Module:documentation

local export = {}

-- it is either here, or in [[Module:ugly hacks]], and it is not in ugly hacks.
function export.CONTENTMODEL()
	return mw.title.getCurrentTitle().contentModel
end

local skins = {
	["common"     ] = "";
	["vector"     ] = "Vector";
	["monobook"   ] = "Monobook";
	["cologneblue"] = "Cologne Blue";
	["modern"     ] = "Modern";
}

local Array = require "Module:array"

local function track(page)
	require("Module:debug/track")("documentation/" .. page)
	return true
end

local function compare_pages(page1, page2, text)
	return "[" .. tostring(
		mw.uri.fullUrl("Special:ComparePages", {page1 = page1, page2 = page2}))
		.. " " .. text .. "]"
end

local function page_exists(title)
	local success, title_obj = pcall(mw.title.new, title)
	return success and title_obj.exists
end

-- Avoid transcluding [[Module:languages/cache]] everywhere.
local lang_cache = setmetatable({}, { __index = function (self, k)
	return require "Module:languages/cache"[k]
end })

local function zh_link(word)
	return require("Module:links").full_link{
		lang = lang_cache.zh,
		term = word
	}
end

local function make_languages_data_documentation(title, cats, division)
	local doc_template, module_cat
	if division:find("/extra$") then
		division = division:gsub("/extra$", "")
		doc_template = "language extradata documentation"
		module_cat = "Language extra data modules"
	else
		doc_template = "language data documentation"
		module_cat = "Language data modules"
	end
	local sort_key
	if division == "exceptional" then
		sort_key = "x"
	else
		sort_key = division:gsub("/", "")
	end
	cats:insert(module_cat .. "|" .. sort_key)
	return {
		title = doc_template
	}
end

local function make_Unicode_data_documentation(title, cats)
	local subpage, first_three_of_code_point
		= title.fullText:match("^Module:Unicode data/([^/]+)/(%x%x%x)$")
	if subpage == "names" or subpage == "images" or subpage == "emoji images" then
		local low, high =
			tonumber(first_three_of_code_point .. "000", 16),
			tonumber(first_three_of_code_point .. "FFF", 16)
		local text, text_type
		if subpage == "names" then
			text_type = "titles of images"
		elseif subpage == "images" then
			text_type = "titles of images"
		elseif subpage == "emoji images" then
			text_type = "emoji-style images"
		end
		text = string.format(
			"This data module contains the " .. text_type .. " of " ..
			"[[Appendix:Unicode|Unicode]] code points within the range U+%04X to U+%04X.",
			low, high)
		if subpage == "images" and pcall(mw.loadData, "Module:Unicode data/emoji images/" .. first_three_of_code_point) then
			text = text .. " This list includes the text variants of emojis. For the list of emoji variants of those characters, see [[Module:Unicode data/emoji images/" .. first_three_of_code_point .. "]]."
		elseif subpage == "emoji images" then
			text = text .. " For text-style images, see [[Module:Unicode data/images/" .. first_three_of_code_point .. "]]."
		end
		return text
	end
end

local function insert_lang_data_module_cats(cats, langcode, overall_data_module_cat)
	local lang = lang_cache[langcode]
	if lang then
		local langname = lang:getCanonicalName()
		cats:insert(overall_data_module_cat .. "|" .. langname)
		cats:insert(langname .. " modules")
		cats:insert(langname .. " data modules")
		return lang, langname
	end
end

--[=[
This provides categories and documentation for various data modules, so that [[Category:Uncategorized modules]] isn't
unnecessarily cluttered. It is a list of tables, each of which have the following possible fields:

`regex` (required): A Lua pattern to match the module's title. If it matches, the data in this entry will be used.
	Any captures in the pattern can by referenced in the `cat` field using %1 for the first capture, %2 for the
	second, etc. (often used for creating the sortkey for the category). In addition, the captures are passed to the
	`process` function as the third and subsequent parameters.

`process` (optional): This may be a function or a string. If it is a function, it is called as follows:
	   `process(TITLE, CATS, CAPTURE1, CAPTURE2, ...)`
	where:
	   * TITLE is a title object describing the module's title; see
	     [https://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Title_objects].
	   * CATS is an array object (see [[Module:array]]) of categories that the module will be added to.
	   * CAPTURE1, CAPTURE2, ... contain any captures in the `regex` field.
	The return value of `process` should either be a string (which will be used as the module's documentation), or a
	table specifying the name of a template to expand to get the documentation, along with the arguments to that
	template. In the latter format, the template name (bare, without the "Template:" prefix) should be in the `title`
	field, and any arguments should be in `args; in this case, the template name will be listed above the generated
	documentation as the source of the documentation, along with an edit button to edit the template's contents.
	If, however, the return value of the `process` function is a string, any template invocations will be expanded
	using frame:preprocess(), and [[Module:documentation]] will be listed as the source of the documentation.

	If `process` itself is a string rather than a function, it should name a submodule under
	[[Module:documentation/functions/]] which returns a function, of the same type as described above. This submodule
	will be specified as the source of the documentation (unless it returns a table naming a template to expand to get
	the documentation, as described above).

	If `process` is omitted entirely, the module will have no documentation.

