--put coal in slot 1 and what to not mine in slot 2. 3 is another not mine.
--so coal, cobble, smooth



x = 0
y = 0
z = 0
--Facing direction start with 1 being 90 degrees left. 2 is backwards etc.
--By convention we will always face 0 when not doing something.
--We will take this to be right.
facing = 0

oldX = 0
oldY = 0
oldZ = 0

hundredStepsCount = 0

function eachStep()


  if z >= oldZ then --we did not just move down
    turtle.select(2)
    if not turtle.compareUp() then
      turtle.select(3)
      if not turtle.compareUp() then
        turtle.digUp()
      end
    end
  end

  if z <= oldZ then --we did not just move up
    turtle.select(2)
    if not turtle.compareDown() then
      turtle.select(3)
      if not turtle.compareDown() then
        turtle.digDown()
      end
    end
  end

  turtle.select(2)
  if not turtle.compare() then
    turtle.select(3)
    if not turtle.compare() then
      turtle.dig()
    end
  end

  --refuel and drop cobble every now and then. Doing this often slows it down
  if hundredStepsCount == 0 then

    for i = 4, 16 do
      turtle.select(i)
      if turtle.compareTo(2) then
        turtle.drop()
      end
    end

    if turtle.getFuelLevel() ~= "unlimited" and turtle.getFuelLevel() < 201 then
      turtle.select(1)
      if turtle.getItemCount() > 5 then
        turtle.refuel(5)
      end
    end

  end


  hundredStepsCount = hundredStepsCount + 1
  if hundredStepsCount == 101 then
    hundredStepsCount = 0
  end


  oldX = x
  oldY = y
  oldZ = z
end





function turnLeft()
  facing = facing - 1
  if facing < 0 then
    facing = facing + 4
  end
  turtle.turnLeft()
end

function turnRight()
  facing = facing + 1
  if facing > 3 then
    facing = facing - 4
  end
  turtle.turnRight()
end






function faceXLeft()
  if facing == 0 then
    turnLeft()
    turnLeft()
  elseif facing == 1 then
    turnRight()
  elseif facing == 2 then
    return
  elseif facing == 3 then
    turnLeft()
  end
end

function faceXRight()
  if facing == 0 then
    return
  elseif facing == 1 then
    turnLeft()
  elseif facing == 2 then
    turnLeft()
    turnLeft()
  elseif facing == 3 then
    turnRight()
  end
end

function faceYUp()
  if facing == 0 then
    turnLeft()
  elseif facing == 1 then
    turnLeft()
    turnLeft()
  elseif facing == 2 then
    turnRight()
  elseif facing == 3 then
    return
  end
end

function faceYDown()
  if facing == 0 then
    turnRight()
  elseif facing == 1 then
    return
  elseif facing == 2 then
    turnLeft()
  elseif facing == 3 then
    turnLeft()
    turnLeft()
  end
end






function zUp()
  while turtle.detectUp() do
    while not turtle.digUp() do
      --loop
    end
  end
  while not turtle.up() do
    turtle.digUp()
  end
  z = z + 1
  eachStep()
end

function zDown()
  while turtle.detectDown() do
    while not turtle.digDown() do
      --loop
    end
  end
  while not turtle.down() do
    turtle.digDown()
  end
  z = z - 1
  eachStep()
end

function xLeft()
  faceXLeft()
  while turtle.detect() do
    while not turtle.dig() do
      --loop
    end
  end
  while not turtle.forward() do
    turtle.dig()
  end
  x = x - 1
  eachStep()
end

function xRight()
  faceXRight()
  while turtle.detect() do
    while not turtle.dig() do
      --loop
    end
  end
  while not turtle.forward() do
    turtle.dig()
  end
  x = x + 1
  eachStep()
end

function yUp()
  faceYUp()
  while turtle.detect() do
    while not turtle.dig() do
      --loop
    end
  end
  while not turtle.forward() do
    turtle.dig()
  end
  y = y + 1
  eachStep()
end

function yDown()
  faceYDown()
  while turtle.detect() do
    while not turtle.dig() do
      --loop
    end
  end
  while not turtle.forward() do
    turtle.dig()
  end
  y = y - 1
  eachStep()
end








function zUpIsBlock()
  return turtle.detectUp()
end

function zDownIsBlock()
  return turtle.detectDown()
end

function xLeftIsBlock()
  faceXLeft()
  return turtle.detect()
end

function xRightIsBlock()
  faceXRight()
  return turtle.detect()
end

function yUpIsBlock()
  faceYUp()
  return turtle.detect()
end

function yDownIsBlock()
  faceYDown()
  return turtle.detect()
end








--find direction to start
while turtle.detect() do
  turtle.turnLeft()
end
facing = 0
--we're assumed to now be facing to the right







--Now well get the params from the spacing.
--Its just a box. We assume to be on x center and edge on y and z.
--First we get to and edge

while not xRightIsBlock() do
  xRight()
end

--Now at right end
maxX = x



while not xLeftIsBlock() do
  xLeft()
end

minX = x

--Now we in top left


minZ = 0
maxZ = 10

--square
minY = -(maxX - minX)
maxY = y






--start (from top left)
--We are on the minX and minY in top left

while y > minY do

  while x < maxX do
    --Mine from far left to right

    if z == minZ then
      while z < maxZ do
        zUp()
      end
    else
      while z > minZ do
        zDown()
      end
    end

    xRight()

  end
  --now at far right

  if z == minZ then
    while z < maxZ do
      zUp()
    end
  else
    while z > minZ do
      zDown()
    end
  end

  yDown()



  if y == minY then
    break
  end

  while x > minX do
    --Mine from far right to left

    if z == minZ then
      while z < maxZ do
        zUp()
      end
    else
      while z > minZ do
        zDown()
      end
    end

    xLeft()
  end

  if z == minZ then
    while z < maxZ do
      zUp()
    end
  else
    while z > minZ do
      zDown()
    end
  end

  --now on far left
  yDown()

end

while z > minZ do
  zDown()
end