turleminedon

local t = turtle
local fuel = 0
local fuelBuffer = 30
local returning = false

local NORTH = 1
local EAST = 2
local SOUTH = 3
local WEST = 4

Point = {}
Point.__index = Point
function Point:new(x,y,z,dir)
    local obj = {x=x,y=y,z=z,dir=dir}
    setmetatable(obj,Point)
    return obj
end

function Point:forward()
    if self.dir == NORTH then
        self.y=self.y+1
    elseif self.dir == South then
        self.y=self.y-1
    elseif self.dir == EAST then
        self.x=self.x+1
    elseif self.dir == WEST then
        self.x=self.x-1
    end
end

function Point:back()
    if self.dir == NORTH then
        self.y=self.y-1
    elseif self.dir == South then
        self.y=self.y+1
    elseif self.dir == EAST then
        self.x=self.x-1
    elseif self.dir == WEST then
        self.x=self.x+1
    end
end

function Point:up()
        self.y=self.y+1
end

function Point:down()
    self.y=self.y-1
end

function Point:right()
    self.dir=self.dir+1
    if self.dir>WEST then
        self.dir = NORTH
    end
end

function Point:left()
    self.dir=self.dir-1
    if self.dir<NORTH then
        self.dir = WEST
    end
end

function Point:print()
    local dirText=""
    if self.dir == NORTH then
        dirText="NORTH"
    elseif self.dir == South then
        dirText="SOUTH"
    elseif self.dir == EAST then
        dirText="EAST"
    elseif self.dir == WEST then
        dirText="WEST"
    end
    print("Point: ("..self.x..","..self.y..","..self.z..","..dirText..")")
end

local relativePos=Point:new(0,0,0,NORTH)

function onTurnon()
    fuel = getFuelLevel()
end

function dumpInventory()
    for i = 0, 15 do
        t.select(i)
        t.dropDown()
    end
end

function restockFuel()
    fFace(SOUTH)
    t.select(0)
    t.suck()
    t.refuel()
end

function refuelReturn()
    --Fix Z
    while relativePos.z>0 do
        fDown()
    end
    while relativePos.z<0 do
        fUp()
    end

    --Fix x
    if relativePos.x<0 then
        fFace(EAST)
    elseif relativePos.x>0 then
        fFace(WEST)
    end
    while relativePos.x~=0 do
        fForward()
    end

    --Fix y
    if relativePos.y<0 then
        fFace(NORTH)
    elseif relativePos.y>0 then
        fFace(SOUTH)
    end

    while relativePos.y~=0 do
        fForward()
    end
end

function goBackTO(pointA)
    --Fix Z
    while pointA.z>0 do
        fDown()
    end
    while pointA.z<0 do
        fUp()
    end

    --Fix y
    if pointA.y<0 then
        fFace(NORTH)
    elseif pointA.y>0 then
        fFace(SOUTH)
    end

    while pointA.y~=0 do
        fForward()
    end

    --Fix x
    if pointA.x<0 then
        fFace(EAST)
    elseif pointA.x>0 then
        fFace(WEST)
    end

    while pointA.x~=0 do
        fForward()
    end

    --Fix dir
    fFace(pointA.dir)
end

--Get the current fuel level and return home if too close to empty
--If we refuel we come back to the same posisiton/orientation
function updateFuel()
    if returning then
        return
    end
    fuel = t.getFuelLevel()
    --Fuel to get back home is calculated
    local blocksBack = relativePos.x+relativePos.y+relativePos.z
    if fuel <= blocksBack + fuelBuffer then
        returning=true
        local returnPoint = Point:new(relativePos.x,relativePos.y,relativePos.z,relativePos.dir)
        refuelReturn()
        restockFuel()
        goBackTo(returnPoint)
        returning=false
    end
end

function fDig()
    while t.detect() do
        updateFuel()
        t.dig()
    end
end

function fDigDown()
    while t.detectDown() do
        updateFuel()
        t.digDown()
    end
end

function fDigUp()
    while t.detectUp() do
        updateFuel()
        t.digUp()
    end
end

function fForward(x)
    x = x or 1
    for i=1,x do
        while not t.forward() do
            updateFuel()
            fDig()
        end
        relativePos:forward()
        updateFuel()
    end
end

function fDown()
    while not t.down() do
        updateFuel()
        fDigDown()
    end
    relativePos:down()
    updateFuel()
end

function fUp()
    while not t.up() do
        updateFuel()
        fDigUp()
    end
    relativePos:up()
    updateFuel()
end

function fRight()
    t.turnRight()
    relativePos:right()
    updateFuel()
end

function fLeft()
    t.turnLeft()
    relativePos:left()
    updateFuel()
end

function fTurnAround()
    fRight()
    fRight()
end

function fBack()
    if not t.back() then
        fTurnAround()
        fDig()
        fTurnAround()
    end
    relativePos:back()
    updateFuel()
end

function fFace(d)
    if d == relativePos.dir then
        return
    elseif d-relativePos.dir==1 then
        fLeft()
    elseif relativePos.dir-d==1 then
        fRight()
    else
        fTurnAround()
    end
end

--Assuming middle start
function mine3By3(x)
    for i=0,x do
        --dig middle part
        fDig()
        fForward()
        fDigUp()
        fDigDown()
        --dig left part
        fLeft()
        fDig()
        fForward()
        fDigUp()
        fDigDown()
        --dig right part
        fTurnAround()
        fForward()
        fDig()
        fForward()
        fDigUp()
        fDigDown()
        --return
        fBack()
        fLeft()
    end
end

function mine()
    fUp()
    fFace(NORTH)
    while true do
        mine3By3(5)
        fLeft()
        fForward()
        mine3By3(5)
        fTurnAround()
        fForward(5+3)
        mine3By3(5)
        fTurnAround()
        fForward(5+2)
        fRight()
    end
end

mine()