Turtle_Mine

local x,y,z = 0,0,0
local Dir = 0
local State = "mine"

local function move(dir)
    if string.lower(dir) == "up" then
        if turtle.detectUp() == false and turtle.getFuelLevel ~= 0 then
            y = y + 1
            turtle.up()
        else
            return false
        end
        return true;
    end
    if string.lower(dir) == "down" then
        if turtle.detectDown() == false and turtle.getFuelLevel ~= 0 then
            y = y - 1
            turtle.down()
        else
            return false
        end
        return true;
    end
    if string.lower(dir) == "forward" then
        if turtle.detect() == false and turtle.getFuelLevel ~= 0 then
            if Dir % 4 == 0 then
                x = x + 1
            elseif Dir % 4 == 1 then
                z = z + 1
            elseif Dir % 4 == 2 then
                x = x -1
            elseif Dir % 34 == 3 then
                z = z - 1
            end
            turtle.forward()
        else
            return false
        end
        return true;
    end
end

local function Turn(dir)
    if string.lower(dir) == "left" then
        turtle.turnLeft()
        Dir = Dir + 1
    end
    if string.lower(dir) == "right" then
        turtle.turnRight()
        Dir = Dir - 1
    end
end

local function mine()
    repeat
        --print("Dig")
        turtle.dig()
        turtle.digUp()
        sleep(.5)
    until turtle.detect() == false
    --print("No Block Found")
end

local function doFuleCheck()
    local TotalDist = math.abs(x) + math.abs(y) + math.abs(z)
    if (TotalDist >= turtle.getFuelLevel()) then
        State = "return"
        return true
    else
        return false
    end
end

local Block = nil
repeat
    move("forward")
    Block = turtle.detect()
until Block or doFuleCheck()

print("Mining")

while true do
    print(State)
    if State == "mine" then
        for i = 1,3 do
            if doFuleCheck() then break end
            mine()
            move("forward")
        end
        Turn("left")
        if turtle.detect() then
            for i = 1,5 do
                if doFuleCheck() then break end
                mine()
                move("forward")
            end

            for i = 1,2 do
                if doFuleCheck() then break end
                Turn("left")
            end

            for i = 1,5 do
                if doFuleCheck() then break end
                mine()
                move("forward")
            end
            Turn("left")
        else
            Turn("right")
        end

        Turn("right")
        if turtle.detect() then
            for i = 1,5 do
                if doFuleCheck() then break end
                mine()
                move("forward")
            end
            for i = 1,2 do
                if doFuleCheck() then break end
                Turn("left")
            end
            for i = 1,5 do
                if doFuleCheck() then break end
                mine()
                move("forward")
            end
            Turn("right")
        else
            Turn("left")
        end

    elseif State == "return" then
        if Dir == 2 or Dir == 4 then
            if Dir % 4 == 2 and z < 0 or Dir % 4 == 4 and z > 0 then
                for i = 1,2 do
                    Turn("left")
                end
            end

            for i = 1,math.abs(z) do
                move("forward")
            end
            Turn("left")

            if Dir == 1 then
                for i = 1,2 do
                    Turn("left")
                end
            end
        end

        if z ~= 0 then
            error("Was not able to return to z0")
        end

        repeat
            move("forward")
        until x == 0

        for i = 1,2 do
            Turn("left")
        end
    end
end