`cat` (optional): A string naming the category into which the module should be placed, or a list of such strings.
	Captures specified in `regex` may be referenced in this string using %1 for the first capture, %2 for the second,
	etc. It is also possible to add categories in the `process` function by inserting them into the passed-in CATS
	array (the second parameter).
]=]

local module_regex = {
	{
		regex = "^Module:languages/data/(3/[a-z]/extra)$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/data/(3/[a-z])$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/data/(2/extra)$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/data/(2)$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/data/(exceptional/extra)$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/data/(exceptional)$",
		process = make_languages_data_documentation,
	},
	{
		regex = "^Module:languages/.+$",
		cat = "Language and script modules",
	},
	{
		regex = "^Module:scripts/.+$",
		cat = "Language and script modules",
	},
	{
		regex = "^Module:data tables/data..?.?.?$",
		cat = "Reference module sharded data tables",
	},
	{
		regex = "^Module:zh/data/dial%-pron/.+$",
		cat = "Chinese dialectal pronunciation data modules",
		process = "zh dial or syn",
	},
	{
		regex = "^Module:zh/data/dial%-syn/.+$",
		cat = "Chinese dialect synonyms data modules",
		process = "zh dial or syn",
	},
	{
		regex = "^Module:zh/data/glyph%-data/.+$",
		cat = "Chinese historical character forms data modules",
		process = function(title, cats)
			local character = title.fullText:match("^Module:zh/data/glyph%-data/(.+)")
			if character then
				return ("This module contains data on historical forms of the Chinese character %s.")
					:format(zh_link(character))
			end
		end,
	},
	{
		regex = "^Module:zh/data/ltc%-pron/(.+)$",
		cat = "Middle Chinese pronunciation data modules|%1",
		process = "zh data",
	},
	{
		regex = "^Module:zh/data/och%-pron%-BS/(.+)$",
		cat = "Old Chinese (Baxter-Sagart) pronunciation data modules|%1",
		process = "zh data",
	},
	{
		regex = "^Module:zh/data/och%-pron%-ZS/(.+)$",
		cat = "Old Chinese (Zhengzhang) pronunciation data modules|%1",
		process = "zh data",
	},
	{
		-- capture rest of zh/data submodules
		regex = "^Module:zh/data/(.+)$",
		cat = "Chinese data modules|%1",
	},
	{
		regex = "^Module:mul/guoxue%-data/cjk%-?(.*)$",
		process = "guoxue-data",
	},
	{
		regex = "^Module:Unicode data/(.+)$",
		cat = "Unicode data modules|%1",
		process = make_Unicode_data_documentation,
	},
	{
		regex = "^Module:number list/data/(.+)$",
		process = function(title, cats, lang_code)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Number data modules")
			if lang then
				return ("This module contains data on various types of numbers in %s.\n%s")
					:format(lang:makeCategoryLink(), require("Module:number list/show").table() or "")
			end
		end,
	},
	{
		regex = "^Module:accel/(.+)$",
		process = function(title, cats)
			local lang_code = title.subpageText
			local lang = lang_cache[lang_code]
			if lang then
				cats:insert(lang:getCanonicalName() .. " modules|accel")
				cats:insert(("Accel submodules|%s"):format(lang:getCanonicalName()))
				return ("This module contains new entry creation rules for %s; see [[WT:ACCEL]] for an overview, and [[Module:accel]] for information on creating new rules.")
					:format(lang:makeCategoryLink())
			end
		end,
	},
	{
		regex = "^Module:inc%-ash/dial/data/(.+)$",
		cat = "Ashokan Prakrit modules|%1",
		process = function(title, cats)
			local word = title.fullText:match("^Module:inc%-ash/dial/data/(.+)$")
			if word then
				local lang = lang_cache["inc-ash"]
				return ("This module contains data on the pronunciation of %s in dialects of %s.")
					:format(require("Module:links").full_link({ term = word, lang = lang }, "term"),
						lang:makeCategoryLink())
			end
		end,
	},
	{
		regex = "^.+%-translit$",
		process = "translit",
	},
	{
		regex = "^Module:form of/lang%-data/(.+)$",
		process = function(title, cats, lang_code)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Language-specific form-of modules")
			if lang then
				-- FIXME, display more info.
				return "This module contains language-specific form-of data (tags, shortcuts, base lemma params. etc.) for " ..
					langname .. ".\n\n'''NOTE:''' If you add a new language-specific module, you must add the language code to the " ..
					"list at the top of [[Module:form of]] in order for the module to be recognized."
			end
		end
	},
	{
		regex = "^Module:labels/data/lang/(.+)$",
		process = function(title, cats, lang_code)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Language-specific label data modules")
			if lang then
				return {
					title = "label language-specific data documentation",
					args = { [1] = lang_code },
				}
			end
		end
	},
	{
		regex = "^Module:category tree/poscatboiler/data/lang%-specific/(.+)$",
		process = function(title, cats, lang_code)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Category tree data modules/poscatboiler")
			if lang then
				return "This module handles generating the descriptions and categorization for " .. langname .. " category pages "
					.. "of the format \"" .. langname .. " LABEL\" where LABEL can be any text. Examples are "
