric.to_s
        metric = "[empty]" if metric.length == 0
        result = [metric, ary[0], ary[1]]
        # handle aggregate
        if ary[2]
          if aggregator_formatter
            result.push aggregator_formatter.call(ary[2], ary[0], ary[1])
          else
            result.push ary[2].sort { |a, b| b[1] <=> a[1] }.first(5).map { |k, v|
            v = "%.2f" % v if Float === v
            "#{k}(#{v})"}.join(" ")
          end
        end

        result
      end
    end
  end

  def initialize(filenames, args = {})
    @filenames = filenames
    @ip_to_rails_duration = Aggeregator.new
    @username_to_rails_duration = Aggeregator.new

    @route_to_rails_duration = Aggeregator.new
    @route_to_rails_duration.aggregate_type = :count

    @url_to_rails_duration = Aggeregator.new
    @status_404_to_count = Aggeregator.new

    @total_requests = 0
    @message_bus_requests = 0
    @limit = args[:limit]
  end

  def analyze
    now = DateTime.now

    @filenames.each do |filename|
      File.open(filename).each_line do |line|
        @total_requests += 1
        parsed = LineParser.parse(line)

        next unless parsed.time
        next if @limit && ((now - parsed.parsed_time) * 24 * 60).to_i > @limit

        @from_time ||= parsed.time
        @to_time = parsed.time

        if parsed.url =~ /(POST|GET) \/message-bus/
          @message_bus_requests += 1
          next
        end

        @ip_to_rails_duration.add(parsed.ip_address, parsed.rails_duration)

        username = parsed.username == "-" ? "[Anonymous]" : parsed.username
        @username_to_rails_duration.add(username, parsed.rails_duration, parsed.route)

        @route_to_rails_duration.add(parsed.route, parsed.rails_duration, parsed.is_mobile? ? "mobile" : "desktop")

        @url_to_rails_duration.add(parsed.url, parsed.rails_duration)

        @status_404_to_count.add(parsed.url, 1) if parsed.status == "404"
      end
    end
    self
  end

end