- ********************************************************************************** --
-- **                                                                                                                                                     ** --
-- **   Minecraft Mining Turtle Ore Quarry v0.4 by AustinKK                                             ** --
-- **   ---------------------------------------------------                                             ** --
-- **                                                                                                                                                     ** --
-- **   For instructions on how to use:                                                                                 ** --
-- **                                                                                                                                                     ** --
-- **     http://www.youtube.com/watch?v=DS1H4OY0yyg                               ** --
-- **                                                                                                                                                     ** --
-- **                                                                                                                                                     ** --
-- **  Change Log:                                                                                                                               ** --
-- **   27th Dec 2012: [v0.2] Initial Draft Release                                                        ** --
-- **   29th Dec 2012: [v0.3] Minor Performance Improvements                                      ** --
-- **   30th Dec 2012: [v0.4] Further Performance Improvements                                  ** --
-- **                                                                                                                                                     ** --
-- ********************************************************************************** --

-- Enumeration to store the the different types of message that can be written
messageLevel = { DEBUG=0, INFO=1, WARNING=2, ERROR=3, FATAL=4 }

-- Enumeration to store names for the 6 directions
direction = { FORWARD=0, RIGHT=1, BACK=2, LEFT=3, UP=4, DOWN=5 }

local messageOutputLevel = messageLevel.INFO
local fuelLevelToRefuelAt = 5
local refuelItemsToUseWhenRefuelling = 63
local emergencyFuelToRetain = 0
local maximumGravelStackSupported = 25 -- The number of stacked gravel or sand blocks supported
local noiseBlocksCount
local bottomLayer = 5 -- The y co-ords of the layer immediately above bedrock
local returningToStart = false
local lookForChests = false -- Determines if chests should be located as part of the quarrying
local miningOffset -- The offset to the mining layer. This is set depending on whether chests are being looked for or not
local lastEmptySlot -- The last inventory slot that was empty when the program started (is either 15 if not looking for chests or 14 if we are)
local turtleId
local currentlySelectedSlot = 0 -- The slot that the last noise block was found in
local lastMoveNeededDig = true -- Determines whether the last move needed a dig first
local haveBeenAtZeroZeroOnLayer -- Determines whether the turtle has been at (0, 0) in this mining layer
local orientationAtZeroZero -- The turtle's orientation when it was at (0, 0)
local levelToReturnTo -- The level that the turtle should return to in order to head back to the start to unload

-- Variables to store the current location and orientation of the turtle. x is right, left, y is up, down and
-- z is forward, back with relation to the starting orientation. Y is the actual turtle level, x and z are
-- in relation to the starting point (i.e. the starting point is (0, 0))
local currX
local currY
local currZ
local currOrient

-- Command line parameters
local startHeight -- Represents the height (y co-ord) that the turtle started at
local quarryWidth -- Represents the length of the mines that the turtle will dig

-- ********************************************************************************** --
-- Writes an output message
-- ********************************************************************************** --
function writeMessage(message, msgLevel)
  if (msgLevel >= messageOutputLevel) then
        print(message)
        if (turtleId == nil) then
          rednet.broadcast(message)
        else
          -- Broadcast the message (prefixed with the turtle's id)
          rednet.broadcast("[".. turtleId.."] "..message)
        end
  end
end

-- ********************************************************************************** --
-- Ensures that the turtle has fuel
-- ********************************************************************************** --
function ensureFuel()

  -- Determine whether a refuel is required
  local fuelLevel = turtle.getFuelLevel()
  if (fuelLevel ~= "unlimited") then
        if (fuelLevel < fuelLevelToRefuelAt) then
          -- Need to refuel
          turtle.select(16)
          currentlySelectedSlot = 16
          local fuelItems = turtle.getItemCount(16)

          -- Do we need to impact the emergency fuel to continue? (always
          -- keep one fuel item in slot 16)
          if (fuelItems == 0) then
                writeMessage("Completely out of fuel!", messageLevel.FATAL)
          elseif (fuelItems == 1) then
                writeMessage("Out of Fuel!", messageLevel.ERROR)
                turtle.refuel()
          elseif (fuelItems <= (emergencyFuelToRetain + 1)) then
                writeMessage("Consuming emergency fuel supply. "..(fuelItems - 2).." emergency fuel items remain", messageLevel.WARNING)
                turtle.refuel(1)
          else
                -- Refuel the lesser of the refuelItemsToUseWhenRefuelling and the number of items more than
                -- the emergency fuel level
                if (fuelItems - (emergencyFuelToRetain + 1) < refuelItemsToUseWhenRefuelling) then
                  turtle.refuel(fuelItems - (emergencyFuelToRetain + 1))
                else
                  turtle.refuel(refuelItemsToUseWhenRefuelling)
                end
          end
        end
  end
end

-- ********************************************************************************** --
-- Checks that the turtle has inventory space by checking for spare slots and returning
-- to the starting point to empty out if it doesn't.
--
-- Takes the position required to move to in order to empty the turtle's inventory
-- should it be full as arguments
-- ********************************************************************************** --
function ensureInventorySpace()

