-- ------------------------------------------------------------------------------ --
--                           TradeSkillMaster_AuctionDB                           --
--           http://www.curse.com/addons/wow/tradeskillmaster_auctiondb           --
--                                                                                --
--             A TradeSkillMaster Addon (http://tradeskillmaster.com)             --
--    All Rights Reserved* - Detailed license information included with addon.    --
-- ------------------------------------------------------------------------------ --

-- Channel sync for sharing AuctionDB scan data between players.

local TSM = select(2, ...)
local ChannelSync = TSM:NewModule("ChannelSync", "AceEvent-3.0")
local L = LibStub("AceLocale-3.0"):GetLocale("TradeSkillMaster_AuctionDB")

local DEFAULT_CHANNEL_NAME = "TSM_AuctionDB"

local function GetChannelConfigName()
	if TSM.db and TSM.db.profile and TSM.db.profile.channelSyncName and TSM.db.profile.channelSyncName ~= "" then
		return TSM.db.profile.channelSyncName
	end
	return DEFAULT_CHANNEL_NAME
end
local COMM_PREFIX = "TSMADB1"
local CHUNK_SIZE = 220
local BUNDLE_TIMEOUT = 45
local SEND_INTERVAL = 0.08
local MAX_TOTAL_CHUNKS = 800
local MAX_ITEMS_PER_PAYLOAD = 250

local private = {
	channelId = nil,
	channelName = nil,
	lastBroadcastHash = nil,
	incoming = {},
	sendQueue = {},
	isSending = false,
	notifiedNewer = {},
	cachedFullScan = {time=nil, itemIDs=nil},
}

local strbyte = string.byte

local libS = LibStub:GetLibrary("AceSerializer-3.0")
local libD = LibStub("LibDeflate", true)
local warnedNoDeflate

local function GetAddonVersion()
	local version = GetAddOnMetadata("TradeSkillMaster_AuctionDB", "X-Curse-Packaged-Version")
		or GetAddOnMetadata("TradeSkillMaster_AuctionDB", "Version")
	if not version or version == "" then
		return "unknown"
	end
	return version
end

local function VersionKey(version)
	local key = 0
	for part in tostring(version or ""):gmatch("%d+") do
		key = key * 1000 + tonumber(part)
	end
	return key
end

private.addonVersion = GetAddonVersion()
private.addonVersionKey = VersionKey(private.addonVersion)

local function DebugPrint(msg)
	if TSM.db and TSM.db.profile and TSM.db.profile.channelSyncDebug then
		TSM:Print("ChannelSync: " .. msg)
	end
end

local function CanEncode()
	if libD then return true end
	if not warnedNoDeflate then
		warnedNoDeflate = true
		TSM:Print("AuctionDB channel sync requires LibDeflate. Install or enable an addon that provides it.")
	end
	return false
end

local function HashString(str)
	local hash = 0
	for i = 1, #str do
		hash = (hash * 31 + strbyte(str, i)) % 4294967296
	end
	return hash
end

local function EnsureChannel()
	if private.channelId and private.channelName and private.channelName ~= GetChannelConfigName() then
		LeaveChannelByName(private.channelName)
		private.channelId = nil
		private.channelName = nil
	end
	if not TSM.db or not TSM.db.profile or not TSM.db.profile.channelSyncEnabled then
		private.channelId = nil
		private.channelName = nil
		return
	end
	local channelName = GetChannelConfigName()
	local channelId = GetChannelName(channelName)
	if channelId == 0 then
		JoinChannelByName(channelName)
		channelId = GetChannelName(channelName)
	end
	private.channelId = channelId > 0 and channelId or nil
	private.channelName = private.channelId and channelName or nil
end

local function GetChannelDisplayName(channelName, channelString, channelNumber, channelBaseName)
	if channelBaseName and channelBaseName ~= "" and not tonumber(channelBaseName) then
		return channelBaseName
	end
	if channelName and channelName ~= "" and not tonumber(channelName) then
		return channelName
	end
	if channelString and channelString ~= "" then
		local parsed = channelString:match("^%d+%.%s*(.+)$")
		if parsed then return parsed end
		local numeric = tonumber(channelString)
		if numeric then return select(2, GetChannelName(numeric)) end
		return channelString
	end
	if channelNumber then
		return select(2, GetChannelName(channelNumber))
	end
end

