Mine

local t = require("libs.tlib")

local direction
local tunnelHeight = 3
local numRepeats = 8
local tunnelLength
local continueWork = false

local tFuel = {
    'charcoal',
    'coal',
}

tProtectedBlocks = {
    ['minecraft:diamond_ore'] = true,
    ['minecraft:lapis_ore'] = true,
    ['minecraft:redstone_ore'] = true,
}

local tkeepItems = {
    ['minecraft:torch'] = true,
    ['minecraft:chest'] = true,
}

local tDropTable = {
    -- 'cobblestone',
    'granite',
    'andesite',
    'diorite',
    'dirt',
    'gravel',
}

local tTurnRightFacing = {
    ['north'] = 'east',
    ['east'] = 'south',
    ['south'] = 'west',
    ['west'] = 'north',
}

local tTurnLeftFacing = {
    ['north'] = 'west',
    ['east'] = 'north',
    ['south'] = 'east',
    ['west'] = 'south',
}

local function isProtectedBlock(success, data)
    if success and tProtectedBlocks[data.name] then
        if data.name == 'minecraft:diamond_ore' then
            print('I found diamonds!')
        end
        return true
    end
    return false
end

local function determineFacing()
    t.forward()
    if not turtle.detect() then
        if not t.existItem('cobblestone') then
            print('add cobblestone')
            while not t.existItem('cobblestone') do
                sleep(1)
            end
        end
        if not (t.selectItem('cobblestone') and turtle.place()) then
            print('ERROR: could not place cobblestone')
            t.back()
            return false
        end
    end
    t.back()
    if not (t.selectItem('torch') and turtle.place()) then
        print('ERROR: could not place torch')
        return false
    end
    success, data = turtle.inspect()
    if not (success and data.state.facing) then
        return false
    else
        local direction = t.tInverseDirection[data.state.facing]
        print('Turtle is facing ' .. direction .. '.')
        return direction
    end
end

local function saveDig()
    if not isProtectedBlock(turtle.inspect()) then
        while turtle.dig() do
            --
        end
    end
end

local function torchTime(step)
    torchPlacement = {
        [2] = true,     [11] = true,
        [20] = true,  [29] = true,
        [38] = true,
      }
    return torchPlacement[step]
end

local function placeTorch()
    if not t.selectItem('torch') then
        print('out of torches!')
        t.turnLeft()
        return
    end
    turtle.place()
    success, data = turtle.inspect()
    if not t.tInverseDirection[direction] then
        print(direction)
        print(t.tInverseDirection[direction])
        error('ERROR in placeTorch(): no direction value')
    end
    if not success or (data.name == 'minecraft:wall_torch' and data.state.facing ~= t.tInverseDirection[direction]) then
        t.forward()
        if t.selectItem('cobblestone') and (turtle.placeDown() or turtle.place()) then
            t.back()
            if t.selectItem('torch') then
                turtle.place()
            end
        else
            t.turnAround()
            t.forward()
            if t.selectItem('torch') then
                turtle.place()
            end
            t.turnRight()
            return
        end
    elseif isProtectedBlock(turtle.inspect()) then
        t.turnAround()
        if t.selectItem('torch') then
            turtle.place()
        end
        t.turnRight()
        return
    end
    t.turnLeft()
    turtle.select(1)
end

local function dig3x3(torch)
    --recursive digging function:
    local function digOutLevel(level, max)
        saveDig()
        if (level < max) and (not isProtectedBlock(turtle.inspectUp())) then
            t.up()
            digOutLevel(level + 1, max)
            t.down()
        else
            t.turnAround()
        end
        saveDig()
    end

    if (not turtle.detectDown()) and t.selectItem('cobblestone') then
        turtle.placeDown()
    end
    t.turnLeft()
    digOutLevel(1, tunnelHeight)
    if torch then
        placeTorch()
    else
        t.turnLeft()
    end
end

local function emptySlots()
    local numEmptySlots = 0
    for slot=1, 16 do
        if turtle.getItemCount(slot) == 0 then
            numEmptySlots = numEmptySlots + 1
        end
    end
    return numEmptySlots
end



local function cleanUpInventory()
    for slot_n = 16, 2, -1 do
        if turtle.getItemCount(slot_n) > 0 then
            item_source = turtle.getItemDetail(slot_n)
            for slot_m = 1, slot_n-1 do
                if turtle.getItemSpace(slot_m) > 0 then
                    item_target = turtle.getItemDetail(slot_m)
                    if (item_source and item_target) and (item_source.name == item_target.name) then
                        turtle.select(slot_n)
                        turtle.transferTo(slot_m)
                        if turtle.getItemCount(slot_n) == 0 then
                            break
                        end
                    end
                end
            end
        end
    end
    for slot_n = 16, 2, -1 do
        if turtle.getItemCount(slot_n) > 0 then
            for slot_m = 1, slot_n-1 do
                if turtle.getItemCount(slot_m) == 0 then
                    turtle.select(slot_n)
                    turtle.transferTo(slot_m)
                    break
                end
            end
        end
    end
end

