local game_state = {
  size = 10,
  field = {
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 1, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
    {0, 1, 1, 1, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  },
  time = 0
}

function game_state:next()
  local neighbours = function(i, j)
    local left = (i > 1) and (i - 1) or self.size
    local right = (i < self.size) and i + 1 or 1
    local up = (j > 1) and j - 1 or self.size
    local down = (j < self.size) and j + 1 or 1
    local field = self.field
    return {
      field[left][up], field[i][up], field[right][up],
      field[left][j], field[right][j],
      field[left][down], field[i][down], field[right][down]
    }
  end

  local sum = function(arr)
    local s = 0
    for i, v in ipairs(arr) do
      s = s + v
    end
    return s
  end

  local temp = {}
  for i = 1, self.size do
    temp[i] = {}
    for j = 1, self.size do
      local n = sum(neighbours(i, j))
      if self.field[i][j] == 1 then
        temp[i][j] = (n < 2 or 3 < n) and 0 or 1
      else
        temp[i][j] = (n == 3) and 1 or 0
      end
    end
  end
  self.field = temp
  return temp
end

local g = love.graphics
local dimension = 800
local update_interval = 0.15

function love.load()
  love.window.setMode(dimension, dimension)
end

function love.draw()
  local cell_size = dimension / game_state.size
  for i = 1, game_state.size do
    for j = 1, game_state.size do
      if game_state.field[i][j] == 1 then
        g.rectangle("fill",
                    cell_size * (j - 1), cell_size * (i - 1),
                    cell_size, cell_size)
      end
    end
  end
end

function love.update(dt)
  game_state.time = game_state.time + dt
  if game_state.time > update_interval then
    game_state:next()
    game_state.time = 0
  end
end