Module:Jct

 local p = {}
 -- Change to "" upon deployment.
 local moduleSuffix = ""

 local parserModuleName = "Module:Road data/parser" .. moduleSuffix
 local statenameModuleName = "Module:Jct/statename" .. moduleSuffix -- TODO transition
 local cityModuleName = "Module:Jct/city" .. moduleSuffix

 local concat = table.concat
 local insert = table.insert
 local format = mw.ustring.format
 local trim = mw.text.trim

 local parserModule = require(parserModuleName)
 local parser = parserModule.parser
 local util = require("Module:Road data/util")


 -- Shields
 local defaultShieldSize = 24

 local function addContextBanner(route, name, suffix, bannerSpec)
	local bannerModule = 'Module:Road data/banners/' .. string.upper(route.country)
	local shieldfield = name .. 'shield'
	local shield = parser(route, shieldfield)
	if shield == nil then
		-- This route type does not define shield.
		-- Find shield in the default banner table.
		shield = parser(route, 'shield', name, bannerModule)
		if shield and shield ~= '' then
			if suffix == nil then
				suffix = parser(route, 'shield', 'suffix', bannerModule)
			end
			if suffix and suffix ~= '' then
				shield = shield .. " " .. suffix
			end
			shield = shield .. ".svg"
		end
	end
	if shield and shield ~= '' then
		local shieldSize = defaultShieldSize
		-- Add banner plate.
		insert(bannerSpec, {shield, shieldSize})
	end
 end

 local function bannerSpec(banner, bannerSize, bannerSuffix, route)
	local banners = {}
	if type(banner) == "table" then
		local bannerSizeIsNotTable = type(bannerSize) ~= "table"
		for i,filename in ipairs(banner) do
			local bannersize = bannerSizeIsNotTable and bannerSize or bannerSize[i] or defaultShieldSize
			insert(banners, {filename, bannersize})
		end
	elseif banner ~= '' then
		insert(banners, {banner, bannerSize})
	end

	if route.dir then
		addContextBanner(route, 'dir', bannerSuffix, banners)
	end
	if route.to then
		addContextBanner(route, 'to', bannerSuffix, banners)
	end

	return banners
 end

 local function shieldSpec(route, mainShield, shieldList)
	local shieldSpec = {}

	local shield
	local shieldto = parser(route, 'shieldto')
	
	if route.to then
		if not shield then shield = shieldto or parser(route, 'shield') or '' end
	else
		if not shield then shield = parser(route, 'shield') or '' end
	end
	if shield == '' then return shieldSpec end
	local orientation = parser(route, 'orientation')

	local function size(route)
		if orientation == "upright" then
			return defaultShieldSize
			else return "x" .. defaultShieldSize
		end
	end
	
	local shieldsize = size(route)
	
	local banner = parser(route, 'banner') or {}
	local bannersize = defaultShieldSize
	local bannersuffix = parser(route, 'bannersuffix')

	local bannerIsNotTable = type(banner) ~= "table"
	local bannersizeIsNotTable = type(bannersize) ~= "table"
	local bannersuffixIsNotTable = type(bannersuffix) ~= "table"

	if type(shield) == "table" then
		for i,filename in ipairs(shield) do
			local size = shieldsize or shieldsize[i]
			if size == "" then size = nil end
			-- banner.all describes banners that apply to all multiple shields.
			local shieldBanner = bannerIsNotTable and banner or (banner[i] or banner.all or {})
			-- Banner size is default if the corresponding entry
			-- in bannerSize table is not set.
			local shieldBannerSize =
				bannersizeIsNotTable and bannersize
				or (bannersize[i] or bannersize.all or defaultShieldSize)
			local shieldBannerSuffix = bannersuffix and (bannersuffixIsNotTable and bannersuffix or bannersuffix[i])
			insert(shieldSpec, {
				shield = {filename, size},
				banners = bannerSpec(shieldBanner, shieldBannerSize, shieldBannerSuffix, route)
			})
		end
	elseif shield ~= '' then
		if shieldsize == "" then shieldsize = nil end
		insert(shieldSpec, {
			shield = {shield, shieldsize},
			banners = bannerSpec(banner, bannersize, bannersuffix, route)
		})
	end

	return shieldSpec
 end

 local missingShields

 local shieldExistsCache = {}

 local function render(shieldEntry, scale, showLink)
	local shield = shieldEntry.shield
	local banners = shieldEntry.banners

