require "./common.cr"

lines = File.read("day7_input").split("\n")
lines.pop

REGEX = /Step (.+) must be finished before step (.+) can begin./

all_children = {} of String => Set(String)
all = Set(String).new
finished = Set(String).new
finished_array = Array(String).new

lines.map(&.match(REGEX)).each do |match|
  match = match.not_nil!
  child = match[1]
  parent = match[2]

  all << child
  all << parent
  parent_set = all_children[parent]? || Set(String).new
  parent_set << child
  
  all_children[parent] = parent_set
end

available_at = {} of String => Int32

class String
  def cost
    return (self[0].bytes[0] - 'A'.bytes[0]).to_i32 + 1
  end
end

def get_available(all, finished, children)
  available = all.select do |it|
    next false if finished.includes? it
    next true unless set = children[it]?
    next true if set.size == 0
  end
end

children = all_children.clone
while finished.size != all.size
  available = get_available(all, finished, children)
  available.sort!

  first = available.first
  finished << first
  finished_array << first

  children.values.each do |value|
    value.delete first
  end
end
puts finished_array.join ""

finished.clear
finished_array.clear
children = all_children.clone
workers = [0, 0, 0, 0, 0]
current_time = 0
finished_at = {} of String => Int32

while finished.size < all.size
  workers.each_with_index do |worker, index|
    next if worker > current_time

    current_finished = finished_at.select { |k, v| v <= current_time }.map(&.[0]).to_set
    available = all.select do |it|
      next false if finished.includes? it
      next true unless nodes = children[it]?
      (nodes - current_finished).size == 0
    end
    
    available = available.sort!
    next if available.empty?

    first = available.first
    finished_at[first] = current_time + first.cost + 60
    workers[index] = current_time + first.cost + 60
    finished_array << first
    finished << first
  end

  current_time += 1
end
puts finished_at.values.max