# 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(,displacement,varstoreturn)  
local parent=.getParent  
local currentpage,indexmodule,defaultpage,noerr  
---- args in the #invoke itself trump args in the parent  
currentpage = .args.page and mw.text.trim(.args.page)  
defaultpage = .args.defaultpage and mw.text.trim(.args.defaultpage)  
indexmodule = .args.index and mw.text.trim(.args.index)  
displacement = displacement or .args.displacement -- can be passed from the other function names at the end  
noerr=.args.noerr -- used as boolean  
anonymizereturn = .args.anonymize -- used as boolean  
---- args in the parent 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  
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:  
---
-- Used like this to find the next page after a specified page:  
---

function p.next_page  
local returnpage,pagenumber,totalpages,errcode=p.main(,1,true)  
return returnpage  
end  
p.next = p.next_page  

-- Same as above, but returns the previous page  
function p.last_page  
local returnpage,pagenumber,totalpages,errcode=p.main(,-1,true)  
return returnpage  
end  
p.last = p.last_page  

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

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

return p