  -- If already returning to start, then don't need to do anything
  if (returningToStart == false) then

        -- If the last inventory slot is full, then need to return to the start and empty
        if (turtle.getItemCount(lastEmptySlot) > 0) then

          -- Return to the starting point and empty the inventory, then go back to mining
          returnToStartAndUnload(true)
        end
  end
end

-- ********************************************************************************** --
-- Function that is called when the turtle has returned to the start in order to
-- empty its inventory into the chest and also pick up any fuel that is
-- available
-- ********************************************************************************** --
function emptyInventory()

  local slotLoop = 1

  -- Face the chest
  turtleSetOrientation(direction.BACK)

  -- Loop over each of the slots (except the 16th one which stores fuel)
  while (slotLoop < 16) do
        -- If this is one of the slots that contains a noise block, empty all blocks except
        -- one
        turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
        if ((slotLoop <= noiseBlocksCount) or ((slotLoop == 15) and (lookForChests == true))) then
          turtle.drop(turtle.getItemCount(slotLoop) - 1)
        else
          -- Not a noise block, drop all of the items in this slot
          turtle.drop()
        end

        slotLoop = slotLoop + 1
  end

  -- While we are here, refill the fuel items
  turtleSetOrientation(direction.LEFT)
  turtle.select(16) -- Don't bother updating selected slot variable as it will set later in this function
  local currFuelItems = turtle.getItemCount(16)
  turtle.suck()
  while ((currFuelItems ~= turtle.getItemCount(16)) and (turtle.getItemCount(16) < 64)) do
        currFuelItems = turtle.getItemCount(16)
        turtle.suck()
  end

  slotLoop = noiseBlocksCount + 1
  -- Have now picked up all the items that we can. If we have also picked up some
  -- additional fuel in some of the other slots, then drop it again
  while (slotLoop < lastEmptySlot) do
        -- Drop any items found in this slot
        turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
        turtle.drop()
        slotLoop = slotLoop + 1
  end

  -- Select the 1st slot because sometimes when leaving the 15th or 16th slots selected it can result
  -- in that slot being immediately filled (resulting in the turtle returning to base again too soon)
  turtle.select(1)
  currentlySelectedSlot = 1
end

-- ********************************************************************************** --
-- Function to move to the starting point, call a function that is passed in
-- and return to the same location (if required)
-- ********************************************************************************** --
function returnToStartAndUnload(returnBackToMiningPoint)

  writeMessage("returnToStartAndUnload called", messageLevel.DEBUG)
  returningToStart = true

  -- Store the current location and orientation so that it can be returned to
  local storedX = currX
  local storedY = currY
  local storedZ = currZ
  local storedOrient = currOrient

  writeMessage("Return to start, return level: "..levelToReturnTo, messageLevel.DEBUG)

  -- Move down to the correct layer to return via
  if (currY > levelToReturnTo) then
        while (currY > levelToReturnTo) do
          turtleDown()
        end
  elseif (currY < levelToReturnTo) then
        while (currY < levelToReturnTo) do
          turtleUp()
        end
  end

  if ((haveBeenAtZeroZeroOnLayer == false) or (orientationAtZeroZero == direction.FORWARD)) then
        -- Move back to the correct X position first
        if (currX > 0) then
          turtleSetOrientation(direction.LEFT)
          while (currX > 0) do
                turtleForward()
          end
        elseif (currX < 0) then
          -- This should never happen
          writeMessage("Current x is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
        end

        -- Then move back to the correct Z position
        if (currZ > 0) then
          turtleSetOrientation(direction.BACK)
          while (currZ > 0) do
                turtleForward()
          end
        elseif (currZ < 0) then
          -- This should never happen
          writeMessage("Current z is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
        end
  else
        -- Move back to the correct Z position first
        if (currZ > 0) then
          turtleSetOrientation(direction.BACK)
          while (currZ > 0) do
                turtleForward()
          end
        elseif (currZ < 0) then
          -- This should never happen
          writeMessage("Current z is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
        end

        -- Then move back to the correct X position
        if (currX > 0) then
          turtleSetOrientation(direction.LEFT)
          while (currX > 0) do
                turtleForward()
          end
        elseif (currX < 0) then
          -- This should never happen
          writeMessage("Current x is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
        end
  end

  -- Return to the starting layer
  if (currY < startHeight) then
        while (currY < startHeight) do
          turtleUp()
        end
  elseif (currY > startHeight) then
        -- This should never happen
        writeMessage("Current height is greater than start height in returnToStartAndUnload", messageLevel.ERROR)
  end

  -- Empty the inventory
  local slotLoop = 1

  -- Face the chest
  turtleSetOrientation(direction.BACK)

