Editing Module:TrainingPages

--The purpose of this module is to take a list of linked page, and use it to determine the next and previous page in the list as well as the total number of pages.
 
local p = {}
 
function anonymize(name)
	return mw.ustring.gsub(name,"^"..mw.site.siteName,"Project") or name
end

function out(name)
	return mw.ustring.gsub(name,"^Project",mw.site.siteName) or name
end

function keyize(pagename)
	-- there was a complaint about "_" breaking things.  Do all lookups with _ in place of any space.
	-- also spaces in the index file (non-module) were causing trouble
	pagename = mw.text.trim(pagename)
	pagename = mw.ustring.gsub(pagename, " ", "_")
	pagename = mw.uri.decode(pagename)
	pagename = anonymize(pagename)
	return pagename
end

function p.main(frame,displacement,varstoreturn)
	local parent=frame.getParent(frame)
	local currentpage,indexmodule,defaultpage,noerr
	---- args in the #invoke itself trump args in the parent frame
	currentpage = frame.args.page and mw.text.trim(frame.args.page)
	defaultpage = frame.args.defaultpage and mw.text.trim(frame.args.defaultpage)
	indexmodule = frame.args.index and mw.text.trim(frame.args.index)
	displacement = displacement or frame.args.displacement -- can be passed from the other function names at the end
	noerr=frame.args.noerr -- used as boolean
	anonymizereturn = frame.args.anonymize -- used as boolean
	---- args in the parent frame come next
	if parent then
		currentpage=currentpage or (parent.args.page and mw.text.trim(parent.args.page))
		indexmodule=indexmodule or (parent.args.index and mw.text.trim(parent.args.index)) -- index is a module return{'page1','page2', ...}
		defaultpage=defaultpage or (parent.args.defaultpage and mw.text.trim(parent.args.defaultpage))
		noerr=noerr or parent.args.noerr
		anonymizereturn = anonymizereturn or parent.args.anonymize
	end
	---- default values if parameters aren't provided
	defaultpage=defaultpage or "" -- don't know where to send people by default
	if not(indexmodule) then
		return "[[Module:TrainingPages]] error:no index parameter specified"
	end
	if not(currentpage) then
		local pp=mw.title.getCurrentTitle()
		if not pp then
			if noerr then
				return "","",""
			else return "[[Module:TrainingPages]] error:failed to access getCurrentTitle" -- this shouldn't happen anyway, I don't think....
			end
		end
		currentpage=pp.fullText
	end
	currentpage=anonymize(currentpage) --- convert "Wikipedia:, "Meta:" etc. into "Project:
	local index={}
	if mw.ustring.sub(indexmodule,1,6)=="Module" then
		---- get a table of the pages in order from indexmodule
		index=mw.loadData(indexmodule)
	else pp=mw.title.new(indexmodule)
		if not pp then
			if noerr then
				return "","",""
			else return "[[Module:TrainingPages]] error (''index'' parameter): failed to access mw.title.new("..tostring(indexmodule)..") to load the index file",false,false,true
			end
		end
		local textindex=pp.getContent(pp)
		if not textindex then
			if noerr then
				return "","",""
			else return "[[Module:TrainingPages]] error (''index'' parameter):failed to access mw.title.new("..indexmodule.."):getContent() to load the index data",false,false,true
			end
		end
		prowl=mw.ustring.gmatch(textindex,"%[%[(.-)[%]|]") -- first half of any wikilink
		index={}
		repeat
			link=prowl()
			if not(link) then break end
			link = mw.text.trim(link)
			if link~="" then table.insert(index,link) end
		until false
	end
	displacement = displacement or 0 -- assume a null parameter is just display the same
	---- set up the reverse lookup in lookup.
	---- it would be faster to set this up in the indexmodule
	---- but we don't want inconsistencies from user input!
	local lookup={}
	local i=0
	repeat
		i=i+1
		local j=index[i]
		if j then lookup[keyize(j)]=i else break end -- lookup["page name"] => page number
	until false
	--- get the page to return
	local returnpage,currentpagenumber
	if tonumber(currentpage) then
		currentpagenumber=tonumber(currentpage)
		returnpage=index[currentpagenumber+displacement] or defaultpage
	elseif (lookup[keyize(currentpage)]) then
		currentpagenumber=lookup[keyize(currentpage)]
		returnpage=index[currentpagenumber+displacement] or defaultpage
	else returnpage=defaultpage
	end
	if anonymizereturn then
		returnpage=anonymize(returnpage)
	else
		returnpage=out(returnpage)
	end
	if returnpage then returnpage = mw.text.trim(returnpage) end
	if not(varstoreturn) then return tostring(returnpage) else return tostring(returnpage),currentpagenumber,#index end
end
 
-- Return the next page in the index
-- Used like if on a page that is part of the index:
--{{#invoke:TrainingPages| next_page | index=Project:Training/For students/Editing module index }}
-- Used like this to find the next page after a specified page:
--{{#invoke:TrainingPages| next_page | index=Project:Training/For students/Editing module index | currentpage=Project:Training/For students/My sandbox }}

function p.next_page(frame)
	local returnpage,pagenumber,totalpages,errcode=p.main(frame,1,true)
	return returnpage
end
p.next = p.next_page
 
-- Same as above, but returns the previous page
function p.last_page(frame)
	local returnpage,pagenumber,totalpages,errcode=p.main(frame,-1,true)
	return returnpage
end
p.last = p.last_page
 
function p.page_number(frame)
	local returnpage,pagenumber,totalpages,errcode=p.main(frame,0,true)
	if errcode then return returnpage else return pagenumber end
end
p.page = p.page_number

function p.total_pages(frame)
	local returnpage,pagenumber,totalpages,errcode=p.main(frame,0,true)
	if errcode then return returnpage else return totalpages end
end
p.total = p.total_pages

return p