MiningTurtle = {
    position = {
        x = 0, -- WEST/EAST
        y = 0, -- UP/DOWN
        z = 0  -- SOUTH/NORTH
    },
    direction = 0
    -- 0 = SOUTH -> Z++
    -- 1 = WEST -> X--
    -- 2 = NORTH -> Z--
    -- 3 = EAST -> X++
}

-- Constructor

function MiningTurtle:new()

    local object = { }

    setmetatable(object, { __index = MiningTurtle })
    return object
end

-- Check if the Turtle needs to be refueled ( <= refuelLevel )
-- if yes, try to refuel it taking the contents of the inventory
-- if this is not possible or not enough, go back to base
function MiningTurtle:requiredRefuel( refuelLevel, requiredFuelLevel )
    local slot

    if refuelLevel == nil then
        refuelLevel         = 25
    end

    if requiredFuelLevel == nil then
        requiredFuelLevel   = 500
    end

    -- should we refuel?
    if turtle.getFuelLevel() <= refuelLevel then

        print("Turtle needs refuel!!!")

        -- iterate through our inventory
        for slot = 1,16 do

            -- select slot
            turtle.select(slot)

            -- refuel from active slot...
            if turtle.refuel( turtle.getItemCount( slot ) ) then

            end

            -- ...and check again
            if turtle.getFuelLevel() >= requiredFuelLevel then
                return true
            end

        end

        -- check if we did not refueled enough alreay
        if not (turtle.getFuelLevel() >= requiredFuelLevel) then
            -- if yes, go back to base

            MiningTurtle:toBase()
            -- refuel: to be implemented!!!!
        end

        return false
    end

    return true
end

-- Go back to the base of the MiningTurtle
function MiningTurtle:toBase( )

end

-- Go to ground
function MiningTurtle:toGround( )

    while not turtle.detectDown() do
        MiningTurtle:down()
    end

end

-- Go the our "base" Ground (z = 0)
function MiningTurtle:toBaseLevel( )

    while self.position.y > 0 do
        MiningTurtle:saveDown()
    end

end

-- forward
function MiningTurtle:forward()
    local ret

    ret = turtle.forward()

    if ret then


        if self.direction == 0 then
            -- 0 = SOUTH -> Z++
            self.position.z = self.position.z + 1

        elseif self.direction == 1 then
            -- 1 = WEST -> X--
            self.position.x = self.position.x - 1

        elseif self.direction == 2 then
            -- 2 = NORTH -> Z--
            self.position.z = self.position.z -  1

        elseif self.direction == 3 then
            -- 3 = EAST -> X++
            self.position.x = self.position.x + 1

        end

    end

    MiningTurtle:tick()

    return ret
end

-- back
function MiningTurtle:back()
    local ret

    ret = turtle.back()

    if ret then

        -- all directions reverse!!! (moving back)

        if self.direction == 0 then
            -- 0 = SOUTH -> Z++
            self.position.z = self.position.z - 1

        elseif self.direction == 1 then
            -- 1 = WEST -> X--
            self.position.x = self.position.x + 1

        elseif self.direction == 2 then
            -- 2 = NORTH -> Z--
            self.position.z = self.position.z +  1

        elseif self.direction == 3 then
            -- 3 = EAST -> X++
            self.position.x = self.position.x - 1

        end

    end

    MiningTurtle:tick()

    return ret
end

-- up
function MiningTurtle:up()
    local ret

    ret = turtle.up()

    if ret then
        self.position.y = self.position.y + 1
    end

    MiningTurtle:tick()

    return ret
end

-- down
function MiningTurtle:down()
    local ret

    ret = turtle.down()

    if ret then
        self.position.y = self.position.y - 1
    end


    MiningTurtle:tick()

    return ret
end

-- turn Left
function MiningTurtle:turnLeft()
    local ret

    ret = turtle.turnLeft()

    if ret then
        self.direction = self.direction + 1

        while self.direction >= 4 do
            self.direction = self.direction - 4
        end
    end

    MiningTurtle:outPos()

    return ret
end

-- turn Right
function MiningTurtle:turnRight()
    local ret

    ret = turtle.turnRight()

    if ret then
        self.direction = self.direction - 1

        while self.direction < 0 do
            self.direction = self.direction - 4
        end
    end

    MiningTurtle:outPos()

    return ret
end

-- Save forward
function MiningTurtle:saveForward()

    while not MiningTurtle:forward() do
        turtle.dig()
    end
end

-- Save up
function MiningTurtle:saveUp()

    while not MiningTurtle:up() do
        turtle.digUp()
    end
end

-- Save down
function MiningTurtle:saveDown()

    while not MiningTurtle:down() do
        turtle.digDown()
    end
end

-- 180 degree turn
function MiningTurtle:turn()