	local size
	if shield[2] then
		local width, height = mw.ustring.match(shield[2], "(%d*)x?(%d*)")
		width = tonumber(width)
		height = tonumber(height)
		local sizeparts = {}
		if width then
			insert(sizeparts, format("%d", width * scale))
		end
		if height then
			insert(sizeparts, format("x%d", height * scale))
		end
		size = concat(sizeparts)
	else
		size = format("%s%d", landscape and "x" or "", defaultShieldSize * scale)
	end
	local shieldCode = format("[[File:%s|%spx|link=|alt=]]", shield[1], size)
	if not banners[1] then return shieldCode end

	for _,banner in ipairs(banners) do
		shieldCode = format("[[File:%s|%spx|link=|alt=]]<br>%s",
			banner[1],
			defaultShieldSize,
			shieldCode)
	end
	return '<span style="display: inline-block; vertical-align: baseline; line-height: 0; text-align: center;">' .. shieldCode .. '</span>'
 end

 function p.shield(route, scale, showLink, mainShield, shieldList)
	missingShields = {}

	scale = scale or 1

	local rendered = {}
	for _,entry in ipairs(shieldSpec(route, mainShield, shieldList)) do
		insert(rendered, render(entry, scale, showLink))
	end
	return concat(rendered), missingShields
 end

 -- Links/abbreviations
 function p.link(route)
	local nolink = route.nolink
	local abbr = parser(route, 'abbr')
	if nolink then
		return abbr
	else
		local link = parser(route, 'link')
		if not link or link == '' then
			return abbr
		else
			return format("[[%s|%s]]", link, abbr)
		end
	end
 end
 -------------------------------------------

 -- Links/abbreviations
 local function routeText(route, jctname, frame)
	local link
	local type = route.type
	if not type or type == '' then
		link = route.route
	else
		link = p.link(route)
	end

	local dir = route.dir and ' ' .. string.lower(route.dir) or ''
	local routeText = link .. dir

	local name = route.name
	if name and name ~= '' then
		local mainText = jctname and name or routeText
		local parenText = jctname and routeText or name
		
		return format('%s (%s)', mainText, parenText)
	else
		return routeText
	end
 end

 local function extra(args)
	local extraTypes = mw.loadData('Module:Road data/extra')
	local extraIcon = extraTypes[string.lower(args.extra or '')]
	if not extraIcon then return '' end
	local size = defaultShieldSize .. 'px'
	local countryIcon = extraIcon[args.country] or extraIcon.default
	if type(countryIcon) == 'table' then
		local localIcon = countryIcon[args.state] or countryIcon.default
		return string.format("[[File:%s|%s|alt=|link=]]", localIcon, size)
	else
		return string.format("[[File:%s|%s|alt=|link=]]", countryIcon, size)
	end
 end

 local function parseArgs(args)
	local state = args.state or args.province or ''
	args.state = state
	local country
	if args.country and args.country ~= '' then
		country = string.upper(args.country)
	else
		local countryModule = mw.loadData("Module:Road data/countrymask")
		country = countryModule[state] or 'UNK'
	end
	args.country = country

	local params = {'denom', 'county', 'township', 'dab', 'nolink', 'noshield', 'to', 'dir', 'name'}
	local routes = {}
	local routeCount = 1
	local seenTo = false
	while true do
		local routeType = args[routeCount * 2 - 1]
		if not routeType then break end
		local route = {type = routeType, route = args[routeCount * 2]}
		for _,v in pairs(params) do
			route[v] = args[v .. routeCount]
		end
		
		if args.nolink then
			route.nolink = args.nolink
		end
		
		route.country = country
		route.state = state

		-- Set the first .to to true.
		-- Set all following .to to ''.
		if seenTo then
			if route.to then
				-- Report duplicate to flag.
				route.toerror = true
			end
			route.to = ''
		elseif route.to then
			route.to = true
			seenTo = true
		end

		insert(routes, route)
		routeCount = routeCount + 1
	end
	return routes
 end

 local function prefix(to, num)
	if to and to ~= '' then
		return num == 1 and 'To ' or ' to '
	end
	return num == 1 and '' or '&nbsp;/ '
 end

 local function addErrorMsg(catCode, msg, errorMsg)
	errorMsg.code = errorMsg.code or catCode
	insert(errorMsg, format('<span style="display: none;">Module:Jct %s</span>', msg))
 end