					.. "[[:Category:Bulgarian conjugation 2.1 verbs]] and [[:Category:Russian velar-stem neuter-form nouns]]. "
					.. "This module is part of the poscatboiler system, which is a general framework for generating the "
					.. "descriptions and categorization of category pages.\n\n"
					.. "For more information, see [[Module:category tree/poscatboiler/data/lang-specific/documentation]].\n\n"
					.. "'''NOTE:''' If you add a new language-specific module, you must add the language code to the "
					.. "list at the top of [[Module:category tree/poscatboiler/data/lang-specific]] in order for the module to be "
					.. "recognized."
			end
		end
	},
	{
		regex = "^Module:category tree/poscatboiler/data/(.+)$",
		process = function(title, cats, submodule)
			cats:insert("Category tree data modules/poscatboiler| ")
			return {
				title = "poscatboiler data submodule documentation"
			}
		end
	},
	{
		regex = "^Module:category tree/topic cat/data/(.+)$",
		process = function(title, cats, submodule)
			cats:insert("Category tree data modules/topic cat| ")
			return {
				title = "topic cat data submodule documentation"
			}
		end
	},
	{
		regex = "^Module:ja/data/(.+)$",
		cat = "Japanese data modules|%1",
	},
	{
		regex = "^Module:fi%-dialects/data/feature/Kettunen1940 ([0-9]+)$",
		cat = "Finnish dialectal data atlas modules|%1",
		process = function(title, cats, shard)
			return "This module contains shard " .. shard .. " of the online version of Lauri Kettunen's 1940 work " ..
				"''Suomen murteet III A. Murrekartasto'' (\"Finnish dialects III A: Dialect atlas\"). " ..
				"It was imported and converted from urn:nbn:fi:csc-kata20151130145346403821, published by the " ..
				"''Kotimaisten kielten keskus'' under the CC BY 4.0 license."
		end
	},
	{
		regex = "^Module:fi%-dialects/data/feature/(.+)",
		cat = "Finnish dialectal data modules|%1",
	},
	{
		regex = "^Module:fi%-dialects/data/word/(.+)",
		cat = "Finnish dialectal data modules|%1",
	},
	{
		regex = "^Module:Swadesh/data/([a-z-]+)$",
		process = function(title, cats, lang_code)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Swadesh modules")
			if lang then
				return "This module contains the [[Swadesh list]] of basic vocabulary in " .. langname .. "."
			end
		end
	},
	{
		regex = "^Module:Swadesh/data/([a-z-]+)/([^/]*)$",
		process = function(title, cats, lang_code, variety)
			local lang, langname = insert_lang_data_module_cats(cats, lang_code, "Swadesh modules")
			if lang then
				local prefix = "This module contains the [[Swadesh list]] of basic vocabulary in the "
				local etym_lang = require("Module:languages").getByCode(variety, nil, "allow etym")
				if etym_lang then
					return ("%s %s variety of %s."):format(prefix, etym_lang:getCanonicalName(), langname)
				end
				local script = require("Module:scripts").getByCode(variety)
				if script then
					return ("%s %s %s script."):format(prefix, langname, script:getCanonicalName())
				end
				return ("%s %s variety of %s."):format(prefix, variety, langname)
			end
		end
	},
	{
		regex = "^Module:typing%-aids",
		process = function(title, cats)
			local data_suffix = title.fullText:match("^Module:typing%-aids/data/(.+)$")
			local sortkey
			if data_suffix then
				if data_suffix:find "^[%l-]+$" then
					local lang = require("Module:languages").getByCode(data_suffix)
					if lang then
						sortkey = lang:getCanonicalName()
						cats:insert(sortkey .. " data modules")
					end
				elseif data_suffix:find "^%u%l%l%l$" then
					local script = require("Module:scripts").getByCode(data_suffix)
					if script then
						sortkey = script:getCanonicalName()
						cats:insert(script:getCategoryName())
					end
				end
				cats:insert("Character insertion data modules|" .. (sortkey or data_suffix))
			end
		end,
	},
	{
		regex = "^Module:R:([a-z%-]+):(.+)$",
		process = function(title, cats, lang_code, refname)
			local lang = lang_cache[lang_code]
			if lang then
				cats:insert(lang:getCanonicalName() .. " modules|" .. refname)
				cats:insert(("Reference modules|%s"):format(lang:getCanonicalName()))
				return "This module implements the reference template {{temp|R:" ..	lang_code .. ":" .. refname .. "}}."
			end
		end,
	},
	{
		regex = "^Module:Quotations/([a-z-]+)/?(.*)",
		process = "Quotation",
	},
	{
		regex = "^Module:affix/lang%-data/([a-z-]+)",
		process = "affix lang-data",
	},
	{
		regex = "^Module:dialect synonyms/([a-z-]+)$",
		process = function(title, cats, lang_code)
			local lang = lang_cache[lang_code]
			if lang then
				local langname = lang:getCanonicalName()
				cats:insert("Dialect synonyms data modules|" .. langname)
				cats:insert(langname .. " dialect synonyms data modules| ")
				return "This module contains data on specific varieties of " .. langname .. ", for use by " ..
					"{{tl|dialect synonyms}}. The actual synonyms themselves are contained in submodules."
			end
		end,
	},
	{
		regex = "^Module:dialect synonyms/([a-z-]+)/(.+)$",
		process = function(title, cats, lang_code, term)
			local lang = lang_cache[lang_code]
			if lang then
				local langname = lang:getCanonicalName()
				cats:insert("Dialect synonyms data modules|" .. langname)
				cats:insert(langname .. " dialect synonyms data modules|" .. term)
				return ("This module contains dialectal %s synonyms for {{m|%s|%s}}."):format(langname, lang_code, term)
			end
		end,
	},
}

