Module:CRTBrandList

Documentation for this module may be created at Module:CRTBrandList/doc

-- Module:CRTBrandList
-- Dynamically generates a list of CRT brand buttons by querying
-- distinct brands from actual CRT model pages.
-- This approach ensures all brands with at least one CRT model appear,
-- even if they don't have a dedicated brand category page.
--
-- Uses format=plainlist for efficiency with large datasets (2000+ CRTs).

local p = {}

local function trim(s)
	if s == nil then return nil end
	s = tostring(s)
	s = s:gsub('^%s+', ''):gsub('%s+$', '')
	if s == '' then return nil end
	return s
end

function p.list(frame)
	local args = frame.args
	local linkType = trim(args.link)
	
	-- Query distinct brands from actual CRT model pages
	-- Using plainlist format with custom separator for efficient parsing
	local queryWikitext =
		'{{#ask:\n' ..
		' [[Category:CRT models]]\n' ..
		' [[Has brand::+]]\n' ..
		' |?Has brand\n' ..
		' |format=plainlist\n' ..
		' |sep=@@SEP@@\n' ..
		' |valuesep=@@VAL@@\n' ..
		' |link=none\n' ..
		' |mainlabel=-\n' ..
		' |limit=5000\n' ..
		' |searchlabel=\n' ..
		'}}'
	
	local queryResult = frame:preprocess(queryWikitext)
	
	-- Extract and deduplicate brand names from result
	local seen = {}
	local brandsList = {}
	
	if queryResult then
		-- Split by our custom separator
		for entry in (queryResult .. '@@SEP@@'):gmatch('(.-)@@SEP@@') do
			-- Each entry might have multiple values separated by @@VAL@@
			for brand in (entry .. '@@VAL@@'):gmatch('(.-)@@VAL@@') do
				brand = trim(brand)
				if brand and brand ~= '' and not seen[brand] then
					seen[brand] = true
					table.insert(brandsList, brand)
				end
			end
		end
	end
	
	-- Sort alphabetically
	table.sort(brandsList)
	
	if #brandsList == 0 then
		return '<p><em>No CRT brands found.</em></p>'
	end
	
	-- Build the output: render each brand using Template:Brand entry
	local output = {}
	for _, brand in ipairs(brandsList) do
		local templateCall
		if linkType then
			templateCall = '{{Brand entry|brand=' .. brand .. '|link=' .. linkType .. '}}'
		else
			templateCall = '{{Brand entry|brand=' .. brand .. '}}'
		end
		table.insert(output, frame:preprocess(templateCall))
	end
	
	return table.concat(output, '\n')
end

return p