Module:Sandbox/Wnt/NewestAtTop

--This module aims to reorder the sections on a page so that, for example, you can reorder a talk page from newest sections at bottom to newest sections at top. 

local p = {}

-- Return the reordered page, used like this: {{#invoke:NewestAtTop|main|page=Module talk:NewestAtTop/Test|top=yes}}
function p.main(frame,header)
    local parent=frame.getParent(frame) or {}
    local currentpage,top
    ---- args in the #invoke itself trump args in the parent frame
    currentpage = frame.args.page
    header = header or frame.args.header or parent.args.header -- can get from function name
    top = frame.args.top or parent.args.top
    ---- args in the parent frame come next
    if parent then
        currentpage=currentpage or parent.args.page
        header=header or parent.args.header
        top = top or parent.args.top
        end
    ---- default values if parameters aren't provided
    header=header or 2 -- Reorder even = = sections.  Note this isn't tested and may not work...
    local pagepointer
    if top then top=1 else top=0 end
    if not(currentpage) then
        pagepointer=mw.title.getCurrentTitle()
        assert(pagepointer,"failed to access getCurrentTitle")
        currentpage=pagepointer.fullText
    else pagepointer=mw.title.new(currentpage)
        assert(pagepointer,"failed to access mw.title.new("..tostring(currentpage)..")")
    end
    ---- get the text of the currentpage
    local text=pagepointer.getContent(pagepointer)
    assert (text,"error: failed to get text from ".. currentpage)
    local headerdef=mw.ustring.rep("=",header)
    local headermatch="%s*\n%s*"..headerdef.."(=*)(.-)(=*)"..headerdef.."%s*\n%s*"
    local prowl=mw.ustring.gmatch(text,"(.-)"..headermatch)
    local archive={}
    local chunk,h1,title,h2=prowl()
    local level=math.min(mw.ustring.len(h1),mw.ustring.len(h2)) -- if unmatched, higher level trumps
    local lastchunk="";local lasth1="==";local lasth2="==" -- keeps track of the title from the previous iteration to recover at end
    local tinsertpoint={};local insertpoint=1;local lastlevel=level
    table.insert(archive,insertpoint,chunk or "") --- top chunk is the first thing in.  Top means display it at bottom
    table.insert(archive,insertpoint+top,"\n"..headerdef..title..headerdef.."\n")
    repeat
        chunk, h1,title,h2=prowl()
        h1=h1 or lasth1;h2=h2 or lasth2 -- default to normal header and to avoid script error
        if not(chunk) then break end
        lastchunk=chunk; -- to find next section.  You can't find a title in the string it came from.
        table.insert(archive,1+insertpoint+top,chunk) --- insert the OLDER chunk under LAST iteration's title and level
        local lastlevel=level
        level=math.min(mw.ustring.len(h1),mw.ustring.len(h2)) -- if unmatched, higher level trumps
        if level>lastlevel then
            tinsertpoint[lastlevel]=insertpoint;insertpoint=insertpoint+2
        else if level < lastlevel then
            insertpoint=tinsertpoint[level]
            end
        end
        if title then
            lasth1=h1;lasth2=h2
            table.insert(archive,insertpoint+top,"\n"..string.rep("=",header+level)..title..string.rep("=",header+level).."\n")
        end --- insert the new title at the beginning
    until false
    h1,title,h2,chunk=mw.ustring.match(text,lastchunk..headermatch.."(.*)$")-- everything from the last section header to the end of string.  Fails if two identical section headers.
    table.insert(archive,insertpoint+1+top,chunk)
    local output=""
    for i = 1, table.maxn(archive) do
        output=output..(archive[i] or "")
    end
    return frame.preprocess(frame,output)
end

return p