quarry

tArgs = { ... }
if #tArgs < 2 then
 print("Usage: quarry <width> <length>")
 return
end

xParam = tonumber(tArgs[1])
zParam = tonumber(tArgs[2])

homeX = 0
homeY = 0
homeZ = 0

x = 0
y = 0
z = 0
facing = 0

lastX = 0
lastY = 0
lastZ = 0
lastFacing = 0

function checkFuel()
 while turtle.getFuelLevel() < 10 do
  turtle.select(16)
  turtle.refuel(1)
  turtle.select(1)
 end
 if turtle.getItemCount(15) < 5 then
  emptyInv()
 end
end

function forward()
 while turtle.forward() == false do
  checkFuel()
  turtle.dig()
  turtle.attack()
 end
 if facing == 0 then
  z = z + 1
 end
 if facing == 1 then
  x = x - 1
 end
 if facing == 2 then
  z = z - 1
 end
 if facing == 3 then
  x = x + 1
 end
end

function back()
 while turtle.forward() == false do
  checkFuel()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.dig()
  turtle.attack()
  turtle.turnLeft()
  turtle.turnLeft()
 end
 if facing == 0 then
  z = z - 1
 end
 if facing == 1 then
  x = x + 1
 end
 if facing == 2 then
  z = z + 1
 end
 if facing == 3 then
  x = x - 1
 end
end

function up()
 while turtle.up() == false do
  checkFuel()
  turtle.digUp()
  turtle.attackUp()
 end
 y = y + 1
end

function down()
 while turtle.down() == false do
  checkFuel()
  turtle.digDown()
  turtle.attackDown()
 end
 y = y - 1
end

function turnLeft()
 turtle.turnLeft()
 if facing == 0 then
  facing = 3
 else
  facing = facing - 1
 end
end

function turnRight()
 turtle.turnRight()
 if facing == 3 then
  facing = 0
 else
  facing = facing + 1
 end
end

function checkFull()
 if turtle.getItemCount(15) > 0 then
  emptyInv()
  return
 end
end

function emptyInv()
 lastX = x
 lastY = y
 lastZ = z
 lastFacing = facing
 while homeY > y do
  up()
 end
 while homeY < y do
  down()
 end
 while homeX > x do
  while facing ~= 3 do
   turnLeft()
  end
  forward()
 end
 while homeX < x do
  while facing ~= 1 do
   turnLeft()
  end
  forward()
 end
 while homeZ > z do
  while facing ~= 0 do
   turnLeft()
  end
  forward()
 end
 while homeZ < z do
  while facing ~= 2 do
   turnLeft()
  end
  forward()
 end
 while facing ~= 2 do
  turnLeft()
 end
 for i = 1,15 do
  turtle.select(i)
  turtle.drop()
 end
 turtle.select(16)
 if turtle.getItemCount(16) < 5 then
  turnRight()
  turtle.refuel()
  turtle.suck()
 end
 turtle.select(1)
 while lastX > x do
  while facing ~= 3 do
   turnLeft()
  end
  forward()
 end
 while lastX < x do
  while facing ~= 1 do
   turnLeft()
  end
  forward()
 end
 while lastZ > z do
  while facing ~= 0 do
   turnLeft()
  end
  forward()
 end
 while lastZ < z do
  while facing ~= 2 do
   turnLeft()
  end
  forward()
 end
 while lastY > y do
  up()
 end
 while lastY < y do
  down()
 end
 while facing ~= lastFacing do
  turnLeft()
 end
 return
end

function goHome()
 while homeY > y do
  up()
 end
 while homeY < y do
  down()
 end
 while homeX > x do
  while facing ~= 3 do
   turnLeft()
  end
  forward()
 end
 while homeX < x do
  while facing ~= 1 do
   turnLeft()
  end
  forward()
 end
 while homeZ > z do
  while facing ~= 0 do
   turnLeft()
  end
  forward()
 end
 while homeZ < z do
  while facing ~= 2 do
   turnLeft()
  end
  forward()
 end
 while facing ~= 2 do
  turnLeft()
 end
 for i = 1,15 do
  turtle.select(i)
  turtle.drop()
 end
 turnRight()
 turnRight()
end

function checkBedRock()
 if turtle.detectDown() == true then
  goHome()
  return true
 end
 return false
end

uselessVar = 0

function dig()
  turtle.select(1)
  while true do
     for q = 1,xParam do
      for p = 1,zParam-1 do
       forward()
       checkFull()
      end
      if q ~= xParam then
       if facing == 0 then
        turnRight()
        forward()
        turnRight()
        checkFull()
       else
        turnLeft()
        forward()
        turnLeft()
        checkFull()
       end
      end
     end
     while homeX > x do
      while facing ~= 3 do
       turnLeft()
      end
      forward()
     end
     while homeX < x do
      while facing ~= 1 do
       turnLeft()
      end
      forward()
     end
     while homeZ > z do
      while facing ~= 0 do
       turnLeft()
      end
      forward()
     end
     while homeZ < z do
      while facing ~= 2 do
       turnLeft()
      end
      forward()
     end
     while facing ~= 0 do
      turnRight()
     end
     turtle.digDown()
     if checkBedRock() == true then
      break
     end
     down()
  end
end
dig()