  -- Loop over each of the slots (except the 16th one which stores fuel)
  while (slotLoop < 16) do
        -- If this is one of the slots that contains a noise block, empty all blocks except
        -- one
        turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
        if ((slotLoop <= noiseBlocksCount) or ((slotLoop == 15) and (lookForChests == true))) then
          turtle.drop(turtle.getItemCount(slotLoop) - 1)
        else
          -- Not a noise block, drop all of the items in this slot
          turtle.drop()
        end

        slotLoop = slotLoop + 1
  end

  -- While we are here, refill the fuel items if there is capacity
  if (turtle.getItemCount(16) < 64) then
        turtleSetOrientation(direction.LEFT)
        turtle.select(16) -- Don't bother updating selected slot variable as it will set later in this function
        local currFuelItems = turtle.getItemCount(16)
        turtle.suck()
        while ((currFuelItems ~= turtle.getItemCount(16)) and (turtle.getItemCount(16) < 64)) do
          currFuelItems = turtle.getItemCount(16)
          turtle.suck()
        end

        slotLoop = noiseBlocksCount + 1
        -- Have now picked up all the items that we can. If we have also picked up some
        -- additional fuel in some of the other slots, then drop it again
        while (slotLoop <= lastEmptySlot) do
          -- Drop any items found in this slot
          turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
          turtle.drop()
          slotLoop = slotLoop + 1
        end
  end

  -- Select the 1st slot because sometimes when leaving the 15th or 16th slots selected it can result
  -- in that slot being immediately filled (resulting in the turtle returning to base again too soon)
  turtle.select(1)
  currentlySelectedSlot = 1

  -- If required, move back to the point that we were mining at before returning to the start
  if (returnBackToMiningPoint == true) then
        -- Return back to the required layer
        while (currY > levelToReturnTo) do
          turtleDown()
        end

        if ((haveBeenAtZeroZeroOnLayer == false) or (orientationAtZeroZero == direction.FORWARD)) then
          -- Move back to the correct Z position first
          writeMessage("Stored Z: "..storedZ..", currZ: "..currZ, messageLevel.DEBUG)
          if (storedZ > currZ) then
                writeMessage("Orienting forward", messageLevel.DEBUG)
                writeMessage("Moving in z direction", messageLevel.DEBUG)
                turtleSetOrientation(direction.FORWARD)
                while (storedZ > currZ) do
                  turtleForward()
                end
          elseif (storedZ < currZ) then
                -- This should never happen
                writeMessage("Stored z is less than current z in returnToStartAndUnload", messageLevel.ERROR)
          end

          -- Then move back to the correct X position
          if (storedX > currX) then
                writeMessage("Stored X: "..storedX..", currX: "..currX, messageLevel.DEBUG)
                writeMessage("Orienting right", messageLevel.DEBUG)
                writeMessage("Moving in x direction", messageLevel.DEBUG)
                turtleSetOrientation(direction.RIGHT)
                while (storedX > currX) do
                  turtleForward()
                end
          elseif (storedX < currX) then
                -- This should never happen
                writeMessage("Stored x is less than current x in returnToStartAndUnload", messageLevel.ERROR)
          end
        else
          -- Move back to the correct X position first
          if (storedX > currX) then
                writeMessage("Stored X: "..storedX..", currX: "..currX, messageLevel.DEBUG)
                writeMessage("Orienting right", messageLevel.DEBUG)
                writeMessage("Moving in x direction", messageLevel.DEBUG)
                turtleSetOrientation(direction.RIGHT)
                while (storedX > currX) do
                  turtleForward()
                end
          elseif (storedX < currX) then
                -- This should never happen
                writeMessage("Stored x is less than current x in returnToStartAndUnload", messageLevel.ERROR)
          end

          -- Then move back to the correct Z position
          writeMessage("Stored Z: "..storedZ..", currZ: "..currZ, messageLevel.DEBUG)
          if (storedZ > currZ) then
                writeMessage("Orienting forward", messageLevel.DEBUG)
                writeMessage("Moving in z direction", messageLevel.DEBUG)
                turtleSetOrientation(direction.FORWARD)
                while (storedZ > currZ) do
                  turtleForward()
                end
          elseif (storedZ < currZ) then
                -- This should never happen
                writeMessage("Stored z is less than current z in returnToStartAndUnload", messageLevel.ERROR)
          end
        end

        -- Move back to the correct layer
        if (storedY < currY) then
          while (storedY < currY) do
                turtleDown()
          end
        elseif (storedY > currY) then
          while (storedY > currY) do
                turtleUp()
          end
        end

        -- Finally, set the correct orientation
        turtleSetOrientation(storedOrient)

        writeMessage("Have returned to the mining point", messageLevel.DEBUG)
  end

  returningToStart = false

end

-- ********************************************************************************** --
-- Empties a chest's contents
-- ********************************************************************************** --
function emptyChest(suckFn)

  local prevInventoryCount = {}
  local inventoryLoop
  local chestEmptied = false

  -- Record the number of items in each of the inventory slots
  for inventoryLoop = 1, 16 do
        prevInventoryCount[inventoryLoop] = turtle.getItemCount(inventoryLoop)
  end

  while (chestEmptied == false) do
        -- Pick up the next item
        suckFn()

