-- This module implements ((documentation)).

-- Get required modules.
local getArgs = require('Module:Arguments').getArgs

-- Get the config table.
local cfg = mw.loadData('Module:Documentation/config')

local p = {}

-- Often-used functions.
local ugsub = mw.ustring.gsub
local format = mw.ustring.format

----------------------------------------------------------------------------
-- Helper functions
--
-- These are defined as local functions, but are made available in the p
-- table for testing purposes.
----------------------------------------------------------------------------

local function message(cfgKey, valArray, expectType)
	--[[
	-- Gets a message from the cfg table and formats it if appropriate.
	-- The function raises an error if the value from the cfg table is not
	-- of the type expectType. The default type for expectType is 'string'.
	-- If the table valArray is present, strings such as $1, $2 etc. in the
	-- message are substituted with values from the table keys [1], [2] etc.
	-- For example, if the message "foo-message" had the value 'Foo $2 bar $1.',
	-- message('foo-message', {'baz', 'qux'}) would return "Foo qux bar baz."
	--]]
	local msg = cfg[cfgKey]
	expectType = expectType or 'string'
	if type(msg) ~= expectType then
		error('message: type error in message cfg.' .. cfgKey .. ' (' .. expectType .. ' expected, got ' .. type(msg) .. ')', 2)
	end
	if not valArray then
		return msg
	end

	local function getMessageVal(match)
		match = tonumber(match)
		return valArray[match] or error('message: no value found for key $' .. match .. ' in message cfg.' .. cfgKey, 4)
	end

	return ugsub(msg, '$([1-9][0-9]*)', getMessageVal)
end

p.message = message

local function makeWikilink(page, display)
	if display then
		return format('[[%s|%s]]', page, display)
	else
		return format('[[%s]]', page)
	end
end

p.makeWikilink = makeWikilink

local function makeCategoryLink(cat, sort)
	local catns = mw.site.namespaces[14].name
	return makeWikilink(catns .. ':' .. cat, sort)
end

p.makeCategoryLink = makeCategoryLink

local function makeUrlLink(url, display)
	return format('[%s %s]', url, display)
end

p.makeUrlLink = makeUrlLink

local function makeToolbar(...)
	local ret = {}
	local lim = select('#', ...)
	if lim < 1 then
		return nil
	end
	for i = 1, lim do
		ret[#ret + 1] = select(i, ...)
	end
	-- 'documentation-toolbar'
	return format(
		'<span class="%s">(%s)</span>',
		message('toolbar-class'),
		table.concat(ret, ' &#124; ')
	)
end	

p.makeToolbar = makeToolbar

----------------------------------------------------------------------------
-- Argument processing
----------------------------------------------------------------------------

local function makeInvokeFunc(funcName)
	return function (frame)
		local args = getArgs(frame, {
			valueFunc = function (key, value)
				if type(value) == 'string' then
					value = value:match('^%s*(.-)%s*$') -- Remove whitespace.
					if key == 'heading' or value ~= '' then
						return value
					else
						return nil
					end
				else
					return value
				end
			end
		})
		return p[funcName](args)
	end
end

----------------------------------------------------------------------------
-- Entry points
----------------------------------------------------------------------------

function p.nonexistent(frame)
	if mw.title.getCurrentTitle().subpageText == 'testcases' then
		return frame:expandTemplate{title = 'module test cases notice'}
	else
		return p.main(frame)
	end
end

p.main = makeInvokeFunc('_main')

function p._main(args)
	--[[
	-- This function defines logic flow for the module.
	-- @args - table of arguments passed by the user
	--]]
	local env = p.getEnvironment(args)
	local root = mw.html.create()
	root
		:wikitext(p._getModuleWikitext(args, env))
		:wikitext(p.protectionTemplate(env))
		:wikitext(p.sandboxNotice(args, env))
		:tag('div')
			-- 'documentation-container'
			:addClass(message('container'))
			:attr('role', 'complementary')
			:attr('aria-labelledby', args.heading ~= '' and 'documentation-heading' or nil)
			:attr('aria-label', args.heading == '' and 'Documentation' or nil)
			:newline()
			:tag('div')
				-- 'documentation'
				:addClass(message('main-div-classes'))
				:newline()
				:wikitext(p._startBox(args, env))
				:wikitext(p._content(args, env))
				:tag('div')
					-- 'documentation-clear'
					:addClass(message('clear'))
					:done()
				:newline()
				:done()
			:wikitext(p._endBox(args, env))
			:done()
		:wikitext(p.addTrackingCategories(env))
	-- 'Module:Documentation/styles.css'
	return mw.getCurrentFrame():extensionTag (
		'templatestyles', '', {src=cfg['templatestyles']
	}) .. tostring(root)
end

