Modul:Multilingual

local Multilingual = { suite = "Multilingual",

                      serial = "2015-06-19" };

-- local globals local Frame

local favorite = function ()

   -- Postcondition:
   --     Returns code of curent project language
   if not Multilingual.self then
       Multilingual.self = mw.language.getContentLanguage():getCode()
                                                           :lower()
   end
   return Multilingual.self

end -- favorite()

local fetch = function ( access, allow )

   -- Attach config or library module
   -- Precondition:
   --     access  -- module title
   --     allow   -- permit non-existence
   -- Postcondition:
   --     Returns  table or false, with library
   --     Throws error, if not available
   if type( Multilingual.ext ) ~= "table" then
       Multilingual.ext = { }
   end
   if Multilingual.ext[ access ] == false then
   elseif not Multilingual.ext[ access ] then
       local lucky, got = pcall( require, "Module:" .. access )
       if lucky then
           if type( got ) == "table" then
               Multilingual.ext[ access ] = got
               if type( got[ access ] ) == "function" then
                   Multilingual.ext[ access ] = got[ access ]()
               end
           end
       end
       if type( Multilingual.ext[ access ] ) ~= "table" then
           if allow then
               Multilingual.ext[ access ] = false
           else
               got = string.format( "Module:%s invalid", access )
               error( got, 0 )
           end
       end
   end
   return Multilingual.ext[ access ]

end -- fetch()

function find( ask, alien )

   -- Derive language code from name
   -- Precondition:
   --     ask    -- language name, downcased
   --     alien  -- language code of ask
   -- Postcondition:
   --     nil, or
   local codes = mw.language.fetchLanguageNames( alien, "all" )
   local r
   for k, v in pairs( codes ) do
       if mw.ustring.lower( v ) == ask then
           r = k
           break -- for k, v
       end
   end -- for k, v
   return r

end -- find()

function isSupported( ask, accept )

   -- Is ask to be supported by application?
   -- Precondition:
   --     ask     -- lowercase code
   --     accept  -- space separated/terminated list of lowercase codes
   -- Postcondition:
   --     nil, or else
   local seek = string.format( " %s ", ask )
   local supported = string.format( " %s", accept )
   return supported:find( seek, 1, true )

end -- isSupported()

Multilingual.findCode = function ( ask )

   -- Retrieve code of local (current project or English) language name
   -- Precondition:
   --     ask  -- string, with presumable language name
   --             A code itself will be identified, too.
   -- Postcondition:
   --     Returns string, or false
   local seek = mw.text.trim( ask )
   local r = false
   if #seek > 1 then
       if seek:find( "[", 1, true ) then
           seek = fetch( "WLink" ).getPlain( seek )
       end
       seek = mw.ustring.lower( seek )
       if Multilingual.isLang( seek ) then
           r = seek
       else
           local slang = favorite()
           r = find( seek, slang )
           if not r  and  slang ~= "en" then
               r = find( seek, "en" )
           end
       end
   end
   return r

end -- Multilingual.findCode()