        -- Determine the number of items in each of the inventory slots now
        local newInventoryCount = {}
        for inventoryLoop = 1, 16 do
          newInventoryCount[inventoryLoop] = turtle.getItemCount(inventoryLoop)
        end

        -- Now, determine whether there have been any items taken from the chest
        local foundDifferentItemCount = false
        inventoryLoop = 1
        while ((foundDifferentItemCount == false) and (inventoryLoop <= 16)) do
          if (prevInventoryCount[inventoryLoop] ~= newInventoryCount[inventoryLoop]) then
                foundDifferentItemCount = true
          else
                inventoryLoop = inventoryLoop + 1
          end
        end

        -- If no items have been found with a different item count, then the chest has been emptied
        chestEmptied = not foundDifferentItemCount

        if (chestEmptied == false) then
          prevInventoryCount = newInventoryCount
          -- Check that there is sufficient inventory space as may have picked up a block
          ensureInventorySpace()
        end
  end

  writeMessage("Finished emptying chest", messageLevel.DEBUG)
end


-- ********************************************************************************** --
-- Generic function to move the Turtle (pushing through any gravel or other
-- things such as mobs that might get in the way).
--
-- The only thing that should stop the turtle moving is bedrock. Where this is
-- found, the function will return after 15 seconds returning false
-- ********************************************************************************** --
function moveTurtle(moveFn, detectFn, digFn, attackFn, compareFn, suckFn, maxDigCount)

  ensureFuel()

  -- Flag to determine whether digging has been tried yet. If it has
  -- then pause briefly before digging again to allow sand or gravel to
  -- drop
  local digCount = 0
  local moveSuccess = false

  if (lastMoveNeededDig == false) then
        -- Didn't need to dig last time the turtle moved, so try moving first
        writeMessage("Trying to move before digging", messageLevel.DEBUG)
        moveSuccess = moveFn()

        -- Don't need to set the last move needed dig. It is already false, if
        -- move success is now true, then it won't be changed
  else
        writeMessage("Trying to dig before moving", messageLevel.DEBUG)
        -- If we are looking for chests, then check that this isn't a chest before trying to dig it
        if (lookForChests == true) then
          if (isNoiseBlock(compareFn) == false) then
                if (detectFn() == true) then
                  -- Determine if it is a chest before digging it
                  if (isChestBlock(compareFn) == true) then
                        -- Have found a chest, empty it before continuing
                        emptyChest (suckFn)
                  end
                end
          end
        end

        -- Try to dig (without doing a detect as it is quicker)
        local digSuccess = digFn()
        if (digSuccess == true) then
          digCount = 1
        end
        moveSuccess = moveFn()

        if (moveSuccess == true) then
          lastMoveNeededDig = digSuccess
        end
  end

  -- Loop until we've successfully moved
  if (moveSuccess == false) then
        while ((moveSuccess == false) and (digCount < maxDigCount)) do

          -- If there is a block in front, dig it
          if (detectFn() == true) then

                  -- If we've already tried digging, then pause before digging again to let
                  -- any sand or gravel drop, otherwise check for a chest before digging
                  if(digCount == 0) then
                        -- Am about to dig a block - check that it is not a chest if necessary
                        -- If we are looking for chests, then check that this isn't a chest before moving
                        if (lookForChests == true) then
                          if (isNoiseBlock(compareFn) == false) then
                                if (detectFn() == true) then
                                  -- Determine if it is a chest before digging it
                                  if (isChestBlock(compareFn) == true) then
                                        -- Have found a chest, empty it before continuing
                                        emptyChest (suckFn)
                                  end
                                end
                          end
                        end
                  else
                        sleep(0.1)
                  end

                  digFn()
                  digCount = digCount + 1
          else
                 -- Am being stopped from moving by a mob, attack it
                 attackFn()
          end

          -- Try the move again
          moveSuccess = moveFn()
        end

        if (digCount == 0) then
          lastMoveNeededDig = false
        else
          lastMoveNeededDig = true
        end
  end

  -- Return the move success
  return moveSuccess

end

-- ********************************************************************************** --
-- Move the turtle forward one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleForward()
  local returnVal = moveTurtle(turtle.forward, turtle.detect, turtle.dig, turtle.attack, turtle.compare, turtle.suck, maximumGravelStackSupported)
  if (returnVal == true) then
        -- Update the current co-ordinates
        if (currOrient == direction.FORWARD) then
          currZ = currZ + 1
        elseif (currOrient == direction.LEFT) then
          currX = currX - 1
        elseif (currOrient == direction.BACK) then
          currZ = currZ - 1
        elseif (currOrient == direction.RIGHT) then
          currX = currX + 1
        else
          writeMessage ("Invalid currOrient in turtleForward function", messageLevel.ERROR)
        end