local function ChatFilter(_, _, msg, _, channelString, _, channelNumber, channelName, channelBaseName)
	local channelNameKey = GetChannelConfigName()
	local displayName = GetChannelDisplayName(channelName, channelString, channelNumber, channelBaseName)
	if displayName ~= channelNameKey then return end
	if strsub(msg, 1, #COMM_PREFIX) == COMM_PREFIX then
		return true
	end
end

function ChannelSync:OnEnable()
	self:RegisterEvent("PLAYER_ENTERING_WORLD", "OnPlayerEnteringWorld")
	self:RegisterEvent("CHAT_MSG_CHANNEL_NOTICE", "OnChannelNotice")
	self:RegisterEvent("CHAT_MSG_CHANNEL", "OnChannelMessage")
	if ChatFrame_AddMessageEventFilter then
		ChatFrame_AddMessageEventFilter("CHAT_MSG_CHANNEL", ChatFilter)
	end
	EnsureChannel()
end

function ChannelSync:OnPlayerEnteringWorld()
	EnsureChannel()
end

function ChannelSync:OnChannelNotice()
	EnsureChannel()
end

function ChannelSync:ReloadConfig()
	EnsureChannel()
end

local function EncodePayload(payload)
	if not CanEncode() then return end
	local serialized = libS:Serialize(payload)
	if not serialized then
		DebugPrint("Serialize failed.")
		return
	end
	local compressed = libD:CompressDeflate(serialized, { level = 9 })
	if not compressed then
		DebugPrint("CompressDeflate failed.")
		return
	end
	return libD:EncodeForPrint(compressed)
end

local function DecodePayload(encoded)
	if not CanEncode() then return end
	local decoded = libD:DecodeForPrint(encoded)
	if not decoded then
		DebugPrint("DecodeForPrint failed.")
		return
	end
	local decompressed = libD:DecompressDeflate(decoded)
	if not decompressed then
		DebugPrint("DecompressDeflate failed.")
		return
	end
	local ok, payload = libS:Deserialize(decompressed)
	if not ok then
		DebugPrint("Deserialize failed.")
		return
	end
	return payload
end

local function MaybeNotifyNewerVersion(remoteVersion, sender)
	local remoteKey = VersionKey(remoteVersion)
	local localKey = private.addonVersionKey
	if remoteKey == 0 or localKey == 0 or remoteKey <= localKey then return end
	local noticeKey = tostring(sender or "unknown") .. ":" .. tostring(remoteVersion)
	if private.notifiedNewer[noticeKey] then return end
	private.notifiedNewer[noticeKey] = true
	TSM:Printf(L["A newer version of AuctionDB (%s) was received from %s. You are running %s."], remoteVersion, sender or "unknown", private.addonVersion)
end

function ChannelSync:BroadcastScanData(scanType, items)
	if scanType ~= "Full" and scanType ~= "Group" and scanType ~= "Search" then
		return
	end
	if TSM.processingData then
		TSMAPI:CreateTimeDelay("auctionDBChannelSyncBroadcast", 0.5, function()
			ChannelSync:BroadcastScanData(scanType, items)
		end)
		return
	end
	EnsureChannel()
	if not TSM.db or not TSM.db.profile or not TSM.db.profile.channelSyncEnabled then return end
	if TSM.db.profile.channelSyncReceiveOnly then return end
	if not private.channelName or not private.channelId then return end

	local itemIDs = ChannelSync:CollectItemIDs(items)
	if not itemIDs or #itemIDs == 0 then return end

	local function QueueEncoded(encoded)
		local hash = HashString(encoded)
		if hash == private.lastBroadcastHash then return end
		private.lastBroadcastHash = hash
		local total = ceil(#encoded / CHUNK_SIZE)
		if total > MAX_TOTAL_CHUNKS then return false end
		tinsert(private.sendQueue, {hash = hash, encoded = encoded, total = total})
		if not private.isSending then
			private.isSending = true
			TSMAPI.Threading:Start(ChannelSync.SendQueueThread, 0.3)
		end
		return true
	end

