Module:Namespace detect

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--                                                                                                --
--                                           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 "cfg" table.          --
--                                                                                                --
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--                                          Configuration data                                    --
--      Language-specific parameter names can be set here.                                        --
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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 "other" 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 "yes", "no", 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'

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--                                       End configuration data                                   --
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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 "demospace = main" 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="wikitable"'
		.. '\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| <code>' .. cfg.main .. '</code>'
		.. '\n|'
	if useTalk then
		ret = ret .. '\n|-'
			.. '\n| <code>' .. cfg.talk .. '</code>'
			.. '\n|'
	end
	-- Enclose all parameter names in <code> 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] = '<code>' .. param .. '</code>'
			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

return p