        -- Check that there is sufficient inventory space as may have picked up a block
        ensureInventorySpace()
  end

  return returnVal
end

-- ********************************************************************************** --
-- Move the turtle up one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleUp()
  local returnVal = moveTurtle(turtle.up, turtle.detectUp, turtle.digUp, turtle.attackUp, turtle.compareUp, turtle.suckUp, maximumGravelStackSupported)
  if (returnVal == true) then
        currY = currY + 1

        -- Check that there is sufficient inventory space as may have picked up a block
        ensureInventorySpace()
  end
  return returnVal
end

-- ********************************************************************************** --
-- Move the turtle down one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleDown()
  local returnVal

  -- Because the turtle is digging down, can fail fast (only allow 1 dig attempt).
  returnVal = moveTurtle(turtle.down, turtle.detectDown, turtle.digDown, turtle.attackDown, turtle.compareDown, turtle.suckDown, 1)
  if (returnVal == true) then
        currY = currY - 1

        -- Check that there is sufficient inventory space as may have picked up a block
        ensureInventorySpace()
  end
  return returnVal
end

-- ********************************************************************************** --
-- Move the turtle back one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleBack()
  -- First try to move back using the standard function
  local returnVal = turtle.back()

  -- Moving back didn't work (might be a block or a mob in the way). Turn round and move
  -- forward instead (whereby anything in the way can be cleared)
  if(returnVal == false) then
        turtle.turnRight()
        turtle.turnRight()
        returnVal = turtleForward()
        turtle.turnRight()
        turtle.turnRight()
  end

  if (returnVal == true) then
        -- Update the current co-ordinates
        if (currOrient == direction.FORWARD) then
          currZ = currZ - 1
        elseif (currOrient == direction.LEFT) then
          currX = currX + 1
        elseif (currOrient == direction.BACK) then
          currZ = currZ + 1
        elseif (currOrient == direction.RIGHT) then
          currX = currX - 1
        else
          writeMessage ("Invalid currOrient in turtleBack function", messageLevel.ERROR)
        end

        -- Check that there is sufficient inventory space as may have picked up a block
        ensureInventorySpace()
  end

  return returnVal
end

-- ********************************************************************************** --
-- Turns the turtle (updating the current orientation at the same time)
-- ********************************************************************************** --
function turtleTurn(turnDir)

  if (turnDir == direction.LEFT) then
        if (currOrient == direction.FORWARD) then
          currOrient = direction.LEFT
          turtle.turnLeft()
        elseif (currOrient == direction.LEFT) then
          currOrient = direction.BACK
          turtle.turnLeft()
        elseif (currOrient == direction.BACK) then
          currOrient = direction.RIGHT
          turtle.turnLeft()
        elseif (currOrient == direction.RIGHT) then
          currOrient = direction.FORWARD
          turtle.turnLeft()
        else
          writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
        end
  elseif (turnDir == direction.RIGHT) then
        if (currOrient == direction.FORWARD) then
          currOrient = direction.RIGHT
          turtle.turnRight()
        elseif (currOrient == direction.LEFT) then
          currOrient = direction.FORWARD
          turtle.turnRight()
        elseif (currOrient == direction.BACK) then
          currOrient = direction.LEFT
          turtle.turnRight()
        elseif (currOrient == direction.RIGHT) then
          currOrient = direction.BACK
          turtle.turnRight()
        else
          writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
        end
  else
        writeMessage ("Invalid turnDir in turtleTurn function", messageLevel.ERROR)
  end
end

-- ********************************************************************************** --
-- Sets the turtle to a specific orientation, irrespective of its current orientation
-- ********************************************************************************** --
function turtleSetOrientation(newOrient)

  if (currOrient ~= newOrient) then
        if (currOrient == direction.FORWARD) then
          if (newOrient == direction.RIGHT) then
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.BACK) then
                turtle.turnRight()
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.LEFT) then
                turtle.turnLeft()
                currOrient = newOrient
          else
                writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
          end
        elseif (currOrient == direction.RIGHT) then
          if (newOrient == direction.BACK) then
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.LEFT) then
                turtle.turnRight()
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.FORWARD) then
                turtle.turnLeft()
                currOrient = newOrient
          else
                writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
          end
        elseif (currOrient == direction.BACK) then
          if (newOrient == direction.LEFT) then
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.FORWARD) then
                turtle.turnRight()
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.RIGHT) then
                turtle.turnLeft()
                currOrient = newOrient
          else
                writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
          end
        elseif (currOrient == direction.LEFT) then
          if (newOrient == direction.FORWARD) then
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.RIGHT) then
                turtle.turnRight()
                turtle.turnRight()
                currOrient = newOrient
          elseif (newOrient == direction.BACK) then
                turtle.turnLeft()
                currOrient = newOrient
          else
                writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
          end
        else
          writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
        end
  end
end

-- ********************************************************************************** --
-- Determines if a particular block is considered a noise block or not. A noise
-- block is one that is a standard block in the game (stone, dirt, gravel etc.) and
-- is one to ignore as not being an ore. Function works by comparing the block
-- in question against a set of blocks in the turtle's inventory which are known not to
-- be noise blocks. Param is the function to use to compare the block for a noise block
-- ********************************************************************************** --
function isNoiseBlock(compareFn)

