Module:wlink


local WLink = { suite  = "WLink",

                serial = "2016-10-05" };

--[=[

ansiPercent()

formatURL()

getArticleBase()

getBaseTitle()

getEscapedTitle()

getExtension()

getFile()

getFragment()

getLanguage()

getNamespace()

getPlain()

getProject()

getTarget()

getTargetPage()

getTitle()

getWeblink()

isBracketedLink()

isBracketedURL()

isCategorization()

isExternalLink()

isInterlanguage()

isInterwiki()

isMedia()

isTitledLink()

isValidLink()

isWikilink()

wikilink()

failsafe()

]=]







-- local globals

local URLutil = false;







local utilURL = function ()

    -- Attach URLutil library module

    -- Postcondition:

    --     Returns  table, with URLutil library

    --     Throws error, if not available

    if not URLutil then

        local lucky, util = pcall( require, "Module:URLutil" );

        if lucky then

            if type( util ) == "table" then

                URLutil = util.URLutil();

            end

            util = "library URLutil invalid";

        end

        if type( URLutil ) ~= "table" then

            error( util, 0 );

        end

    end

    return URLutil;

end -- utilURL()







local contentExtlink = function ( attempt )

    -- Retrieve span of external link between brackets

    -- Precondition:

    --     attempt  -- string, with presumable link

    --                         the first char is expected to be "["

    -- Postcondition:

    --     Returns  string, number, number

    --                  string including whitespace

    --                  number with index of relevant "["

    --                  number with index after relevant "]"

    --              false if nothing found

    local r1 = false;

    local r2 = false;

    local r3 = attempt:find( "]", 2, true );

    if r3 then

        local s = attempt:sub( 2,  r3 - 1 );

        local i = s:find( "[", 1, true );

        if i then

            r1 = s:sub( i + 1 );

            r2 = i;

        else

            r1 = s;

            r2 = 1;

        end

    else

        r3 = false;

    end

    return r1, r2, r3;

end -- contentExtlink()







local contentWikilink = function ( attempt )

    -- Retrieve span of wikilink between brackets

    -- Precondition:

    --     attempt  -- string, with presumable link

    --                        the first two chars are expected to be "[["

    -- Postcondition:

    --     Returns  string, number, number

    --                  string including whitespace

    --                  number with index of relevant "[["

    --                  number with index after relevant "]]"

    --              false if nothing found

    local r1 = false;

    local r2 = false;

    local r3 = attempt:find( "]]", 3, true );

    if r3 then

        local s = attempt:sub( 3,  r3 - 1 );

        local i = s:find( "[[", 1, true );

        if i then

            r1 = s:sub( i + 2 );

            r2 = i;

        else

            r1 = s;

            r2 = 1;

        end

    end

    return r1, r2, r3;

end -- contentWikilink()







local extractExtlink = function ( attempt )

    -- Retrieve external link

    -- Precondition:

    --     attempt  -- string, with presumable link

    --                        the first char is expected to be "["

    -- Postcondition:

    --     Returns  string, string

    --                  first with target and title

    --                  second result false if not titled

    --              false if nothing found

    local r1 = false;

    local r2 = false;

    local s = contentExtlink( attempt );

    if s then

        local i = s:find( "%s", 1 );

        if i then

            r1 = s:sub( 1,  i - 1 );

            r2 = mw.text.trim( s:sub( i + 1 ) );

            if r2 == "" then

                r2 = false;

            end

        else

            r1 = s;

        end

        if r1 then

            r1 = mw.text.trim( r1 );

            if r1 == ""  or

               not utilURL().isResourceURL( r1 ) then

                r1 = false;

            end

        end

        if not r1 then

            r2 = false;

        end

    end

    return r1, r2;

end -- extractExtlink()







local extractWikilink = function ( attempt )

    -- Retrieve wikilink

    -- Precondition:

    --     attempt  -- string, with presumable link

    --                        the first two chars are expected to be "[["

    -- Postcondition:

    --     Returns  string, string

    --                  first with target

    --                  second result title, or false if not piped

    --              false if nothing found

    local r1 = false;

    local r2 = false;

    local s = contentWikilink( attempt );

    if s then

        local i = s:find( "|", 1, true );

        if i then

            r1 = s:sub( 1,  i - 1 );

            r2 = s:sub( i + 1 );

        else

            r1 = s;

        end

        r1 = mw.text.trim( r1 );

        if r1 == "" then

            r1 = false;

        else

            r1 = r1:gsub( "_",        " " )

