miner v1.2

local function find(itemName)
    for curSlot = 1,16 do
        if turtle.getItemCount(curSlot) >= 1 then
            local data = turtle.getItemDetail(curSlot)
            if data.name == itemName then
                return curSlot
            end
        end
    end
    return false
end

local tArgs = { ... }
if #tArgs ~= 1 then
    print( "Usage: miner <distance>" )
    return
end

local maxDist = tonumber( tArgs[1] )
if maxDist < 1 then
    print( "Distance must be positive" )
    return
end

local function getFreeInventorySpace()
    local freeSpace = 16
    for curSlot = 1,16 do
        if turtle.getItemCount(curSlot) ~= 0 then
            freeSpace = freeSpace - 1
        end
    end
    return freeSpace
end

local function sortInventory()
    local inventory = {}
    for curSlot=1,16 do
        if turtle.getItemCount(curSlot) ~= 0 then
            inventory[curSlot] = turtle.getItemDetail(curSlot)
        else
            inventory[curSlot] = "empty"
        end
    end
    for slotA=1,16 do
        if inventory[slotA] ~= "empty" then
            for slotB=1,16 do
                if inventory[slotB] ~= "empty" then
                    if slotA ~= slotB then
                        if (inventory[slotA].name == inventory[slotB].name) and (inventory[slotA].damage == inventory[slotB].damage) then
                            if inventory[slotA].count + inventory[slotB].count <= 64 then
                                turtle.select(slotB)
                                turtle.transferTo(slotA)
                                inventory[slotB] = "empty"
                            end
                        end
                    end
                end
            end
        end
    end
end

local function digAround()
    while turtle.detectUp() do
        turtle.digUp()
    end
    if turtle.detectDown() then
        local success, data = turtle.inspectDown()
        if success then
            if not (data.name == "minecraft:cobblestone") and not (data.name == "minecraft:stone") and not (data.name == "minecraft:sand") and not (data.name == "minecraft:dirt") and not (data.name == "minecraft:gravel") and not (data.name == "chisel:marble2") and not (data.name == "chisel:limestone2") then
                turtle.digDown()
            end
        end

    end
    if find("minecraft:cobblestone") then
        turtle.select(find("minecraft:cobblestone"))
        turtle.placeDown()
    elseif find("minecraft:stone") then
        turtle.select(find("minecraft:stone"))
        turtle.placeDown()
    end
end

local function checkFuel(level)
    if (turtle.getFuelLevel() <= level) and (find("minecraft:coal")) then
        turtle.select(find("minecraft:coal"))
        turtle.refuel(1)
    end
end

local function returnToStart(travelled, continue)
    if continue then
        print("Returning to deposit items, then continuing")
    else
        print("Returning to deposit items; job done")
    end
    turtle.turnLeft()
    turtle.turnLeft()
    for curDist=0,travelled do
        checkFuel(10)
        local success, data = turtle.inspect()
        if success then
            if data.name ~= "minecraft:chest" then
                while not turtle.forward() do
                    turtle.dig()
                end
            end
        else
            while not turtle.forward() do
                turtle.dig()
            end
        end
    end

    local success, data = turtle.inspect()
    if success then
        if data.name == "minecraft:chest" then
            for curSlot = 1,16 do
                if turtle.getItemCount(curSlot) ~= 0 then
                    block = turtle.getItemDetail(curSlot)
                    if (block.name ~= "minecraft:coal") and (block.name ~= "minecraft:torch") and (block.name ~= "tconstruct:stone_torch") then
                        turtle.select(curSlot)
                        turtle.drop()
                    end
                end
            end
        end
    end

    if continue then
        turtle.turnLeft()
        turtle.turnLeft()
        for curDist=0,travelled-1 do
            checkFuel(10)
            local success, data = turtle.inspect()
            if success then
                if data.name ~= "minecraft:chest" then
                    while not turtle.forward() do
                        turtle.dig()
                    end
                end
            else
                while not turtle.forward() do
                    turtle.dig()
                end
            end
        end
    end
end

local travelDist = 0

while travelDist <= maxDist do
    checkFuel(10)
    if (find("minecraft:torch") == false) and (find("tconstruct:stone_torch") == false) then
        break
    end
    sortInventory()
    if getFreeInventorySpace() <= 1 then
        returnToStart(travelDist,true)
    end
    digAround()
    turtle.turnLeft()
    while not turtle.forward() do
        turtle.dig()
    end
    digAround()
    turtle.turnRight()
    turtle.turnRight()
    turtle.forward()
    while not turtle.forward() do
        turtle.dig()
    end
    digAround()
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.forward()
    if (travelDist % 6 == 0) and ((find("minecraft:torch") or (find("tconstruct:stone_torch"))) then
        if find("tconstruct:stone_torch") then
            turtle.select(find("tconstruct:stone_torch"))
        else
            turtle.select(find("minecraft:torch"))
        end
        turtle.place()
    end
    turtle.turnRight()
    if travelDist <= maxDist then
        while not turtle.forward() do
            turtle.dig()
        end
        travelDist = travelDist + 1
    end
end

returnToStart(travelDist,false)