  -- Consider air to be a noise block
  local returnVal = false
  local seamLoop = 1
  local prevSelectedSlot

  -- If the currently selected slot is a noise block, then compare against this first
  -- so that the slot doesn't need to be selected again (there is a 0.05s cost to do
  -- this even if it is the currently selected slot)
  if (currentlySelectedSlot <= noiseBlocksCount) then
        returnVal = compareFn()
  end

  if (returnVal == false) then
        prevSelectedSlot = currentlySelectedSlot
        while((returnVal == false) and (seamLoop <= noiseBlocksCount)) do
          if (seamLoop ~= prevSelectedSlot) then
                turtle.select(seamLoop)
                currentlySelectedSlot = seamLoop
                returnVal = compareFn()
          end
          seamLoop = seamLoop + 1
        end
  end

  -- Return the calculated value
  return returnVal

end

-- ********************************************************************************** --
-- Determines if a particular block is a chest. Returns false if it is not a chest
-- or chests are not being detected
-- ********************************************************************************** --
function isChestBlock(compareFn)

  -- Check the block in the appropriate direction to see whether it is a chest. Only
  -- do this if we are looking for chests
  local returnVal = false
  if (lookForChests == true) then
        turtle.select(15)
        currentlySelectedSlot = 15
        returnVal = compareFn()
  end

  -- Return the calculated value
  return returnVal

end

-- ********************************************************************************** --
-- Function to calculate the number of non seam blocks in the turtle's inventory. This
-- is all of the blocks at the start of the inventory (before the first empty slot is
-- found
-- ********************************************************************************** --
function determineNoiseBlocksCountCount()
  -- Determine the location of the first empty inventory slot. All items before this represent
  -- noise items.
  local foundFirstBlankInventorySlot = false
  noiseBlocksCount = 1
  while ((noiseBlocksCount < 16) and (foundFirstBlankInventorySlot == false)) do
        if (turtle.getItemCount(noiseBlocksCount) > 0) then
          noiseBlocksCount = noiseBlocksCount + 1
        else
          foundFirstBlankInventorySlot = true
        end
  end
  noiseBlocksCount = noiseBlocksCount - 1

  -- Determine whether a chest was provided, and hence whether we should support
  -- looking for chests
  if (turtle.getItemCount(15) > 0) then
        lookForChests = true
        lastEmptySlot = 14
        miningOffset = 0
        writeMessage("Looking for chests...", messageLevel.DEBUG)
  else
        lastEmptySlot = 15
        miningOffset = 1
        writeMessage("Ignoring chests...", messageLevel.DEBUG)
  end
end

-- ********************************************************************************** --
-- Creates a quarry mining out only ores and leaving behind any noise blocks
-- ********************************************************************************** --
function createQuarry()

  -- Determine the top mining layer layer. The turtle mines in layers of 3, and the bottom layer
  -- is the layer directly above bedrock.
  --
  -- The actual layer that the turtle operates in is the middle of these three layers,
  -- so determine the top layer
  local topMiningLayer = startHeight + ((bottomLayer - startHeight - 2) % 3) - 1 + miningOffset

  -- If the top layer is up, then ignore it and move to the next layer
  if (topMiningLayer > currY) then
        topMiningLayer = topMiningLayer - 3
  end

  local startedLayerToRight = true -- Only used where the quarry is of an odd width

  -- Loop over each mining row
  local miningLevel
  for miningLevel = (bottomLayer + miningOffset), topMiningLayer, 3 do
        writeMessage("Mining Layer: "..miningLevel, messageLevel.INFO)
        haveBeenAtZeroZeroOnLayer = false

        -- While the initial shaft is being dug out, set the level to return to in order to unload
        -- to the just take the turtle straight back up
        if (miningLevel == (bottomLayer + miningOffset)) then
          levelToReturnTo = startHeight
        end

        -- Move to the correct level to start mining
        if (currY > miningLevel) then
          while (currY > miningLevel) do
                turtleDown()
          end
        elseif (currY < miningLevel) then
          while (currY < miningLevel) do
                turtleUp()
          end
        end

        -- Set the layer to return via when returning to the surface as the one below the currently
        -- mined one
        if (miningLevel == (bottomLayer + miningOffset)) then
          levelToReturnTo = (bottomLayer + miningOffset)
        else
          levelToReturnTo = miningLevel - 3
        end

        -- Move turtle into the correct orientation to start mining (if this is the
        -- first row to be mined, then don't need to turn, otherwise turn towards the next
        -- mining section)

        writeMessage("Mining Level: "..miningLevel..", Bottom Layer: "..bottomLayer..", Mining Offset: "..miningOffset, messageLevel.DEBUG)

        if (miningLevel > (bottomLayer + miningOffset)) then
          writeMessage ("Turning at start of layer", messageLevel.DEBUG)
          -- Turn towards the next mining layer
          if (quarryWidth % 2 == 0) then
                -- An even width quarry, always turn right
                turtleTurn(direction.RIGHT)
          else
                -- Turn the opposite direction to that which we turned before
                if (startedLayerToRight == true) then
                  turtleTurn(direction.LEFT)
                  startedLayerToRight = false
                else
                  turtleTurn(direction.RIGHT)
                  startedLayerToRight = true
                end
          end
        end

        local mineRows
        local onNearSideOfQuarry = true
        local diggingAway = true
        for mineRows = 1, quarryWidth do

