excavate2

local targs = { ... }

local size = tonumber ( targs[1] )

local depth = 0

if #targs == 2 then
	depth = tonumber(tArgs[2])
else
	depth = tonumber(tArgs[3]) - tonumber(tArgs[2]))
end

local xPos,zPos = 0,0
local xDir,zDir = 0,1

local goTo -- Filled in further down
local refuel -- Filled in further down

local function unload()
	print( "unloading items..." )
	for n=1, 16 do
		turtle.select(n)
		if (turtle.drop()) == false then
			return false
		end
	end
	turtle.select(n)
	return true
end

local function returnSupplies()
	local x,y,z,xd,zd = xPos,depth,zPos,xDir,zDir
        print( "Returning to surface..." )
        goTo( 0,0,0,0,-1 )

	-- Attempts to unloads
	local notStuck == false
	repeat
		local notStuck = unload()
		if notStuck == false then
			sleep(5)
		end
	until notStuck

        local fuelNeeded = x+y+z + x+y+z + 5
        if not refuel( fuelNeeded ) then

                print( "Waiting for fuel" )
                while not refuel( fuelNeeded ) do
                        sleep(5)
                end
        end

        print( "Resuming mining..." )
        goTo( x,y,z,xd,zd )
end

local function collect()
	local bFull = true
	for n=1, 16 do
		local nCount = turtle.getItemCount(n)
		if nCount == 0 then
			bFull = false
		end
	end

	if bFull then
		print("No empty slots left")
		return false
	end
	return true
end

function refuel( ammount )
        local fuelLevel = turtle.getFuelLevel()
        if fuelLevel == "unlimited" then
                return true
        end

        local needed = ammount or (xPos + zPos + depth + 1)
        if turtle.getFuelLevel() < needed then
		if turtle.refuel() then
			return true
		else
                	return false
		end
        end

        return true
end

local function dig()
	if turtle.detectUp() then
		if turtle.digUp() then
			if not collect() then
				returnSupplies()
			end
		else
			sleep(1)
		end
	end

	if turtle.detectDown() then
		if turtle.digDown() then
			if not collect() then
				returnSupplies()
			end
		else
			sleep(1)
		end


end


local function tryForwards()
	if not refuel() then
		print("Not enough Fuel")
		returnSupplies()
	end

	while not turtle.forward() do
		if turtle.detect() then
			if turtle.dig() then
				if not collect() then
					returnSupplies()
				end
			else
				return false
			end
		elseif turtle.attack() then
			if not collect() then
				returnSupplies()
			end
		else
			sleep( 1 )
		end
	end

        xPos = xPos + xDir
        zPos = zPos + zDir
        return true
end

local function tryDown()
        if not refuel() then
                print( "Not enough Fuel" )
                returnSupplies()
        end

        while not turtle.down() do
                if turtle.detectDown() then
                        if turtle.digDown() then
                                if not collect() then
                                        returnSupplies()
                                end
                        else
                                return false
                        end
                elseif turtle.attackDown() then
                        if not collect() then
                                returnSupplies()
                        end
                else
                        sleep( 1 )
                end
        end

        depth = depth + 1
        return true
end


local function turnLeft()
        turtle.turnLeft()
        xDir, zDir = -zDir, xDir
end

local function turnRight()
        turtle.turnRight()
        xDir, zDir = zDir, -xDir
end

function goTo( x, y, z, xd, zd )
        while depth > y do
                if turtle.up() then
                        depth = depth - 1
                elseif turtle.digUp() or turtle.attackUp() then
                        collect()
                else
                        sleep( 0.5 )
                end
        end

        if xPos > x then
                while xDir ~= -1 do
                        turnLeft()
                end
                while xPos > x do
                        if turtle.forward() then
                                xPos = xPos - 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        elseif xPos < x then
                while xDir ~= 1 do
                        turnLeft()
                end
                while xPos < x do
                        if turtle.forward() then
                                xPos = xPos + 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        end

        if zPos > z then
                while zDir ~= -1 do
                        turnLeft()
                end
                while zPos > z do
                        if turtle.forward() then
                                zPos = zPos - 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        elseif zPos < z then
                while zDir ~= 1 do
                        turnLeft()
                end
                while zPos < z do
                        if turtle.forward() then
                                zPos = zPos + 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        end

        while depth < y do
                if turtle.down() then
                        depth = depth + 1
                elseif turtle.digDown() or turtle.attackDown() then
                        collect()
                else
                        sleep( 0.5 )
                end
        end

        while zDir ~= zd or xDir ~= xd do
                turnLeft()
        end
end

-- Here is the start of the program really

if not refuel() then
        print( "Out of Fuel" )
        return
end

print( "Excavating..." )


local alternate = 0
local done = false


if depth > 0 then
	for n=0, depth do
		tryDown()
	end
end

while not done do
        for n=1,size do
                for m=1,size-1 do

			dig() -- dig top and bottom

                        if not tryForwards() then
                                done = true
                                break
                        end
                end
                if done then
                        break
                end
                if n<size then
                        if math.fmod(n + alternate,2) == 0 then
                                turnLeft()
				dig()
                                if not tryForwards() then
                                        done = true
                                        break
                                end
				dig()
                                turnLeft()
                        else
                                turnRight()
				dig()
                                if not tryForwards() then
                                        done = true
                                        break
                                end
				dig()
                                turnRight()
                        end
                end
        end
        if done then
                break
        end

        if size > 1 then
                if math.fmod(size,2) == 0 then
                        turnRight()
                else
                        if alternate == 0 then
                                turnLeft()
                        else
                                turnRight()
                        end
                        alternate = 1 - alternate
                end
        end
	dig()
	tryDown()
	tryDown() -- we go down twice

        if not tryDown() then
                done = true
                break
        end
end

print( "Returning to surface..." )

-- Return to where we started
goTo( 0,0,0,0,-1 )
unload()
goTo( 0,0,0,0,1 )