-- ------------------------------------------------------------------------------ --
--                           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.    --
-- ------------------------------------------------------------------------------ --

-- load the parent file (TSM) into a local variable and register this file as a module
local TSM = select(2, ...)
local Scan = TSM:NewModule("Scan", "AceEvent-3.0")
local L = LibStub("AceLocale-3.0"):GetLocale("TradeSkillMaster_AuctionDB") -- loads the localization table

Scan.groupScanStartTime = 0
Scan.groupScanData = {}
Scan.filterList = {}
Scan.numFilters = 0
Scan.fullScanStartTime = 0
Scan.fullScanSecondsPerPage = -1
Scan.fullScanCompleteElapsed = nil

local verifyNewAlgorithm = false  -- DEVELOPERS: Set to "true" to validate and benchmark the new market data algorithm!


local function FullScanCallback(event, ...)
	if event == "SCAN_PAGE_UPDATE" then
		-- We're running a "Full Scan" and have received an auction page.
		-- NOTE: These normal per-page scans receive 50 items per page, and will
		-- successfully download ALL auctions on private servers, thanks to pagination.
		-- For example, a full scan retrieves all pages of 50 items each,
		-- meaning that it covers the entire auction list.
		local page, total = ...

		-- Calculate the current page progress and the remainder as floating-point values.
		local progress_float = page / total
		local remaining_float = 1.0 - progress_float

		-- Estimate the total scan time, based on a MIX of the average per-page so far,
		-- and the previous scan's averages stored in the database (if available).
		-- NOTE: This callback triggers after we RECEIVED "page", so we count "page" too.
		-- NOTE: We don't do any "live" updates of the progress bar text. We only
		-- update the text labels when we receive a page, which is very CPU-efficient.
		local time_estimate_str = ""
		if (page >= 1) and (total > page) then
			-- Calculate how many seconds have elapsed per page-request so far.
			-- NOTE: We time it via the less-precise "time()" function, which
			-- bluntly returns whole seconds. The alternative would be to use
			-- "debugprofilestop()", which has millisecond-precision, but breaks
			-- if another addon calls "debugprofilestart()" (which resets that
			-- timer back to zero). It doesn't really matter, since our "seconds
			-- per page" is constantly re-calculated based on the latest "total
			-- amount of whole seconds elapsed", so it doesn't accumulate any
			-- rounding errors and gets more precise the more pages have been
			-- downloaded (after ~10 pages, it's practically as accurate as the
			-- debug-timer). We have to use this technique for safety!
			-- NOTE: Most servers will gradually slow down the page requests
			-- across the first 300 requests or so, which will become slower
			-- and slower, which means that the initial time estimate will
			-- grow until it settles on the correct time remainder. There's
			-- nothing we can do to predict those gradual slowdowns / throttling,
			-- which is why we're also storing the last scan's "final average"
			-- in the database and using that for our subsequent scan estimates.
			local seconds_elapsed = abs(time() - Scan.fullScanStartTime)
			local seconds_per_page = seconds_elapsed / page
			-- local pages_remaining = total - page  -- Not used for anything.

			-- Remember our "real", unweighted value, for later DB storage.
			Scan.fullScanSecondsPerPage = seconds_per_page

