-- imports
local gT = require("goTo")
local ul = require("unload")
local dR = require("doRefuel")

-- definition
local function returnSupplies()
    local x, y, z, xd, zd = xPos, depth, zPos, xDir, zDir    
    print("Returning to surface...")
    gT.goTo(0, 0, 0, 0, -1)

    local fuelNeeded = 2 * (x + y + z) + 1
    if not dR.doRefuel(fuelNeeded) then
        ul.unload(true)
        print("Waiting for fuel")
        while not dR.doRefuel(fuelNeeded) do
            os.pullEvent("turtle_inventory")
        end
    else
        ul.unload(true)
    end

    print("Resuming mining...")
    gT.goTo(x, y, z, xd, zd)
end

-- export
return  { returnSupplies = returnSupplies }