Module:Redirect hatnote

--[[
-- This module produces a "redirect" hatnote. It looks like this:
-- '"X" redirects here. For other uses, see Y.'
-- It implements the {{redirect}} template.
--]]

local mHatnote = require('Module:Hatnote')
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType

local p = {}

local function getTitle(...)
	local success, titleObj = pcall(mw.title.new, ...)
	if success then
		return titleObj
	else
		return nil
	end
end

function p.redirect(frame)
	-- Get the args table and work out the maximum arg key.
	local origArgs = frame:getParent().args
	local args = {}
	local maxArg = 0
	for k, v in pairs(origArgs) do
		if type(k) == 'number' and k > maxArg then
			maxArg = k
		end
		v = v:match('^%s*(.-)%s*$') -- Trim whitespace
		if v ~= '' then
			args[k] = v
		end
	end

	-- Return an error if no redirect was specified.
	local redirect = args[1]
	if not redirect then
		return mHatnote.makeWikitextError(
			'no redirect specified',
			'Template:Redirect#Errors',
			args.category
		)
	end

	-- Create the data table.
	local data = {}
	local iArg = 0
	local iData = 1
	repeat
		iArg = iArg + 2
		local useTable = data[iData] or {}
		local pages = useTable.pages or {}
		local use = args[iArg]
		local page = args[iArg + 1]
		local nextUse = args[iArg + 2]
		pages[#pages + 1] = page
		useTable.pages = pages
		if use ~= 'and' then
			useTable.use = use
		end
		data[iData] = useTable
		if nextUse ~= 'and' then
			iData = iData + 1
		end
	until iArg >= maxArg - 1

	-- Create the options table.
	local options = {}
	options.selfref = args.selfref
		
	return p._redirect(redirect, data, options)
end

local function formatUseTable(useTable, isFirst, redirect)
	-- Formats one use table. Use tables are the tables inside the data array.
	-- Each one corresponds to one use. (A use might be the word "cats" in the
	-- phrase "For cats, see [[Felines]]".)
	-- Returns a string, or nil if no use was specified.
	-- The isFirst parameter is used to apply special formatting for the first
	-- table in the data array. If isFirst is specified, the redirect parameter
	useTable = useTable or {}
	local use
	if isFirst then
		use = useTable.use or 'other uses'
	elseif not useTable.use then
		return nil
	elseif tonumber(useTable.use) == 1 then
		use = 'other uses'
	else
		use = useTable.use
	end
	local pages = useTable.pages or {}
	if isFirst then
		redirect = redirect or error(
			'isFirst was set in formatUseTable, but no redirect was supplied',
			2
		)
		pages[1] = pages[1] or redirect .. ' (disambiguation)'
	else
		pages[1] = pages[1] or useTable.use .. ' (disambiguation)'
	end
	pages = mHatnote.formatPages(unpack(pages))
	pages = mw.text.listToText(pages)
	return string.format(
		'For %s, see %s.',
		use,
		pages
	)
end

function p._redirect(redirect, data, options, currentTitle, redirectTitle, targetTitle)
	-- Validate the input. Don't bother checking currentTitle, redirectTitle or
	-- targetTitle, as they are only used in testing.
	checkType('_redirect', 1, redirect, 'string')
	checkType('_redirect', 2, data, 'table', true)
	checkType('_redirect', 3, options, 'table', true)
	data = data or {}
	options = options or {}
	currentTitle = currentTitle or mw.title.getCurrentTitle()

	-- Generate the text.
	local text = {}
	text[#text + 1] = '"' .. redirect .. '" redirects here.'
	text[#text + 1] = formatUseTable(data[1] or {}, true, redirect)
	if data[1] and data[1].use and data[1].use ~= 'other uses' then
		for i = 2, #data do
			text[#text + 1] = formatUseTable(data[i] or {}, false)
		end
	end
	text = table.concat(text, ' ')
	
	-- Generate the tracking category.
	-- We don't need a tracking category if the template invocation has been
	-- copied directly from the docs, or if we aren't in mainspace.
	local category
	if not redirect:find('^REDIRECT%d*$') and redirect ~= 'TERM' -- 
		and currentTitle.namespace == 0
	then
		redirectTitle = redirectTitle or getTitle(redirect)
		if not redirectTitle or not redirectTitle.exists then
			category = 'Missing redirects'
		elseif not redirectTitle.isRedirect then
			category = 'Articles with redirect hatnotes needing review'
		else
			local mRedirect = require('Module:Redirect')
			local target = mRedirect.getTarget(redirectTitle)
			targetTitle = targetTitle or target and getTitle(target)
			if targetTitle and targetTitle ~= currentTitle then
				category = 'Articles with redirect hatnotes needing review'
			end
		end
	end
	category = category and string.format('[[Category:%s]]', category) or ''

	-- Generate the options to pass to [[Module:Hatnote]].
	local mhOptions = {}
	if currentTitle.namespace == 0
		and redirectTitle and redirectTitle.namespace ~= 0
	then
		-- We are on a mainspace page, and the hatnote starts with something
		-- like "Wikipedia:Foo redirects here", so automatically label it as a
		-- self-reference.
		mhOptions.selfref = true
	else
		mhOptions.selfref = options.selfref
	end

	return mHatnote._hatnote(text, mhOptions) .. category
end
 
return p