--
--  TjBagWatch.lua
--    by Tuhljin
--
--  An easy way to get useful notifications about what has changed in the player's bags. Notifications aren't sent
--  when items are moved around, only when they are lost or gained. (Items turning into other items count as
--  "losing" the old item(s) and "gaining" the new one(s).) In addition to the backpack and equipped bags, the
--  keyring, and, when applicable, the bank (including bank bags) are checked. (Equipped items are not checked.)
--
--  TjBagWatch.RegisterFunc( func[, multiItem] )
--    func       A function to be called when bag contents change. Note that multiple firings of the BAG_UPDATE
--               event at essentially the same time are condensed into a single call (or a single call per itemID
--               that changed in count depending on the value used for the multiItem parameter) to registered
--               functions.
--
--               If the function was already registered, it is not "registered twice" - it will be called just as
--               many times as it would have been were RegisterFunc called only once for that function. However,
--               you can change a function registered as "multi-item" into a non-multi-item registration or vice
--               versa by calling RegisterFunc again by using a different value for the multiItem parameter).
--
--    multiItem  Registered functions are called in one of two ways. If multiItem is omitted or it evaluates to
--               false, then the function is called in the following manner once per each item that was changed:
--                  func( itemID, oldCount, newCount )
--               If multiItem evaluates to true, it is instead called in this manner:
--                  func( itemID1, oldCount1, newCount1 [, itemID2, oldCount2, newCount2 [, ...
--                        itemIDX, oldCountX, newCountX ]] )
--               The itemID arguments give the item's ID while the oldCount and newCount arguments give the old
--               number of that item in the inventory and the new number, respectively. For items that stack, the
--               numbers from each stack are added together to give the count.
--
--  TjBagWatch.UnregisterFunc( func )
--    func      A previously registered function that is no longer to be called by TjBagWatch.
--
--


local THIS_VERSION = 0.05

if (not TjBagWatch or TjBagWatch.Version < THIS_VERSION) then
  TjBagWatch = TjBagWatch or {}
  local TjBagWatch = TjBagWatch
  TjBagWatch.Version = THIS_VERSION

  TjBagWatch.regfunc = TjBagWatch.regfunc or {}
  local regfunc = TjBagWatch.regfunc
  TjBagWatch.regfunc_multiItem = TjBagWatch.regfunc_multiItem or {}
  local regfunc_multiItem = TjBagWatch.regfunc_multiItem
  TjBagWatch.ItemCount = TjBagWatch.ItemCount or {}
  local ItemCount = TjBagWatch.ItemCount
  TjBagWatch.ItemCount_InBag = TjBagWatch.ItemCount_InBag or {}
  local ItemCount_InBag = TjBagWatch.ItemCount_InBag
  TjBagWatch.NeedRecount = TjBagWatch.NeedRecount or {}
  local NeedRecount = TjBagWatch.NeedRecount
  
  TjBagWatch.regfunc_multiItem_num = TjBagWatch.regfunc_multiItem_num or 0
  
  local tonumber = tonumber

  local frame = TjBagWatch.frame
  if (not frame) then
    frame = CreateFrame("Frame")
    TjBagWatch.frame = frame
    frame:Hide()
  end

  local UpdateCount
  do
    local prevcount, changes

    local function getCountFromBag(bagID)
      local tab = 0
      local prev
      if (ItemCount_InBag[bagID]) then
        prev = wipe(prevcount)
        tab = ItemCount_InBag[bagID]
        for k,v in pairs(tab) do  prev[k] = v;  end
        wipe(tab)
      else
        ItemCount_InBag[bagID] = {}
        tab = ItemCount_InBag[bagID]
      end

      -- Tally up number of items currently in the bag:
      local _, num, link, itemID, total
      for i=1,GetContainerNumSlots(bagID) do
        _, num, _, _, _, _, link = GetContainerItemInfo(bagID, i)
        if (link) then
          _, _, itemID = strfind(link, "item:(%d+)")
          itemID = tonumber(itemID)
          tab[itemID] = (tab[itemID] or 0) + num
        end
      end
      -- Compare to number of these items previously in the bag:
      for itemID, num in pairs(tab) do
        total = (ItemCount[itemID] or 0) + num - (prev and prev[itemID] or 0)
        if (total == 0) then  total = nil;  end
        if (ItemCount[itemID] ~= total) then
          --print(bagID,select(2,GetItemInfo(itemID)),num,"total:",total)
          if (prev) then  changes[itemID] = (changes[itemID] or 0) + (total or 0) - (ItemCount[itemID] or 0);  end
          ItemCount[itemID] = total
        end
      end
      if (prev) then
      -- Account for items previously in the bag that now have a count of zero:
        for itemID, num in pairs(prev) do
          if (not tab[itemID]) then
            ItemCount[itemID] = (ItemCount[itemID] or 0) - num
            if (ItemCount[itemID] == 0) then  ItemCount[itemID] = nil;  end
            changes[itemID] = (changes[itemID] or 0) - num
          end
        end
      end
    end

