Aux.scan = {}

local AUCTIONS_PER_PAGE = 50

local controller = (function()
	local controller
	return function()
		controller = controller or Aux.control.controller()
		return controller
	end
end)()

local state, abort, new_job

local scan, scan_auctions, scan_auctions_helper, submit_query, wait_for_callback, wait_for_results, abort

function Aux.scan.start(job)
	Aux.control.on_next_update(function()
		abort()
		state = {
			job = job,
			page = job.page
		}
		return scan()
	end)
end

function Aux.scan.abort(k)
	Aux.control.on_next_update(function()
		abort()
		
		if k then
			return k()
		end
	end)
end

function abort()
	controller().reset()
	if state and state.job and state.job.on_abort then
		state.job.on_abort()
	end
	state = nil
end

function wait_for_results(k)
	local ok
	Aux.control.on_next_event('AUCTION_ITEM_LIST_UPDATE', function()
		ok = true
	end)

	return controller().wait(function() return ok end, k)
end

function wait_for_callback(f, args, k)
	local ok

	if not f then
		ok = true
	else
		tinsert(args, 1, function() ok = true end)
		f(unpack(args))
	end

	return controller().wait(function() return ok end, k)
end

function scan()
	
	submit_query(function()
		
	local count, total_count = GetNumAuctionItems("list")
	
	scan_auctions(count, function()
	
	state.total_pages = math.ceil(total_count / AUCTIONS_PER_PAGE)
	
	state.page = state.job.next_page and state.job.next_page(state.page, state.total_pages)
	
	if state.page then
		return scan()
	else
		if state.job.on_complete then
			state.job.on_complete()
		end
		state = nil
	end
	
	end)end)
end

function scan_auctions(count, k)
	return scan_auctions_helper(1, count, k)
end

function scan_auctions_helper(i, n, k)
	wait_for_callback(state.job.on_read_auction, {i}, function()
	
	if i >= n then
		return k()
	else
		return scan_auctions_helper(i + 1, n, k)
	end
	
	end)
end

function submit_query(k)
	if state.page then
		wait_for_callback(state.job.on_start_page, {state.page, state.total_pages}, function()
		controller().wait(CanSendAuctionQuery, function()
		wait_for_results(k)
		QueryAuctionItems(
			state.job.query.name,
			state.job.query.min_level,
			state.job.query.max_level,
			state.job.query.slot,
			state.job.query.class,
			state.job.query.subclass,
			state.page,
			state.job.query.usable,
			state.job.query.quality
		)
		end)end)
	else
		return k()
	end
end