local p = {}

function proc(text,fcn,args) -- processes text sequentially according to a list of functions separated by spaces fcn
    text=text or ""
    fcn=fcn or ""
    local keepfile
    repeat
        fcnext=mw.ustring.match(fcn,"(%S+)")
        if fcnext then
            fcn=mw.ustring.gsub(fcn,fcnext,"") -- function names SHALL not contain pattern chars
            if fcnext=="dewiki" then          
                 -- protect all single [ and ] by temporarily converting to a password.  This allows links to remain inside file text while doing only a dewiki
                text=mw.ustring.gsub(text,"([^%[])%[([^%[])","%1<Module:WikiLink internal lsbracket token>%2")
                text=mw.ustring.gsub(text,"^%[([^%[])","<Module:WikiLink internal lsbracket token>%1")
                text=mw.ustring.gsub(text,"([^%[])%[$","%1<Module:WikiLink internal lsbracket token>")
                text=mw.ustring.gsub(text,"([^%]])%]([^%]])","%1<Module:WikiLink internal rsbracket token>%2")
                text=mw.ustring.gsub(text,"^%]([^%]])","<Module:WikiLink internal rsbracket token>%1")
                text=mw.ustring.gsub(text,"([^%]])%]$","%1<Module:WikiLink internal rsbracket token>")
                if keepfile then
                    text=mw.ustring.gsub(text,"%[%[%s*File:([^%[%]])%]%]","<Module:WikiLink internal filestart token>%1<Module:WikiLink internal 2rsbracket token>")
                    text=mw.ustring.gsub(text,"%[%[%s*Image:([^%[%]])%]%]","<Module:WikiLink internal imagestart token>%1<Module:WikiLink internal 2rsbracket token>")                
                end

                 -- process File: and Image: links, using alt text when available
                text=mw.ustring.gsub(text,"%[%[File:[^%[%]]-|%s*alt=([^%[%]|]-)|[^%[%]]-%]%]","%1") -- case for File: where alt= text is present but not at end
                text=mw.ustring.gsub(text,"%[%[Image:[^%[%]]-|%s*alt=([^%[%]|]-)|[^%[%]]-%]%]","%1") -- case for Image: where alt= text is present but not at end
                text=mw.ustring.gsub(text,"%[%[File:[^%[%]]-|%s*alt=([^%[%]|]-)%]%]","%1") -- case for File: where alt= text is present at end
                text=mw.ustring.gsub(text,"%[%[Image:[^%[%]]-|%s*alt=([^%[%]|]-)%]%]","%1") -- case for Image: where alt= text is present at end
                
                text=mw.ustring.gsub(text,"%[%[[^%[%]]-|([^%[%]|]-)%]%]","%1") -- link, text separated by "|".  Handles case of File: when no alt= is specified, -assuming- last field is the legend
                text=mw.ustring.gsub(text,"%[%[([^%[%]|]-)%]%]","%1") -- link with no funny |s at all
                 -- deprotect all tokens
                text=mw.ustring.gsub(text,"<Module:WikiLink internal lsbracket token>","[")
                text=mw.ustring.gsub(text,"<Module:WikiLink internal rsbracket token>","]")
                text=mw.ustring.gsub(text,"<Module:WikiLink internal filestart token>","[[File:")
                text=mw.ustring.gsub(text,"<Module:WikiLink internal imagestart token>","[[Image:")
                text=mw.ustring.gsub(text,"<Module:WikiLink internal 2rsbracket token>","]]")
                
            elseif fcnext=="delink" then
                text=mw.ustring.gsub(text,"%[%s*http://%S*%s+([^%]%[]+)%]","%1")
            elseif fcnext=="wikiall" then
                if args.space then
                    text=mw.ustring.gsub(text, "([^ %p]) ", "%1#spacetoken#")
                    text=mw.ustring.gsub(text,"(%S+)","[[%1]]")
                    text=mw.ustring.gsub(text, "(%S)#spacetoken#(%S)", "%1 %2")
                else
                    text=mw.ustring.gsub(text,"(%S+)","[[%1]]")
                end
            elseif fcnext=="wikiline" then
                text=mw.ustring.gsub(text,"([^\n]+)","[[%1]]")
            elseif fcnext=="keepfile" then
                keepfile=true
            end -- if fcnext==etc.
            if args.external then
            	text = mw.ustring.gsub(text,"%[%[([^%[%]]*)%]%]", function(x) return "[" .. args.external .. mw.ustring.gsub(mw.text.encode(x)," ","_") .. " " .. x .. "]" end)
            end
        end -- if fcnext
    until not fcnext
    return text --- when all functions are used up (or no valid function given) return the input text straight
    end
    
function p.main(frame,fcn) -- gets the parameters and sets up to call proc
    local args=frame.args
    local parent=frame.getParent(frame)
    if parent then pargs=parent.args else pargs={} end
    local text=args.text or args[1] or pargs.text or pargs[1] or ""
    local nowiki=args.nowiki or pargs.nowiki
    fcn=(fcn or "") ..  (args["function"] or pargs["function"] or "")  
    --local page=mw.title.getCurrentTitle() --- in the long run this cheesy tactic won't fly - I should rewrite as a proper module and recommend Module:Page invocation in the #invoke instead.
    --if page then text=page.getContent(page) else return "error didn't get the page contents :(" end
    text=proc(text,fcn,args)
    if nowiki then text="<nowiki>" .. text .. "</nowiki>" end
    return frame:preprocess(text)
end

 --- the function "parameter" is added to the beginning of the list of functions to be performed as specified by "function =".
function p.dewiki(frame)
    return p.main(frame,"dewiki ")
end

function p.delink(frame)
    return p.main(frame,"delink ")
end

function p.wikiall(frame)
    return p.main(frame,"wikiall ")
end

function p.wikiline(frame)
    return p.main(frame,"wikiline ")
end

function p.keepfile(frame)
    return p.main(frame,"keepfile ")
end

function p.keepfile_dewiki(frame)
    return p.main(frame,"keepfile dewiki")
end
return p