Module:Titlelib

 -- == Titlelib.lua == --
 localp={}

 --[[ Checks wether the given String is a valid interwiki prefix.

 	I.e. wether the prefix is registered in mw.site.interwikiMap()

 	@param onlyInterlang bool Wether to look only for interlang wiki prefix.
 	False by default.

 	@return true if str is a registered interwiki prefix, false else
 ]]
 functionp.isInterwiki(str,onlyInterlang)
 ifnotonlyInterlangthenonlyInterlang=falseend
 str=mw.ustring.lower(str)--prefixes are stored as lower case

 ifmw.site.interwikiMap()[str]then-- `str` is in interwikiMap
 -- When requested, ensures `str` is a valid language code
 returnnotonlyInterlangormw.language.isKnownLanguageTag(str)
 end

 returnfalse-- `str` is not in interwikiMap
 end

 --[[ Checks wether the given String is a valid interlang wiki prefix.

 	I.e. wether the prefix is registered in mw.site.interwikiMap() and is a
 	known language code.

 	@param str String the prefix to check for.

 	@return true if str is a registered interlang prefix, false else.
 ]]
 functionp.isInterlangPrefix(str)
 returnp.isInterwiki(str,true)
 end

 --[[ Checks wether the given String is a valid namespace prefix on Meta.

 	I.e. wether the prefix is registered in mw.site.namespaces

 	@return true if str is a registered interwiki prefix, false else
 ]]
 functionp.isNamespace(str)
 str=mw.ustring.lower(str)
 fori,detailsinpairs(mw.site.namespaces)do
 ifstr==mw.ustring.lower(details.name)
 orstr==mw.ustring.lower(details.canonicalName)
 or(details.aliases[1]andstr==mw.ustring.lower(details.aliases[1]))
 --on Meta there is no more than 1 alias; else we should use
 --table.contains(aliases, str)
 then
 returntrue
 end
 end

 returnfalse
 end

 --[[ Split given title into two parts: interwiki prefixes and page title
 	@Return table containing 2 strings:
 		* first one is all prefixes which are recognized as interwikis, joined
 		with colon
 		* second one is the rest of the given string
 ]]
 functionp.splitPrefixedTitle(linkStr)
 ifnotmw.ustring.find(linkStr,':')then--if there is no colon in title
 return':',linkStr--that means there is no prefix
 end

 locallinkTable=mw.text.split(linkStr,':',true)

 localoutwikiPart=''--interwiki prefixes and language code
 localinwikiPart=''--page name, including namespace prefix

 localhasGotLastInterwikiPrefix=false
 localhasInterwikiPrefix=false

 fori,linkPartinipairs(linkTable)do
 iflinkPart==''then
 elseifhasGotLastInterwikiPrefixorp.isNamespace(linkPart)then
 hasGotLastInterwikiPrefix=true
 inwikiPart=inwikiPart..':'..linkPart
 elseifp.isInterlangPrefix(linkPart)then
 outwikiPart=outwikiPart..':'..linkPart
 hasGotLastInterwikiPrefix=true
 elseifnothasInterwikiPrefixandp.isInterwiki(linkPart)then
 outwikiPart=outwikiPart..':'..linkPart
 hasInterwikiPrefix=true
 else
 hasGotLastInterwikiPrefix=true
 inwikiPart=linkPart
 end
 end

 returnoutwikiPart..':',inwikiPart
 end

 --[[ Gives the interwiki prefix for a given language code or database project id.
 	E.g. langToWiki("de-formal") will return 'de'.

 	Currently, doesn’t provide any fallback.

 	@param lang String Language code or database project identifier (project
 	code on Wikidata).

 	@Return String|bool Related interwiki prefix (without colon), or false if
 	there is none.

 	@Seealso T253387
 ]]
 functionp.langToWiki(lang)
 lang=lang:gsub('_','-')--DB-prefixes use `_` instead of `-`
 localexceptions={
 --		['lang-code']	= 'interwiki-prefix'

 ['ady-cyrl']='ady',
 ['aeb']='ar',
 ['aeb-arab']='ar',
 ['aeb-latn']='ar',
 ['arq']='ar',
 ['ban-bali']='ban',
 ['be-x-old']='be-tarask',-- Both work
 ['bho']='bh',
 ['crh-latn']='crh',
 ['crh-cyrl']='crh',
 ['de-at']='de',
 ['de-ch']='de',
 ['de-formal']='de',
 ['egl']='eml',
 ['en-ca']='en',
 ['en-gb']='en',
 ['es-419']='es',
 ['es-formal']='es',
 ['frc']='fr',
 ['gan-hans']='gan',
 ['gan-hant']='gan',
 ['gom-deva']='gom',
 ['gom-latn']='gom',
 ['gsw']='als',
 ['hif-latn']='hif',
 ['hu-formal']='hu',
 ['hsn']='zh',
 ['ike']='iu',
 ['ike-cans']='iu',
 ['ike-latn']='iu',
 ['kbd-cyrl']='kbd',
 ['kk-arab']='kk',
 ['kk-cn']='kk',
 ['kk-cyrl']='kk',
 ['kk-kz']='kk',
 ['kk-latn']='kk',
 ['kk-tr']='kk',
 ['ko-kp']='ko',
 ['ks-arab']='ks',
 ['ks-deva']='ks',
 ['ku-arab']='ku',
 ['ks-latn']='ku',
 ['lzh']='zh-classical',-- Both work
 ['ms-arab']='ms',
 ['nan']='zh-min-nan',-- Both work
 ['nb']='no',-- Both work
 ['nl-informal']='nl',
 ['mo']='ro',-- Both work
 ['pt-br']='pt',
 ['rgn']='eml',
 ['rup']='roa-rup',
 ['sgs']='bat-smg',
 ['shi-latn']='shi',
 ['shi-tfng']='shi',
 ['shy-latn']='shy',-- Wikipedia in Incubator
 ['skr-arab']='skr',
 ['se-fi']='se',
 ['se-no']='se',
 ['se-se']='se',
 ['sr-ec']='sr',
 ['sr-el']='sr',
 ['tg-cyrl']='tg',
 ['tg-latn']='tg',
 ['tt-cyrl']='tt',
 ['tt-latn']='tt',
 ['ug-arab']='ug',
 ['ug-latn']='ug',
 ['uz-cyrl']='uz',
 ['uz-latn']='uz',
 ['vro']='fiu-vro',
 ['yue']='zh-yue',-- Both work
 ['zh-cn']='zh',
 ['zh-hans']='zh',
 ['zh-hant']='zh',
 ['zh-hk']='zh',
 ['zh-mo']='zh',
 ['zh-my']='zh',
 ['zh-sg']='zh',
 ['zh-tw']='zh',-- Both work
 }
 ifexceptions[lang]then
 returnexceptions[lang]
 elseifp.isInterlangPrefix(lang)then
 returnlang
 else--given string is not a valid interlang prefix
 returnfalse
 -- We may consider returning first fallback language code, if it is a
 -- valid non-English interwiki.
 end
 end

 --[[ Prefixes page name with Special:MyLanguage.

 	@param pageLink String Page name, eventually prefixed with
 	interwiki prefixes and namespace.

 	@return String Name of page which links to given page link
 	in user language.
 ]]
 functionp.myLangLink(pageLink)
 localoutPrefix,pageName=p.splitPrefixedTitle(pageLink)
 returnoutPrefix..'Special:MyLanguage/'..pageName
 end

 returnp