----------------------------------------------------------------------------
-- Environment settings
----------------------------------------------------------------------------

function p.getEnvironment(args)
	--[[
	-- Returns a table with information about the environment, including title
	-- objects and other namespace- or path-related data.
	-- @args - table of arguments passed by the user
	--
	-- Title objects include:
	-- env.title - the page we are making documentation for (usually the current title)
	-- env.templateTitle - the template (or module, file, etc.)
	-- env.docTitle - the /doc subpage.
	-- env.sandboxTitle - the /sandbox subpage.
	-- env.testcasesTitle - the /testcases subpage.
	--
	-- Data includes:
	-- env.protectionLevels - the protection levels table of the title object.
	-- env.subjectSpace - the number of the title's subject namespace.
	-- env.docSpace - the number of the namespace the title puts its documentation in.
	-- env.docpageBase - the text of the base page of the /doc, /sandbox and /testcases pages, with namespace.
	-- env.compareUrl - URL of the Special:ComparePages page comparing the sandbox with the template.
	-- 
	-- All table lookups are passed through pcall so that errors are caught. If an error occurs, the value
	-- returned will be nil.
	--]]
	
	local env, envFuncs = {}, {}

	-- Set up the metatable. If triggered we call the corresponding function in the envFuncs table. The value
	-- returned by that function is memoized in the env table so that we don't call any of the functions
	-- more than once. (Nils won't be memoized.)
	setmetatable(env, {
		__index = function (t, key)
			local envFunc = envFuncs[key]
			if envFunc then
				local success, val = pcall(envFunc)
				if success then
					env[key] = val -- Memoise the value.
					return val
				end
			end
			return nil
		end
	})	

	function envFuncs.title()
		-- The title object for the current page, or a test page passed with args.page.
		local title
		local titleArg = args.page
		if titleArg then
			title = mw.title.new(titleArg)
		else
			title = mw.title.getCurrentTitle()
		end
		return title
	end

	function envFuncs.templateTitle()
		--[[
		-- The template (or module, etc.) title object.
		-- Messages:
		-- 'sandbox-subpage' --> 'sandbox'
		-- 'testcases-subpage' --> 'testcases'
		--]]
		local subjectSpace = env.subjectSpace
		local title = env.title
		local subpage = title.subpageText
		if subpage == message('sandbox-subpage') or subpage == message('testcases-subpage') then
			return mw.title.makeTitle(subjectSpace, title.baseText)
		else
			return mw.title.makeTitle(subjectSpace, title.text)
		end
	end

	function envFuncs.docTitle()
		--[[
		-- Title object of the /doc subpage.
		-- Messages:
		-- 'doc-subpage' --> 'doc'
		--]]
		local title = env.title
		local docname = args[1] -- User-specified doc page.
		local docpage
		if docname then
			docpage = docname
		else
			docpage = env.docpageBase .. '/' .. message('doc-subpage')
		end
		return mw.title.new(docpage)
	end
	
	function envFuncs.sandboxTitle()
		--[[
		-- Title object for the /sandbox subpage.
		-- Messages:
		-- 'sandbox-subpage' --> 'sandbox'
		--]]
		return mw.title.new(env.docpageBase .. '/' .. message('sandbox-subpage'))
	end
	
	function envFuncs.testcasesTitle()
		--[[
		-- Title object for the /testcases subpage.
		-- Messages:
		-- 'testcases-subpage' --> 'testcases'
		--]]
		return mw.title.new(env.docpageBase .. '/' .. message('testcases-subpage'))
	end

	function envFuncs.protectionLevels()
		-- The protection levels table of the title object.
		return env.title.protectionLevels
	end

	function envFuncs.subjectSpace()
		-- The subject namespace number.
		return mw.site.namespaces[env.title.namespace].subject.id
	end

	function envFuncs.docSpace()
		-- The documentation namespace number. For most namespaces this is the
		-- same as the subject namespace. However, pages in the Article, File,
		-- MediaWiki or Category namespaces must have their /doc, /sandbox and
		-- /testcases pages in talk space.
		local subjectSpace = env.subjectSpace
		if subjectSpace == 0 or subjectSpace == 6 or subjectSpace == 8 or subjectSpace == 14 then
			return subjectSpace + 1
		else
			return subjectSpace
		end
	end