function export.show(frame)
	local boolean_default_false = {type = "boolean", default = false}
	local args = require("Module:parameters").process(frame.args, {
		["hr"] = true,
		["for"] = true,
		["from"] = true,
		["allowondoc"] = boolean_default_false, -- Don't throw an error if used on a documentation subpage.
		["notsubpage"] = boolean_default_false,
		["nodoc"] = boolean_default_false,
		["nolinks"] = boolean_default_false, -- suppress all "Useful links"
	})
	
	local output = Array('\n<div class="documentation" style="display:block; clear:both">\n')
	local cats = Array()
	
	local nodoc = args.nodoc
	
	if (not args.hr) or (args.hr == "above") then
		output:insert("----\n")
	end
	
	local title = args["for"] and mw.title.new(args["for"])	or mw.title.getCurrentTitle()
	local doc_title = args.from ~= "-" and mw.title.new(args.from or title.fullText .. '/documentation') or nil
	local contentModel = title.contentModel
	local pagetype = require("Module:pages").pagetype(title)
	local preload, fallback_docs, doc_content, old_doc_title, user_name, skin_name, needs_doc
	local doc_content_source = "Module:documentation"
	local auto_generated_cat_source
	local cats_auto_generated = false
	
	if pagetype == "script" then -- .js
		if title.nsText == "MediaWiki" then
			if title.text:find("Gadget-") then
				preload = "Template:documentation/preloadGadget"
			else
				preload = "Template:documentation/preloadMediaWikiJavaScript"
			end
		else
			preload  = "Template:documentation/preloadTemplate" -- XXX
		end
		if title.nsText == "User" then
			user_name = title.rootText
		end
	elseif pagetype == "stylesheet" then -- .css
		preload  = "Template:documentation/preloadTemplate" -- XXX
		if title.nsText == "User" then
			user_name = title.rootText
		end
	elseif pagetype == "module" or pagetype == "module testcase page" then
		preload  = "Template:documentation/preloadModule"
	elseif pagetype == "module sandbox" then
		user_name = title.rootText:match("^[Uu]ser:(.+)")
		if user_name then
			preload  = "Template:documentation/preloadModuleUserSandbox"
		else
			preload  = "Template:documentation/preloadModuleSandbox"
		end
	elseif pagetype == "template" or pagetype == "template testcase page" then
		preload  = "Template:documentation/preloadTemplate"
	elseif pagetype == "template sandbox" then
		user_name = title.rootText:match("^[Uu]ser:(.+)")
		if user_name then
			preload  = "Template:documentation/preloadTemplateUserSandbox"
		else
			preload  = "Template:documentation/preloadTemplateSandbox"
		end
	elseif pagetype == "project page" then
		preload  = "Template:documentation/preloadTemplate" -- XXX
	elseif not args.allowondoc and (pagetype == "template documentation page" or pagetype == "module documentation page") then
		-- TODO: merge with {{documentation subpage}}, and choose behaviour based on the page type.
		error("This template should not be used on a documentation page. Please use [[Template:documentation subpage]].")
	end

	if doc_title and doc_title.isRedirect then
		old_doc_title = doc_title
		doc_title = doc_title.redirectTarget
	end

	output:insert("<dl class=\"plainlinks\" style=\"font-size: smaller;\">")

	local function get_module_doc_and_cats(categories_only)
		cats_auto_generated = true
		local automatic_cats = nil
		if user_name then
			fallback_docs = "documentation/fallback/user module"
			automatic_cats = {"User sandbox modules"}
		else
			for _, data in ipairs(module_regex) do
				local captures = {mw.ustring.match(title.fullText, data.regex)}
				if #captures > 0 then
					local cat
					local process_function
					if type(data.process) == "function" then
						process_function = data.process
					elseif type(data.process) == "string" then
						doc_content_source = "Module:documentation/functions/" .. data.process
						process_function = require(doc_content_source)
					end

					if process_function then
						doc_content = process_function(title, cats, unpack(captures))
					end
					if type(doc_content) == "table" then
						doc_content_source = doc_content.title and "Template:" .. doc_content.title or doc_content_source
						doc_content = mw.getCurrentFrame():expandTemplate(doc_content)
					elseif doc_content and doc_content:find("{{") then
						doc_content = mw.getCurrentFrame():preprocess(doc_content)
					end
					cat = data.cat
					
					if cat then
						if type(cat) == "string" then
							cat = {cat}
						end
						for _, c in ipairs(cat) do
							-- gsub() and Lua :gsub() return two arguments, which causes all sorts of problems.
							-- Terrible design, there should have been a separate two-argument function.
							local gsub_sucks = mw.ustring.gsub(title.fullText, data.regex, c)
							table.insert(cats, gsub_sucks)
						end
					end
					break
				end
			end
		end

		if title.subpageText == "templates" then
			cats:insert("Template interface modules")
		end

		if automatic_cats then
			for _, c in ipairs(automatic_cats) do
				cats:insert(c)
			end
		end
		
		if #cats == 0 then
			local auto_cats = require("Module:module categorization").categorize(frame, "return raw", "noerror")
			if #auto_cats > 0 then
				auto_generated_cat_source = "Module:module categorization"
			end
			for _, category in ipairs(auto_cats) do
				cats:insert(category)
			end
		end

		-- meaning module is not in user’s sandbox or one of many datamodule boring series
		needs_doc = not categories_only and not (automatic_cats or doc_content or fallback_docs)
	end

