Module:Namespace detect
----------------------------------------------------------------------------------------------------
 --                                                                                                --
 --                                           NAMESPACE DETECT                                     --
 --                                                                                                --
 --      This module implements the {{namespace detect}} template in Lua, with a few               --
 --      improvements: all namespaces and all namespace aliases are supported, and namespace       --
 --      names are detected automatically for the local wiki. The module can also use the          --
 --      corresponding subject namespace value if it is used on a talk page. Parameter names       --
 --      can be configured for different wikis by altering the values in the &quot;cfg&quot; table.          --
 --                                                                                                --
 ----------------------------------------------------------------------------------------------------
 
 ----------------------------------------------------------------------------------------------------
 --                                          Configuration data                                    --
 --      Language-specific parameter names can be set here.                                        --
 ----------------------------------------------------------------------------------------------------
 
 local cfg = {}
 
 -- This parameter displays content for the main namespace:
 cfg.main = 'main'
 
 -- This parameter displays in talk namespaces:
 cfg.talk = 'talk'
 
 -- This parameter displays content for &quot;other&quot; namespaces (namespaces for which
 -- parameters have not been specified, or for when cfg.demospace is set to cfg.other):
 cfg.other = 'other'
 
 -- This parameter makes talk pages behave as though they are the corresponding subject namespace.
 -- Note that this parameter is used with [[Module:Yesno]]. Edit that module to change
 -- the default values of &quot;yes&quot;, &quot;no&quot;, etc.
 cfg.subjectns = 'subjectns'
 
 -- This parameter sets a demonstration namespace:
 cfg.demospace = 'demospace'
 
 -- This parameter sets a specific page to compare:
 cfg.page = 'page'
 
 -- The header for the namespace column in the wikitable containing the list of possible subject-space parameters.
 cfg.wikitableNamespaceHeader = 'Namespace'
 
 -- The header for the wikitable containing the list of possible subject-space parameters.
 cfg.wikitableAliasesHeader = 'Aliases'
 
 ----------------------------------------------------------------------------------------------------
 --                                       End configuration data                                   --
 ----------------------------------------------------------------------------------------------------
 
 local yesno = require('Module:Yesno')
 
 local p = {}
 
 function p.getPageObject(page)
 	-- Get the page object, passing the function through pcall in case we are over the expensive function count limit.
 	if page then
 		local noError, pageObject = pcall(mw.title.new, page)
 		if not noError then
 			return nil
 		else
 			return pageObject
 		end
 	else
 		return mw.title.getCurrentTitle()
 	end
 end
 
 function p.getParamMappings()
 	--[[ Returns a table of how parameter names map to namespace names. The keys are the actual namespace 
 	  names, in lower case, and the values are the possible parameter names for that namespace, also in
 	  lower case. The table entries are structured like this:
 		{
 			[''] = {'main'},
 			['wikipedia'] = {'wikipedia', 'project', 'wp'},
 			...
 		}
 	]] 
 	local mappings = {}
 	mappings[mw.ustring.lower(mw.site.namespaces[0].name)] = {cfg.main}
 	mappings[cfg.talk] = {cfg.talk}
 	for nsid, ns in pairs(mw.site.subjectNamespaces) do
 		if nsid ~= 0 then -- Exclude main namespace.
 			local nsname = mw.ustring.lower(ns.name)
 			local canonicalName = mw.ustring.lower(ns.canonicalName)
 			mappings[nsname] = {nsname}
 			if canonicalName ~= nsname then
 				table.insert(mappings[nsname], canonicalName)
 			end
 			for _, alias in ipairs(ns.aliases) do
 				table.insert(mappings[nsname], mw.ustring.lower(alias))
 			end
 		end
 	end
 	return mappings
 end
 
 local function getNamespace(args)
 	-- Gets the namespace name from the page object.
 	local page = args[cfg.page]
 	local demospace = args[cfg.demospace]
 	local subjectns = args[cfg.subjectns]
 	local ret
 	if demospace then
 		-- Handle &quot;demospace = main&quot; properly.
 		if mw.ustring.lower(demospace) == cfg.main then
 			ret = mw.site.namespaces[0].name
 		else
 			ret = demospace
 		end
 	else
 		local pageObject = p.getPageObject(page)
 		if pageObject then
 			if pageObject.isTalkPage then
 				-- If cfg.subjectns is set, get the subject namespace, otherwise use cfg.talk.
 				if yesno(subjectns) then
 					ret = mw.site.namespaces[pageObject.namespace].subject.name
 				else
 					ret = cfg.talk
 				end
 			else
 				ret = pageObject.nsText
 			end
 		else
 			return nil -- return nil if the page object doesn't exist.
 		end
 	end
 	ret = mw.ustring.gsub(ret, '_', ' ')
 	return mw.ustring.lower(ret)
 end
 
