-- Guda Bag Scanner
-- Scans and stores bag contents with caching and event pending tracking

local addon = Guda

local BagScanner = {}
addon.Modules.BagScanner = BagScanner

-- Cache for bag data to avoid re-scanning all slots on every update
local bagCache = nil
local cacheValid = false

-- Event pending tracking (like Baganator's IsBagEventPending)
local eventPending = false
local dirtySlots = {}  -- Track specific slots that changed: dirtySlots[bagID][slotID] = true

--=====================================================
-- Item Data Pool (Baganator-inspired memory optimization)
-- Reuses item data tables instead of creating new ones
--=====================================================
local itemDataPool = {}
local ITEM_DATA_POOL_MAX = 200  -- Limit pool size to prevent unbounded growth

-- Acquire item data table from pool
local function AcquireItemData()
    return table.remove(itemDataPool) or {}
end

-- Release item data table back to pool
local function ReleaseItemData(data)
    if data and table.getn(itemDataPool) < ITEM_DATA_POOL_MAX then
        -- Clear all fields for reuse
        data.link = nil
        data.texture = nil
        data.count = nil
        data.quality = nil
        data.name = nil
        data.iLevel = nil
        data.type = nil
        data.class = nil
        data.subclass = nil
        data.equipSlot = nil
        data.locked = nil
        table.insert(itemDataPool, data)
    end
end

-- Release all item data in a bag cache entry
local function ReleaseBagCacheData(bagData)
    if bagData and bagData.slots then
        for slotID, itemData in pairs(bagData.slots) do
            if itemData then
                ReleaseItemData(itemData)
            end
        end
    end
end

-- Clear the bag cache (releases pooled data)
function BagScanner:ClearCache()
    if bagCache then
        for bagID, bagData in pairs(bagCache) do
            ReleaseBagCacheData(bagData)
        end
    end
    bagCache = nil
    cacheValid = false
    dirtySlots = {}
end

-- Check if a bag event is pending (use before transfers)
function BagScanner:IsEventPending()
    return eventPending
end

-- Clear the pending flag (call after processing)
function BagScanner:ClearEventPending()
    eventPending = false
end

-- Mark a specific slot as dirty (incremental tracking)
function BagScanner:MarkSlotDirty(bagID, slotID)
    if not dirtySlots[bagID] then
        dirtySlots[bagID] = {}
    end
    dirtySlots[bagID][slotID] = true
    eventPending = true
end

-- Get dirty slots and clear them
function BagScanner:GetAndClearDirtySlots()
    local dirty = dirtySlots
    dirtySlots = {}
    return dirty
end

-- Get cached bag data, or scan if cache is invalid
function BagScanner:GetBagData()
    if cacheValid and bagCache then
        -- Process any dirty slots incrementally
        for bagID, slots in pairs(dirtySlots) do
            if bagID ~= nil and type(slots) == "table" then
                if bagCache[bagID] then
                    for slotID in pairs(slots) do
                        -- Validate slotID is a valid number
                        if type(slotID) == "number" and slotID >= 1 then
                            local oldData = bagCache[bagID].slots[slotID]
                            local newData = self:ScanSlot(bagID, slotID)
                            bagCache[bagID].slots[slotID] = newData

                            -- Update free slot count
                            local wasEmpty = (oldData == nil)
                            local isEmpty = (newData == nil)
                            if wasEmpty and not isEmpty then
                                bagCache[bagID].freeSlots = bagCache[bagID].freeSlots - 1
                            elseif not wasEmpty and isEmpty then
                                bagCache[bagID].freeSlots = bagCache[bagID].freeSlots + 1
                            end
                        end
                    end
                else
                    -- Bag not in cache, scan it
                    bagCache[bagID] = self:ScanBag(bagID)
                end
            end
        end
        dirtySlots = {}
        return bagCache
    end

    -- Cache miss - do full scan
    bagCache = self:ScanBags()
    cacheValid = true
    dirtySlots = {}
    return bagCache
end

-- Invalidate cache (force full re-scan on next update)
function BagScanner:InvalidateCache()
    cacheValid = false
end

-- Invalidate a specific bag in the cache
function BagScanner:InvalidateBag(bagID)
    if not bagCache then return end
    bagCache[bagID] = nil
end