	function envFuncs.docpageBase()
		-- The base page of the /doc, /sandbox, and /testcases subpages.
		-- For some namespaces this is the talk page, rather than the template page.
		local templateTitle = env.templateTitle
		local docSpace = env.docSpace
		local docSpaceText = mw.site.namespaces[docSpace].name
		-- Assemble the link. docSpace is never the main namespace, so we can hardcode the colon.
		return docSpaceText .. ':' .. templateTitle.text
	end
	
	function envFuncs.compareUrl()
		-- Diff link between the sandbox and the main template using [[Special:ComparePages]].
		local templateTitle = env.templateTitle
		local sandboxTitle = env.sandboxTitle
		if templateTitle.exists and sandboxTitle.exists then
			local compareUrl = mw.uri.canonicalUrl(
				'Special:ComparePages',
				{ page1 = templateTitle.prefixedText, page2 = sandboxTitle.prefixedText}
			)
			return tostring(compareUrl)
		else
			return nil
		end
	end		

	return env
end	

----------------------------------------------------------------------------
-- Auxiliary templates
----------------------------------------------------------------------------

p.getModuleWikitext = makeInvokeFunc('_getModuleWikitext')

function p._getModuleWikitext(args, env)
	local currentTitle = mw.title.getCurrentTitle()
	if currentTitle.contentModel ~= 'Scribunto' then return end
	pcall(require, currentTitle.prefixedText) -- if it fails, we don't care
	local moduleWikitext =  package.loaded["Module:Module wikitext"]
	if moduleWikitext then
		return moduleWikitext.main()
	end
end

function p.sandboxNotice(args, env)
	--[=[
	-- Generates a sandbox notice for display above sandbox pages.
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	-- Messages:
	-- 'sandbox-notice-image' --> '[[File:Sandbox.svg|50px|alt=|link=]]'
	-- 'sandbox-notice-blurb' --> 'This is the $1 for $2.'
	-- 'sandbox-notice-diff-blurb' --> 'This is the $1 for $2 ($3).'
	-- 'sandbox-notice-pagetype-template' --> '[[Wikipedia:Template test cases|template sandbox]] page'
	-- 'sandbox-notice-pagetype-module' --> '[[Wikipedia:Template test cases|module sandbox]] page'
	-- 'sandbox-notice-pagetype-other' --> 'sandbox page'
	-- 'sandbox-notice-compare-link-display' --> 'diff'
	-- 'sandbox-notice-testcases-blurb' --> 'See also the companion subpage for $1.'
	-- 'sandbox-notice-testcases-link-display' --> 'test cases'
	-- 'sandbox-category' --> 'Template sandboxes'
	-- 'module-sandbox-category' --> 'Module sandboxes'
	-- 'other-sandbox-category' --> 'Sandboxes outside of template or module namespace'
	--]=]
	local title = env.title
	local sandboxTitle = env.sandboxTitle
	local templateTitle = env.templateTitle
	local subjectSpace = env.subjectSpace
	if not (subjectSpace and title and sandboxTitle and templateTitle
		and mw.title.equals(title, sandboxTitle)) then
		return nil
	end
	-- Build the table of arguments to pass to ((ombox)). We need just two fields, "image" and "text".
	local omargs = {}
	omargs.image = message('sandbox-notice-image')
	-- Get the text. We start with the opening blurb, which is something like
	-- "This is the template sandbox for [[Template:Foo]] (diff)."
	local text = ''
	local pagetype, sandboxCat
	if subjectSpace == 10 then
		pagetype = message('sandbox-notice-pagetype-template')
		sandboxCat = message('sandbox-category')
	elseif subjectSpace == 828 then
		pagetype = message('sandbox-notice-pagetype-module')
		sandboxCat = message('module-sandbox-category')
	else
		pagetype = message('sandbox-notice-pagetype-other')
		sandboxCat = message('other-sandbox-category')
	end
	local templateLink = makeWikilink(templateTitle.prefixedText)
	local compareUrl = env.compareUrl
	if compareUrl then
		local compareDisplay = message('sandbox-notice-compare-link-display')
		local compareLink = makeUrlLink(compareUrl, compareDisplay)
		text = text .. message('sandbox-notice-diff-blurb', {pagetype, templateLink, compareLink})
	else
		text = text .. message('sandbox-notice-blurb', {pagetype, templateLink})
	end
	-- Get the test cases page blurb if the page exists. This is something like
	-- "See also the companion subpage for [[Template:Foo/testcases|test cases]]."
	local testcasesTitle = env.testcasesTitle
	if testcasesTitle and testcasesTitle.exists then
		if testcasesTitle.contentModel == "Scribunto" then
			local testcasesLinkDisplay = message('sandbox-notice-testcases-link-display')
			local testcasesRunLinkDisplay = message('sandbox-notice-testcases-run-link-display')
			local testcasesLink = makeWikilink(testcasesTitle.prefixedText, testcasesLinkDisplay)
			local testcasesRunLink = makeWikilink(testcasesTitle.talkPageTitle.prefixedText, testcasesRunLinkDisplay)
			text = text .. '<br />' .. message('sandbox-notice-testcases-run-blurb', {testcasesLink, testcasesRunLink})
		else
			local testcasesLinkDisplay = message('sandbox-notice-testcases-link-display')
			local testcasesLink = makeWikilink(testcasesTitle.prefixedText, testcasesLinkDisplay)
			text = text .. '<br />' .. message('sandbox-notice-testcases-blurb', {testcasesLink})
		end
	end
	
