plotCornerBL = vector.new(13,0,1)
plotCornerTR = vector.new(0,0,13)

plotLimitxLeft = 13
plotLimitxRight = 0
plotStrips = { 4, 10 }

plotHoverHeight = 1
chestFaceDir = 3
blueWoolFaceDir = 2
woodChestAccessHeight = 0
fuelChestAccessHeight = 1
saplChestAccessHeight = 2

fuelInvSlot = 16
saplingInvSlot = 15

blueWoolIdentifier = "minecraft:blue_wool"
cobbleIdentifier = "minecraft:cobblestone"
birchLogIdentifier = "minecraft:birch_log"
birchSaplIdentifier = "minecraft:birch_sapling"

currentPos = nil
currentDirection = nil

function panic()
  while true do
    turtle.turnRight()
  end
end

function turnToDir(targetDir)
  while currentDirection ~= targetDir do
    turtle.turnRight()
    currentDirection = currentDirection + 1
    if currentDirection == 5 then
      currentDirection = 1
    end
  end 
end

function moveForward()
  success = turtle.forward()
  delta = vector.new(0,0,0)
  if not success then
    return success
  end
  
  if currentDirection == 1 then
    delta = vector.new(0,0,1)
  elseif currentDirection == 2 then
    delta = vector.new(-1,0,0)
  elseif currentDirection == 3 then
    delta = vector.new(0,0,-1)
  elseif currentDirection == 4 then
    delta = vector.new(1,0,0)
  end
  currentPos = currentPos + delta
  
  turtle.suckDown()
  
  return success
end

function moveUp()
  success = turtle.up()
  
  if success then
    currentPos = currentPos + vector.new(0,1,0)
  end
  
  return success       
end

function moveDown()
  success = turtle.down()
  
  if success then
    currentPos = currentPos + vector.new(0,-1,0)
  end
  
  return success
end

function goToPos(dx,dy,dz,df)
  while currentPos.y ~= plotHoverHeight do
    if currentPos.y > plotHoverHeight then
      moveDown()
    else
      moveUp()
    end  
  end
      
  if currentPos.z > dz then
    turnToDir(3)
  elseif currentPos.z < dz then
    turnToDir(1)
  end
  
  while currentPos.z ~= dz do
    success = moveForward()
    if not success then
      blockpres, blockdata = turtle.inspect()
      if not blockpres then 
        panic()
      else
        if blockdata.name == birchLogIdentifier then
          turtle.dig()
        end 
      end
    end
  end
  
  if currentPos.x > dx then
    turnToDir(2)
  elseif currentPos.x < dx then
    turnToDir(4)
  end
  
  while currentPos.x ~= dx do
    success = moveForward()
    if not success then
      blockpres, blockdata = turtle.inspect()
      if not blockpres then
        panic()
      elseif blockdata.name == birchLogIdentifier then
        turtle.dig()
      end 
    end  
  end
  
  while currentPos.y ~= dy do
    if currentPos.y > dy then
      moveDown()
    else
      moveUp()
    end  
  end
  
  if df ~= 0 then
    turnToDir(df)
  end
end

function powerOnSelfTest()
  if turtle.getFuelLevel() < 20 then
    turtle.select(fuelInvSlot)
    if not turtle.refuel() then
      return false -- needs fuel to POST
    end
  end
  
  while not turtle.detectDown() do
    turtle.down()
  end
  
  dpres, ddata = turtle.inspectDown()
  if ddata.name == cobbleIdentifier then
    while currentDirection == nil do
      bwpres, bwdata = turtle.inspect() 
      if bwpres then
        if bwdata.name == blueWoolIdentifier then
          currentDirection = blueWoolFaceDir
        else
          turtle.turnRight()
        end
      else
        turtle.turnRight()
      end  
    end
  end
  
  currentPos = vector.new(0,0,0)
  
  turnToDir(1)
  
  print("POST complete, home set.")
  return true
end

function dumpInventory()
  goToPos(0,woodChestAccessHeight,0,chestFaceDir)
  for i = 1, 16, 1 do
    turtle.select(i)
    if turtle.getItemDetail() ~= nil then
      if turtle.getItemDetail().name == birchLogIdentifier then
        turtle.drop(turtle.getItemDetail().count)
      end
    end
  end
  goToPos(0,saplChestAccessHeight,0,chestFaceDir)
  for i = 1, 14, 1 do
    turtle.select(i)
    if turtle.getItemDetail() ~= nil then
      if turtle.getItemDetail().name == birchSaplIdentifier then
        if not turtle.transferTo(saplingInvSlot, turtle.getItemDetail().count) then
          turtle.drop(turtle.getItemDetail().count)
        end
      end
    end
  end
  turtle.select(15)
  if turtle.getItemDetail() ~= nil then
    if turtle.getItemDetail().count < 64 then
      turtle.suck(64 - turtle.getItemDetail().count)
    end
  else
    turtle.suck(64)
  end
  goToPos(0,fuelChestAccessHeight,0,chestFaceDir)
  for i = 1, 16, 1 do
    turtle.select(i)
    if turtle.getItemDetail() ~= nil then
      if turtle.getItemDetail().name == "minecraft:stick" then
        turtle.drop(turtle.getItemDetail().count)
      end  
    end
  end
end

function preCheckFuel(min)
  goToPos(0,fuelChestAccessHeight,0,chestFaceDir)
  for i = 1,15,1 do
    if turtle.getItemDetail() ~= nil then
      if turtle.getItemDetail().name == "minecraft:charcoal" then
        turtle.drop(turtle.getItemDetail().count)
      end
    end
  end
  turtle.select(16)
  if turtle.getItemDetail() ~= nil then
    fuelCountNeeded = 64 - turtle.getItemDetail().count
  else 
    fuelCountNeeded = 64
  end
  turtle.suck(64)
  turtle.refuel()
end

function harvestSweep()
  for i = 1,#plotStrips,1 do
    goToPos(plotLimitxRight,1,plotStrips[i] - 1,0)
    goToPos(plotLimitxRight,1,plotStrips[i],4)
    turtle.dig()
    moveForward()
    while currentPos.x < plotLimitxLeft do  
      blockpres, blockdata = turtle.inspectDown()
      if blockdata.name == birchLogIdentifier then
        turtle.digUp()
        moveUp()
        turtle.digUp()
        moveUp()
        turtle.digUp()
        moveDown()
        moveDown()
        turtle.digDown()
        turtle.select(saplingInvSlot)
        turtle.placeDown()
      end
      turtle.dig()
      moveForward()
    end
  end
end

function saplingSweep()    
  for iz = plotCornerBL.z,plotCornerTR.z,1 do
    for ix = plotCornerTR.x,plotCornerBL.x,1 do
      goToPos(ix,plotHoverHeight,iz,0)
      turtle.suckDown()
    end
  end
end

if not powerOnSelfTest() then
  print("POST failed")
end

while true do
  preCheckFuel()
  harvestSweep()
  sleep()
  --saplingSweep()
  dumpInventory() 
  goToPos(0,0,0,1)
  sleep(1200)
end