require 'json'
require 'csv'
require 'fileutils'

class SlackParser
  attr_accessor :channels, :users

  OUTPUT_USERS_DIR = 'output/users'
  OUTPUT_TRAFFIC_DIR = 'output/traffic'

  def self.run(*args)
    new(*args).run
  end

  def initialize
    @channels = Dir['data/*'].select { |f| File.directory?(f) }
    @users = JSON.parse(File.read("data/users.json"))
  end

  def run
    channels.each do |channel_path|
      days = Dir["#{channel_path}/*.json"]
      channel = File.basename(channel_path)

      FileUtils.mkdir_p(OUTPUT_USERS_DIR)
      FileUtils.mkdir_p(OUTPUT_TRAFFIC_DIR)

      user_stats = days.reduce({}) { |channel_stats, day|
        messages = JSON.parse(File.read(day))
        real_messages = messages.reject { |m| m.key?('subtype') }

        stats = real_messages.reduce({}) { |daily_stats, message|
          user = message['user']
          daily_stats.merge(user => 1) { |key, old, new| old + new }
        }

        channel_stats.merge(stats) { |key, old, new| old + new }
      }

      user_stats = ids_to_names(user_stats)
      sorted_stats = user_stats.to_a.sort { |a, b| a[1] <=> b[1] }.reverse

      CSV.open("#{OUTPUT_USERS_DIR}/#{channel}.csv", 'wb', headers: %w(username messages), write_headers: true) do |csv|
        sorted_stats.each do |row|
          csv << row
        end
      end

      CSV.open("#{OUTPUT_TRAFFIC_DIR}/#{channel}.csv", 'wb', headers: %w(date messages users_active), write_headers: true) do |csv|
        messages_per_day = days.each do |day|

          messages = JSON.parse(File.read(day))
          real_messages = messages.reject { |m| m.key?('subtype') }

          csv << [
            File.basename(day, '.*'),
            real_messages.count,
            real_messages.map { |m| m['user'] }.uniq.count,
          ]
        end
      end
    end
  end

  private

  def ids_to_names(by_id)
    by_name = {}

    users.each do |user|
      by_name[user['name']] = by_id[user['id']] if by_id.key?(user['id'])
    end

    by_name
  end
end

SlackParser.run