	-- Add the sandbox to the sandbox category.
	omargs.text = text .. makeCategoryLink(sandboxCat)

	-- 'documentation-clear'
	return '<div class="' .. message('clear') .. '"></div>'
		.. require('Module:Message box').main('ombox', omargs)
end

function p.protectionTemplate(env)
	-- Generates the padlock icon in the top right.
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- Messages:
	-- 'protection-template' --> 'pp-template'
	-- 'protection-template-args' --> {docusage = 'yes'}
	local protectionLevels = env.protectionLevels
	if not protectionLevels then
		return nil
	end
	local editProt = protectionLevels.edit and protectionLevels.edit[1]
	local moveProt = protectionLevels.move and protectionLevels.move[1]
	if editProt then
		-- The page is edit-protected.
		return require('Module:Protection banner')._main{
			message('protection-reason-edit'), small = true
		}
	elseif moveProt and moveProt ~= 'autoconfirmed' then
		-- The page is move-protected but not edit-protected. Exclude move
		-- protection with the level "autoconfirmed", as this is equivalent to
		-- no move protection at all.
		return require('Module:Protection banner')._main{
			action = 'move', small = true
		}
	else
		return nil
	end
end

----------------------------------------------------------------------------
-- Start box
----------------------------------------------------------------------------

p.startBox = makeInvokeFunc('_startBox')

function p._startBox(args, env)
	--[[
	-- This function generates the start box.
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	-- The actual work is done by p.makeStartBoxLinksData and p.renderStartBoxLinks which make
	-- the [view] [edit] [history] [purge] links, and by p.makeStartBoxData and p.renderStartBox
	-- which generate the box HTML.
	--]]
	env = env or p.getEnvironment(args)
	local links
	local content = args.content
	if not content or args[1] then
		-- No need to include the links if the documentation is on the template page itself.
		local linksData = p.makeStartBoxLinksData(args, env)
		if linksData then
			links = p.renderStartBoxLinks(linksData)
		end
	end
	-- Generate the start box html.
	local data = p.makeStartBoxData(args, env, links)
	if data then
		return p.renderStartBox(data)
	else
		-- User specified no heading.
		return nil
	end
end

function p.makeStartBoxLinksData(args, env)
	--[[
	-- Does initial processing of data to make the [view] [edit] [history] [purge] links.
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	-- Messages:
	-- 'view-link-display' --> 'view'
	-- 'edit-link-display' --> 'edit'
	-- 'history-link-display' --> 'history'
	-- 'purge-link-display' --> 'purge'
	-- 'module-preload' --> 'Template:Documentation/preload-module-doc'
	-- 'docpage-preload' --> 'Template:Documentation/preload'
	-- 'create-link-display' --> 'create'
	--]]
	local subjectSpace = env.subjectSpace
	local title = env.title
	local docTitle = env.docTitle
	if not title or not docTitle then
		return nil
	end
	if docTitle.isRedirect then 
		docTitle = docTitle.redirectTarget
	end