    function UpdateCount()
      prevcount = prevcount or {}
      changes = changes and wipe(changes) or {}
      --[[
      if (countAll) then
        getCountFromBag(BACKPACK_CONTAINER)
        for i=1,NUM_BAG_SLOTS do  getCountFromBag(i);  end
        getCountFromBag(KEYRING_CONTAINER)
        if (BankFrame:IsVisible()) then
          getCountFromBag(BANK_CONTAINER)
          for i=NUM_BAG_SLOTS + 1,NUM_BAG_SLOTS + NUM_BANKBAGSLOTS do  getCountFromBag(i);  end
        end
      else
      --]]
      for bagID in pairs(NeedRecount) do
        getCountFromBag(bagID)
        NeedRecount[bagID] = nil
      end
      --end

      return changes, (TjBagWatch.regfunc_multiItem_num > 0) and wipe(prevcount)
    end
  end

  local function doOnUpdate()
    frame:Hide()
    local changes, tab = UpdateCount()
    local i, num = 1
    for itemID, diff in pairs(changes) do
      if (diff ~= 0) then
        num = ItemCount[itemID] or 0
        for func in pairs(regfunc) do  func(itemID, num - diff, num);  end
        if (tab) then
          tab[i], tab[i+1], tab[i+2] = itemID, num - diff, num
          i = i + 3
        end
      end
    end
    if (i > 1) then
      for func in pairs(regfunc_multiItem) do  func( unpack(tab) );  end
    end
  end

  frame:SetScript("OnEvent", function(self, event, arg1)
    if (event == "PLAYER_ENTERING_WORLD") then
      frame:UnregisterEvent("PLAYER_ENTERING_WORLD")
      frame:SetScript("OnUpdate", doOnUpdate)
      return;
    end

    if (event == "BANKFRAME_OPENED") then
      frame:UnregisterEvent("BANKFRAME_OPENED")
      TjBagWatch.AllowBankCheck = true
      -- Scan the bank when it is visited for the first time:
      NeedRecount[BANK_CONTAINER] = true
      for i=NUM_BAG_SLOTS + 1,NUM_BAG_SLOTS + NUM_BANKBAGSLOTS do  NeedRecount[i] = true;  end
    elseif (event == "PLAYERBANKSLOTS_CHANGED") then
      NeedRecount[BANK_CONTAINER] = true
    else
      if (not TjBagWatch.AllowBankCheck and (arg1 == BANK_CONTAINER or arg1 > NUM_BAG_SLOTS)) then
        return;  -- If this is a bank bag but we haven't been at the bank this session, ignore it.
      end
      NeedRecount[arg1] = true
    end
    frame:Show()
  end)

  function TjBagWatch.UnregisterFunc( func )
    if (func) then
      if (regfunc_multiItem[func]) then
        regfunc_multiItem[func] = nil
        TjBagWatch.regfunc_multiItem_num = TjBagWatch.regfunc_multiItem_num - 1
      else
        regfunc[func] = nil
      end
    end
  end

  local UpdateCount_ran
  TjBagWatch.RegisterFunc = function(func, multiItem)
    assert(type(func) == "function", "Usage: TjBagWatch.RegisterFunc( function )")
    if (not UpdateCount_ran) then
      UpdateCount_ran = true
      frame:RegisterEvent("BAG_UPDATE")
      frame:RegisterEvent("PLAYERBANKSLOTS_CHANGED")

      NeedRecount[BACKPACK_CONTAINER] = true
      for i=1,NUM_BAG_SLOTS do  NeedRecount[i] = true;  end
      NeedRecount[KEYRING_CONTAINER] = true
      if (BankFrame:IsVisible()) then
        NeedRecount[BANK_CONTAINER] = true
        for i=NUM_BAG_SLOTS + 1,NUM_BAG_SLOTS + NUM_BANKBAGSLOTS do  NeedRecount[i] = true;  end
        TjBagWatch.AllowBankCheck = true
      else
        frame:RegisterEvent("BANKFRAME_OPENED")
      end
      frame:Show()
    end

    if (multiItem) then
      if (not regfunc_multiItem[func]) then
        regfunc[func] = nil
        regfunc_multiItem[func] = true
        TjBagWatch.regfunc_multiItem_num = TjBagWatch.regfunc_multiItem_num + 1
      end
    else
      regfunc[func] = true
      if (regfunc_multiItem[func]) then
        regfunc_multiItem[func] = nil
        TjBagWatch.regfunc_multiItem_num = TjBagWatch.regfunc_multiItem_num - 1
      end
    end
  end

  frame:RegisterEvent("PLAYER_ENTERING_WORLD")

end

--[[
function TjBagWatch.TEST()
  TjBagWatch.RegisterFunc( function(itemID, old, new)
    local _, link = GetItemInfo(itemID)
    print(">|cff00ffff", link, old, new)
  end)

  TjBagWatch.RegisterFunc( function(...)
    local itemID, old, new, _, link
    local msg = ""
    for i=1,select("#", ...),3 do
      itemID, old, new = select(i, ...)
      _, link = GetItemInfo(itemID)
      msg = msg.."* "..link..", "..old..", "..new.." "
    end
    print(msg)
  end, true )
end
--]]