#!/bin/env ruby
require 'pry'
def convert (seats)
    seats.map! do |row|
        row.map! do |seat|
            case seat
            when 0 then 'L'
            when 1 then '#'
            when nil then '.'
            end
        end
        row.reduce(:+)
    end
end

def fill_seats (seats)
    output = Array.new(seats.length, Array.new(seats[0].length, nil))
    output.map!.with_index do |row, i|
        row.map.with_index do |seat, j|
            next if seats[i][j] == nil
            i == 0 ? row_min = 0 : row_min = i - 1
            i == seats.length - 1 ? row_max = -1 : row_max = i + 1
            j == 0 ? col_min = 0 : col_min = j - 1
            j == seats[0].length - 1 ? col_max = -1 : col_max = j + 1

            row_range = (row_min..row_max)
            col_range = (col_min..col_max)
            adjecents = seats[row_range].map {|line| line[col_range]}.flatten.compact.sum - seats[i][j]
            combo = {:occupied? => seats[i][j], :adjecents => adjecents}
            case
            when combo[:occupied?] == 0 && combo[:adjecents] == 0 then 1
            when combo[:occupied?] == 0 && combo[:adjecents] != 0 then 0
            when combo[:occupied?] == 1 && combo[:adjecents] < 4 then 1
            when combo[:occupied?] == 1 && combo[:adjecents] >= 4 then 0
            end
        end
    end
    return output
end


seats = File.readlines('./input').map(&:strip)
    .map! {|line| line.split('') }
    .map! {|line| line.map { |char| char == 'L' ? 0 : nil }}

steps = []
steps[0] = seats
until steps[-1] == steps[-2] do
    steps.push(fill_seats(steps[-1]))
end
p steps[-1].map(&:compact).flatten.sum