			-- Calculate a smoothly weighted "seconds per page" value based on
			-- a linear mix between the current "seconds per page" and the
			-- stored "final seconds per page value" from our previous scan.
			-- As we reach 100%, we'll use 100% of the current "real seconds
			-- per page". But at 0%, we'll use the stored value instead.
			-- Between that, we linearly fade the values so that we react
			-- smoothly to changes in speed. This solves the issue that all
			-- servers face, which is their gradual slowdown of page fetches,
			-- where they start out very fast (such as 1.1 seconds per page),
			-- but will have slowed down when you're at the end (such as 2.5 per
			-- page). Typical server slowdown in speed is roughly linear, which
			-- is why our linear blend between "current estimate" and "finished
			-- estimate from previous scan" creates the most accurate results
			-- we're able to get, given the server behavior. It should also
			-- work perfectly on servers which don't follow this pattern, such
			-- as if they have a perfectly linear time between all pages without
			-- any throttling at all, in which case both estimates will basically
			-- agree anyway (both the current and the saved value). This is the
			-- best we can do with the facts of the game. A totally accurate
			-- estimate is impossible, but we're as accurate as we can be.
			-- NOTE: This estimate cannot be improved, since practically all
			-- servers apply random throttling, have various loads and slowdowns
			-- throughout the day, etc. This is the best we can do since the
			-- actual speed depends on the server and is pretty unpredictable.
			-- It would be like trying to predict "the total download-time of a
			-- file that keeps fluctuating between fast and slow speeds". The
			-- best we can do is estimate based on current and previous speeds.
			local last_scan_seconds_per_page = TSM.db.realm.lastScanSecondsPerPage
			if last_scan_seconds_per_page and last_scan_seconds_per_page > 0 then
				-- TSM:Print(format("Read from DB: %f (Our unweighted estimate: %f)", last_scan_seconds_per_page, seconds_per_page))  -- DEBUG
				seconds_per_page = (seconds_per_page * progress_float) + (last_scan_seconds_per_page * remaining_float)
				-- TSM:Print(format("New, weighted estimate: %f (Progress: %f / Remaining: %f)", seconds_per_page, progress_float, remaining_float))  -- DEBUG
			else
				-- TSM:Print(format("Nothing in DB yet (Our unweighted estimate: %f)", seconds_per_page))  -- DEBUG
			end

			-- Estimate the "total time" requirement for ALL pages, rounded to
			-- the nearest whole second, at least 1 second.
			-- NOTE: We calculate the total estimate instead of the "remaining
			-- time", because servers tend to fluctuate constantly between slowly
			-- and then quickly sending the pages, which means a "pages_remaining"
			-- timer is hard to understand in terms of real time remaining, since
			-- we might get 10 pages within a few seconds and count down their
			-- "seconds per page" amounts much faster than natural time, and
			-- then suddenly stall for 30 seconds without getting any pages.
			-- So a "remaining time" estimate would not move naturally. Instead,
			-- we use a constantly updating "total time estimate" which follows
			-- the server performance beautifully and is easy to understand.
			-- NOTE: Thanks to the linear blend between historical and current
			-- server performance, our estimate is very accurate yet responsive.
			-- NOTE: The total page count is able to change during AH scan, when
			-- more auctions are added or removed, which further contributes to
			-- the confusion if we would use a "time remaining" display instead,
			-- but since we use a "total time" estimate the user instead smoothly
			-- sees the total estimate change when the page count changes.
			local seconds_total_estimate = max(1, floor((total * seconds_per_page) + 0.5))

			-- Convert the "elapsed / estimated" seconds into hours, minutes and seconds.
			time_estimate_str = format(" (%s / ~%s)", TSMAPI:FormatHMS(TSMAPI:SecondsToHMS(seconds_elapsed)), TSMAPI:FormatHMS(TSMAPI:SecondsToHMS(seconds_total_estimate)))
		end

		-- Calculate progress bar from 0-100%.
		local progress_bar = min(100 * progress_float, 100)

		-- Display the progress bar with the time estimate.
		TSM.GUI:UpdateStatus(format(L["Scanning page %s/%s"], page, total) .. time_estimate_str, progress_bar)
	elseif event == "SCAN_COMPLETE" then
		-- The whole scan is complete, and wasn't interrupted by the player.