	-- Override automatic documentation, if present.
	if doc_title and doc_title.exists then
		local cats_auto_generated_text = ""
		if contentModel == "Scribunto" then
			local doc_page_content = doc_title:getContent()
			-- Track then do nothing if there are uses of includeonly. The
			-- pattern is slightly too permissive, but any false-positives are
			-- obvious typos that should be corrected.
			if doc_page_content:lower():match("</?includeonly%f[%s/>][^>]*>") then
				track("module-includeonly")
			else
				-- Check for uses of {{module cat}}. find_templates treats the
				-- input as transcluded by default (i.e. it parses the wikitext
				-- which will be transcluded through to the module page).
				local module_cat
				for template in require("Module:template parser").find_templates(doc_page_content) do
					if template:get_name() == "module cat" then
						module_cat = true
						break
					end
				end
				if not module_cat then
					get_module_doc_and_cats("categories only")
					auto_generated_cat_source = auto_generated_cat_source or doc_content_source
					cats_auto_generated_text = " Categories were auto-generated by [[" .. auto_generated_cat_source .. "]]. <sup>[[" ..
						mw.title.new(auto_generated_cat_source):fullUrl{action = "edit"} ..  " edit]]</sup>"
				end
			end
		end

		output:insert(
			"<dd><i style=\"font-size: larger;\">The following " ..
			"[[Help:Documenting templates and modules|documentation]] is located at [[" ..
			doc_title.fullText .. "]]. " .. "<sup>[[" .. doc_title:fullUrl{action = "edit"} .. " edit]]</sup>" ..
			cats_auto_generated_text .. "</i></dd>")
	else
		if contentModel == "Scribunto" then
			get_module_doc_and_cats(false)
		elseif title.nsText == "Template" then
			--cats:insert("Uncategorized templates")
			needs_doc = not (fallback_docs or nodoc)
		elseif pagetype == "script" or pagetype == "stylesheet" then
			if user_name then
				skin_name = skins[title.text:sub(#title.rootText + 1):match("^/([a-z]+)%.[jc]ss?$")]
				if skin_name then
					fallback_docs = "documentation/fallback/user " .. contentModel
				end
			end
		end
		
		if doc_content then
			output:insert(
				"<dd><i style=\"font-size: larger;\">The following " ..
				"[[Help:Documenting templates and modules|documentation]] is " ..
				"generated by [[" .. doc_content_source .. "]]. <sup>[[" ..
				mw.title.new(doc_content_source):fullUrl{action = "edit"} ..
				" edit]]</sup> </i></dd>")
		elseif not nodoc then
			if doc_title then
				output:insert(
					"<dd><i style=\"font-size: larger;\">This " .. pagetype ..
					" lacks a [[Help:Documenting templates and modules|documentation subpage]]. " ..
					(fallback_docs and "You may " or "Please ") ..
					"[" .. doc_title:fullUrl{action = "edit", preload = preload}
					.. " create it].</i></dd>\n")
			else
				output:insert(
					"<dd><i style=\"font-size: larger; color: #FF0000;\">Unable to auto-generate " ..
					"documentation for this " .. pagetype ..".</i></dd>\n")
			end
		end
	end
	
	if title.fullText:match("^MediaWiki:Gadget%-") then
		local is_gadget = false
		local gadget_list = mw.title.new("MediaWiki:Gadgets-definition"):getContent()
		
		for line in mw.text.gsplit(gadget_list, "\n") do
			local gadget, opts, items = line:match("^%*%s*([A-Za-z][A-Za-z0-9_%-]*)%[(.-)%]|(.+)$") -- opts is unused
			if not gadget then
				gadget, items = line:match("^%*%s*([A-Za-z][A-Za-z0-9_%-]*)|(.+)$")
			end
			
			if gadget then
				items = Array(mw.text.split(items, "|"))
				for i, item in ipairs(items) do
					if title.fullText == ("MediaWiki:Gadget-" .. item) then
						is_gadget = true

						output:insert("<dd> ''This script is a part of the <code>")
						output:insert(gadget)
						output:insert("</code> gadget ([")
						output:insert(tostring(mw.uri.fullUrl("MediaWiki:Gadgets-definition", {action = "edit"})))
						output:insert(" edit definitions])'' <dl>")
						
						output:insert("<dd> ''Description ([")
						output:insert(tostring(mw.uri.fullUrl("MediaWiki:Gadget-" .. gadget, {action = "edit"})))
						output:insert(" edit])'': ")
						
						local gadget_description = mw.message.new('Gadget-' .. gadget):plain()
						gadget_description = frame:preprocess(gadget_description)
						output:insert(gadget_description)
						output:insert(" </dd>")

						items:remove(i)
						if #items > 0 then
							for j, item in ipairs(items) do
								items[j] = '[[MediaWiki:Gadget-' .. item .. '|' .. item .. ']]'
							end
							output:insert("<dd> ''Other parts'': ")
							output:insert(mw.text.listToText(items))
							output:insert("</dd>")
						end

						output:insert("</dl></dd>")

						break
					end
				end
			end
		end
		
		if not is_gadget then
			output:insert("<dd> ''This script is not a part of any [")
			output:insert(tostring(mw.uri.fullUrl("Special:Gadgets", {uselang = "en"})))
			output:insert(' gadget] ([')
			output:insert(tostring(mw.uri.fullUrl("MediaWiki:Gadgets-definition", {action = "edit"})))
			output:insert(' edit definitions]).</dd>')
		-- else
			-- cats:insert("Wiktionary gadgets")
		end
	end
	