	-- Create link if /doc doesn't exist.
	local preload = args.preload
	if not preload then
		if subjectSpace == 828 then -- Module namespace
			preload = message('module-preload')
		else
			preload = message('docpage-preload')
		end
	end
	
	return {
		title = title,
		docTitle = docTitle,
		-- View, display, edit, and purge links if /doc exists.
		viewLinkDisplay = message('view-link-display'),
		editLinkDisplay = message('edit-link-display'),
		historyLinkDisplay = message('history-link-display'),
		purgeLinkDisplay = message('purge-link-display'),
		preload = preload,
		createLinkDisplay = message('create-link-display')
	}
end

function p.renderStartBoxLinks(data)
	--[[
	-- Generates the [view][edit][history][purge] or [create][purge] links from the data table.
	-- @data - a table of data generated by p.makeStartBoxLinksData
	--]]
	local docTitle = data.docTitle
	-- yes, we do intend to purge the template page on which the documentation appears
	local purgeLink = makeWikilink("Special:Purge/" .. data.title.prefixedText, data.purgeLinkDisplay)
	
	if docTitle.exists then
		local viewLink = makeWikilink(docTitle.prefixedText, data.viewLinkDisplay)
		local editLink = makeWikilink("Special:EditPage/" .. docTitle.prefixedText, data.editLinkDisplay)
		local historyLink = makeWikilink("Special:PageHistory/" .. docTitle.prefixedText, data.historyLinkDisplay)
		return "&#91;" .. viewLink .. "&#93; &#91;" .. editLink .. "&#93; &#91;" .. historyLink .. "&#93; &#91;" .. purgeLink .. "&#93;"
	else
		local createLink = makeUrlLink(docTitle:canonicalUrl{action = 'edit', preload = data.preload}, data.createLinkDisplay)
		return  "&#91;" .. createLink .. "&#93; &#91;" .. purgeLink .. "&#93;"
	end
	return ret
end

function p.makeStartBoxData(args, env, links)
	--[=[
	-- Does initial processing of data to pass to the start-box render function, p.renderStartBox.
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- @links - a string containing the [view][edit][history][purge] links - could be nil if there's an error.
	--
	-- Messages:
	-- 'documentation-icon-wikitext' --> '[[File:Test Template Info-Icon - Version (2).svg|50px|link=|alt=]]'
	-- 'template-namespace-heading' --> 'Template documentation'
	-- 'module-namespace-heading' --> 'Module documentation'
	-- 'file-namespace-heading' --> 'Summary'
	-- 'other-namespaces-heading' --> 'Documentation'
	-- 'testcases-create-link-display' --> 'create'
	--]=]
	local subjectSpace = env.subjectSpace
	if not subjectSpace then
		-- Default to an "other namespaces" namespace, so that we get at least some output
		-- if an error occurs.
		subjectSpace = 2
	end
	local data = {}
	
	-- Heading
	local heading = args.heading -- Blank values are not removed.
	if heading == '' then
		-- Don't display the start box if the heading arg is defined but blank.
		return nil
	end
	if heading then
		data.heading = heading
	elseif subjectSpace == 10 then -- Template namespace
		data.heading = message('documentation-icon-wikitext') .. ' ' .. message('template-namespace-heading')
	elseif subjectSpace == 828 then -- Module namespace
		data.heading = message('documentation-icon-wikitext') .. ' ' .. message('module-namespace-heading')
	elseif subjectSpace == 6 then -- File namespace
		data.heading = message('file-namespace-heading')
	else
		data.heading = message('other-namespaces-heading')
	end
	
	-- Heading CSS
	local headingStyle = args['heading-style']
	if headingStyle then
		data.headingStyleText = headingStyle
	else
		-- 'documentation-heading'
		data.headingClass = message('main-div-heading-class')
	end
	
	-- Data for the [view][edit][history][purge] or [create] links.
	if links then
		-- 'mw-editsection-like plainlinks'
		data.linksClass = message('start-box-link-classes')
		data.links = links
	end
	
	return data
end

function p.renderStartBox(data)
	-- Renders the start box html.
	-- @data - a table of data generated by p.makeStartBoxData.
	local sbox = mw.html.create('div')
	sbox
		-- 'documentation-startbox'
		:addClass(message('start-box-class'))
		:newline()
		:tag('span')
			:addClass(data.headingClass)
			:attr('id', 'documentation-heading')
			:cssText(data.headingStyleText)
			:wikitext(data.heading)
	local links = data.links
	if links then
		sbox:tag('span')
			:addClass(data.linksClass)
			:attr('id', data.linksId)
			:wikitext(links)
	end
	return tostring(sbox)
end