	local function QueueBatch(startIndex, endIndex)
		local batch = {}
		for i = startIndex, endIndex do
			tinsert(batch, itemIDs[i])
		end
		local payload = ChannelSync:BuildPayloadFromItemIDs(scanType, batch)
		if not payload then return end
		local encoded = EncodePayload(payload)
		if not encoded then return end
		local total = ceil(#encoded / CHUNK_SIZE)
		if total > MAX_TOTAL_CHUNKS and #batch > 1 then
			local mid = floor((startIndex + endIndex) / 2)
			QueueBatch(startIndex, mid)
			QueueBatch(mid + 1, endIndex)
			return
		end
		if total > MAX_TOTAL_CHUNKS then
			if TSM.db and TSM.db.profile and TSM.db.profile.channelSyncDebug then
				TSM:Print("AuctionDB channel sync payload too large; skipping batch.")
			end
			return
		end
		QueueEncoded(encoded)
	end

	for i = 1, #itemIDs, MAX_ITEMS_PER_PAYLOAD do
		QueueBatch(i, min(i + MAX_ITEMS_PER_PAYLOAD - 1, #itemIDs))
	end
end

function ChannelSync:CollectItemIDs(items)
	local itemIDs, list = {}, {}
	if items then
		if #items > 0 then
			for _, itemString in ipairs(items) do
				local itemID = TSMAPI:GetItemID(itemString)
				if itemID and not itemIDs[itemID] then
					itemIDs[itemID] = true
					tinsert(list, itemID)
				end
			end
		else
			for itemString in pairs(items) do
				local itemID = TSMAPI:GetItemID(itemString)
				if itemID and not itemIDs[itemID] then
					itemIDs[itemID] = true
					tinsert(list, itemID)
				end
			end
		end
	else
		local scanTime = TSM.db.realm.lastCompleteScan
		if private.cachedFullScan.time == scanTime and private.cachedFullScan.itemIDs then
			return private.cachedFullScan.itemIDs
		end
		for itemID in pairs(TSM.data) do
			TSM:DecodeItemData(itemID)
			if TSM.data[itemID].lastScan == scanTime then
				tinsert(list, itemID)
			end
		end
		private.cachedFullScan.time = scanTime
		private.cachedFullScan.itemIDs = list
	end
	return list
end

function ChannelSync:BuildPayloadFromItemIDs(scanType, itemIDList)
	local payloadItems = {}
	for _, itemID in ipairs(itemIDList) do
		local data = TSM.data[itemID]
		if data then
			TSM:EncodeItemData(itemID)
			if data.encoded then
				payloadItems[itemID] = data.encoded
			end
		end
	end
	if not next(payloadItems) then return end

	return {
		v = 1,
		scanType = scanType,
		scanTime = TSM.db.realm.lastCompleteScan,
		version = private.addonVersion,
		items = payloadItems,
	}
end

local function DecodeIncomingItem(itemID, encoded)
	local tmp = {}
	tmp[itemID] = {encoded = encoded}
	TSM:DecodeItemData(itemID, tmp)
	return tmp[itemID]
end

local function MergeIncomingData(payload, sender)
	if type(payload) ~= "table" then return end

	local incoming = {}
	if payload.items then
		incoming = payload.items
	elseif type(payload.scanData) == "string" then
		TSM:Deserialize(payload.scanData, incoming, true)
	else
		return
	end
	local updated = 0
	local lastItemID
	for itemID, data in pairs(incoming) do
		local incomingData = data
		if payload.items then
			incomingData = DecodeIncomingItem(itemID, data)
		end
		if incomingData then
			local existing = TSM.data[itemID]
			if existing then
				TSM:DecodeItemData(itemID)
				if incomingData.lastScan and (not existing.lastScan or incomingData.lastScan > existing.lastScan) then
					TSM.data[itemID] = incomingData
					updated = updated + 1
					lastItemID = itemID
				end
			else
				TSM.data[itemID] = incomingData
				updated = updated + 1
				lastItemID = itemID
			end
		end
	end

	if payload.scanTime and (not TSM.db.realm.lastCompleteScan or payload.scanTime > TSM.db.realm.lastCompleteScan) then
		TSM.db.realm.lastCompleteScan = payload.scanTime
	end