 function p._jct(args, frame)
	local routes = parseArgs(args)
	local shields = {}
	local links = {}
	local allMissingShields = {}
	local typeErr = false
	local toErr = false
	frame = frame or mw.getCurrentFrame()
	for num,route in ipairs(routes) do
		if not (args.noshield or route.noshield) then
			local shield, missingShields = p.shield(route)
			insert(shields, shield)
			if missingShields[1] then
				insert(allMissingShields, concat(missingShields, ' / '))
			end
		end
		local prefix = prefix(route.to, num)
		if prefix ~= '' then insert(links, prefix) end
		insert(links, routeText(route, args.jctname, frame))
		typeErr = typeErr or route.typeerror or false
		toErr = toErr or route.toerror or false
	end
	local graphics = concat(shields) .. extra(args) .. ' '
	local linkText = concat(links)
	local cities = ''
	if args.city1 or args.location1 then
		local citiesPrefix
		if args.citiesprefix then
			citiesPrefix = args.citiesprefix ~= '' and format(" %s ", args.citiesprefix) or ''
		else
			citiesPrefix = '&nbsp;'
		end
		local cityModule = require(cityModuleName)
		cities = citiesPrefix .. cityModule.city(args)
	end

	local errorMsg = {}
	-- Errors must be reported by the level of severity, most severe first.
	if typeErr then
		-- Report invalid type errors.
		addErrorMsg("§", 'error: Invalid route type', errorMsg)
	end
	if #allMissingShields > 0 then
		-- Report missing shield error.
		-- shieldExists() would have populated missingShields if shields are missing.
		addErrorMsg("¶", 'error: Missing route marker graphics: ' .. concat(allMissingShields, ' / '), errorMsg)
	end
	if toErr then
		-- Report invalid to errors.
		addErrorMsg("&", 'error: Invalid "to" argument', errorMsg)
	end
	if args.road then
		-- Report deprecated "road" warning.
		addErrorMsg("∆", 'warning: "road" parameter is deprecated', errorMsg)
	end
	if args.rdt then
		-- Report deprecated "rdt" warning.
		addErrorMsg("£", 'warning: "rdt" parameter is deprecated', errorMsg)
	end
	if #errorMsg > 0 then
		local page = mw.title.getCurrentTitle().prefixedText -- Get transcluding page's title
		-- Add a category for the first, most severe error.
		insert(errorMsg, format('[[Category:Jct template errors|%s %s]]', errorMsg.code, page))
		errorMsg = concat(errorMsg)
	else
		errorMsg = ''
	end

	return graphics .. linkText .. cities .. errorMsg
 end

 function p.jct(frame)
	-- Import module function to work with passed arguments
	local getArgs = require('Module:Arguments').getArgs
	local args = getArgs(frame, {removeBlanks = false})
	return p._jct(args, frame)
 end

 function p._roadlink(args, frame)
	local routes = parseArgs(args)
	local links = {}
	local typeErr = false
	local toErr = false
	frame = frame or mw.getCurrentFrame()
	for num,route in ipairs(routes) do
		local prefix = prefix(route.to, num)
		if prefix ~= '' then insert(links, prefix) end
		insert(links, routeText(route, args.jctname, frame))
		typeErr = typeErr or route.typeerror or false
		toErr = toErr or route.toerror or false
	end
	local linkText = concat(links)
	local cities = ''
	if args.city1 or args.location1 then
		local citiesPrefix
		if args.citiesprefix then
			citiesPrefix = args.citiesprefix ~= '' and format(" %s ", args.citiesprefix) or ''
		else
			citiesPrefix = '&nbsp;'
		end
		local cityModule = require(cityModuleName)
		cities = citiesPrefix .. cityModule.city(args)
	end

	local errorMsg = {}
	-- Errors must be reported by the level of severity, most severe first.
	if typeErr then
		-- Report invalid type errors.
		addErrorMsg("2", 'error: Invalid route type', errorMsg)
	end
	if toErr then
		-- Report invalid to errors.
		addErrorMsg("3", 'error: Invalid "to" argument', errorMsg)
	end
	if args.road then
		-- Report deprecated "road" warning.
		addErrorMsg("W", 'warning: "road" parameter is deprecated', errorMsg)
	end
	if #errorMsg > 0 then
		local page = mw.title.getCurrentTitle().prefixedText -- Get transcluding page's title
		-- Add a category for the first, most severe error.
		insert(errorMsg, format('[[Category:Jct template errors|%s %s]]', errorMsg.code, page))
		errorMsg = concat(errorMsg)
	else
		errorMsg = ''
	end

	return linkText .. cities
 end

 function p.roadlink(frame)
	-- Import module function to work with passed arguments
	local getArgs = require('Module:Arguments').getArgs
	local args = getArgs(frame, {removeBlanks = true})
	return p._roadlink(args, frame)
 end

 return p