include("utils.jl")

function parse_input(filename)
    map(x->parse.(Int, x), split.(non_empty_lines(filename), ""))
end

function flash(octopuses)
    sum(map(CartesianIndices((2:11, 2:11))) do coord
        if octopuses[coord] > 9
            octopuses[coord] = -8
            for neighbor in CartesianIndices((coord[1]-1:coord[1]+1, coord[2]-1:coord[2]+1))
                octopuses[neighbor] += 1
            end
            1
        else
            0
        end
    end)
end

function solution11_1()
    octopuses = transpose(reshape(reduce(vcat, [[fill(-2000000, 12)]; map(x -> [-2000000; x; -2000000], parse_input("11.data")); [fill(-2000000, 12)]]),(12,12)))
    sum(map(1:100) do _
        map!(x->x+1, octopuses, octopuses)
        flashes = sum(collect(Iterators.takewhile(>(0), (flash(octopuses) for _ in 1:100))))
        clamp!(octopuses, 0, 9)
        flashes
    end)
end

function solution11_2()
    octopuses = transpose(reshape(reduce(vcat, [[fill(-2000000, 12)]; map(x -> [-2000000; x; -2000000], parse_input("11_ex.data")); [fill(-2000000, 12)]]),(12,12)))
    for i in 1:1000
        map!(x->x+1, octopuses, octopuses)
        flashes = sum(collect(Iterators.takewhile(>(0), (flash(octopuses) for _ in 1:100))))
        if flashes == 100
            return i
        end
        clamp!(octopuses, 0, 9)
    end
end

solution11_2()