 function p._main(args)
 	-- Get the namespace to compare the parameters to, and the parameter mapping table.
 	local namespace = getNamespace(args)
 	local mappings = p.getParamMappings()
 	-- Check for any matches in the namespace arguments. The order we check them doesn't matter,
 	-- as there can only be one match.
 	for ns, params in pairs(mappings) do
 		if ns == namespace then
 			-- Check all aliases for matches. The default local namespace is checked first, as
 			-- {{namespace detect}} checked these before alias names.
 			for _, param in ipairs(params) do
 				if args[param] ~= nil then
 					return args[param]
 				end
 			end
 		end
 	end
 	-- If there were no matches, return parameters for other namespaces. This happens if there
 	-- was no text specified for the namespace that was detected or if the demospace parameter
 	-- is not a valid namespace. Note that the parameter for the detected namespace must be
 	-- completely absent for this to happen, not merely blank.
 	if args[cfg.other] ~= nil then
 		return args[cfg.other]
 	end
 end
 
 function p.main(frame)
 	-- If called via #invoke, use the args passed into the invoking template, or the args
 	-- passed to #invoke if any exist. Otherwise assume args are being passed directly in.
 	local origArgs
 	if frame == mw.getCurrentFrame() then
 		origArgs = frame:getParent().args
 		for k, v in pairs(frame.args) do
 			origArgs = frame.args
 			break
 		end
 	else
 		origArgs = frame
 	end
 	-- Trim whitespace and remove blank arguments for demospace and page parameters.
 	local args = {}
 	for k, v in pairs(origArgs) do
 		if type(v) == 'string' then
 			v = mw.text.trim(v) -- Trim whitespace.
 		end
 		if k == cfg.demospace or k == cfg.page then
 			if v ~= '' then
 				args[k] = v
 			end
 		else
 			args[k] = v
 		end
 	end
 	return p._main(args)
 end
 
 function p.table(frame)
 	--[[ Create a wikitable of all subject namespace parameters, for documentation purposes. The talk 
 	  parameter is optional, in case it needs to be excluded in the documentation.
 	]]
 	local useTalk = type(frame) == 'table' and type(frame.args) == 'table' and frame.args.talk == 'yes' -- Whether to use the talk parameter.
 	local mappings = p.getParamMappings()
 	-- Start the wikitable.
 	local ret = '{| class=&quot;wikitable&quot;'
 		.. '\n|-'
 		.. '\n! ' .. cfg.wikitableNamespaceHeader
 		.. '\n! ' .. cfg.wikitableAliasesHeader
 	
 	-- Generate the row for the main namespace, as we want this to be first in the list.
 	ret = ret .. '\n|-'
 		.. '\n| &lt;code&gt;' .. cfg.main .. '&lt;/code&gt;'
 		.. '\n|'
 	if useTalk then
 		ret = ret .. '\n|-'
 			.. '\n| &lt;code&gt;' .. cfg.talk .. '&lt;/code&gt;'
 			.. '\n|'
 	end
 	-- Enclose all parameter names in &lt;code&gt; tags.
 	for ns, params in pairs(mappings) do
 		if ns ~= mw.site.namespaces[0].name then
 			for i, param in ipairs(params) do
 				mappings[ns][i] = '&lt;code&gt;' .. param .. '&lt;/code&gt;'
 			end
 		end
 	end
 	-- Generate the other wikitable rows.
 	for ns, params in pairs(mappings) do
 		if ns ~= mw.site.namespaces[0].name then -- Ignore the main namespace.
 			ret = ret .. '\n|-'
 				.. '\n| ' .. params[1]
 				.. '\n| ' .. table.concat(params, ', ', 2)
 		end
 	end
 	-- End the wikitable.
 	ret = ret .. '\n|-'
 		.. '\n|}'
 	return ret
 end