-- ------------------------------------------------------------------------------ --
--                           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 CHANNEL_NAME = "TSM_AuctionDB"
local COMM_PREFIX = "TSMAuctionDB"
local CHUNK_SIZE = 180
local BUNDLE_TIMEOUT = 45

local private = {
	channelId = nil,
	channelName = nil,
	lastBroadcastHash = nil,
	incoming = {},
}

local strbyte = string.byte

local libS = LibStub:GetLibrary("AceSerializer-3.0")
local libC = LibStub:GetLibrary("LibCompress")
local libCE

local function GetCodec()
	if libCE then return libCE end
	libCE = libC:GetChatEncodeTable("", "\031")
	if not libCE then
		libCE = libC:GetChatEncodeTable()
	end
	return libCE
end

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

local function EnsureChannel()
	local channelId = GetChannelName(CHANNEL_NAME)
	if channelId == 0 then
		JoinChannelByName(CHANNEL_NAME)
		channelId = GetChannelName(CHANNEL_NAME)
	end
	private.channelId = channelId > 0 and channelId or nil
	private.channelName = private.channelId and CHANNEL_NAME or nil
end

local function ChatFilter(_, _, msg, _, _, _, _, _, channelName)
	if channelName ~= CHANNEL_NAME then return end
	if strsub(msg, 1, #COMM_PREFIX + 1) == 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

local function EncodePayload(payload)
	local serialized = libS:Serialize(payload)
	local codec = GetCodec()
	if not codec then return end
	local encoded = codec:Encode(libC:CompressHuffman(serialized))
	if not encoded then
		encoded = codec:Encode(libC:CompressLZW(serialized))
	end
	if not encoded then
		encoded = codec:Encode("\001" .. serialized)
	end
	return encoded
end

local function DecodePayload(encoded)
	local codec = GetCodec()
	if not codec then return end
	local decoded = codec:Decode(encoded)
	if not decoded then return end
	local decompressed = libC:Decompress(decoded)
	if not decompressed then return end
	local ok, payload = libS:Deserialize(decompressed)
	if not ok then return end
	return payload
end

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

	TSM:Serialize()
	local payload = {
		scanTime = TSM.db.realm.lastCompleteScan,
		scanData = TSM.db.realm.scanData,
	}
	local encoded = EncodePayload(payload)
	if not encoded then return end

	local hash = HashString(encoded)
	if hash == private.lastBroadcastHash then return end
	private.lastBroadcastHash = hash

	local total = ceil(#encoded / CHUNK_SIZE)
	for i = 1, total do
		local chunk = strsub(encoded, (i - 1) * CHUNK_SIZE + 1, i * CHUNK_SIZE)
		local msg = strjoin("|", COMM_PREFIX, hash, i .. "/" .. total, chunk)
		SendChatMessage(msg, "CHANNEL", nil, private.channelId)
	end
end

local function MergeIncomingData(payload)
	if type(payload) ~= "table" or type(payload.scanData) ~= "string" then return end

	local incoming = {}
	TSM:Deserialize(payload.scanData, incoming, true)
	for itemID, data in pairs(incoming) do
		local existing = TSM.data[itemID]
		if existing then
			TSM:DecodeItemData(itemID)
			if data.lastScan and (not existing.lastScan or data.lastScan > existing.lastScan) then
				TSM.data[itemID] = data
			end
		else
			TSM.data[itemID] = data
		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()
end

function ChannelSync:OnChannelMessage(_, msg, source, _, _, _, _, _, channelName)
	if channelName ~= CHANNEL_NAME then return end
	if strsub(msg or "", 1, #COMM_PREFIX + 1) ~= COMM_PREFIX .. "|" then return end

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

	local header, hash, seqInfo, chunk = msg:match("^(.-)|([^|]+)|([^|]+)|(.+)$")
	if header ~= COMM_PREFIX or not hash or not seqInfo or not chunk then return end

	local seq, total = seqInfo:match("^(%d+)%/(%d+)$")
	seq, total = tonumber(seq), tonumber(total)
	if not seq or not total then return end

	local bundle = private.incoming[hash]
	if not bundle or (time() - bundle.time) > BUNDLE_TIMEOUT then
		bundle = {time = time(), total = total, chunks = {}, received = 0}
		private.incoming[hash] = bundle
	end

	if bundle.total ~= total then
		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 return end
	MergeIncomingData(payload)
end