Bagshui/Components/ActiveQuestItems.lua

-- Bagshui Active Quest Item Manager
-- Exposes: Bagshui.components.ActiveQuestItemManager
-- Raises: BAGSHUI_ACTIVE_QUEST_ITEM_UPDATE
--
-- Contains code based on QuestItem: https://github.com/wow-vanilla-addons/QuestItem/blob/master/QuestItem/QuestItem.lua
--
-- Keeps Bagshui.activeQuestItems updated with the NAMES of items which are objectives of current quests.
-- (We can't get item IDs due to Vanilla limitations).
--
-- Raises BAGSHUI_ACTIVE_QUEST_ITEM_UPDATE when changes to Bagshui.activeQuestItems occur.
--
-- This works by receiving QUEST_LOG_UPDATE events, which tend to come in fast and furious. To avoid constantly
-- rebuilding the list of active quest items, we're using an event queue:
-- 1. QUEST_LOG_UPDATE event comes in and BAGSHUI_QUEST_LOG_UPDATE event is queued to fire 1 second later.
--    If another QUEST_LOG_UPDATE event arrives before that 1 second is up, the timer is reset.
-- 2. BAGSHUI_QUEST_LOG_UPDATE event fires and triggers the actual parsing of the quest log.
--    After that is complete, BAGSHUI_ACTIVE_QUEST_ITEM_UPDATE event is fired immediately.
-- 3. Other components that have registered to received BAGSHUI_ACTIVE_QUEST_ITEM_UPDATE are now notified
--    and can trigger recategorization and resorting.

Bagshui:AddComponent(function()
  -- Key in _G.BagshuiData where active quest items will be stored.
  local ACTIVE_QUEST_ITEMS_DATA_STORAGE_KEY = "activeQuestItems"

  -- Initialization (happens when this component is loaded during `ADDON_LOADED`)
  if not Bagshui.currentCharacterData[ACTIVE_QUEST_ITEMS_DATA_STORAGE_KEY] then
    Bagshui.currentCharacterData[ACTIVE_QUEST_ITEMS_DATA_STORAGE_KEY] = {}
  end

  local ActiveQuestItemManager = {

    -- List of active quest items by item name.
    --
    -- Items must be stored in SavedVariables to to prevent inventory items from
    -- jumping around during UI reload, because there is a delay before the quest
    -- log can be read. The list is when QUEST_LOG_UPDATE fires for the first time.
    -- ```
    -- {
    -- 	["Item Name"] = {
    -- 		questName = "Quest Name",
    -- 		needed = #,
    -- 		obtained = #,
    -- 	}
    -- }
    --
    -- ```
    ---@type table<string, { questName: string, needed: number, obtained: number }>
    items = Bagshui.currentCharacterData[ACTIVE_QUEST_ITEMS_DATA_STORAGE_KEY],
  }

  --- Event handling.
  ---@param event string Event name.
  ---@param arg1 any Event argument.
  function ActiveQuestItemManager:OnEvent(event, arg1)
    -- WoW says "Something has happened with the quest log!" (it says this a lot).
    -- Queue an event so that we only do our update after all the events have finished firing
    -- This will be the most common event received, by far, so it goes first.
    if event == "QUEST_LOG_UPDATE" then
      Bagshui:QueueEvent("BAGSHUI_QUEST_LOG_UPDATE", 1)
      return
    end

    -- Enough time has elapsed since the last QUEST_LOG_UPDATE event to actually do our update.
    if event == "BAGSHUI_QUEST_LOG_UPDATE" then
      self:Update()
      Bagshui:RaiseEvent("BAGSHUI_ACTIVE_QUEST_ITEM_UPDATE")
      return
    end
  end

  --- Parse the quest log to find the names of items that are quest objectives.
  function ActiveQuestItemManager:Update()
    -- The quest log is one of those annoying things where you can't directly ask
    -- about a quest; you have the tell the client to *select* the quest, and then
    -- all the quest info functions work on that. This becomes a problem if the
    -- Quest Log is open and we want to update, since we need to loop through
    -- all quests, we're going to have to change the selected quest. What ends up
    -- happening is that once we're done, the very last quest in the log remains
    -- selected and is out of sync with the Quest Log UI. This matters when someone
    -- abandons multiple quests in a row, because the first abandonment will be
    -- accurate, but then the next Abandon Quest click will target the last quest
    -- in the list instead of the one that looks like it's selected.
    -- All that to say -- we need to store the currently selected quest number
    -- before we start so it can be restored once we're done.
    local previouslySelectedQuestNum = _G.GetQuestLogSelection()

    -- In theory we could keep a list of the items we've actually seen and remove the ones
    -- we don't see, but erasing it is easier. (Can always change if it's not performant enough).
    BsUtil.TableClear(self.items)

    local questName, isHeader, objectiveText, itemType, itemName, numNeeded, numObtained

    for questNum = 1, _G.GetNumQuestLogEntries(), 1 do
      -- Only need a couple pieces of information from GetQuestLogTitle.
      questName, _, _, isHeader, _, _ = _G.GetQuestLogTitle(questNum)

      if not isHeader then
        itemName = nil
        numNeeded = 1
        numObtained = 0

        -- All subsequent function calls depend on selecting the quest log entry.
        _G.SelectQuestLogEntry(questNum)

        -- If description and quest objective text is ever needed, here's how to get it:
        -- local questionDescription, questObjectiveText = _G.GetQuestLogQuestText()

        -- Quest objectives are in the "Leader Boards".
        for i = 1, _G.GetNumQuestLeaderBoards() do
          objectiveText, itemType = _G.GetQuestLogLeaderBoard(i)

          -- We only care if type is item/object (not monster, event, etc.).
          if itemType ~= nil and (itemType == "item" or itemType == "object") then
            -- Parse and store the item information from the objective text, which is formatted as:
            -- `<Item Name>: <Number Obtained>/<Total Needed>`
            _, _, itemName, numObtained, numNeeded = string.find(objectiveText, "(.+): (%d+)/(%d+)")
            if itemName then
              self.items[itemName] = {
                questName = questName,
                needed = numNeeded,
                obtained = numObtained,
              }
            end
          end
        end
      end
    end

    -- Restore Quest Log selection, if any (see the dissertation at the beginning of this function).
    if previouslySelectedQuestNum then
      _G.SelectQuestLogEntry(previouslySelectedQuestNum)
    end
  end

  -- Exports and registration.
  Bagshui.components.ActiveQuestItemManager = ActiveQuestItemManager
  Bagshui.activeQuestItems = ActiveQuestItemManager.items
  Bagshui:RegisterEvent("QUEST_LOG_UPDATE", ActiveQuestItemManager) -- Quest log changes.
  Bagshui:RegisterEvent("BAGSHUI_QUEST_LOG_UPDATE", ActiveQuestItemManager) -- Our custom trigger to parse the quest log.
end)