Module:Template translation

Documentation for this module may be created at Module:Template translation/doc

local this = {}

function this.checkLanguage(subpage, default)
    --[[Check first if there's an any invalid character that would cause the
        mw.language.isKnownLanguageTag function() to throw an exception:
        - all ASCII controls in [\000-\031\127],
        - double quote ("), sharp sign (#), ampersand (&), apostrophe ('),
        - slash (/), colon (:), semicolon (;), lower than (<), greater than (>),
        - brackets and braces ([, ], {, }), pipe (|), backslash (\\)
        All other characters are accepted, including space and all non-ASCII
        characters (including \192, which is invalid in UTF-8).
    --]]
    if mw.language.isValidCode(subpage) and mw.language.isKnownLanguageTag(subpage)
    --[[However "SupportedLanguages" are too restrictive, as they discard many
        valid BCP47 script variants (only because MediaWiki still does not
        define automatic transliterators for them, e.g. "en-dsrt" or
        "fr-brai" for French transliteration in Braille), and country variants,
        (useful in localized data, even if they are no longer used for
        translations, such as zh-cn, also useful for legacy codes).
        We want to avoid matching subpagenames containing any uppercase letter,
        (even if they are considered valid in BCP 47, in which they are
        case-insensitive; they are not "SupportedLanguages" for MediaWiki, so
        they are not "KnownLanguageTags" for MediaWiki).
        To be more restrictive, we exclude any character that is not
        ASCII and not a lowercase letter, minus-hyphen, or digit, and any code
        that does not start by a letter or does not finish by a letter or digit.
        of that has more than 8 characters between hyphens, or has two hyphens.
    --]]
    or  string.find(subpage, "^[%l][%-%d%l]*[%d%l]$") ~= nil
    and string.find(subpage, "[%d%l][%d%l][%d%l][%d%l][%d%l][%d%l][%d%l][%d%l][%d%l]") == nil
    and string.find(subpage, "%-%-") == nil
    then
        return subpage
    end
    -- Otherwise there's currently no known language subpage
    return default
end

--[[Get the last subpage of the current page if it is a translation.
    ]]
function this.getLanguageSubpage()
	--[[This code does not work ib all namespaces where the Translate tool works.
	--  It works in the main namespace on Meta because it allows subpages there
	--  It would not work in the main namespace of English Wikipedia (but the
	--  articles are monolignual on that wiki).
	--  On Meta-Wiki the main space uses subpages and its pages are translated.
	--  The Translate tool allows translatng pages in all namespaces, even if
	--  the namespace officially does not have subpages.
	--  On Meta-Wiki the Category namespace still does not have subpages enabled,
	--  even if they would be very useful for categorizing templates, that DO have
	--  subpages (for documentatio and tstboxes pages). This is a misconfiguration
	--  bug of Meta-Wiki. The work-around is to split the full title and then
	--  get the last titlepart.
	local subpage = mw.title.getCurrentTitle().subpageText
	--]]
    local titleparts = mw.text.split(mw.title.getCurrentTitle().fullText, '/')
    local subpage = titleparts[#titleparts]
    return this.checkLanguage(subpage, '')
end

--[[Get the last subpage of the current frame if it is a translation.
    Not used locally.
    ]]
function this.getFrameLanguageSubpage(frame)
    local titleparts = mw.text.split(frame:getParent():getTitle(), '/')
    local subpage = titleparts[#titleparts]
    return this.checkLanguage(subpage, '')
end

--[[Get the language of the current page.
    Not used locally.
    ]]
function this.getLanguage()
    local subpage = mw.title.getCurrentTitle().subpageText
    return this.checkLanguage(subpage, mw.language.getContentLanguage():getCode())
end