          -- If this is not the first row, then get into position to mine the next row
          if ((mineRows == 1) and (lookForChests == false)) then
                -- Not looking for chests, check the block below for being an ore. Only do this
                -- if we're not looking for chests since the program doesn't support chests in
                -- bedrock
                if (isNoiseBlock(turtle.compareDown) == false) then
                  turtle.digDown()
                  ensureInventorySpace()
                end
          elseif (mineRows > 1) then
                -- Move into position for mining the next row
                if (onNearSideOfQuarry == diggingAway) then
                  if (startedLayerToRight == true) then
                        turtleTurn(direction.LEFT)
                  else
                        turtleTurn(direction.RIGHT)
                  end
                else
                  if (startedLayerToRight == true) then
                        turtleTurn(direction.RIGHT)
                  else
                        turtleTurn(direction.LEFT)
                  end
                end

                turtleForward()

                -- Before making the final turn, check the block below. Do this
                -- now because if it is a chest, then we want to back up and
                -- approach it from the side (so that we don't lose items if we
                -- have to return to the start through it).
                --
                -- This is the point at which it is safe to back up without moving
                -- out of the quarry area (unless at bedrock in which case don't bother
                -- as we'll be digging down anyway)
                if (miningLevel ~= bottomLayer) then
                  if (isNoiseBlock(turtle.compareDown) == false) then
                        -- If we are not looking for chests, then just dig it (it takes
                        -- less time to try to dig and fail as it does to do detect and
                        -- only dig if there is a block there)
                        if (lookForChests == false) then
                          turtle.digDown()
                          ensureInventorySpace()
                        elseif (turtle.detectDown() == true) then
                          if (isChestBlock(turtle.compareDown) == true) then
                                -- There is a chest block below. Move back and approach
                                -- from the side to ensure that we don't need to return to
                                -- start through the chest itself (potentially losing items)
                                turtleBack()
                                turtleDown()
                                emptyChest(turtle.suck)
                                turtleUp()
                                turtleForward()
                                turtle.digDown()
                                ensureInventorySpace()
                          else
                                turtle.digDown()
                                ensureInventorySpace()
                          end
                        end
                  end
                end

                -- Move into final position for mining the next row
                if (onNearSideOfQuarry == diggingAway) then
                  if (startedLayerToRight == true) then
                        turtleTurn(direction.LEFT)
                  else
                        turtleTurn(direction.RIGHT)
                  end
                else
                  if (startedLayerToRight == true) then
                        turtleTurn(direction.RIGHT)
                  else
                        turtleTurn(direction.LEFT)
                  end
                end
          end

          -- Dig to the other side of the quarry
          local blocksMined
          for blocksMined = 0, (quarryWidth - 1) do
                if (blocksMined > 0) then
                  -- Only move forward if this is not the first space
                  turtleForward()
                end

                -- If the current block is (0,0), then record the fact that the
                -- turtle has been through this block and what it's orientation was and update the layer
                -- that it should return via to get back to the surface (it no longer needs to go down
                -- a level to prevent losing ores).
                if ((currX == 0) and (currZ == 0)) then
                  -- Am at (0, 0). Remember this, and what direction I was facing so that the quickest route
                  -- to the surface can be taken
                  levelToReturnTo = miningLevel
                  haveBeenAtZeroZeroOnLayer = true
                  orientationAtZeroZero = currOrient
                end

                -- If currently at bedrock, just move down until the turtle can't go any
                -- further. This allows the blocks within the bedrock to be mined
                if (miningLevel == bottomLayer) then
                  -- Temporarily turn off looking for chests to increase bedrock mining speed (this
                  -- means that the program doesn't support chests below level 5 - but I think
                  -- they they don't exist anyway)
                  local lookForChestsPrev = lookForChests
                  lookForChests = false

                  -- Manually set the flag to determine whether the turtle should try to move first or
                  -- dig first. At bedrock, is very rarely any space

                  -- Just above bedrock layer, dig down until can't dig any lower, and then
                  -- come back up. This replicates how the quarry functions
                  lastMoveNeededDig = true
                  local moveDownSuccess = turtleDown()
                  while (moveDownSuccess == true) do
                        moveDownSuccess = turtleDown()
                  end

                  -- Know that we are moving back up through air, therefore set the flag to force the
                  -- turtle to try moving first
                  lastMoveNeededDig = false

                  -- Have now hit bedrock, move back to the mining layer
                  writeMessage("Moving back to mining layer", messageLevel.DEBUG)
                  writeMessage("currY: "..currY..", bottomLayer: "..bottomLayer, messageLevel.DEBUG)
                  while (currY < bottomLayer) do
                        turtleUp()
                  end