	if old_doc_title then
		output:insert("<dd> ''Redirected from'' [")
		output:insert(old_doc_title:fullUrl{redirect = "no"})
		output:insert(" ")
		output:insert(old_doc_title.fullText)
		output:insert("] ([")
		output:insert(old_doc_title:fullUrl{action = "edit"})
		output:insert(" edit]).</dd>\n")
	end
	
	if not args.nolinks then	
		local links = Array()

		if title.isSubpage and not args.notsubpage then
			links:insert("[[:" .. title.nsText .. ":" .. title.rootText .. "|root page]]")
			links:insert("[[Special:PrefixIndex/" .. title.nsText .. ":" .. title.rootText .. "/|root page’s subpages]]")
		else
			links:insert("[[Special:PrefixIndex/" .. title.fullText .. "/|subpage list]]")
		end
		
		links:insert(
			"[" .. tostring(mw.uri.fullUrl("Special:WhatLinksHere/" .. title.fullText, {hidetrans = true, hideredirs = true})) .. " links]")
	
		if contentModel ~= "Scribunto" then
			links:insert(
				"[" .. tostring(mw.uri.fullUrl("Special:WhatLinksHere/" .. title.fullText, {hidelinks = true, hidetrans = true})) .. " redirects]")
		end
	
		if pagetype == "script" or pagetype == "stylesheet" then
			if user_name then
				links:insert("[[Special:MyPage" .. title.text:sub(#title.rootText + 1) .. "|your own]]")
			end
		else
			links:insert(
				"[" .. tostring(mw.uri.fullUrl("Special:WhatLinksHere/" .. title.fullText, {hidelinks = true, hideredirs = true})) .. " transclusions]")
		end
		
		if contentModel == "Scribunto" then
			local is_testcases = title.isSubpage and title.subpageText == "testcases"
			local without_subpage = title.nsText .. ":" .. title.baseText
			if is_testcases then
				links:insert("[[:" .. without_subpage .. "|tested module]]")
			else
				links:insert("[[" .. title.fullText .. "/testcases|testcases]]")
			end
			
			if user_name then
				links:insert("[[User:" .. user_name .. "|user page]]")
				links:insert("[[User talk:" .. user_name .. "|user talk page]]")
				links:insert("[[Special:PrefixIndex/User:" .. user_name .. "/|userspace]]")
			else
				-- If sandbox module, add a link to the module that this is a sandbox of.
				-- Exclude user sandbox modules like [[User:Dine2016/sandbox]].
				if title.text:find("/sandbox%d*%f[/%z]") then
					cats:insert("Sandbox modules")
					
					track("sandbox to be moved")
					
					-- Sandbox modules don’t really need documentation.
					needs_doc = false
					
					-- Will behave badly if “/sandbox” occurs twice in title!
					local sandbox_of = title.fullText:gsub("/sandbox%d*%f[/%z]", "")
					
					local diff
					if page_exists(sandbox_of) then
						diff = " (" .. compare_pages(title.fullText, sandbox_of, "diff") .. ")"
					else
						track("no sandbox of")
					end
					
					links:insert("[[:" .. sandbox_of .. "|sandbox of]]" .. (diff or ""))
				
				-- If not a sandbox module, add link to sandbox module.
				-- Sometimes there are multiple sandboxes for a single module:
				-- [[Module:sa-pronunc/sandbox]],  [[Module:sa-pronunc/sandbox2]].
				-- Occasionally sandbox modules have their own subpages that are also
				-- sandboxes: [[Module:grc-decl/sandbox/decl]].
				else
					local sandbox_title
					if title.fullText:find("^Module:grc%-decl/") then
						sandbox_title = title.fullText:gsub("^Module:grc%-decl/", "Module:grc-decl/sandbox/")
					elseif is_testcases then
						sandbox_title = title.fullText:gsub("/testcases", "/sandbox/testcases")
					else
						sandbox_title = title.fullText .. "/sandbox"
					end
					local sandbox_link = "[[:" .. sandbox_title .. "|sandbox]]"
					
					local diff
					if page_exists(sandbox_title) then
						diff = " (" .. compare_pages(title.fullText, sandbox_title, "diff") .. ")"
					end
					
					links:insert(sandbox_link .. (diff or ""))
				end
			end
		end
		
		if title.nsText == "Template" then
			-- Error search: all(any namespace), hastemplate (show pages using the template), insource (show source code), incategory (any/specific error) -- [[mw:Help:CirrusSearch]], [[w:Help:Searching/Regex]]
			-- apparently same with/without: &profile=advanced&fulltext=1
			local errorq = 'searchengineselect=mediawiki&search=all: hastemplate:\"'..title.rootText..'\" insource:\"'..title.rootText..'\" incategory:'
			local eincategory = "Pages_with_module_errors|ParserFunction_errors|DisplayTitle_errors|Pages_with_ISBN_errors|Pages_with_ISSN_errors|Pages_with_reference_errors|Pages_with_syntax_highlighting_errors|Pages_with_TemplateStyles_errors"
			
			links:insert(
				'[' .. tostring(mw.uri.fullUrl('Special:Search', errorq..eincategory )) .. ' errors]'
				.. ' (' ..
				'[' .. tostring(mw.uri.fullUrl('Special:Search', errorq..'ParserFunction_errors' )) .. ' parser]'
				.. '/' ..
				'[' .. tostring(mw.uri.fullUrl('Special:Search', errorq..'Pages_with_module_errors' )) .. ' module]'
				.. ')'
			)
			
			if title.isSubpage and title.text:find("/sandbox%d*%f[/%z]") then -- This is a sandbox template.
				-- At the moment there are no user sandbox templates with subpage
				-- “/sandbox”.
				cats:insert("Sandbox templates")
				