Multilingual.format = function ( apply, alien, alter, active, alert,

                                frame, assembly, adjacent, ahead )
   -- Format one or more languages
   -- Precondition:
   --     apply     -- string with language list or item
   --     alien     -- language of the answer
   --                  -- nil, false, "*": native
   --                  -- "!": current project
   --                  -- "#": code, downcased, space separated
   --                  -- any valid code
   --     alter     -- capitalize, if "c"; downcase all, if "d"
   --                  capitalize first item only, if "f"
   --                  downcase every first word only, if "m"
   --     active    -- link items, if true
   --     alert     -- string with category title in case of error
   --     frame     -- if available
   --     assembly  -- string with split pattern, if list expected
   --     adjacent  -- string with list separator, else assembly
   --     ahead     -- string to prepend first element, if any
   -- Postcondition:
   --     Returns string, or false
   local r = false
   if apply then
       local slang
       if assembly then
           local bucket = mw.text.split( apply, assembly )
           local shift = alter
           local separator
           if adjacent then
               separator = adjacent
           elseif alien == "#" then
               separator = " "
           else
               separator = assembly
           end
           for k, v in pairs( bucket ) do
               slang = Multilingual.format( v, alien, shift, active,
                                            alert )
               if slang then
                   if r then
                       r = string.format( "%s%s%s",
                                          r, separator, slang )
                   else
                       r = slang
                       if shift == "f" then
                           shift = "d"
                       end
                   end
               end
           end -- for k, v
           if r and ahead then
               r = ahead .. r
           end
       else
           local single = mw.text.trim( apply )
           if single == "" then
               r = false
           else
               local lapsus, slot
               slang = Multilingual.findCode( single )
               if slang then
                   if alien == "#" then
                       r = slang
                   else
                       r = Multilingual.getName( slang, alien )
                       if active then
                           local cnf = fetch( "Multilingual/config",
                                              true )
                           if cnf then
                               if not frame then
                                   if not Frame then
                                       Frame = mw.getCurrentFrame()
                                   end
                                   frame = Frame
                               end
                               slot = cnf.getLink( slang, frame )
                               if slot then
                                   local wlink = fetch( "WLink" )
                                   slot = wlink.getTarget( slot )
                               else
                                   lapsus = alert
                               end
                           end
                       end
                   end
               else
                   r = single
                   if active then
                       local title = mw.title.makeTitle( 0, single )
                       if title.exists then
                           slot = single
                       end
                   end
                   lapsus = alert
               end
               if alter == "c" or alter == "f" then
                   r = mw.ustring.upper( mw.ustring.sub( r, 1, 1 ) )
                       .. mw.ustring.sub( r, 2 )
               elseif alter == "d" then
                   r = mw.ustring.lower( r )
               elseif alter == "m" then
                   r = mw.ustring.lower( mw.ustring.sub( r, 1, 1 ) )
                       .. mw.ustring.sub( r, 2 )
               end
               if slot then
                   if r == slot then
                       r = string.format( "%s", r )
                   else
                       r = string.format( "%s", slot, r )
                   end
               end
               if lapsus then
                   r = string.format( "%s", r, alert )
               end
           end
       end
   end
   return r

end -- Multilingual.format()

Multilingual.getBase = function ( ask )

   -- Retrieve base language from possibly combined ISO language code
   -- Precondition:
   --     ask  -- language code
   -- Postcondition:
   --     Returns string, or false
   local r
   if ask then
       local slang = ask:match( "^%s*(%a%a%a?)-?%a*%s*$" )
       if slang then
           r = slang:lower()
       else
           r = false
       end
   else
       r = false
   end
   return r

end -- Multilingual.getBase()

Multilingual.getName = function ( ask, alien )

   -- Which name is assigned to this language code?
   -- Precondition:
   --     ask    -- language code
   --     alien  -- language of the answer
   --               -- nil, false, "*": native
   --               -- "!": current project
   --               -- any valid code
   -- Postcondition:
   --     Returns string, or false
   local r
   if ask then
       local slang   = alien
       local support = "Multilingual/names"
       local tLang
       if slang then
           if slang == "*" then
               slang = ask:lower()
           elseif slang == "!" then
               slang = favorite()
           else
               slang = slang:lower()
           end
       else
           slang = ask:lower()
       end
       fetch( support, true )
       tLang = Multilingual.ext.tNames
       if tLang then
           tLang = tLang[ slang ]
           if tLang then
               r = tLang[ ask ]
           end
       end
       if not r then
           if not Multilingual.ext.tMW then
               Multilingual.ext.tMW = { }
           end
           tLang = Multilingual.ext.tMW[ slang ]
           if tLang == nil then
               tLang = mw.language.fetchLanguageNames( slang )
               if tLang then
                   Multilingual.ext.tMW[ slang ] = tLang
               else
                   Multilingual.ext.tMW[ slang ] = false
               end
           end
           if tLang then
               r = tLang[ ask ]
           end
       end
       if not r then
           r = mw.language.fetchLanguageName( ask, slang )
       end
   else
       r = false
   end
   return r

end -- Multilingual.getName()

Multilingual.isLang = function ( ask )

   -- Could this be an ISO language code?
   -- Precondition:
   --     ask  -- language code
   -- Postcondition:
   --     Returns boolean
   local r
   local s = Multilingual.getBase( ask )
   if s then
       r = mw.language.isKnownLanguageTag( s )
   else
       r = false
   end
   return r

end -- Multilingual.isLang()

Multilingual.isLangWiki = function ( ask )

   -- Could this be a Wiki language version?
   -- Precondition:
   --     ask  -- language version specifier
   -- Postcondition:
   --     Returns boolean
   local r
   local s = Multilingual.getBase( ask )
   if s then
       r = mw.language.isSupportedLanguage( s )
   else
       r = false
   end
   return r

end -- Multilingual.isLangWiki()

Multilingual.kannDeutsch = function ( ask )