                   :gsub( "&nbsp;",   " " )

                   :gsub( "&thinsp;", " " )

                   :gsub( "&#160;",   " " )

                   :gsub( "&#8239;",  " " )

                   :gsub( "  +",      " " );

            r1 = mw.text.decode( r1 );

        end

    end

    return r1, r2;

end -- extractWikilink()







local prefix = function ( ask, ahead )

    -- Interprete prefix of language or project type

    -- Precondition:

    --     ask    -- string, with presumable prefix

    --     ahead  -- true, if first segment

    -- Postcondition:

    --     Returns  string,string or nil

    --                     first  string one of "lead", "lang", "project"

    --                     second string is formatted value

    --                       type is one of "lead", "lang", "project"

    --              nil if nothing found

    local r1, r2;

    local prefixes = { b           = true,

                       c           = "commons",

                       d           = true,

                       commons     = true,

                       m           = "meta",

                       mediawiki   = "mw",

                       mw          = true,

                       meta        = true,

                       n           = true,

                       q           = true,

                       s           = true,

                       simple      = false,

                       v           = true,

                       voy         = true,

                       w           = true,

                       wikibooks   = "b",

                       wikidata    = "d",

                       wikinews    = "n",

                       wikipedia   = "w",

                       wikiquote   = "q",

                       wikisource  = "s",

                       wikiversity = "v",

                       wikivoyage  = "voy",

                       wikt        = true,

                       wiktionary  = "wikt"

                     };

    local s = mw.text.trim( ask );

    if s == "" then

        if ahead then

            r1 = "lead";

            r2 = true;

        end

    else

        local p;

        s = s:lower();

        p = prefixes s ];

        if p == true then

            r1 = "project";

            r2 = s;

        elseif p then

            r1 = "project";

            r2 = p;

        elseif p == false then

            r1 = "lang";

            r2 = s;

        elseif s:match( "^%l%l%l?$" )

               and  mw.language.isSupportedLanguage( s ) then

            r1 = "lang";

            r2 = s;

        end

    end

    return r1, r2;

end -- prefix()







local target = function ( attempt, lonely )

    -- Retrieve first target (wikilink or URL), or entire string

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    --     lonely   -- remove fragment, if true

    -- Postcondition:

    --     Returns  string, number

    --                  string, with detected link target, or entire

    --                  number, with number of brackets, if found, or 2

    local r1, r2 = WLink.getTarget( attempt );

    if not r1 then

        r1 = mw.text.trim( attempt );

        r2 = 2;

    end

    if lonely then

        local i = r1:find( "#", 1, true );

        if i == 1 then

            r1 = "";

        elseif i then

            r1 = r1:sub( 1, i - 1 );

        end

    end

    return r1, r2;

end -- target()







function WLink.ansiPercent( attempt, alter )

    -- Convert string by ANSI encoding rather than UTF-8 encoding

    -- Precondition:

    --     attempt  -- string, with presumable ANSI characters

    --     alter    -- string or nil, to use for spaces instead of %20

    -- Postcondition:

    --     Returns  string, encoded

    local k, s;

    local r = attempt;

    if alter then

        r = r:gsub( " ", alter );

    end

    for i = mw.ustring.len( r ), 1, -1 do

        k = mw.ustring.codepoint( r, i, i );

        if k <= 32  or  k > 126 then

            if k > 255 then

                s = mw.ustring.sub( r, i, i );

                if k > 2047 then

                    s = string.format( "%%%2X%%%2X%%%2X",

                                       s:byte( 1, 1 ),

                                       s:byte( 2, 2 ),

                                       s:byte( 3, 3 ) );

                else

                    s = string.format( "%%%2X%%%2X",

                                       s:byte( 1, 1 ),

                                       s:byte( 2, 2 ) );

                end

            else

                s = string.format( "%%%2X", k );

            end

            r = string.format( "%s%s%s",

                               mw.ustring.sub( r,  1,  i - 1 ),

                               s,

                               mw.ustring.sub( r,  i + 1 ) );

        end

    end -- for --i

    r = mw.ustring.gsub(r, '^%*', '%%2A')

    return r;

end -- WLink.ansiPercent()







function WLink.formatURL( adjust )

