if posx == nil then posx = 1 end
if posy == nil then posy = 0 end

if north == nil then north = 1 end
if east == nil then east = 2 end
if south == nil then south = 3 end
if west == nil then west = 4 end


if fieldx == nil then fieldx = 9 end
if fieldy == nil then fieldy = 9 end

if wait == nil then wait = 4200 end
if waitafter == nil then waitafter = true end



function refuel()
  if turtle.getFuelLevel() < 324 then
    turtle.select(15)
    turtle.refuel()
    turtle.select(1)
  end
end

if direction == nil then direction = 0 end

function turn(newdirection)
    if newdirection==direction then
        return true
    else
        while not (direction==newdirection)
        if newdirection > direction then
            turtle.turnLeft((newdirection - direction))
            direction = direction + 1
        else turtle.turnRight((newdirection - direction))
            direction = direction + 1
        end
    end
end

function coord()
print("Position: "..posx.." / "..posy)
end

function iposx()
posx = posx + 1
end

function iposy()
posy = posy + 1
end

function dposx()
posx = posx - 1
end

function dposy()
posy = posy - 1
end

function mine()
    print("doing stuff here")
    turtle.select(1)
    turtle.placeDown()
    turtle.digDown()

    for i=14,5,-1 do
      turtle.select(i)
      turtle.placeDown()
    end
    turtle.select(1)
end

function move(dx, dy)
--coord()
  if dy >= posy then
    moveDirY(posy, dy)
    moveDirX(posx, dx)
  else
    moveDirX(posx, dx)
    moveDirY(posy, dy)
  end
  coord()
end

function moveDirX(ax, dx)
    if ax==dx then return true end
    if ax == 0 then step(dx, 0) else
        delta = dx - ax
        return step(delta, 0)
    end
end

function moveDirY(ay, dy)
    if not (ay==dy) then
        if ay == 0 then step(dy, 1) else
            delta = dy - ay
            return step(delta, 1)
        end
    else
        return true
    end
end

function betrag(zahl1)
    if zahl1 < 0 then return zahl1 * -1
    else return zahl1
    end
end

function step(count, axis)
    refuel()
    if axis == 0 then
        if count < 0 then
            return moveLeft(betrag(count))
        else
            return moveRight(betrag(count))
        end
    else
        if count > 0 then
            return moveForward(betrag(count))
        else
            return moveBack(betrag(count))
        end
    end

end

function problem()
    if turtle.getFuelLevel() < (fieldx*fieldy) and turtle.getItemCount(16) == 0 then
        print("not enough fuel")
        return true
    end
    if turtle.detect() then
        print("Uups!")
        return false
    end
    return false
end

function detect()
    if turtle.detect() then
        return true
    else
        return false
end

function moveRight(ci)
    if problem() then return false end

    refuel()
    turtle.turnRight(1)
        for i=1, ci do
            print("Moving right. New: "..(posx+1).." / "..posy)
            if not turtle.detect() then
                turtle.forward()
                iposx()
            else print("Resetting X-Axis to "..(fieldx+1))
                 posx=fieldx+1
            turn180()
            return false
            end
        end
    turtle.turnLeft(1)
end

function moveLeft(ci)
    if problem() then return false end

    refuel()
    turtle.turnLeft(1)
        for i=1, ci do
            print("Moving left. New: "..(posx-1).." / "..posy)
            if not turtle.detect() then
                turtle.forward()
                dposx()
            else print("Resetting X-Axis to 0")
                 posx=0
            turn180()
            return false
            end
        end
    turtle.turnRight(1)
end

function moveForward(ci)
    if problem() then return false end

    refuel()
    for i=1, ci do
        print("Moving forward. New: "..posx.." / "..(posy+1))
        if not turtle.detect() then
            turtle.forward()
            iposy()
        else print("Resetting Y-Axis to "..(fieldy+1))
             posy=(fieldy+1)
            turn180()
            return false
        end
    end
end

function moveBack(ci)
    if problem() then return false end

    refuel()
    turn180()
    for i=1, ci do
        print("Moving back. New: "..posx.." / "..(posy-1))
        if not turtle.detect() then
            turtle.forward()
            dposy()
        else print("Resetting Y-Axis to 0 and stopping.")
             posy=0
            turn180()
            return false
        end
    end
    turn180()
    return true
end

function turn180()
    turtle.turnRight()
    turtle.turnRight()
end

function moveup(uct)
    for i=1, uct do
      turtle.up(1)
    end
end

function movedown(dct)
    for i=1, dct do
      turtle.down(1)
    end
end

function homing()
    print("Assuming crash. Homing...")
    moveLeft((fieldx+1))

    if detect() then posx=0
    else moveLeft(1) end
    moveBack((fieldy+1))

    if detect() then posx=0
    else moveLeft(1) end
end

function loop1()
print("Initializing Harvester GPS alpha 0.905")
while turtle.getItemCount(15) >= 1 do
for f=1, 8 do

  for i=1, 9 do
    for j=1, 9 do
      if crashcount > 4 then homing() end
      if not ((i==5) and (j==5)) then
        move(i,j)
        mine()

      else
        move(i,j)
      end
    end
    refuel()
  end
  move(1,0)
  movedown(4)
end
return true
end

while true do

if not waitafter then
    print("Sleep before farming...")
else
    print("\\")
    print("Getting shit done.")
end


if not waitafter then
    sleep(wait)
end

while(loop1()) end

homing()

end

if waitafter then sleep(wait) print("Sleeping after...") end