   -- Kann man mit diesem Sprachcode deutsch verstehen?
   -- Precondition:
   --     ask  -- language version specifier
   -- Postcondition:
   --     Returns boolean
   local r
   local s = Multilingual.getBase( ask )
   if s then
       local support = [=[ de als bar dsb frr gsw hsb ksh |
                           lb nds pdc pdt pfl sli stq vmf ]=]
       if support:find( string.format( " %s ", s ),  1,  true ) then
           r = true
       else
           r = false
       end
   else
       r = false
   end
   return r

end -- Multilingual.kannDeutsch()

Multilingual.userLang = function ( accept, frame )

   -- Try to support user language by application
   -- Precondition:
   --     accept  -- space separated list of available ISO 639 codes
   --                Default: project language, or English
   --     frame   -- frame, if available
   -- Postcondition:
   --     Returns string with appropriate code
   local r, slang, support
   if not frame then
       if not Frame then
           Frame = mw.getCurrentFrame()
       end
       frame = Frame
   end
   slang = frame:callParserFunction( "int", "lang" ):lower()
   if type( accept ) == "string" then
       support = accept:lower() .. " "
   else
       support = favorite()
       if mw.language.isKnownLanguageTag( support ) then
           support = string.format( "%s en ", support )
       else
           support = "en "
       end
   end
   if isSupported( slang, support ) then
       r = slang
   elseif slang:find( "-", 1, true ) then
       slang = Multilingual.getBase( slang )
       if isSupported( slang, support ) then
           r = slang
       end
   end
   if not r then
       if Multilingual.kannDeutsch( slang )  and
          isSupported( "de", support ) then
           r = "de"
       end
       if not r then
           r = support:match( "^(%S+) " )
       end
   end
   return r

end -- Multilingual.userLang()

-- Export local p = { }

p.findCode = function ( frame )

   -- Retrieve language code from language name
   --     1  -- name in current project language
   return Multilingual.findCode( frame.args[ 1 ] )  or  ""

end -- p.findCode

p.format = function ( frame )

   -- Format one or more languages
   --     1          -- language list or item
   --     slang      -- language of the answer, if not native
   --                   * -- native
   --                   ! -- current project
   --                   any valid code
   --     shift      -- capitalize, if "c"; downcase, if "d"
   --                   capitalize first item only, if "f"
   --     link       -- 1 -- link items
   --     scream     -- category title in case of error
   --     split      -- split pattern, if list expected
   --     separator  -- list separator, else assembly
   --     start      -- prepend first element, if any
   local r
   local link
   if frame.args.link == "1" then
       link = true
   end
   r = Multilingual.format( frame.args[ 1 ],
                            frame.args.slang,
                            frame.args.shift,
                            link,
                            frame.args.scream,
                            frame,
                            frame.args.split,
                            frame.args.separator,
                            frame.args.start )
   return r or ""

end -- p.format

p.getBase = function ( frame )

   -- Retrieve base language from possibly combined ISO language code
   --     1  -- code
   return Multilingual.getBase( frame.args[ 1 ] )  or  ""

end -- p.getBase

p.getName = function ( frame )

   -- Retrieve language name from ISO language code
   --     1  -- code
   --     2  -- language to be used for the answer, if not native
   --           ! -- current project
   --           * -- native
   --           any valid code
   local slang = frame.args[ 2 ]
   local r
   if slang then
       slang = mw.text.trim( slang )
   end
   r = Multilingual.getName( frame.args[ 1 ], slang )
   return r or ""

end -- p.getName

p.isLang = function ( frame )

   -- Could this be an ISO language code?
   --     1  -- code
   local lucky, r = pcall( Multilingual.isLang,
                           frame.args[ 1 ] )
   return r and "1" or ""

end -- p.isLang

p.isLangWiki = function ( frame )

   -- Could this be a Wiki language version?
   --     1  -- code
   local lucky, r = pcall( Multilingual.isLangWiki,
                           frame.args[ 1 ] )
   return r and "1" or ""

end -- p.isLangWiki

p.kannDeutsch = function ( frame )

   -- Kann man mit diesem Sprachcode deutsch verstehen?
   --     1  -- code
   local r = Multilingual.kannDeutsch( frame.args[ 1 ] )
   return r and "1" or ""

end -- p.kannDeutsch

p.userLang = function ( frame )

   -- Which language does the current user prefer?
   --     1  -- space separated list of available ISO 639 codes
  return Multilingual.userLang( frame.args[ 1 ], frame )

end -- p.userLang

p.Multilingual = function ()

   return Multilingual

end -- p.Multilingual

return p