----------------------------------------------------------------------------
-- Documentation content
----------------------------------------------------------------------------

p.content = makeInvokeFunc('_content')

function p._content(args, env)
	-- Displays the documentation contents
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	env = env or p.getEnvironment(args)
	local docTitle = env.docTitle
	local content = args.content
	if not content and docTitle and docTitle.exists then
		content = args._content or mw.getCurrentFrame():expandTemplate{title = docTitle.prefixedText}
	end
	-- The line breaks below are necessary so that "=== Headings ===" at the start and end
	-- of docs are interpreted correctly.
	return '\n' .. (content or '') .. '\n' 
end

p.contentTitle = makeInvokeFunc('_contentTitle')

function p._contentTitle(args, env)
	env = env or p.getEnvironment(args)
	local docTitle = env.docTitle
	if not args.content and docTitle and docTitle.exists then
		return docTitle.prefixedText
	else
		return ''
	end
end

----------------------------------------------------------------------------
-- End box
----------------------------------------------------------------------------

p.endBox = makeInvokeFunc('_endBox')

function p._endBox(args, env)
	--[=[
	-- This function generates the end box (also known as the link box).
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	--]=]
	
	-- Get environment data.
	env = env or p.getEnvironment(args)
	local subjectSpace = env.subjectSpace
	local docTitle = env.docTitle
	if not subjectSpace or not docTitle then
		return nil
	end
		
	-- Check whether we should output the end box at all. Add the end
	-- box by default if the documentation exists or if we are in the
	-- user, module or template namespaces.
	local linkBox = args['link box']
	if linkBox == 'off'
		or not (
			docTitle.exists
			or subjectSpace == 2
			or subjectSpace == 828
			or subjectSpace == 10
		)
	then
		return nil
	end

	-- Assemble the link box.
	local text = ''
	if linkBox then
		text = text .. linkBox
	else
		text = text .. (p.makeDocPageBlurb(args, env) or '') -- "This documentation is transcluded from [[Foo]]." 
		if subjectSpace == 2 or subjectSpace == 10 or subjectSpace == 828 then
			-- We are in the user, template or module namespaces.
			-- Add sandbox and testcases links.
			-- "Editors can experiment in this template's sandbox and testcases pages."
			text = text .. (p.makeExperimentBlurb(args, env) or '') .. '<br />'
			if not args.content and not args[1] then
				-- "Please add categories to the /doc subpage."
				-- Don't show this message with inline docs or with an explicitly specified doc page,
				-- as then it is unclear where to add the categories.
				text = text .. (p.makeCategoriesBlurb(args, env) or '')
			end
			text = text .. ' ' .. (p.makeSubpagesBlurb(args, env) or '') --"Subpages of this template"
		end
	end
	
	local box = mw.html.create('div')
	-- 'documentation-metadata'
	box:attr('role', 'note')
		:addClass(message('end-box-class'))
		-- 'plainlinks'
		:addClass(message('end-box-plainlinks'))
		:wikitext(text)
		:done()

	return '\n' .. tostring(box)
end

function p.makeDocPageBlurb(args, env)
	--[=[
	-- Makes the blurb "This documentation is transcluded from [[Template:Foo]] (edit, history)".
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	-- Messages:
	-- 'edit-link-display' --> 'edit'
	-- 'history-link-display' --> 'history'
	-- 'transcluded-from-blurb' --> 
	-- 'The above [[Wikipedia:Template documentation|documentation]] 
	-- is [[Help:Transclusion|transcluded]] from $1.'
	-- 'module-preload' --> 'Template:Documentation/preload-module-doc'
	-- 'create-link-display' --> 'create'
	-- 'create-module-doc-blurb' -->
	-- 'You might want to $1 a documentation page for this [[Wikipedia:Lua|Scribunto module]].'
	--]=]
	local docTitle = env.docTitle
	if not docTitle then
		return nil
	end
	local ret
	if docTitle.exists then
		-- /doc exists; link to it.
		local docLink = makeWikilink(docTitle.prefixedText)
		local editDisplay = message('edit-link-display')
		local editLink = makeWikilink("Special:EditPage/" .. docTitle.prefixedText, editDisplay)
		local historyDisplay = message('history-link-display')
		local historyLink = makeWikilink("Special:PageHistory/" .. docTitle.prefixedText, historyDisplay)
		ret = message('transcluded-from-blurb', {docLink})
			.. ' '
			.. makeToolbar(editLink, historyLink)
			.. '<br />'
	elseif env.subjectSpace == 828 then
		-- /doc does not exist; ask to create it.
		local createUrl = docTitle:canonicalUrl{action = 'edit', preload = message('module-preload')}
		local createDisplay = message('create-link-display')
		local createLink = makeUrlLink(createUrl, createDisplay)
		ret = message('create-module-doc-blurb', {createLink})
			.. '<br />'
	end
	return ret
end