				-- Sandbox templates don’t really need documentation.
				needs_doc = false
				
				-- Will behave badly if “/sandbox” occurs twice in title!
				local sandbox_of = title.fullText:gsub("/sandbox%d*%f[/%z]", "")
				
				local diff
				if page_exists(sandbox_of) then
					diff = " (" .. compare_pages(title.fullText, sandbox_of, "diff") .. ")"
				else
					track("no sandbox of")
				end
				
				links:insert("[[:" .. sandbox_of .. "|sandbox of]]" .. (diff or ""))
			else -- This is a template that can have a sandbox.
				local sandbox_title = title.fullText .. "/sandbox"
				
				local diff
				if page_exists(sandbox_title) then
					diff = " (" .. compare_pages(title.fullText, sandbox_title, "diff") .. ")"
				end
				
				links:insert("[[:" .. sandbox_title .. "|sandbox]]" .. (diff or ""))
			end
		end
		
		if #links > 0 then
			output:insert("<dd> ''Useful links'': " .. links:concat(" • ") .. "</dd>")
		end
	end
	
	output:insert("</dl>\n")
	
	-- Show error from [[Module:category tree/topic cat/data]] on its submodules'
	-- documentation to, for instance, warn about duplicate labels.
	if title.fullText:find("Module:category tree/topic cat/data", 1, true) == 1 then
		local ok, err = pcall(require, "Module:category tree/topic cat/data")
		if not ok then
			output:insert('<span class="error">' .. err .. '</span>\n\n')
		end
	end
	
	if doc_title and doc_title.exists then
		-- Override automatic documentation, if present.
		doc_content = frame:expandTemplate { title = doc_title.fullText }
	elseif not doc_content and fallback_docs then
		doc_content = frame:expandTemplate {
			title = fallback_docs,
			args = {
				['user'] = user_name,
				['page'] = title.fullText,
				['skin name'] = skin_name,
			},
		}
	end

	if doc_content then
		output:insert(doc_content)
	end

	output:insert(('\n<%s style="clear: both;" />'):format(args.hr == "below" and "hr" or "br"))
	
	if cats_auto_generated and not cats[1] and (not doc_content or not doc_content:find("%[%[Category:")) then
		if contentModel == "Scribunto" then
			cats:insert("Uncategorized modules")
		-- elseif title.nsText == "Template" then
			-- cats:insert("Uncategorized templates")
		end
	end
	
	if needs_doc then
		cats:insert("Templates and modules needing documentation")
	end
	
	for _, cat in ipairs(cats) do
		output:insert("[[Category:" .. cat .. "]]")
	end
	
	output:insert("</div>\n")

	return output:concat()
end

function export.module_auto_doc_table()
	local parts = {}
	local function ins(text)
		table.insert(parts, text)
	end
	ins('{|class="wikitable"')
	ins("! Regex !! Category !! Handling modules")
	for _, spec in ipairs(module_regex) do
		local cat_text
		local cats = spec.cat
		if cats then
			local cat_parts = {}
			if type(cats) == "string" then
				cats = {cats}
			end
			for _, cat in ipairs(cats) do
				table.insert(cat_parts, ("<code>%s</code>"):format((cat:gsub("|", "&#124;"))))
			end
			cat_text = table.concat(cat_parts, ", ")
		else
			cat_text = "''(unspecified)''"
		end
		ins("|-")
		ins(("| <code>%s</code> || %s || %s"):format(spec.regex, cat_text,
			type(spec.process) == "function" and "''(handled internally)''" or
			type(spec.process) == "string" and ("[[Module:documentation/functions/%s]]"):format(spec.process) or
			"''(no documentation generator)''"))
	end
	ins("|}")
	return table.concat(parts, "\n")
end

-- Used by {{translit module documentation}}.
function export.translitModuleLangList(frame)
	local pagename, subpage
	
	if frame.args[1] then
		pagename = frame.args[1]
	else
		local title = mw.title.getCurrentTitle()
		subpage = title.subpageText
		pagename = title.text
		
		if subpage ~= pagename then
			pagename = title.rootText
		end
	end
	
	local translitModule = pagename
	
	local languageObjects = require("Module:languages/byTranslitModule")(translitModule)
	local codeInPagename = pagename:match("^([%l-]+)%-.*translit$")
	
	local categories = Array()
	local codeInPagenameInList = false
	if codeInPagename then
		if languageObjects[1] and subpage ~= "documentation" then
			local agreement = languageObjects[2] and "s" or ""
			categories:insert("[[Category:Transliteration modules used by " ..
				#languageObjects .. " language" .. agreement .. "]]")
		end
		
		languageObjects = Array(languageObjects)
			:filter(
				function (lang)
					local result = lang:getCode() ~= codeInPagename
					codeInPagenameInList = codeInPagenameInList or result
					return result
				end)
	end
	
