signal = {}
file = io.open(arg[1])
for num in file:read("a"):gmatch("%d") do
    table.insert(signal, tonumber(num))
end
file:close()

function calc(signal, num)
    local fin = #signal
    local cur = num
    local val = 0
    while cur <= fin do
        for _, x in ipairs({1, 0, -1, 0}) do
            if x == 0 then
                cur = cur + num
            else
                local cur_val = 0
                for i = 1, num do
                    cur_val = cur_val + signal[cur]
                    cur = cur + 1
                    if cur > fin then
                        break
                    end
                end
                val = val + cur_val * x
            end
            if cur > fin then
                break
            end
        end
    end

    return math.abs(val) % 10
end

function calc_dumb_p2(signal, offset)
    local val = 0
    for i = #signal, offset, -1 do
        val = (val + signal[i]) % 10
        signal[i] = val
    end
end

function signal_tostring(signal, start, len)
    local str = ""
    for i = start, len do
        str = str .. string.format("%d", signal[i])
    end
    return str
end

offset = signal[1] * (10 ^ 6) + signal[2] * (10 ^ 5) + signal[3] * (10 ^ 4) + signal[4] * (10 ^ 3) + signal[5] * (10 ^ 2) + signal[6] * (10 ^ 1) + signal[7]
signal_p2 = {}
for i = 1, 10000 do
    for i = 1, #signal do
        table.insert(signal_p2, signal[i])
    end
end
print(offset)
offset = offset % #signal_p2
print(offset)

for i = 1, 100 do
    for i = 1, #signal do
        signal[i] = calc(signal, i)
    end
end

print("Part 1:", signal_tostring(signal, 1, 8))

for i = 1, 100 do
    calc_dumb_p2(signal_p2, offset)
end

print("Part 2:", signal_tostring(signal_p2, offset + 1, offset + 8))