require "./common.cr"

lines = File.read("day4_input").split("\n")
lines.pop
lines.sort!

REGEX = /\[(\d+)-(\d+)-(\d+) (\d+):(\d+)\].+/
GUARD_REGEX = /.+#(\d+).+/

active = 0
last_time = {0, 1, 0, 0, 0}
minutes = {} of Int32 => Array(Int32)

lines.each do |line|
  match = line.match(REGEX).not_nil!
  year = match[1].to_i32
  month = match[2].to_i32
  day = match[3].to_i32
  hour = match[4].to_i32
  minute = match[5].to_i32
  new_time = {year, month, day, hour, minute}

  if line.includes? "Guard"
    active = line.match(GUARD_REGEX).not_nil![1].to_i32
  elsif line.includes? "wakes"
    old_year, old_month, old_day, old_hour, old_minute = last_time
    difference = (day - old_day) * 24 * 60 +
      (hour - old_hour) * 60 +
      (minute - old_minute)

    array = minutes[active]? || Array.new(60, 0)
    60.times do |m|
      array[m] += difference / 60
    end
    (difference % 60).times do |m|
      actual_minute = (old_minute + m) % 60
      array[actual_minute] += 1
    end
    minutes[active] = array
  end
  last_time = new_time
end

guard_num, guard_minutes = minutes.max_by &.[1].sum
puts "Guard num: #{guard_num}"
puts "Guard minute: #{(guard_minutes.index guard_minutes.max).not_nil!}"
puts "Answer num: #{guard_num * (guard_minutes.index guard_minutes.max).not_nil!}"

guard_num, guard_minutes = minutes.max_by &.[1].max
puts "Guard num: #{guard_num}"
puts "Guard minute: #{(guard_minutes.index guard_minutes.max).not_nil!}"
puts "Answer num: #{guard_num * (guard_minutes.index guard_minutes.max).not_nil!}"