function p.makeExperimentBlurb(args, env)
	--[[
	-- Renders the text "Editors can experiment in this template's sandbox (edit | diff) and testcases (edit) pages."
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- 
	-- Messages:
	-- 'sandbox-link-display' --> 'sandbox'
	-- 'sandbox-edit-link-display' --> 'edit'
	-- 'compare-link-display' --> 'diff'
	-- 'module-sandbox-preload' --> 'Template:Documentation/preload-module-sandbox'
	-- 'template-sandbox-preload' --> 'Template:Documentation/preload-sandbox'
	-- 'sandbox-create-link-display' --> 'create'
	-- 'mirror-edit-summary' --> 'Create sandbox version of $1'
	-- 'mirror-link-display' --> 'mirror'
	-- 'mirror-link-preload' --> 'Template:Documentation/mirror'
	-- 'sandbox-link-display' --> 'sandbox'
	-- 'testcases-link-display' --> 'testcases'
	-- 'testcases-edit-link-display'--> 'edit'
	-- 'template-sandbox-preload' --> 'Template:Documentation/preload-sandbox'
	-- 'testcases-create-link-display' --> 'create'
	-- 'testcases-link-display' --> 'testcases'
	-- 'testcases-edit-link-display' --> 'edit'
	-- 'module-testcases-preload' --> 'Template:Documentation/preload-module-testcases'
	-- 'template-testcases-preload' --> 'Template:Documentation/preload-testcases'
	-- 'experiment-blurb-module' --> 'Editors can experiment in this module's $1 and $2 pages.'
	-- 'experiment-blurb-template' --> 'Editors can experiment in this template's $1 and $2 pages.'
	--]]
	local subjectSpace = env.subjectSpace
	local templateTitle = env.templateTitle
	local sandboxTitle = env.sandboxTitle
	local testcasesTitle = env.testcasesTitle
	local templatePage = templateTitle.prefixedText
	if not subjectSpace or not templateTitle or not sandboxTitle or not testcasesTitle then
		return nil
	end
	-- Make links.
	local sandboxLinks, testcasesLinks
	if sandboxTitle.exists then
		local sandboxPage = sandboxTitle.prefixedText
		local sandboxDisplay = message('sandbox-link-display')
		local sandboxLink = makeWikilink(sandboxPage, sandboxDisplay)
		local sandboxEditDisplay = message('sandbox-edit-link-display')
		local sandboxEditLink = makeWikilink("Special:EditPage/" .. sandboxPage, sandboxEditDisplay)
		local compareUrl = env.compareUrl
		local compareLink
		if compareUrl then
			local compareDisplay = message('compare-link-display')
			compareLink = makeUrlLink(compareUrl, compareDisplay)
		end
		sandboxLinks = sandboxLink .. ' ' .. makeToolbar(sandboxEditLink, compareLink)
	else
		local sandboxPreload
		if subjectSpace == 828 then
			sandboxPreload = message('module-sandbox-preload')
		else
			sandboxPreload = message('template-sandbox-preload')
		end
		local sandboxCreateUrl = sandboxTitle:canonicalUrl{action = 'edit', preload = sandboxPreload}
		local sandboxCreateDisplay = message('sandbox-create-link-display')
		local sandboxCreateLink = makeUrlLink(sandboxCreateUrl, sandboxCreateDisplay)
		local mirrorSummary = message('mirror-edit-summary', {makeWikilink(templatePage)})
		local mirrorPreload = message('mirror-link-preload')
		local mirrorUrl = sandboxTitle:canonicalUrl{action = 'edit', preload = mirrorPreload, summary = mirrorSummary}
		if subjectSpace == 828 then
			mirrorUrl = sandboxTitle:canonicalUrl{action = 'edit', preload = templateTitle.prefixedText, summary = mirrorSummary}
		end
		local mirrorDisplay = message('mirror-link-display')
		local mirrorLink = makeUrlLink(mirrorUrl, mirrorDisplay)
		sandboxLinks = message('sandbox-link-display') .. ' ' .. makeToolbar(sandboxCreateLink, mirrorLink)
	end
	if testcasesTitle.exists then
		local testcasesPage = testcasesTitle.prefixedText
		local testcasesDisplay = message('testcases-link-display')
		local testcasesLink = makeWikilink(testcasesPage, testcasesDisplay)
		local testcasesEditUrl = testcasesTitle:canonicalUrl{action = 'edit'}
		local testcasesEditDisplay = message('testcases-edit-link-display')
		local testcasesEditLink = makeWikilink("Special:EditPage/" .. testcasesPage, testcasesEditDisplay)
		-- for Modules, add testcases run link if exists
		if testcasesTitle.contentModel == "Scribunto"  and testcasesTitle.talkPageTitle and testcasesTitle.talkPageTitle.exists then
			local testcasesRunLinkDisplay = message('testcases-run-link-display')
			local testcasesRunLink = makeWikilink(testcasesTitle.talkPageTitle.prefixedText, testcasesRunLinkDisplay)
			testcasesLinks = testcasesLink .. ' ' .. makeToolbar(testcasesEditLink, testcasesRunLink)
		else
			testcasesLinks = testcasesLink .. ' ' .. makeToolbar(testcasesEditLink)
		end
	else
		local testcasesPreload
		if subjectSpace == 828 then
			testcasesPreload = message('module-testcases-preload')
		else
			testcasesPreload = message('template-testcases-preload')
		end
		local testcasesCreateUrl = testcasesTitle:canonicalUrl{action = 'edit', preload = testcasesPreload}
		local testcasesCreateDisplay = message('testcases-create-link-display')
		local testcasesCreateLink = makeUrlLink(testcasesCreateUrl, testcasesCreateDisplay)
		testcasesLinks = message('testcases-link-display') .. ' ' .. makeToolbar(testcasesCreateLink)
	end
	local messageName
	if subjectSpace == 828 then
		messageName = 'experiment-blurb-module'
	else
		messageName = 'experiment-blurb-template'
	end
	return message(messageName, {sandboxLinks, testcasesLinks})
end

