Module:Redirect

Documentation for this module may be created at Module:Redirect/doc

 ---- This module accepts the name of a single page.  It determines if the page is a redirect; if so it looks up the page,
 ---- extracts the target, and returns the target name as text. Its usage is {{#invoke:redirect|main|redirect-page-name}}.
 ---- The template neither takes nor gives square brackets, so to show the result as a link use
 ---- [[{{#invoke:redirect|main|redirect-page-name}}]].  An error is produced if the redirect does not exist,
 ---- but for versatility no error is given if the file is not a redirect (returns the original text)
 ---- or if the file name is blank (returns blank).

p={}

function p.main(frame)
    local args, pargs = frame.args, (frame:getParent() or {}).args or {}
    local rname, bracket = args[1] or pargs[1], args.bracket or pargs.bracket
    
    if not rname or not mw.ustring.match(rname, "%S") then return "" end
    bracket = bracket and "[[%s]]" or "%s"
    rname = mw.ustring.match(rname,"%[%[(.+)%]%]") or rname
    
    local rpage, err = mw.title.new(rname)
    
    -- avoid expensive operation when nothing to do
    if not rpage then
        err = "File not found (mw.title.new failed)"
    elseif rpage.id == 0 then
        err = "File not found (id=0):"
    elseif not rpage.isRedirect then
        return mw.ustring.format(bracket, rname) -- not a redirect so use passed page name (for some general-purpose template use)
    else
        local redirect = mw.ustring.match( rpage:getContent() or "", "^#[Rr][Ee][Dd][Ii][Rr][Ee][Cc][Tt]%s*%[%[(.-)%]%]" )
        
        if redirect then
            return mw.ustring.format(bracket, redirect)
        end
        
        err = "failed to understand"
    end
    
    return '<span style="text-color:red;">[[Module:redirect]] error: ' .. err .. ' - [[' .. rname .. ']]</span>'
end

return p