	if subpage ~= "documentation" then
		for script_code in pagename:gmatch("%f[^-%z]%u%l%l%l%f[-]") do
			local script = require "Module:scripts".getByCode(script_code)
			if script then
				categories:insert("[[Category:" .. script:getCategoryName() .. "]]")
			end
		end
	end
	
	if subpage ~= "documentation" and not page_exists("Module:" .. pagename .. "/testcases") then
		categories:insert("[[Category:Transliteration modules without a testcases subpage]]")
	end
	
	if not languageObjects[1] then
		return categories:concat()
	end
	
	local langs = Array(languageObjects)
		:sort(
			function(lang1, lang2)
				return lang1:getCode() < lang2:getCode()
			end)
		-- This will not error because languageObjects is not empty.
		:map(languageObjects[1].makeCategoryLink)
		:serial_comma_join()
	
	return "It is " .. ( codeInPagenameInList and "also" or "" ) ..
		" used to transliterate " .. langs .. "." .. categories:concat()
end

-- Used by {{entry name module documentation}}.
function export.entryNameModuleLangList(frame)
	local pagename, subpage
	
	if frame.args[1] then
		pagename = frame.args[1]
	else
		local title = mw.title.getCurrentTitle()
		subpage = title.subpageText
		pagename = title.text
		
		if subpage ~= pagename then
			pagename = title.rootText
		end
	end
	
	local entryNameModule = pagename
	
	local languageObjects = require("Module:languages/byEntryNameModule")(entryNameModule)
	local codeInPagename = pagename:match("^([%l-]+)%-.*entryname$")
	
	local categories = Array()
	local codeInPagenameInList = false
	if codeInPagename then
		if languageObjects[1] and subpage ~= "documentation" then
			local agreement = languageObjects[2] and "s" or ""
			categories:insert("[[Category:Entry name-generating modules used by " ..
				#languageObjects .. " language" .. agreement .. "]]")
		end
		
		languageObjects = Array(languageObjects)
			:filter(
				function (lang)
					local result = lang:getCode() ~= codeInPagename
					codeInPagenameInList = codeInPagenameInList or result
					return result
				end)
	end
	
	if subpage ~= "documentation" then
		for script_code in pagename:gmatch("%f[^-%z]%u%l%l%l%f[-]") do
			local script = require "Module:scripts".getByCode(script_code)
			if script then
				categories:insert("[[Category:" .. script:getCategoryName() .. "]]")
			end
		end
	end
	
	if subpage ~= "documentation" and not page_exists("Module:" .. pagename .. "/testcases") then
		categories:insert("[[Category:Entry name-generating modules without a testcases subpage]]")
	end
	
	if not languageObjects[1] then
		return categories:concat()
	end
	
	local langs = Array(languageObjects)
		:sort(
			function(lang1, lang2)
				return lang1:getCode() < lang2:getCode()
			end)
		-- This will not error because languageObjects is not empty.
		:map(languageObjects[1].makeCategoryLink)
		:serial_comma_join()
	
	return "It is " .. ( codeInPagenameInList and "also" or "" ) ..
		" used to generate entry names for " .. langs .. "." .. categories:concat()
end

-- Used by {{sortkey module documentation}}.
function export.sortkeyModuleLangList(frame)
	local pagename, subpage
	
	if frame.args[1] then
		pagename = frame.args[1]
	else
		local title = mw.title.getCurrentTitle()
		subpage = title.subpageText
		pagename = title.text
		
		if subpage ~= pagename then
			pagename = title.rootText
		end
	end
	
	local sortkeyModule = pagename
	
	local languageObjects = require("Module:languages/bySortkeyModule")(sortkeyModule)
	local codeInPagename = pagename:match("^([%l-]+)%-.*sortkey$")
	
	local categories = Array()
	local codeInPagenameInList = false
	if codeInPagename then
		if languageObjects[1] and subpage ~= "documentation" then
			local agreement = languageObjects[2] and "s" or ""
			categories:insert("[[Category:Sortkey-generating modules used by " ..
				#languageObjects .. " language" .. agreement .. "]]")
		end
		
		languageObjects = Array(languageObjects)
			:filter(
				function (lang)
					local result = lang:getCode() ~= codeInPagename
					codeInPagenameInList = codeInPagenameInList or result
					return result
				end)
	end
	
	if subpage ~= "documentation" then
		for script_code in pagename:gmatch("%f[^-%z]%u%l%l%l%f[-]") do
			local script = require "Module:scripts".getByCode(script_code)
			if script then
				categories:insert("[[Category:" .. script:getCategoryName() .. "]]")
			end
		end
	end
	
	if subpage ~= "documentation" and not page_exists("Module:" .. pagename .. "/testcases") then
		categories:insert("[[Category:Sortkey-generating modules without a testcases subpage]]")
	end
	
	if not languageObjects[1] then
		return categories:concat()
	end
	
	local langs = Array(languageObjects)
		:sort(
			function(lang1, lang2)
				return lang1:getCode() < lang2:getCode()
			end)
		-- This will not error because languageObjects is not empty.
		:map(languageObjects[1].makeCategoryLink)
		:serial_comma_join()
	
	return "It is " .. ( codeInPagenameInList and "also" or "" ) ..
		" used to sort " .. langs .. "." .. categories:concat()
end

return export