local component = require "component"
local computer = require "computer"
local sides = require "sides"
local invc = component.transposer

local inv = {}

inv.drawer = sides.top
inv.input=sides.north
inv.output=sides.south

inv.cache = {}
inv.size = 0
inv.cacheTime = -1000
inv.cacheInvalid = false

function inv.index() -- refresh the index of items in the storage system
 inv.size = invc.getInventorySize(inv.drawer)
 inv.cache = {}
 for k,v in pairs(invc.getAllStacks(inv.drawer).getAll()) do
  if v.name ~= "minecraft:air" then
   inv.cache[#inv.cache+1] = {k,v}
  end
 end
 inv.cacheTime = computer.uptime()
 inv.cacheInvalid = false
end

function inv.cacheInvalidation() -- re-index only if necessary
 if computer.uptime() > inv.cacheTime + 300 or inv.cacheInvalid then
  inv.index()
 end
end

function inv.search(str) -- search names and labels for *str*
 inv.cacheInvalidation()
 str = string.lower(str or "")
 local rt = {}
 for k,v in pairs(inv.cache) do
  item = v[2]
  item.label = item.label or ""
  if item.name:match(str) or item.label:lower():match(str) then
   rt[#rt+1] = v
  end
 end
 return rt,#inv.cache,inv.size
end

function inv.inputItems() -- pull items into the storage system from the input box
 local counter = 0
 local imap = invc.getAllStacks(inv.input).getAll()
 for i = 1, invc.getInventorySize(inv.input) do
  local item = imap[i]
  if item.name ~= "minecraft:air" then
   if item.maxSize < 2 then
    invc.transferItem(inv.input,inv.output,64,i)
   else
    counter=counter+invc.transferItem(inv.input,inv.drawer,64,i)
   end
  end
 end
 if counter > 0 then
  inv.cacheInvalid = true
 end
end

function inv.extractItem(slot,count,output)
 local tcount = 0
 local item = invc.getStackInSlot(inv.drawer,slot)
 if item.size <= count then
  inv.cacheInvalid = true
 end
 count=math.min(count,item.size)
 local transferred = 0
 repeat
  transferred = invc.transferItem(inv.drawer,output or inv.output,count - tcount,slot)
  tcount = tcount + transferred
  for k,v in pairs(inv.cache) do
   if v[1] == slot then
    inv.cache[k][2].size = inv.cache[k][2].size - transferred or 0
    if inv.cache[k][2].size < 1 then
     inv.cacheInvalid = true
     break
    end
   end
  end
 io.write(tcount.." ")
 until tcount >= count
 return tcount
end

inv.index()

return inv