test.lua

Chest = {name = "", itemList = {}, wrap = nil, maxslots = 0}

function Chest:new(o, name)
   o = o or {}
   setmetatable(o, self)
   self.__index = self
   self.name = name or ""
   return o
end

function Chest:init()
    self.itemList = {}
    for slot, item in pairs(self.wrap.list()) do
        --print(("%s:%d in slot %d"):format(item.name, item.count, slot))
        if self.itemList[item.name] == nil then
            self.itemList[item.name] = { slot = { slot }, itemCount = item.count }
        else
            table.insert(self.itemList[item.name]["slot"], slot)
            self.itemList[item.name].itemCount = self.itemList[item.name].itemCount + item.count
         end
    end
    self.maxslots = self.wrap.size()
end

function Chest:connect()
    self.wrap = peripheral.wrap(self.name)
end

function Chest:print()
    for k, v in self:sortedPairs(self.itemList) do
        textutils.pagedPrint(("%s : %d"):format(k, v.itemCount))
    end
end

function Chest:printItem(name)
    textutils.pagedPrint(("Item %s => %s"):format(name, textutils.serialise(self.itemList[name])))
end

function Chest:findFreeSlot()
    slot = 0
    for i, k in ipairs(self.wrap.list()) do
        slot = i
    end
    if (slot + 1) < self.maxslots then
        slot = slot + 1
    else
        slot = -1
    end
    return slot
end

function Chest:moveFromSlotToOtherSlot(name, slot1, slot2)
    return self.wrap.pushItems(name, slot1, 64, slot2)
end

function Chest:moveFromSlotToSlot(slot1, slot2)
    name = self.wrap.getItemDetail(slot1).name
    print(("Moving %s from %d to %d"):format(name, slot1, slot2))
    key = self:findKeyFromValueItem(name, slot1)
    if key ~= nil then
        self.itemList[name].slot[key] = slot2
    end
    return self:moveFromSlotToOtherSlot(self.name, slot1, slot2)
end

function Chest:sortedPairs(tab)
    local keys = {}
    for k in pairs(tab) do
        keys[#keys + 1] = k
    end
    table.sort(keys, function(a, b) return tab[a].itemCount > tab[b].itemCount end)
    local j = 0
    return
        function()
            j = j + 1
            local k = keys[j]
            if k ~= nil then
                return k, tab[k]
        end
    end
end

function Chest:findKeyFromValueItem(itemName, value)
    for k,v in pairs(self.itemList[itemName].slot) do
        if v==value then return k end
      end
      return nil
end

function Chest:sort()
    slotN = 1
    stop = false
    for itemName, item in self:sortedPairs(self.itemList) do
        increased = false
        if stop or (slotN > self.maxslots) then
            break
        end
        for _, itemSlot in pairs(item.slot) do
            increased = false
            freeSlot = self:findFreeSlot()
            if freeSlot == -1 then
                print("Can't sort without at least one free slot!")
                stop = true
                break
            end
            if (self.wrap.getItemDetail(slotN) ~= nil) and (itemSlot ~= slotN) then
                self:moveFromSlotToSlot(slotN, freeSlot)
            end

            self:moveFromSlotToSlot(itemSlot, slotN)
            if (self.wrap.getItemDetail(itemSlot) ~= nil) and (itemSlot ~= (slotN)) then
                print(("Adding padding %d"):format(itemSlot))
                table.insert(item.slot, itemSlot)
            end
            if self.wrap.getItemDetail(slotN).count >= self.wrap.getItemDetail(slotN).maxCount then
                slotN = slotN + 1
                increased = true
                print("Increasing slotN")
            end

        end
        if increased == false then
            slotN = slotN + 1
        end
        self:init()
    end
end

chest = Chest:new{name = "expandedstorage:chest_1"}

chest:connect()
chest:init()
--chest:print()
chest:sort()
--chest:printItem("minecraft:redstone")
print(("First free slot found: %d"):format(chest:findFreeSlot()))

--print(chest:moveFromSlotToSlot(1, 2))