                  -- Now back at the level above bedrock, again reset the flag to tell the turtle to
                  -- try digging again (because it is rare to find air at bedrock level)
                  lastMoveNeededDig = false

                  -- Reset the look for chests value
                  lookForChests = lookForChestsPrev
                elseif ((blocksMined > 0) and ((currX ~= 0) or (currZ ~= 0))) then
                  -- This isn't the first block of the row, nor are we at (0, 0) so we need to check the
                  -- block below

                  -- Check the block down for being a noise block (don't need to check the first
                  -- block as it has already been checked in the outer loop)
                  if (isNoiseBlock(turtle.compareDown) == false) then
                        -- If we are not looking for chests, then just dig it (it takes
                        -- less time to try to dig and fail as it does to do detect and
                        -- only dig if there is a block there)
                        if (lookForChests == false) then
                          turtle.digDown()
                          ensureInventorySpace()
                        elseif (turtle.detectDown() == true) then
                          if (isChestBlock(turtle.compareDown) == true) then
                                -- There is a chest block below. Move back and approach
                                -- from the side to ensure that we don't need to return to
                                -- start through the chest itself (potentially losing items)
                                turtleBack()
                                turtleDown()
                                emptyChest(turtle.suck)
                                turtleUp()
                                turtleForward()
                                turtle.digDown()
                                ensureInventorySpace()
                          else
                                turtle.digDown()
                                ensureInventorySpace()
                          end
                        end
                  end
                end

                -- Check the block above for ores (if we're not a (0, 0) in which case
                -- we know it's air)
                if ((currX ~= 0) or (currZ ~= 0)) then
                  if (isNoiseBlock(turtle.compareUp) == false) then
                        -- If we are not looking for chests, then just dig it (it takes
                        -- less time to try to dig and fail as it does to do detect and
                        -- only dig if there is a block there)
                        if (lookForChests == false) then
                          turtle.digUp()
                          ensureInventorySpace()
                        elseif (turtle.detectUp() == true) then
                          -- Determine if it is a chest before digging it
                          if (isChestBlock(turtle.compareUp) == true) then
                                -- There is a chest block above. Empty it before digging it
                                emptyChest(turtle.suckUp)
                                turtle.digUp()
                                ensureInventorySpace()
                          else
                                turtle.digUp()
                                ensureInventorySpace()
                          end
                        end
                  end
                end
          end

          -- Am now at the other side of the quarry
          onNearSideOfQuarry = not onNearSideOfQuarry
        end

        -- If we were digging away from the starting point, will be digging
        -- back towards it on the next layer
        diggingAway = not diggingAway
  end

  -- Return to the start
  returnToStartAndUnload(false)

  -- Face forward
  turtleSetOrientation(direction.FORWARD)
end

-- ********************************************************************************** --
-- Main Function
-- ********************************************************************************** --
-- Process the input arguments - storing them to global variables
local args = { ... }
local paramsOK = true

turtleId = os.getComputerLabel()
rednet.open("right")

if (#args == 1) then
  quarryWidth = tonumber(args[1])
  local x, y, z = gps.locate(5)
  startHeight = y
  if (startHeight == nil) then
        writeMessage("Can't locate GPS", messageLevel.FATAL)
        paramsOK = false
  end
elseif (#args == 2) then
  quarryWidth = tonumber(args[1])
  startHeight = tonumber(args[2])
else
  writeMessage("Usage: OreQuarry <diameter> <turtleY>", messageLevel.FATAL)
  paramsOK = false
end

if (paramsOK == true) then
  if ((startHeight < 6) or (startHeight > 128)) then
        writeMessage("turtleY must be between 6 and 128", messageLevel.FATAL)
        paramsOK = false
  end

  if ((quarryWidth < 2) or (quarryWidth > 64)) then
        writeMessage("diameter must be between 2 and 64", messageLevel.FATAL)
        paramsOK = false
  end
end

if (paramsOK == true) then
  writeMessage("---------------------------------", messageLevel.INFO)
  writeMessage("** Ore Quarry v0.4 by AustinKK **", messageLevel.INFO)
  writeMessage("---------------------------------", messageLevel.INFO)

  -- Set the turtle's starting position
  currX = 0
  currY = startHeight
  currZ = 0
  currOrient = direction.FORWARD

  -- Calculate which blocks in the inventory signify noise blocks
  determineNoiseBlocksCountCount()

  if ((noiseBlocksCount == 0) or (noiseBlocksCount == 15)) then
        writeMessage("No noise blocks have been been added. Please place blocks that the turtle should not mine (e.g. Stone, Dirt, Gravel etc.) in the first few slots of the turtle\'s inventory. The first empty slot signifies the end of the noise blocks.", messageLevel.FATAL)
  else
        -- Create a Quary
        turtle.select(1)
        currentlySelectedSlot = 1
        createQuarry()
  end
end