		-- Store the final "seconds elapsed per page request" into the database.
		-- NOTE: We only update it here after complete scans, to avoid poisoning
		-- with incorrect, partial-scan estimates, since most servers heavily
		-- slow down their page requests over time. The completed scan is the truth.
		if Scan.fullScanSecondsPerPage > 0 then
			TSM.db.realm.lastScanSecondsPerPage = Scan.fullScanSecondsPerPage
		end

		-- Calculate how many seconds the completed "Full Scan" took.
		-- NOTE: We must cache it in this external variable, because "Full Scans"
		-- use a threading callback which calls "DoneScanning()" one more time,
		-- so we preserve the value to still display it via that callback too.
		Scan.fullScanCompleteElapsed = abs(time() - Scan.fullScanStartTime)

		-- Now process all of the fetched auctions, and display the total time elapsed.
		local data = ...
		Scan:ProcessScanData(data)
		Scan:DoneScanning(Scan.fullScanCompleteElapsed)
	elseif event == "SCAN_INTERRUPTED" or event == "INTERRUPTED" then
		-- We've been interrupted by the Auction House closing.
		-- NOTE: "SCAN_INTERRUPTED" is from LibAuctionScan-1.0, which isn't used
		-- by TSM anymore, and "INTERRUPTED" is from "TSM/Auction/AuctionScanning.lua",
		-- which is what this scanner uses nowadays.
		local data = ...
		Scan:ProcessScanData(data)
		Scan:DoneScanning()
	end
end


local function GroupScanCallback(event, ...)
	if event == "QUERY_COMPLETE" then
		local filterList = ...
		local numItems = 0
		for _, v in ipairs(filterList) do
			numItems = numItems + #v.items
		end
		Scan.filterList = filterList
		Scan.numFilters = #filterList
		Scan:ScanNextGroupFilter()
	elseif event == "QUERY_UPDATE" then
		local current, total = ...
		TSM.GUI:UpdateStatus(format(L["Preparing Filter %d / %d"], current, total))
	elseif event == "SCAN_INTERRUPTED" or event == "INTERRUPTED" then
		-- We've been interrupted by the Auction House closing.
		-- NOTE: "SCAN_INTERRUPTED" is from LibAuctionScan-1.0, which isn't used
		-- by TSM anymore, and "INTERRUPTED" is from "TSM/Auction/AuctionScanning.lua",
		-- which is what this scanner uses nowadays.
		Scan:DoneScanning()
	elseif event == "SCAN_TIMEOUT" then
		tremove(Scan.filterList, 1)
		Scan:ScanNextGroupFilter()
	elseif event == "SCAN_PAGE_UPDATE" then
		local page, total = ...
		-- We have now received at least 1 page for this item. Show how many pages remain.
		-- NOTE: We can't provide any time estimate here, since the other group sizes are unknown.
		-- NOTE: We use this particular item's page-progress as the progress bar.
		-- NOTE: We add "+1" to the page counter, to indicate that we've received that page and are working on the next page.
		local progress_bar = min(100*(page/total), 100)  -- Calculate progress bar from 0-100%.
		TSM.GUI:UpdateStatus(format(L["Scanning %d / %d (Page %d / %d)"], ((Scan.numFilters-#Scan.filterList) + 1), Scan.numFilters, min(page + 1, total), total), nil, progress_bar)
	elseif event == "SCAN_COMPLETE" then
		local data = ...
		for _, itemString in ipairs(Scan.filterList[1].items) do
			if not Scan.groupScanData[itemString] then
				Scan.groupScanData[itemString] = data[itemString]
			end
		end
		tremove(Scan.filterList, 1)
		Scan:ScanNextGroupFilter()
	end
end

function Scan:ScanNextGroupFilter(data)
	if #Scan.filterList == 0 then
		-- Calculate how many seconds the completed "Group Scan" took.
		local seconds_elapsed = abs(time() - Scan.groupScanStartTime)

		-- Now process all of the fetched auctions, and display the total time elapsed.
		Scan:ProcessScanData(Scan.groupScanData)
		Scan:DoneScanning(seconds_elapsed)
		return
	end