    -- Create bracketed link, if not yet

    -- Precondition:

    --     adjust  -- string, with URL or domain/path or bracketed link

    -- Postcondition:

    --     Returns  string, with bracketed link

    --              false on invalid format

    local r;

    if type( adjust ) == "string" then

        if WLink.isBracketedLink( adjust ) then

            r = adjust;

        else

            local url = mw.text.trim( adjust );

            local host;

            utilURL();

            host = URLutil.getHost( adjust );

            if not host then

                url  = "http://" .. adjust;

                host = URLutil.getHost( url );

            end

            if host then

                local path = URLutil.getRelativePath( url );

                local show;

                if path == "/" then

                    if not url:match( "/$" ) then

                        url = url .. "/";

                    end

                    show = host;

                else

                    local i = path:find( "#" );

                    if i then

                        path = path:sub( 1,  i - 1 );

                    end

                    show = host .. path;

                end

                r = string.format( "[%s %s]", url, show );

            else

                r = adjust;

            end

        end

    else

        r = false;

    end

    return r;

end -- WLink.formatURL()







function WLink.getArticleBase( attempt )

    -- Retrieve generic article title, no fragment nor brackets

    -- Precondition:

    --     attempt  -- string, with wikilink or page title

    --                         current page title, if missing

    -- Postcondition:

    --     Returns  string, with identified lemma, or all

    --              false on invalid format

    local r;

    if attempt then

        local m;

        r, m = target( attempt, true );

        if m ~= 2 then

            r = false;

        end

    else

        r = mw.title.getCurrentTitle().text;

    end

    if r then

        local sub = r:match( "^(.*%S) *%(.+%)$" );

        if sub then

            r = sub;

        end

    end

    return r;

end -- WLink.getArticleBase()







function WLink.getBaseTitle( attempt )

    -- Retrieve last segment in subpage, no fragment

    -- Precondition:

    --     attempt  -- string, with wikilink or page title

    -- Postcondition:

    --     Returns  string, with identified segment, or all

    local r;

    local s, m = target( attempt, true );

    if m == 2 then

        local sub = s:match( "/([^/]+)$" );

        if sub then

            r = sub;

        else

            r = s;

        end

    else

        r = false;

    end

    return r;

end -- WLink.getBaseTitle()



function WLink.getEscapedTitle( attempt )

    -- Retrieve escaped link title

    -- Precondition:

    --     attempt  -- string, with presumable link title

    -- Postcondition:

    --     Returns  string, with suitable link title

    local s = mw.text.trim( attempt );

    return s:gsub( "\n", " " )

            :gsub( "%[", "&#91;" )

            :gsub( "%]", "&#93;" )

            :gsub( "|",  "&#124;" );

end -- WLink.getEscapedTitle()



function WLink.getExtension( attempt )

    -- Retrieve media extension

    -- Precondition:

    --     attempt  -- string, with wikilink (media link) or page title

    --                         if URL, PDF may be detected

    -- Postcondition:

    --     Returns  string, with detected downcased media type

    --              false if no extension found

    local r = false;

    local s, m = target( attempt );

    if m == 2 then

        s = s:match( "%.(%a+)$" );

        if s then

            r = s:lower();

        end

    elseif s:upper():match( "[%./](PDF)%W?" ) then

        r = "pdf";

    end

    return r;

end -- WLink.getExtension()







function WLink.getFile( attempt )

    -- Retrieve media page identifier

    -- Precondition:

    --     attempt  -- string, with wikilink (media link) or page title

    -- Postcondition:

    --     Returns  string, with detected file title

    --                      no namespace nor project

    --              false if no file found

    local r = false;

    local s, m = target( attempt );

    if m == 2 then

        local slow    = ":" .. s:lower();

        local find = function ( a )

                         local seek = string.format( ":%s:().+%%.%%a+$",

                                                     a:lower() );

                         local join = slow:find( seek );

                         local ret;

                         if join then

                             ret = s:sub( join + #a + 1 );

