Editing Module:Redirect template

require('Module:No globals')

local p = {}

-- key is beginning of arg name. value is table with namespace number and link
-- alternatively, a function taking the namespace number and returning a validity
-- can be used
local namespaceCategories = {
	all = { function() return true end },
	main = { 0, '[[wp:mainspace|main]]' },
	help = { 12, '[[wp:help namespace|help]]' },
	portal = { 100, '[[wp:portal|portal]]' },
	talk = { function(n) return n > 0 and n%2 == 1 end, '[[Help:Using talk pages|talk]]' },
	template = { 10, '[[wp:template namespace|template]]' },
	wikipedia = { 4, '[[wp:project namespace|Wikipedia project]]' },
	category = { 14, '[[wp:categorization|category]]' },
	user = { 2, '[[wp:user pages|user]]' },
}

-- Don't convert blank category to nil
local function valueFunc(key, val)
	if type(val) == 'string' then
		val = val:match('^%s*(.-)%s*$')
		if val == '' and key ~= 'category' and key ~= 'embed' then
			return nil
		end
	end
	return val
end

local function getPrettyName(args)
	for k in pairs(namespaceCategories) do
		if args[k .. ' category'] then
			return  "'''[[:Category:" .. args[k .. ' category'] .. "|" .. args.name .. "]]''': "
		end
	end
	return "'''" .. args.name .. "''': "
end

function p.core(frame, args)
	if not args then
		args = require('Module:Arguments').getArgs(frame, {wrappers = 'Template:Redirect template/core', valueFunc = valueFunc})
	end
	local namespace = mw.title.getCurrentTitle().namespace
	local otherCategory = args['other category'] and (args.category or string.format('[[Category:%s]]', args['other category']))
	local embedPossible = args.embed == nil or args.embed == 'yes'

	--- XXX: this is a HORRIBLE HACK. kill it with fire as soon as https://bugzilla.wikimedia.org/show_bug.cgi?id=12974 is fixed
	local beCompatibleWithBug12974 = args.info and (args.info:find('^[:;#*]', 1) == 1 or args.info:find('{|', 1, true) == 1) and '\n' or ' '
	
	local retval = string.format('*%sThis is a redirect%s%s.%s%s',
		embedPossible and args.name and getPrettyName(args) or '',
		args.from and (' from ' .. args.from) or '',
		args.to and (' to ' .. args.to) or '',
		args.info and beCompatibleWithBug12974 or '',
		args.info or ''
	)
	for k,v in pairs(namespaceCategories) do
		if args[k .. ' category'] then
			if type(v[1]) == 'function' and v[1](namespace) or v[1] == namespace then
				retval = retval .. (args.category or string.format('[[Category:%s]]', args[k .. ' category']))
			elseif args['other category'] then
				retval = retval .. otherCategory
			else
				retval = retval .. frame:expandTemplate{title = 'Incorrect redirect template', args = {v[2]}}
			end
		end
	end
	return retval
end

function p.main(frame)
	local args = require('Module:Arguments').getArgs(frame, {wrappers = 'Template:Redirect template', valueFunc = valueFunc})
	local retval = p.core(frame, args)
	if mw.title.getCurrentTitle().namespace == 0 then
		if args.printworthy == 'yes' then
			return retval .. (args.category or '[[Category:Printworthy redirects]]')
		elseif args.printworthy == 'no' then
			return retval .. (args.category or '[[Category:Unprintworthy redirects]]')
		end
	end
	return retval
end

return p