	TSM:Serialize()

	if updated == 0 and sender then
		DebugPrint("No items updated from " .. sender .. ".")
	elseif updated > 0 and sender then
		if TSM.db and TSM.db.profile and TSM.db.profile.channelSyncDebug then
			if updated == 1 and lastItemID then
				local link = select(2, GetItemInfo(lastItemID)) or ("item:" .. tostring(lastItemID))
				TSM:Printf("AuctionDB updated %s from %s.", link, sender)
			else
				TSM:Printf("AuctionDB updated %d items from %s.", updated, sender)
			end
		end
	end
end

function ChannelSync:OnChannelMessage(_, msg, source, _, channelString, _, channelNumber, channelName, channelBaseName)
	local channelNameKey = GetChannelConfigName()
	local displayName = GetChannelDisplayName(channelName, channelString, channelNumber, channelBaseName)
	if displayName ~= channelNameKey then
		if strsub(msg or "", 1, #COMM_PREFIX) == COMM_PREFIX then
			DebugPrint("Prefix received; displayName=" .. tostring(displayName) .. " channelNumber=" .. tostring(channelNumber) .. " channelString=" .. tostring(channelString) .. " channelName=" .. tostring(channelName) .. " channelBaseName=" .. tostring(channelBaseName))
		end
		return
	end
	if strsub(msg or "", 1, #COMM_PREFIX) ~= COMM_PREFIX then
		DebugPrint("Message on channel without prefix: '" .. strsub(msg or "", 1, #COMM_PREFIX) .. "'.")
		return
	end

	source = ("-"):split(source or "")
	if strlower(source or "") == strlower(UnitName("player") or "") then return end

	local headerLen = #COMM_PREFIX + 16
	if #msg <= headerLen then return end
	local meta = strsub(msg, #COMM_PREFIX + 1, headerLen)
	local chunk = strsub(msg, headerLen + 1)
	local hashHex = strsub(meta, 1, 8)
	local seqHex = strsub(meta, 9, 12)
	local totalHex = strsub(meta, 13, 16)
	local hash = tonumber(hashHex, 16)
	local seq = tonumber(seqHex, 16)
	local total = tonumber(totalHex, 16)
	if not hash or not seq or not total then return end

	local bundle = private.incoming[hash]
	if not bundle or (time() - bundle.time) > BUNDLE_TIMEOUT then
		if bundle then
			DebugPrint("Bundle timeout " .. format("%08x", hash) .. " (" .. bundle.received .. "/" .. bundle.total .. ").")
		end
		bundle = {time = time(), total = total, chunks = {}, received = 0}
		private.incoming[hash] = bundle
	end

	if bundle.total ~= total then
		DebugPrint("Bundle total mismatch for " .. format("%08x", hash) .. ". Resetting.")
		private.incoming[hash] = {time = time(), total = total, chunks = {}, received = 0}
		bundle = private.incoming[hash]
	end

	if not bundle.chunks[seq] then
		bundle.chunks[seq] = chunk
		bundle.received = bundle.received + 1
	end

	if bundle.received < bundle.total then return end

	local parts = {}
	for i = 1, bundle.total do
		if not bundle.chunks[i] then return end
		tinsert(parts, bundle.chunks[i])
	end
	private.incoming[hash] = nil

	local payload = DecodePayload(table.concat(parts))
	if not payload then
		DebugPrint("Payload decode failed for bundle " .. format("%08x", hash))
		return
	end
	if payload.version then
		MaybeNotifyNewerVersion(payload.version, source)
	end
	MergeIncomingData(payload, source)
end

function ChannelSync:SendQueueThread()
	while #private.sendQueue > 0 do
		local job = private.sendQueue[1]
		for i = 1, job.total do
			local chunk = strsub(job.encoded, (i - 1) * CHUNK_SIZE + 1, i * CHUNK_SIZE)
			local msg = COMM_PREFIX .. string.format("%08x%04x%04x", job.hash, i, job.total) .. chunk
			SendChatMessage(msg, "CHANNEL", nil, private.channelId)
			self:Sleep(SEND_INTERVAL)
		end
		DebugPrint("Sent bundle " .. format("%08x", job.hash) .. " (" .. job.total .. " chunks).")
		tremove(private.sendQueue, 1)
	end
	private.isSending = false
end