                         end

                         return ret;

                     end;

        r = find( "file" );

        if not r then

            local trsl = mw.site.namespaces6];

            r = find( trsl.name );

            if not r then

                trsl = trsl.aliases;

                for k, v in pairs( trsl ) do

                    r = find( v );

                    if r then

                        break; -- for k, v

                    end

                end -- for k, v

            end

        end

    end

    return r;

end -- WLink.getFile()







function WLink.getFragment( attempt )

    -- Retrieve fragment

    -- Precondition:

    --     attempt  -- string, with presumable fragment

    -- Postcondition:

    --     Returns  string, with detected fragment

    --              false if no address found

    local r = false;

    local s, m = target( attempt );

    if s then

        local i = s:find( "#", 1, true );

        if i then

            if i > 1 then

                s = s:sub( i - 1 );

                i = 2;

            end

            if s:find( "&#", 1, true ) then

                s = mw.text.decode( s );

                i = s:find( "#", 1, true );

                if not i then

                   s = "";

                   i = 0;

                end

            end

            s = s:sub( i + 1 );

            r = mw.text.trim( s );

            if r == "" then

                r = false;

            elseif m == 2 then

                r = r:gsub( "%.(%x%x)", "%%%1" )

                     :gsub( "_", " " );

                r = mw.uri.decode( r, "PATH" );

            end

        end

    end

    return r;

end -- WLink.getFragment()







function WLink.getLanguage( attempt )

    -- Retrieve language project identifier

    -- Precondition:

    --     attempt  -- string, with wikilink or page title

    -- Postcondition:

    --     Returns  string, with detected downcased language identifier

    --              false if no project language found

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  w.lang then

            r = w.lang;

        end

    end

    return r;

end -- WLink.getLanguage()







function WLink.getNamespace( attempt )

    -- Retrieve namespace number

    -- Precondition:

    --     attempt  -- string, with wikilink or page title

    -- Postcondition:

    --     Returns  number, of detected namespace

    --              false if no namespace found

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  not w.lang  and  not w.project  and  w.ns then

            r = w.ns;

        end

    end

    return r;

end -- WLink.getNamespace()







function WLink.getPlain( attempt )

    -- Retrieve text with all links replaced by link titles

    -- Precondition:

    --     attempt  -- string, with wikitext

    -- Postcondition:

    --     Returns  string, with modified wikitext without links

    local r = attempt;

    local i = 1;

    local j, k, n, lean, s, shift, space, suffix;

    while ( true ) do

        j = r:find( "[", i, true );

        if j then

            suffix = r:sub( j );

            i      = j + 1;

            lean   = ( r:byte( i, i ) == 91 );

            if lean then

                s, k, n = contentWikilink( suffix );

            else

                s, k, n = contentExtlink( suffix );

            end

            if s then

                if k > 1 then

                    n      = n - k;

                    i      = j + k;

                    j      = i - 1;

                    suffix = r:sub( j );

                end

                if lean then

                    s, shift = extractWikilink( suffix );

                    if s then

                        space = s:match( "^([^:]+):" );

                        if space then

                            space = mw.site.namespaces space ];

                            if space then

                                space = space.id;

                            end

                        end

                        if space == 6  or  space == 14 then

                            shift = "";

                        elseif not shift then

                            shift = s;

                        end

                    else

                        s     = "";

                        shift = "";

                    end

                else

                    s, shift = extractExtlink( suffix );

                    if not s then

                        s = "";

                    end

                    if not shift then

                        shift = "";

                    end

                    i = i - 1;

                end

                if j > 1 then

                    s = r:sub( 1, j - 1 );

                else

                    s = "";

                end

                r = string.format( "%s%s%s",

                                   s,  shift,  r:sub( n + i ) );

                i = i + #shift;

            else

                break; -- while true

            end

        else

            break; -- while true

        end

    end -- while true

    return r;

end -- WLink.getPlain()







function WLink.getProject( attempt )

    -- Retrieve wikifarm project identifier

    -- Precondition:

    --     attempt  -- string, with wikilink or page title

    -- Postcondition:

    --     Returns  string, with detected downcased project identifier

    --              false if no project identifier found

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  w.project then

            r = w.project;

        end

    end

    return r;

end -- WLink.getProject()







function WLink.getTarget( attempt )

    -- Retrieve first target (wikilink or URL)

