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 apostrophe, because they break the isKnownLanguageTag
        function. This test does not work with regexps, use plain search instead (no need
        to use Unicode parser, apostrophes can only appear isolated as one byte in UTF-8).
        ]]
    if (string.find(subpage, "'", 1, true) == nil)
    then
        -- Return the subpage only if it is a valid language code.
        if (mw.language.isKnownLanguageTag(subpage))
        then
            return subpage
        end
    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()
    local subpage = mw.title.getCurrentTitle().subpageText
    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

--[[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 = mw.title.new(pagename, namespace) -- Costly
    else -- Supposes that set page is in ns10.
    	namespace = 'Template'
        title = mw.title.new(pagename, namespace) -- Costly
        if (title.id == 0)
        then -- not found in the Template namespace, assume the main namespace (for backward compatibility)
    	    namespace = ''
            title = mw.title.new(pagename, namespace) -- Costly
        end
    end
    
    -- Get the last subpage and check if it matches a known language code.
    local subpage = this.getLanguageSubpage()
    if (subpage == '')
    then
        -- Check if a translation of the pagename exists in English
        local newtitle = mw.title.new(pagename .. '/' .. 'en', namespace) -- Costly
        -- Use the translation when it exists
        if (newtitle.id ~= 0)
        then
            title = newtitle
        end
    else
        -- Check if a translation of the pagename exists in that language
        local newtitle = mw.title.new(pagename .. '/' .. subpage, namespace) -- Costly
        if (newtitle.id == 0)
        then
            -- Check if a translation of the pagename exists in English
            newtitle = mw.title.new(pagename .. '/' .. 'en', namespace) -- Costly
        end
        -- Use the translation when it exists
        if (newtitle.id ~= 0)
        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 == 0)
    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 arguments = {}
    for k, v in pairs((frame:getParent() or {}).args) 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
    
    return frame:expandTemplate{title = ':' .. title.prefixedText, args = arguments}
end

return this