	-- Apply the temporary label for when we've requested the item's 1st page,
	-- but we don't yet know how many results or pages there are for this item.
	-- NOTE: We can't provide any time estimate here, since the other group sizes are unknown.
	-- NOTE: In the label, we count the items starting at 1, to say "Scanning 1 / 2"
	-- (instead of "Scanning 0 / 2"), but for the progress bar we count starting
	-- from 0, so that it fills up properly by only proceeding after an item is done.
	local progress_bar = min(100*((Scan.numFilters-#Scan.filterList)/Scan.numFilters), 100)  -- Calculate progress bar from 0-100%.
	TSM.GUI:UpdateStatus(format(L["Scanning %d / %d (Page 1 / ?)"], ((Scan.numFilters-#Scan.filterList) + 1), Scan.numFilters), progress_bar)
	TSMAPI.AuctionScan:RunQuery(Scan.filterList[1], GroupScanCallback)
end

function Scan:StartGroupScan(items)
	Scan.isScanning = "Group"
	Scan.groupItems = items
	wipe(Scan.filterList)
	wipe(Scan.groupScanData)
	Scan.numFilters = 0
	TSMAPI.AuctionScan:StopScan()
	TSM.GUI:SetPauseEnabled(true)
	TSM.GUI:SetPaused(false)
	Scan.groupScanStartTime = time()  -- Keep track of when we started the "Group Scan".
	TSMAPI:GenerateQueries(items, GroupScanCallback)
	TSM.GUI:UpdateStatus(L["Preparing Filters..."])
end

function Scan:StartFullScan()
	Scan.isScanning = "Full"
	TSM.GUI:UpdateStatus(L["Running query..."])
	Scan.groupItems = nil
	TSMAPI.AuctionScan:StopScan()
	TSM.GUI:SetPauseEnabled(true)
	TSM.GUI:SetPaused(false)
	Scan.fullScanStartTime = time()  -- Keep track of when we started the "Full Scan".
	Scan.fullScanSecondsPerPage = -1  -- Reset the page-speed timer.
	Scan.fullScanCompleteElapsed = nil  -- Reset the "full scan completed" information.
	TSMAPI.AuctionScan:RunQuery({name=""}, FullScanCallback)
end

function Scan:DoneScanning(seconds_elapsed)
	if seconds_elapsed then
		-- If given the "time elapsed", display it as "Done Scanning (1:35:27)".
		TSM.GUI:UpdateStatus(format("%s (%s)", L["Done Scanning"], TSMAPI:FormatHMS(TSMAPI:SecondsToHMS(seconds_elapsed))), 100)
	else
		-- Used when we don't care about showing time (such as scan failures).
		TSM.GUI:UpdateStatus(L["Done Scanning"], 100)
	end
	Scan.isScanning = nil
	TSM.GUI:SetPauseEnabled(false)
	TSM.GUI:SetPaused(false)
end

function Scan:PauseScan()
	if not Scan.isScanning then return end
	if TSMAPI.AuctionScan:PauseScan("AuctionDB") then
		TSM.GUI:SetPaused(true)
		TSM.GUI:UpdateStatus(L["Scan Paused"])
	end
end

function Scan:ResumeScan()
	if not Scan.isScanning then return end
	if not TSMAPI.AuctionScan:IsScanning() then
		Scan:DoneScanning()
		return
	end
	if TSMAPI.AuctionScan:ResumeScan() then
		TSM.GUI:SetPaused(false)
		TSM.GUI:UpdateStatus(L["Resuming Scan..."])
	end
end

function Scan:TogglePause()
	if TSMAPI.AuctionScan:IsPaused() then
		Scan:ResumeScan()
	else
		Scan:PauseScan()
	end
end

function Scan:ProcessScanData(scanData)
	-- Handle scans performed via "Full Scan" and "Group Scan".
	local data = {}

	for itemString, obj in pairs(scanData) do
		if TSMAPI:GetBaseItemString(itemString) == itemString then
			local itemID = obj:GetItemID()
			local quantity, minBuyout = 0, 0
			local records = {}
			for _, record in ipairs(obj.records) do
				-- Only process this auction if we saw a valid buyout price (ignore bid-only auctions, etc).
				if record.buyout and record.buyout > 0 then
					-- Calculate the price per item, always rounded downwards.
					-- NOTE: "GetItemBuyout" returns nil if no buyout or if buyout is "0".
					local itemBuyout = record:GetItemBuyout()
					if itemBuyout then
						-- Calculate the lowest "per-item buyout price" we're seeing for this item.
						if (itemBuyout < minBuyout or minBuyout == 0) then
							minBuyout = itemBuyout
						end

