-- This module provides functions for getting the target of a redirect page.



local p = {}



-- Gets a mw.title object, using pcall to avoid generating script errors if we

-- are over the expensive function count limit (among other possible causes).

local function getTitle(...)

	local success, titleObj = pcall(mw.title.new, ...)

	if success then

		return titleObj

	else

		return nil

	end

end



-- Gets the name of a page that a redirect leads to, or nil if it isn't a

-- redirect.

function p.getTargetFromText(text)

	local target = string.match(

		text,

		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]|]-)%]%]"

	) or string.match(

		text,

		"^%s*#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*:?%s*%[%[([^%[%]|]-)|[^%[%]]-%]%]"

	)

	return target and mw.uri.decode(target, 'PATH')

end



-- Gets the target of a redirect. If the page specified is not a redirect,

-- returns nil.

function p.getTarget(page, fulltext)

	-- Get the title object. Both page names and title objects are allowed

	-- as input.

	local titleObj

	if type(page) == 'string' or type(page) == 'number' then

		titleObj = getTitle(page)

	elseif type(page) == 'table' and type(page.getContent) == 'function' then

		titleObj = page

	else

		error(string.format(

			"bad argument #1 to 'getTarget'"

				.. " (string, number, or title object expected, got %s)",

			type(page)

		), 2)

	end

	if not titleObj then

		return nil

	end

	local targetTitle = titleObj.redirectTarget

	if targetTitle then

		if fulltext then

			return targetTitle.fullText

		else

			return targetTitle.prefixedText

		end

	else

		return nil

	end

end



--[[

-- Given a single page name determines what page it redirects to and returns the

-- target page name, or the passed page name when not a redirect. The passed

-- page name can be given as plain text or as a page link.

--

-- Returns page name as plain text, or when the bracket parameter is given, as a

-- page link. Returns an error message when page does not exist or the redirect

-- target cannot be determined for some reason.

--]]

function p.luaMain(rname, bracket, fulltext)

	if type(rname) ~= "string" or not rname:find("%S") then

		return nil

	end

	bracket = bracket and "[[%s]]" or "%s"

	rname = rname:match("%[%[(.+)%]%]") or rname

	local target = p.getTarget(rname, fulltext)

	local ret = target or rname

	ret = getTitle(ret)

	if ret then

		if fulltext then

			ret = ret.fullText

		else

			ret = ret.prefixedText

		end

		return bracket:format(ret)

	else

		return nil

	end

end



-- Provides access to the luaMain function from wikitext.

function p.main(frame)

	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})

	return p.luaMain(args1], args.bracket, args.fulltext) or ''

end



-- Returns true if the specified page is a redirect, and false otherwise.

function p.luaIsRedirect(page)

	local titleObj = getTitle(page)

	if not titleObj then

		return false

	end

	if titleObj.isRedirect then

		return true

	else

		return false

	end

end



-- Provides access to the luaIsRedirect function from wikitext, returning 'yes'

-- if the specified page is a redirect, and the blank string otherwise.

function p.isRedirect(frame)

	local args = require('Module:Arguments').getArgs(frame, {frameOnly = true})

	if p.luaIsRedirect(args1]) then

		return 'yes'

	else

		return ''

	end

end



return p