    MiningTurtle:turnRight()
    MiningTurtle:turnRight()
end

-- output pos data
function MiningTurtle:outPos()

    print("Pos: " .. self.position.x .. "|" .. self.position.z .. "|" .. self.position.y .. " o: " .. self.direction .. " f: " .. turtle.getFuelLevel() )

end

-- Turn to direction
function MiningTurtle:turnTo( newOrientation )
    while self.direction ~= newOrientation do
        if math.abs(self.direction - newOrientation) < 180 then
            MiningTurtle:turnRight()
        else
            MiningTurtle:turnLeft()
        end
    end
end

-- Go to
function MiningTurtle:goTo( newPosition )
    -- 0 = SOUTH -> Z++
    -- 1 = WEST -> X--
    -- 2 = NORTH -> Z--
    -- 3 = EAST -> X++

    while not ( (newPosition.x - self.position.x) == 0 and (newPosition.z - self.position.z) == 0 and (newPosition.y - self.position.y) == 0 ) do
        print("Was: " .. self.position.x .. "|" .. self.position.z .. "|" .. self.position.y)

        if math.ceil(newPosition.x - self.position.x) < 0 then
            MiningTurtle:turnTo(1)
            MiningTurtle:saveForward()
        elseif math.floor(newPosition.x - self.position.x) > 0 then
            MiningTurtle:turnTo(3)
            MiningTurtle:saveForward()
        end

        if math.ceil(newPosition.z - self.position.z) < 0 then
            MiningTurtle:turnTo(2)
            MiningTurtle:saveForward()
        elseif math.floor(newPosition.z - self.position.z) > 0 then
            MiningTurtle:turnTo(0)
            MiningTurtle:saveForward()
        end

        if math.ceil(newPosition.y - self.position.y) < 0 then
            MiningTurtle:saveDown()
        elseif math.floor(newPosition.y - self.position.y) > 0 then
            MiningTurtle:saveUp()
        end
        print("Is: " .. self.position.x .. "|" .. self.position.z .. "|" .. self.position.y)

    end

end

-- Make a tunnel
function MiningTurtle:tunnel( length, height, width, ret )

    -- default values for parameters, only length is required (!)
    if height == nil then
        height  = 2
    end

    if width == nil then
        width   = 1
    end

    if ret == nil then
        ret     = false
    end

    -- Save our current positon back for later return

    returnPos = {}
    returnPos.x = self.position.x
    returnPos.z = self.position.z
    returnPos.y = self.position.y
    returnDirection = self.direction

    -- Place the turtle at the lower left corner of the new tunnel (so that we were starting from the middle of the new tunnel)
    -- We only need this, if we have a tonnel with a width > 2 (<=2 means we are already on the right position)

    if width > 2 then

        MiningTurtle:turnLeft()

        for i = 0,math.floor( width / 2 ) do
            MiningTurtle:saveForward()
        end

        MiningTurtle:turnRight()
    end

    -- Length loop

    for i = 0,length-1 do

        MiningTurtle:saveForward()

        if i % 2 == 0 then
            -- even

            -- only change direction if we mine a tunnel wider than 1 block
            if width > 1 then
                MiningTurtle:turnRight()
            end

            for x = 0,width-1 do

                for y = 0,height-3 do

                    if x % 2 == 0 then
                        MiningTurtle:saveUp()
                    else
                        MiningTurtle:saveDown()
                    end

                end

                if height > 1 then
                    turtle.digUp()
                end

                if x < width-1 then
                    MiningTurtle:saveForward()
                end
            end

            -- same as above
            if width > 1 then
                MiningTurtle:turnLeft()
            end

        else
            -- odd

            if width > 1 then
                MiningTurtle:turnLeft()
            end

            for x = 0,width-1 do

                for y = 0,height-3 do

                    if x % 2 == 1 or width % 2 == 0 then
                        MiningTurtle:saveUp()
                    else
                        MiningTurtle:saveDown()
                    end

                end

                if height > 1 then
                    turtle.digUp()
                end

                if x < width-1 then
                    MiningTurtle:saveForward()
                end
            end

            if width > 1 then
                MiningTurtle:turnRight()
            end
        end

    end

    if ret then

        -- Go up to not remove torches on the floow
        MiningTurtle:saveUp()

        MiningTurtle:goTo( returnPos )

        MiningTurtle:turnTo( returnDirection )

    end

end

function MiningTurtle:tick()
    MiningTurtle:outPos()

    -- refuel loop
    if not MiningTurtle:requiredRefuel( 20, 50 ) then
        write(".")
        sleep(1)
    end
end

--
function MiningTurtle:matrix( rows, cols )

    MiningTurtle:tick()

    --MiningTurtle:toBaseLevel()
    MiningTurtle:toGround()

    --MiningTurtle:tunnel(5, 2, 2, true)
    MiningTurtle:goTo( { x=0, y=-5, z=-5 } )

end


-- main program

baby = MiningTurtle:new()

baby:matrix( 10, 10 )