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  string, number

    --                  string, with first detected link target

    --                  number, with number of brackets, if found

    --              false if nothing found

    local r1 = false;

    local r2 = false;

    local i  = attempt:find( "[", 1, true );

    if i then

        local m;

        r1 = attempt:sub( i );

        if r1:byte( 2, 2 ) == 91 then

            m  = 2;

            r1 = extractWikilink( r1 );

        else

            m  = 1;

            r1 = extractExtlink( r1 );

        end

        if r1 then

            r2 = m;

        end

    else

        r1 = attempt:match( "%A?([hf]t?tps?://%S+)%s?" );

        if r1 then

            if utilURL().isResourceURL( r1 ) then

                r2 = 0;

            else

                r1 = false;

            end

        else

            r1 = false;

        end

    end

    return r1, r2;

end -- WLink.getTarget()







function WLink.getTargetPage( attempt )

    -- Retrieve first target page (page name or URL of page)

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  string, with first detected linked page

    --              false if nothing found

    local r1, r2 = WLink.getTarget( attempt );

    if r1 then

        local i = r1:find( "#", 1, true );

        if i then

            if i == 1 then

                r1 = false;

            else

                r1 = mw.text.trim( r1:sub( 1,  i - 1 ) );

            end

        end

    end

    return r1, r2;

end -- WLink.getTargetPage()







function WLink.getTitle( attempt )

    -- Retrieve first link title (wikilink or URL), or wikilink target

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  string, with first detected link target

    --              false if nothing found

    local r = false;

    local i = attempt:find( "[", 1, true );

    if i then

        local s1, s2;

        r = attempt:sub( i );

        if r:byte( 2, 2 ) == 91 then

            s1, s2 = extractWikilink( r );

            if s2 then

                r = s2;

            else

                r = s1;

            end

        else

            s1, r = extractExtlink( r );

        end

    end

    return r;

end -- WLink.getTitle()







function WLink.getWeblink( attempt, anURLutil )

    -- Retrieve bracketed link from resource URL

    -- Precondition:

    --     attempt    -- string, with URL, or something different

    --     anURLutil  -- library module object, or nil

    -- Postcondition:

    --     Returns  string, with first detected link target

    --              false if nothing found

    local second = ".ac.co.go.gv.or.";

    local r;

    if type( anURLutil ) == "table" then

        URLutil = anURLutil;

    else

        utilURL();

    end

    if URLutil.isResourceURL( attempt ) then

        local site = URLutil.getAuthority( attempt );

        local show;

        if #attempt == #site then

           site = site .. "/";

        end

        show = URLutil.getTop3domain( "//" .. site );

        if show then

            local scan   = "[%./](%a+)(%.%l%l%.)(%a+)$";

            local search = "." .. show;

            local s1, s2, s3 = search:match( scan );

            if s2 then

                if not second:find( s2, 1, true ) then

                    show = string.format( "%s.%s", s2, s3 );

                end

            else

                show = false;

            end

        end

        if not show then

            show = URLutil.getTop2domain( "//" .. site );

            if not show then

                show = URLutil.getHost( "//" .. site );

            end

        end

        r = string.format( "[%s %s]", attempt, show );

    else

        r = attempt;

    end

    return r;

end -- WLink.getWeblink()







function WLink.isBracketedLink( attempt )

    -- Does attempt match a bracketed link?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local i = attempt:find( "[", 1, true );

    if i then

        local s = attempt:sub( i );

        if s:byte( 2, 2 ) == 91 then

            s = extractWikilink( s );

        else

            s = extractExtlink( s );

        end

        if s then

            r = true;

        end

    end

    return r;

end -- WLink.isBracketedLink()







function WLink.isBracketedURL( attempt )

    -- Does attempt match a bracketed URL?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local s, r = WLink.getTarget( attempt );

    return ( r == 1 );

end -- WLink.isBracketedURL()







function WLink.isCategorization( attempt )

    -- Does attempt match a categorization?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  w.ns == 14

              and  not ( w.lead or w.lang or w.project )

              and  w.title ~= "" then

            r = true;

        end

    end

    return r;

end -- WLink.isCategorization()







function WLink.isExternalLink( attempt )

    -- Does attempt match an external link?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local s, r = WLink.getTarget( attempt );

    if r then

        r = ( r < 2 );

    end

    return r;

end -- WLink.isExternalLink()







function WLink.isInterlanguage( attempt )