-- Scan all bags and return data (full scan)
function BagScanner:ScanBags()
    local bagData = {}

    -- Scan regular bags
    for _, bagID in ipairs(addon.Constants.BAGS) do
        bagData[bagID] = self:ScanBag(bagID)
    end

    -- Also scan keyring (bagID -2)
    bagData[-2] = self:ScanBag(-2)

    return bagData
end

-- Scan a single bag
function BagScanner:ScanBag(bagID)
    -- Determine bag type
    local bagType = addon.Modules.Utils:GetSpecializedBagType(bagID) or "regular"

    local bag = {
        slots = {},
        numSlots = addon.Modules.Utils:GetBagSlotCount(bagID),
        freeSlots = 0,
        bagType = bagType,
    }

    if not addon.Modules.Utils:IsBagValid(bagID) then
        return bag
    end

    for slot = 1, bag.numSlots do
        local itemData = self:ScanSlot(bagID, slot)
        bag.slots[slot] = itemData

        if not itemData then
            bag.freeSlots = bag.freeSlots + 1
        end
    end

    return bag
end

-- Scan a single slot (uses item data pooling)
function BagScanner:ScanSlot(bagID, slot)
    -- Validate parameters to prevent API errors
    if bagID == nil or slot == nil or slot < 1 then
        return nil
    end

    local texture, itemCount, locked, quality, readable, lootable = GetContainerItemInfo(bagID, slot)

    if not texture then
        return nil
    end

    -- In 1.12.1, must use GetContainerItemLink separately!
    local itemLink = GetContainerItemLink(bagID, slot)

    -- Get item info
    local name, link, itemQuality, iLevel, itemCategory, itemType, itemStackCount, itemSubType, itemTexture, itemEquipLoc, itemSellPrice
    if itemLink then
        name, link, itemQuality, iLevel, itemCategory, itemType, itemStackCount, itemSubType, itemTexture, itemEquipLoc, itemSellPrice = addon.Modules.Utils:GetItemInfo(itemLink)
    end

    -- Use pooled item data table instead of creating new one
    local itemData = AcquireItemData()
    itemData.link = itemLink
    itemData.texture = texture
    itemData.count = itemCount or 1
    itemData.quality = quality or itemQuality or 0
    itemData.name = name
    itemData.iLevel = iLevel
    itemData.type = itemType
    itemData.class = itemCategory
    -- Override misclassified Quest items (e.g. Juju consumables) to Consumable
    if itemCategory == "Quest" and itemLink and addon.Constants and addon.Constants.QUEST_CATEGORY_EXCLUSIONS then
        local itemID = addon.Modules.Utils:ExtractItemID(itemLink)
        if itemID and addon.Constants.QUEST_CATEGORY_EXCLUSIONS[itemID] then
            itemData.class = "Consumable"
            itemData.type = "Consumable"
        end
    end
    itemData.subclass = itemSubType
    itemData.equipSlot = itemEquipLoc
    itemData.locked = locked
    return itemData
end

-- Save current bags to database
function BagScanner:SaveToDatabase()
    local bagData = self:ScanBags()
    addon.Modules.DB:SaveBags(bagData)
    addon:Debug("Bag data saved to database")

    -- Clear tooltip cache so counts update immediately
    if addon.Modules.Tooltip and addon.Modules.Tooltip.ClearCache then
        addon.Modules.Tooltip:ClearCache()
    end
end

-- Initialize with event pending tracking
function BagScanner:Initialize()
    local eventFrame = CreateFrame("Frame")
    self.eventFrame = eventFrame

    -- Register bag update events for pending tracking
    eventFrame:RegisterEvent("BAG_UPDATE")
    eventFrame:RegisterEvent("BAG_UPDATE_DELAYED")
    eventFrame:SetScript("OnEvent", function()
        eventPending = true
        -- Mark the specific bag as having changes
        if arg1 then
            if not dirtySlots[arg1] then
                dirtySlots[arg1] = {}
            end
            -- We don't know which slot, so mark entire bag for rescan
            -- by invalidating it
            if bagCache and bagCache[arg1] then
                bagCache[arg1] = nil
            end
        end
    end)

    addon:Debug("Bag scanner initialized with event pending tracking")
end