autoCraft TNT

function suck(count, iter)
    local result = false
    local err = ""
    if iter % 2 == 0 then
        -- Suck gunpowder
        result, err = turtle.suckUp(count)
    else
        -- Suck sand
        result, err = turtle.suckDown(count)
    end
    if turtle.getItemCount(turtle.getSelectedSlot() + (iter % 3)) ~= count then
        result = false
        err = "Not enough resources."
    end
    if (iter + 1) % 3 == 0 then
        turtle.select(turtle.getSelectedSlot() + 4)
    end
    if not result then error(err) end
end

function clearInventory()
    for i = 1, 16, 1
    do
        turtle.select(i)
        turtle.drop(turtle.getItemCount(turtle.getSelectedSlot()))
    end
    turtle.select(1)
    return true
end

function toboolean(str)
    return str == "true"
end

function errorPrinter(err)
    print("Error:", err)
end

function waitForInput()
    print("Press enter to continue...")
    io.read()
end

function setup()
    print("Clearing inventory...")
    clearInventory()

    if redstone.getInput("back") then
        print("Starting crafting...")
    else
        print("Waiting for redstone input...")
    end
end

function mainLoop(itemType, craftAmount, waitForAmount, doCrafting)
    for i = 0, 8, 1
    do
        callSuccess, err = pcall(suck, craftAmount, i)
        if not callSuccess then
            -- Failure
            errorPrinter(err)
            if waitForAmount then
                os.sleep(60)
            else
                waitForInput()
            end
            error()
        end
    end

    turtle.select(1)
    success = doCrafting and turtle.craft()
    success = not doCrafting and clearInventory()
    success = doCrafting and print("Crafted " .. craftAmount .. " " .. itemType)
    turtle.drop(craftAmount)
end

local args = {...}
local itemType = args[1]
local craftAmount = tonumber(args[2])
local waitForAmount = toboolean(args[3]) or true
local doCrafting = toboolean(args[4]) or true

local isCrafting = false

setup()

while true
do
    if redstone.getInput("back") then
        if not isCrafting then
            print("Starting crafting...")
            isCrafting = true
        end
        if not pcall(mainLoop, itemType, craftAmount, waitForAmount, doCrafting) then
            setup()
        end
    else
        isCrafting = false
        os.sleep(0.1)
    end
end