--[[Get the language of the current frame.
    Not used locally.
    ]]
function this.getFrameLanguage(frame)
    local titleparts = mw.text.split(frame:getParent():getTitle(), '/')
    local subpage = titleparts[#titleparts]
    return this.checkLanguage(subpage, mw.language.getContentLanguage():getCode())
end

function this.title(namespace, basepagename, subpage)
    local message, title
    local pagename = basepagename
    if (subpage or '') ~= ''
    then
        pagename = pagename .. '/' .. subpage
    end
    local valid, title = xpcall(function()
            return mw.title.new(pagename, namespace) -- costly
        end, function(msg) -- catch undocumented exception (!?)
            -- thrown when namespace does not exist. The doc still
            -- says it should return a title, even in that case...
            message = msg
        end)
    if valid and title ~= nil and (title.id or 0) ~= 0
    then
        return title
    end
    return { -- "pseudo" mw.title object with id = nil in case of error
        prefixedText = pagename, -- the only property we need below
        message = message -- only for debugging
    }
end

--[[If on a translation subpage (like Foobar/de), this function renders
    a given template in the same language, if the translation is available.
    Otherwise, the template is rendered in its default language, without
    modification.
    This is aimed at replacing the current implementation of Template:TNT.
    ]]
function this.renderTranslatedTemplate(frame)
    local args = frame.args
    local pagename = args['template']
    
    --[[Check whether the pagename is actually in the Template namespace, or
        if we're transcluding a main-namespace page.
        (added for backward compatibility of Template:TNT)
        ]]
    local title
    local namespace = args['namespace'] or ''
    if (namespace ~= '') -- Checks for namespace parameter for custom ns.
    then
        title = this.title(namespace, pagename) -- Costly
    else -- Supposes that set page is in ns10.
    	namespace = 'Template'
        title = this.title(namespace, pagename) -- Costly
        if title.id == nil
        then -- not found in the Template namespace, assume the main namespace (for backward compatibility)
    	    namespace = ''
            title = this.title(namespace, pagename) -- Costly
        end
    end
    
    -- Get the last subpage and check if it matches a known language code.
    local subpage = args['uselang'] or ''
    if (subpage == '')
    then
        subpage = this.getLanguageSubpage()
    end
    if (subpage == '')
    then
        -- Check if a translation of the pagename exists in English
        local newtitle = this.title(namespace, pagename, 'en') -- Costly
        -- Use the translation when it exists
        if newtitle.id ~= nil
        then
            title = newtitle
        end
    else
        -- Check if a translation of the pagename exists in that language
        local newtitle = this.title(namespace, pagename, subpage) -- Costly
        if newtitle.id == nil
        then
            -- Check if a translation of the pagename exists in English
            newtitle = this.title(namespace, pagename, 'en') -- Costly
        end
        -- Use the translation when it exists
        if newtitle.id ~= nil
        then
            title = newtitle
        end
    end
    
    -- At this point the title should exist, otherwise render a red link to the missing page (resolved in its assumed namespace)
    if title.id == nil
    then
    	return '[[' .. title.prefixedText .. ']]'
    end
    
    -- Copy args pseudo-table to a proper table so we can feed it to expandTemplate.
    -- Then render the pagename.
    local pargs = (frame:getParent() or {}).args
    local arguments
    if (args['noshift'] or '') == ''
    then
        arguments = {}
        for k, v in pairs(pargs) do
            -- numbered args >= 1 need to be shifted
            local n = tonumber(k) or 0
            if (n > 0)
            then
                if (n >= 2)
                then
                    arguments[n - 1] = v
                end
            else
                arguments[k] = v
            end
        end
    else -- special case where TNT is used as autotranslate
    	-- (don't shift again what is shifted in the invokation)
        arguments = pargs
    end
    arguments['template'] = title.prefixedText -- override the existing parameter of the base template name supplied with the full name of the actual template expanded
    arguments['namespace'] = nil -- discard the specified namespace override
    arguments['uselang'] = args['uselang'] -- argument forwarded into parent frame
    arguments['noshift'] = args['noshift'] -- argument forwarded into parent frame
    
    return frame:expandTemplate{title = ':' .. title.prefixedText, args = arguments}
end

return this