						-- Count the total amount of this item that exists on the auction house (adds together all stacks).
						quantity = quantity + record.count

						-- BRAINDEAD OLD TSM CODE WHICH ADDS 1 RECORD PER ITEM IN THE STACK,
						-- MEANING 500 STACKS OF 1000 ARROWS WOULD BE HALF A MILLION TABLE
						-- ROWS AND WOULD LEAD TO "OUT OF MEMORY" ERRORS. DON'T DO THIS!
						-- for i=1, record.count do
						-- 	tinsert(records, itemBuyout)
						-- end

						-- Rewritten, intelligent code which adds 1 record per "stack" (auction) instead.
						tinsert(records, {record.count, itemBuyout})
					end
				end
			end

			-- Add this item to "data to process" even if there's zero records,
			-- which can happen if they're all bid-only auctions.
			-- NOTE: Empty records are fine; ProcessData ignores items without buyout prices.
			-- NOTE: Empty records are totally fine either way, since "ProcessData"
			-- simply ignores items that don't contain any buyout prices.
			-- NOTE: If no buyout records were found, the "minBuyout" and "quantity"
			-- fields below both have the default value of "0" (initialized above).
			data[itemID] = {records=records, minBuyout=minBuyout, quantity=quantity}
		end
	end

	-- Mark the collected auction data as a new "complete scan" with today's date,
	-- but only if this was a normal "Full Scan" (not just a "TSM item group" scan).
	if Scan.isScanning ~= "Group" then
		TSM.db.realm.lastCompleteScan = time()
	end

	-- Process the collected auction data.
	TSM.Data:ProcessData(data, Scan.groupItems, verifyNewAlgorithm)
	if TSM.ChannelSync then
		TSM.ChannelSync:BroadcastScanData(Scan.isScanning, Scan.groupItems)
	end
end

function Scan:ProcessImportedData(auctionData)
	-- Handle manually imported auction scan data.
	-- NOTE: This function is deprecated? Nothing seems to call it, unless they're
	-- somehow calling it via another non-named technique, or perhaps it's internal
	-- for developer-use only (basically just a quick way to emulate a full scan).
	local data = {}

	for itemID, auctions in pairs(auctionData) do
		-- Process all imported auction records for this item.
		local quantity, minBuyout = 0, 0
		local records = {}
		for _, auction in ipairs(auctions) do
			-- Fetch the "price per item" and "item-count in this stack" from the auction's data.
			-- NOTE: We only import auctions with per-item buyout values (ignore bid-only auctions, etc).
			local itemBuyout, count = unpack(auction)
			if itemBuyout then
				-- Calculate the lowest "per-item buyout price" we're seeing for this item.
				if (itemBuyout < minBuyout or minBuyout == 0) then
					minBuyout = itemBuyout
				end

				-- Count the total amount of this item that exists on the auction house (adds together all stacks).
				quantity = quantity + count

				-- BRAINDEAD OLD TSM CODE WHICH ADDS 1 RECORD PER ITEM IN THE STACK,
				-- MEANING 500 STACKS OF 1000 ARROWS WOULD BE HALF A MILLION TABLE
				-- ROWS AND WOULD LEAD TO "OUT OF MEMORY" ERRORS. DON'T DO THIS!
				-- for i=1, count do
				-- 	tinsert(records, itemBuyout)
				-- end

				-- Rewritten, intelligent code which adds 1 record per "stack" (auction) instead.
				tinsert(records, {count, itemBuyout})
			end
		end

		-- Add this item to "data to process" even if there's zero records,
		-- which can happen if they're all bid-only auctions.
		data[itemID] = {records=records, minBuyout=minBuyout, quantity=quantity}
	end

	-- Process the imported auction data as a new "complete scan" with today's date.
	TSM.db.realm.lastCompleteScan = time()
	TSM.Data:ProcessData(data, nil, verifyNewAlgorithm)
end