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,&quot;^&quot;..mw.site.siteName,&quot;Project&quot;) or name
 end
 
 function out(name)
     return mw.ustring.gsub(name,&quot;^Project&quot;,mw.site.siteName) or name
 end
 
 function keyize(pagename)
      -- there was a complaint about &quot;_&quot; 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, &quot; &quot;, &quot;_&quot;)
     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 &quot;&quot; -- don't know where to send people by default
     if not(indexmodule) then
         return &quot;[[Module:TrainingPages]] error:no index parameter specified&quot;
     end
     if not(currentpage) then
         local pp=mw.title.getCurrentTitle()
         if not pp then
             if noerr then
                 return &quot;&quot;,&quot;&quot;,&quot;&quot;
             else return &quot;[[Module:TrainingPages]] error:failed to access getCurrentTitle&quot; -- this shouldn't happen anyway, I don't think....
             end
         end
         currentpage=pp.fullText
     end
     currentpage=anonymize(currentpage) --- convert &quot;Wikipedia:, &quot;Meta:&quot; etc. into &quot;Project:
     local index={}
     if mw.ustring.sub(indexmodule,1,6)==&quot;Module&quot; 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 &quot;&quot;,&quot;&quot;,&quot;&quot;
             else return &quot;[[Module:TrainingPages]] error (''index'' parameter): failed to access mw.title.new(&quot;..tostring(indexmodule)..&quot;) to load the index file&quot;,false,false,true
             end
         end
         local textindex=pp.getContent(pp)
         if not textindex then
             if noerr then
                 return &quot;&quot;,&quot;&quot;,&quot;&quot;
             else return &quot;[[Module:TrainingPages]] error (''index'' parameter):failed to access mw.title.new(&quot;..indexmodule..&quot;):getContent() to load the index data&quot;,false,false,true
             end
         end
         prowl=mw.ustring.gmatch(textindex,&quot;%[%[(.-)[%]|]&quot;) -- first half of any wikilink
         index={}
         repeat
             link=prowl()
             if not(link) then break end
             link = mw.text.trim(link)
             if link~=&quot;&quot; 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[&quot;page name&quot;] =&gt; 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
     else if (lookup[keyize(currentpage)]) then
             currentpagenumber=lookup[keyize(currentpage)]
             returnpage=index[currentpagenumber+displacement] or defaultpage
         else returnpage=defaultpage
         end
     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