function p.makeCategoriesBlurb(args, env)
	--[[
	-- Generates the text "Please add categories to the /doc subpage."
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	-- Messages:
	-- 'doc-link-display' --> '/doc'
	-- 'add-categories-blurb' --> 'Please add categories to the $1 subpage.'
	--]]
	local docTitle = env.docTitle
	if not docTitle then
		return nil
	end
	local docPathLink = makeWikilink(docTitle.prefixedText, message('doc-link-display'))
	return message('add-categories-blurb', {docPathLink})
end

function p.makeSubpagesBlurb(args, env)
	--[[
	-- Generates the "Subpages of this template" link.
	-- @args - a table of arguments passed by the user
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	
	-- Messages:
	-- 'template-pagetype' --> 'template'
	-- 'module-pagetype' --> 'module'
	-- 'default-pagetype' --> 'page'
	-- 'subpages-link-display' --> 'Subpages of this $1'
	--]]
	local subjectSpace = env.subjectSpace
	local templateTitle = env.templateTitle
	if not subjectSpace or not templateTitle then
		return nil
	end
	local pagetype
	if subjectSpace == 10 then
		pagetype = message('template-pagetype')
	elseif subjectSpace == 828 then
		pagetype = message('module-pagetype')
	else
		pagetype = message('default-pagetype')
	end
	local subpagesLink = makeWikilink(
		'Special:PrefixIndex/' .. templateTitle.prefixedText .. '/',
		message('subpages-link-display', {pagetype})
	)
	return message('subpages-blurb', {subpagesLink})
end

----------------------------------------------------------------------------
-- Tracking categories
----------------------------------------------------------------------------

function p.addTrackingCategories(env)
	--[[
	-- Check if ((documentation)) is transcluded on a /doc or /testcases page.
	-- @env - environment table containing title objects, etc., generated with p.getEnvironment
	
	-- Messages:
	-- 'display-strange-usage-category' --> true
	-- 'doc-subpage' --> 'doc'
	-- 'testcases-subpage' --> 'testcases'
	-- 'strange-usage-category' --> 'Wikipedia pages with strange ((documentation)) usage'
	-- 
	-- /testcases pages in the module namespace are not categorised, as they may have
	-- ((documentation)) transcluded automatically.
	--]]
	local title = env.title
	local subjectSpace = env.subjectSpace
	if not title or not subjectSpace then
		return nil
	end
	local subpage = title.subpageText
	local ret = ''
	if message('display-strange-usage-category', nil, 'boolean')
		and (
			subpage == message('doc-subpage')
			or subjectSpace ~= 828 and subpage == message('testcases-subpage')
		)
	then
		ret = ret .. makeCategoryLink(message('strange-usage-category'))
	end
	return ret
end

return p