    -- Does attempt match an interlanguage link?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w and w.lang and not w.project and not w.lead

             and  w.title ~= "" then

            r = true;

        end

    end

    return r;

end -- WLink.isInterlanguage()







function WLink.isInterwiki( attempt )

    -- Does attempt match an interwiki link within wikifarm?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  ( w.lang or w.project )  and  w.title ~= "" then

            r = true;

        end

    end

    return r;

end -- WLink.isInterwiki()







function WLink.isMedia( attempt )

    -- Does attempt match a media translusion?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local s, m = WLink.getTarget( attempt );

    if m == 2 then

        local w = WLink.wikilink( s );

        if w  and  w.ns == 6

           and  not ( w.lead or w.lang or w.project )

           and  w.title ~= ""

           and  WLink.getExtension( w.title ) then

            r = true;

        end

    end

    return r;

end -- WLink.isMedia()







function WLink.isTitledLink( attempt )

    -- Does attempt match a titled link?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local r = false;

    local i = attempt:find( "[", 1, true );

    if i then

        local c, n;

        local s = attempt:sub( i );

        if s:byte( 2, 2 ) == 91 then

            n = s:find( "%]%]", 5 );

            c = "|";

        else

            n = s:find( "%]", 8 );

            c = "%s%S";

        end

        if n then

            local m = s:find( c, 2 );

            if m  and  m + 1 < n  and  WLink.getTarget( attempt ) then

                r = true;

            end

        end

    end

    return r;

end -- WLink.isTitledLink()







function WLink.isValidLink( attempt )

    -- Does attempt match a link?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local s, r = WLink.getTarget( attempt );

    if r then

        r = true;

    end

    return r;

end -- WLink.isValidLink()







function WLink.isWikilink( attempt )

    -- Does attempt match a wikilink?

    -- Precondition:

    --     attempt  -- string, with presumable link somewhere

    -- Postcondition:

    --     Returns  boolean

    local s, m = WLink.getTarget( attempt );

    return ( m == 2 );

end -- WLink.isWikilink()







function WLink.wikilink( attempt )

    -- Retrieve wikilink components

    -- Precondition:

    --     attempt  -- string, with presumable link

    --                         expected to be enclosed in "[[" "]]"

    --                         else wikilink

    -- Postcondition:

    --     Returns  table or false

    --              table of assignments with { type, value}

    --                       type is one of "lead",

    --                          "project", "lang",

    --                          "ns", "space", "title"

    --              false if nothing found

    local s = contentWikilink( attempt );

    local got, n, r;

    if not s then

        s = attempt;

    end

    i = s:find( "|", 1, true );

    if i then

        s = s:sub( 1, i - 1 );

    end

    got = mw.text.split( s, ":" );

    n   = table.maxn( got );

    if n == 1 then

        r = { title = mw.text.trim( s ) };

    else

        local j, k, o, v;

        r = { title = "" };

        if n > 4 then

            k = 4;

        else

            k = n - 1;

        end

        j = k;

        for i = 1, j do

            s = mw.text.trim( got i  );

            if s ~= "" then

                o = mw.site.namespaces mw.text.trim( got i  ) ];

                if o then

                    r.ns    = o.id;

                    r.space = o.name;

                    k = i + 1;

                    j = i - 1;

                    break; -- for i

                end

            end

        end -- for i

        for i = 1, j do

            o, v = prefix( got i ],  ( i == 1 ) );

            if o then

                if r o  then

                    k = i;

                    break; -- for i

                else

                    r o  = v;

                end

            else

                k = i;

                break; -- for i

            end

        end -- for i

        for i = k, n do

            r.title = r.title .. got i ];

            if i < n then

                r.title = r.title .. ":";

            end

        end -- for i

    end

    if r.lead and

       ( r.project  or  not r.title  or

         ( not r.lang  and  r.ns ~= 6  and  r.ns ~= 14 ) ) then

        r.lead = false;

    end

    return r;

end -- WLink.wikilink()







function WLink.failsafe( assert )

    -- Retrieve versioning and check for compliance

    -- Precondition:

    --     assert  -- string, with required version, or false

    -- Postcondition:

    --     Returns  string with appropriate version, or false

    local r;

    if assert  and  assert > WLink.serial then

        r = false;

    else

        r = WLink.serial;

    end

    return r

end -- WLink.failsafe()







local function Template( frame, action, leave, lone )

    -- Run actual code from template transclusion

    -- Precondition:

    --     frame   -- object

    --     action  -- string, with function name

    --     leave   -- true: keep whitespace around

    --     lone    -- true: permit call without parameters

    -- Postcondition:

    --     Return string; might be error message

    local lucky = true;

    local s = false;

    local r = false;

    local space;

    for k, v in pairs( frame.args ) do

        if k == 1 then

            if leave then

                s = v;

            else

                s = mw.text.trim( v );

            end

        elseif action == "ansiPercent"  and  k == "space" then

            if v ~= "" then

                space = v;

            end

        elseif k ~= "template" then

            lucky = false;

            if r then

                r = r .. "|";

            else

                r = "Unknown parameter: ";

            end

            r = string.format( "%s%s=", r, k );

        end

    end -- for k, v

    if lucky then

        if s or lone then

            lucky, r = pcall( WLink action ],  s,  space );

        else

            r = "Parameter missing";

            lucky = false;

        end

    end

    if lucky then

        if type( r ) == "boolean" then

            if r then

                r = "1";

            else

                r = "";

            end

        end

    else

        r = string.format( "<span class=\"error\">%s</span>", r );

    end

    return r;

end -- Template()







-- Export

local p = { };



p.ansiPercent = function ( frame )

    return Template( frame, "ansiPercent" );

end

p.formatURL = function ( frame )

    return Template( frame, "formatURL" );

end

p.getArticleBase = function ( frame )

    return Template( frame, "getArticleBase", false, true );

end

p.getBaseTitle = function ( frame )

    return Template( frame, "getBaseTitle" );

end

p.getEscapedTitle = function ( frame )

    return Template( frame, "getEscapedTitle" );

end

p.getExtension = function ( frame )

    return Template( frame, "getExtension" );

end

p.getFile = function ( frame )

    return Template( frame, "getFile" );

end

p.getFragment = function ( frame )

    return Template( frame, "getFragment" );

end

p.getInterwiki = function ( frame )

    return Template( frame, "getInterwiki" );

end

p.getLanguage = function ( frame )

    return Template( frame, "getLanguage" );

end

p.getNamespace = function ( frame )

    return tostring( Template( frame, "getNamespace" ) );

end

p.getPlain = function ( frame )

    return Template( frame, "getPlain" );

end

p.getProject = function ( frame )

    return Template( frame, "getProject" );

end

p.getTarget = function ( frame )

    return Template( frame, "getTarget" );

end

p.getTargetPage = function ( frame )

    return Template( frame, "getTargetPage" );

end

p.getTitle = function ( frame )

    return Template( frame, "getTitle" );

end

p.getWeblink = function ( frame )

    return Template( frame, "getWeblink" );

end

p.isBracketedLink = function ( frame )

    return Template( frame, "isBracketedLink" );

end

p.isBracketedURL = function ( frame )

    return Template( frame, "isBracketedURL" );

end

p.isCategorization = function ( frame )

    return Template( frame, "isCategorization" );

end

p.isExternalLink = function ( frame )

    return Template( frame, "isExternalLink" );

end

p.isInterlanguage = function ( frame )

    return Template( frame, "isInterlanguage" );

end

p.isInterwiki = function ( frame )

    return Template( frame, "isInterwiki" );

end

p.isMedia = function ( frame )

    return Template( frame, "isMedia" );

end

p.isTitledLink = function ( frame )

    return Template( frame, "isTitledLink" );

end

p.isValidLink = function ( frame )

    return Template( frame, "isValidLink" );

end

p.isWeblink = function ( frame )

    return Template( frame, "isWeblink" );

end

p.isWikilink = function ( frame )

    return Template( frame, "isWikilink" );

end

p.failsafe = function ( frame )

    local since = frame.args 1 ];

    if since then

        since = mw.text.trim( since );

        if since == "" then

            since = false;

        end

    end

    return WLink.failsafe( since ) or "";

end

p.WLink = function ()

    return WLink;

end



return p;
Usage

Examples (test page)

Functions for Lua modules (API)
