#!/usr/bin/lua
--Advent of Code - 2025 - Day 4
--
--https://adventofcode.com/2025/day/4

-- Problem, find space for forklift to move
-- Tasks
-- [ ] Load Paper roll in array
-- [ ] Walk through Array finding spots
--
--
--local input_file = "test"
local input_file = "Day4/full"
local warehouse = {}

local row = 0
local col = 0

for line in io.lines(input_file) do
	row = row + 1
	warehouse[row] = {}
	col = 0
	for location in line:gmatch(".") do
		col = col + 1
		warehouse[row][col] = location
	end
end

function space_for_forklift(warehouse, x, y)
	-- I'm making the assuption here that all rows have the same columns
	-- normally I would say write a selfcheck to confirm input is sound
	local rows = table.getn(warehouse)
	local columns = table.getn(warehouse[1])
	local spaces = 0

	if warehouse[x][y] ~= "@" then
		-- No paper roll, so skip
		--print("warehouse check " .. x .. "," .. y .. " no paper roll")
		return false
	end

	local freespace = 0
	local rolls = 0
	for rowskim = -1, 1 do
		if warehouse[x + rowskim] == nil then
			freespace = freespace + 3
		else
			for colskim = -1, 1 do
				local w = warehouse[x + rowskim][y + colskim]
				--print("checking " .. (x + rowskim) .. "," .. (y + colskim) .. "=" .. w)
				if not (rowskim == 0 and colskim == 0) then
					if w == "@" or w == "X" then
						rolls = rolls + 1
					else
						freespace = freespace + 1
					end
				end
			end
		end
	end
	if rolls < 4 then
		--print("warehouse check " .. x .. "," .. y .. " found space")
		warehouse[x][y] = "X"
		return true
	else
		--print("warehouse check " .. x .. "," .. y .. " no space")
		return false
	end
end

function remove_rolls(warehouse)
	local maxrows = table.getn(warehouse)
	local maxcolumns = table.getn(warehouse[1])
	for r = 1, maxrows do
		for c = 1, maxcolumns do
			if warehouse[r][c] == "X" then
				warehouse[r][c] = "."
			end
		end
	end
end

-- print(space_for_forklift(warehouse, 1, 1))
-- print(space_for_forklift(warehouse, 1, 3))
-- print(space_for_forklift(warehouse, 2, 1))
-- print(space_for_forklift(warehouse, 3, 7))
function countrolls(warehouse)
	local maxrows = table.getn(warehouse)
	local maxcolumns = table.getn(warehouse[1])
	local forkliftaccess = 0
	for r = 1, maxrows do
		for c = 1, maxcolumns do
			if space_for_forklift(warehouse, r, c) then
				forkliftaccess = forkliftaccess + 1
			end
		end
	end
	return forkliftaccess
end

totalrolls = 0
for I = 1, 100 do
	cr = countrolls(warehouse)
	totalrolls = totalrolls + cr
	print("Loop " .. I .. ": " .. cr .. " Rolls removed")
	remove_rolls(warehouse)
end
print("Total rolls removed " .. totalrolls)