local function inventoryManagement()
    cleanUpInventory()
    if emptySlots() <= 2 then
        t.back()
        t.turnAround()
        if t.selectItem('chest') and turtle.place() then
            print('Turtle placed chest.')
            for i, v in ipairs(tDropTable) do
                t.dropAll(v)
            end
        end
        t.dropAllButOneStack('cobblestone')
        cleanUpInventory()
        t.turnAround()
        t.forward()
    end
    turtle.select(1)
end

local function stepAround(stepsLeft)
    local level = 1
    while stepsLeft > 0 do
        if isProtectedBlock(turtle.inspectUp()) then
            -- case 1
            t.back()
            stepsLeft = stepsLeft + 1
            if not isProtectedBlock(turtle.inspectUp()) then
                t.up()
                level = level + 1
            end
        elseif isProtectedBlock(turtle.inspect()) then
            -- case 2
            t.up()
            level = level + 1
            if not isProtectedBlock(turtle.inspect()) then
                t.forward()
                stepsLeft = stepsLeft - 1
            end
        elseif isProtectedBlock(turtle.inspectDown()) then
            -- case 3
            t.forward()
            stepsLeft = stepsLeft - 1
        elseif level > 1 then
            -- get down
            t.down()
            level = level - 1
        else
            return stepsLeft
        end
    end
    while level > 1 do
        t.down()
        level = level - 1
    end
    return stepsLeft
end

local function tunnel(stepsLeft)
    local torchCounter = 7
    while stepsLeft > 0 do

        if isProtectedBlock(turtle.inspect()) then
            local temp = stepAround(stepsLeft)
            local diff = stepsLeft - temp
            torchCounter = (torchCounter + diff) % 9
            stepsLeft = temp
        else
            t.forward()
            stepsLeft = stepsLeft - 1
            torchCounter = (torchCounter + 1) % 9
        end
        dig3x3(torchCounter == 0)
        inventoryManagement()
        sleep(0)
    end
end

local function uTurnRight()
    t.back()
    t.turnRight()
    direction = tTurnRightFacing[direction]
    t.forward()
    tunnel(6)
    t.back()
    t.turnRight()
    direction = tTurnRightFacing[direction]
    t.forward()
end

local function uTurnLeft()
    t.back()
    t.turnLeft()
    direction = tTurnLeftFacing[direction]
    t.forward()
    tunnel(6)
    t.back()
    t.turnLeft()
    direction = tTurnLeftFacing[direction]
    t.forward()
end

local function unload()
    for slot=1, 16 do
        item = turtle.getItemDetail(slot)
        if item and not tkeepItems[item.name] then
            turtle.select(slot)
            turtle.drop()
        end
    end
    turtle.select(1)
end

local function gotoNextTunnel()
    t.forward()
    t.forward()
    t.turnLeft()
    if t.selectItem('chest') and turtle.place() then
        unload()
    end
    t.turnRight()
    t.forward()
end

-- **** MAIN ********

-- SETUP
local tArgs = { ... }
if #tArgs == 0 then
    tunnelLength = false
elseif #tArgs ~= 1 then
    print( 'Usage: [mine] OR [mine <length>]' )
    return
else
    tunnelLength = tonumber(tArgs[1])
    if not (tunnelLength ~= nil and tunnelLength > 0 and tunnelLength <= 256) then
        print('Argument "' .. tArgs[1] ..  '" is not a valid number (between 1 and 256)')
        return
    end
end

t.setFuel(tFuel)
if not t.existItem('torch') then
    print('need torches...')
    while not t.existItem('torch') do
        sleep(1)
    end
end
direction = determineFacing()
if direction then
    t.setDirection(direction)
    direction = tTurnRightFacing[direction]
else
    error('ERROR: no Facing value')
end

print('Going Mining...')
print()
-- SETUP END

if tunnelLength then
    tunnel(tunnelLength)
else
    for n=1, numRepeats do
        -- first tunnel
        tunnel(39+3)
        -- U-Turn
        if (n % 2 == 0) then
            uTurnLeft()
        else
            uTurnRight()
        end
        -- second tunnel
        tunnel(39)
        -- cross the road
        gotoNextTunnel()
    end
end