Module:URL to diff

 -- This module converts Wikipedia diff URLs to the {{diff}} template format.

 localnewBuffer=require('Module:OutputBuffer')

 localp={}

 localfunctiondecodeUrl(url)
 iftype(url)~='string'then
 returnnil
 end
 url=mw.uri.new(url)
 ifnoturlorurl.host~='en.wikipedia.org'then
 returnnil
 end
 localdata={}
 data.title=url.query.titleandmw.uri.decode(url.query.title,'WIKI')
 data.diff=url.query.diff
 data.oldid=url.query.oldid
 data.diffonly=url.query.diffonly
 returndata
 end

 localfunctionencodeDiffTemplate(data)
 ifnotdata.titleandnotdata.diffandnotdata.oldidthen
 returnnil
 end
 localisNamed=false-- Track whether we need to use named parameters
 fork,vinpairs(data)do
 ifstring.find(v,'=')then
 isNamed=true
 break
 end
 end
 localgetBuffer,print,printf=newBuffer()
 print('diff')
 printf('%s%s',isNamedand'page='or'',data.titleor'')
 printf('%s%s',isNamedand'diff='or'',data.diffor'')
 printf('%s%s',isNamedand'oldid='or'',data.oldidor'')
 ifdata.labelthen
 printf('%s%s',isNamedand'label='or'',data.label)
 end
 ifdata.diffonlythen
 printf('diffonly=%s',data.diffonly)
 end
 localret=getBuffer('|')
 ret='{{'..ret..'}}'
 returnret
 end

 functionp._url(args)
 localdata=decodeUrl(args.url)
 ifdatathen
 data.label=args.label
 returnencodeDiffTemplate(data)
 else
 returnnil
 end
 end

 functionp.url(frame)
 localargs=require('Module:Arguments').getArgs(frame,{
 wrappers='Template:URL to diff',
 })
 returnp._url(args)
 end

 returnp