airstrike turtle computercraft

local passcode = "1234" --change this code please don't leave it at 1234
rednet.open("right")
local id = os.getComputerID()
local false_pincode_atempts = 0
function checkfuel()
    if turtle.getFuelLevel() < 20 then
        turtle.select(1)
        turtle.refuel()
    end
end
os.setComputerLabel("")
function recieve()
    orders = false

    while orders == false do

        local id, msg = rednet.receive("airstrike")
        local cords = textutils.unserialise(msg)
        if #cords == 5 then
            if passcode == cords[1] then
                tx = tonumber(cords[2])
                ty = tonumber(cords[3])
                tz = tonumber(cords[4])
                tnt = tonumber(cords[5])
                orders = true
                rednet.send(id, "turtle "..id.." on there way", "airstrike")
            else
                rednet.send(id, "acces denied", "airstrike")
                false_pincode_atempts = false_pincode_atempts + 1
                if false_pincode_atempts == 1 then
                    os.setComputerLabel("1 false pincode recieved")
                else
                    os.setComputerLabel(false_pincode_atempts.." false pincodes recieved")
                end

            end
        end
    end
    os.setComputerLabel("")
end
--here starts the code
local hx, hy, hz = gps.locate()
function bomb()
    redstone.setOutput("bottom", true)
    turtle.select(2)
    for i=1, tnt do
        turtle.placeDown()
        sleep(1)
    end
    turtle.select(1)
    redstone.setOutput("bottom", false)
end

function up()
    if hy > ty then
        for i=1,10 do
            checkfuel()
            while not turtle.up() do
                turtle.sigUp()

            end
        end
    else
        for i=1,((ty+20) - hy) do
            checkfuel()
            while not turtle.up() do
                turtle.digUp()

            end
        end
    end
end
function forward()
    checkfuel()
    while not turtle.forward() do
        turtle.dig()

    end
end
function down()
    checkfuel()
    while not turtle.detectDown() do
        turtle.down()
    end
end
function calcdir()
    local hx, hy, hz = gps.locate()
    dx = hx - tx
    dz = hz - tz
end
function go()

    if dx<=0 then
        turtle.turnRight()
        mx = math.abs(dx)
        for i=1,mx do
            forward()
        end
        if dz<=0 then
            turtle.turnRight()
            mz = math.abs(dz)
            for i=1,mz do
                forward()
            end
        elseif dz>0 then
            turtle.turnLeft()
            mz = math.abs(dz)
            for i=1,mz do
                forward()
            end
        end
    elseif dx>0 then
        turtle.turnLeft()
        mx = math.abs(dx)

        for i=1,mx do
            forward()
        end
        if dz>0 then
            turtle.turnRight()
            mz = math.abs(dz)
            for i=1,dz do
                forward()
            end
        elseif dz<=0 then
            turtle.turnLeft()
            mz = math.abs(dz)
            for i=1,mz do
                forward()
            end
        end

    end
end
function rtrn()
    turtle.turnLeft()
    turtle.turnLeft()
    for i=1,mz do
        forward()
    end
    if dz>0 then
        if dx<0 then
            turtle.turnRight()
        elseif dx>0 then
            turtle.turnLeft()
        end
    elseif dz<=0 then
        if dx>0 then
            turtle.turnRight()
        elseif dx<0 then
            turtle.turnLeft()
        end
    end

    for i=1,mx do
        forward()
    end
    if dx>0 then
        turtle.turnLeft()
    elseif dx<0 then
        turtle.turnRight()
    end
end

--script

while 1 do
    local hx, hy, hz = gps.locate()
    recieve()
    calcdir()


    up()
    go()
    bomb()

    rtrn()
    down()
end