Module:LangSwitcher

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

-- Module:LangSwitcher
-- Language subpage switcher for self-hosted MediaWiki
-- Usage:
--   {{#invoke:LangSwitcher|render
--      | langs = en,sv,da,fi
--      | labels = en=English,sv=Svenska,da=Dansk,fi=Suomi
--      | icon = 🌐
--      | class = hh-lang-switcher
--   }}
--
-- Behavior:
-- * Determines base page and current language from title/subpage
-- * Scans configured langs and checks if base/xx exists
-- * Includes the base page itself as the "default" language (first in langs or 'en')
-- * Marks current selection with class "active"
-- * Skips links for languages without existing pages (optional flag to show “redlinks”)

local p = {}

local function trim(s)
    return (s or ""):gsub("^%s+", ""):gsub("%s+$", "")
end

local function splitCSV(s)
    local t = {}
    if not s or s == "" then
        return t
    end
    for part in s:gmatch("([^,]+)") do
        local v = trim(part)
        if v ~= "" then
            table.insert(t, v)  -- append
        end
    end
    return t
end

local function parseKVList(s)
    -- Parse "en=English,sv=Svenska"
    local out = {}
    if not s or s == "" then
        return out
    end
    for pair in s:gmatch("([^,]+)") do
        local k, v = pair:match("^%s*([^=]+)%s*=%s*(.-)%s*$")
        if k and v then
            out[trim(k)] = trim(v)
        end
    end
    return out
end

local function getTitleParts()
    local title = mw.title.getCurrentTitle()
    local full = title.fullText
    local base, lang = full, nil
    -- Accept language subpages like Base/xx or Base/pt-br (2–10 letters/hyphens)
    local b, l = full:match("^(.-)/([A-Za-z%-][A-Za-z%-][A-Za-z%-]*)$")
    if b and l then
        base, lang = b, l:lower()
    end
    return base, lang, title
end

local function exists(page)
    local t = mw.title.new(page)
    return t and t.exists
end

local function makeLink(page, label)
    return string.format('[[%s|%s]]', page, label)
end

local function escapeHtml(s)
    return mw.text.nowiki(s or "")
end

function p.render(frame)
    local args = frame:getParent() and frame:getParent().args or frame.args

    local langs = splitCSV(args.langs or args.languages or "en")
    local labels = parseKVList(args.labels or "")
    local showMissing = (args.show_missing or ""):lower() == "yes"
    local wrapperClass = trim(args.class or "lang-switcher")
    local icon = args.icon or ""

    local base, currentLang = getTitleParts()

    local defaultLang = trim(args.default or (langs[1] or "en")):lower()

    local function labelFor(code)
        return labels[code] or code
    end

    -- Build ordered list, starting with defaultLang
    local seen = {}
    local ordered = {}

    local function add(code)
        if not code or code == "" then
            return
        end
        local lc = code:lower()
        if not seen[lc] then
            table.insert(ordered, lc)
            seen[lc] = true
        end
    end

    add(defaultLang)
    for _, code in ipairs(langs) do
        add(code)
    end

    local items = {}

    for _, code in ipairs(ordered) do
        local target = (code == defaultLang) and base or (base .. "/" .. code)
        local pageExists = exists(target)

        if pageExists or showMissing then
            local isActive
            if currentLang then
                isActive = (currentLang == code)
            else
                isActive = (code == defaultLang)
            end

            local liClass = "lang-item lang-" .. code
            if isActive then
                liClass = liClass .. " active"
            end

            local label = labelFor(code)
            local content
            if pageExists then
                content = makeLink(target, label)
            else
                content = makeLink(target, label) -- redlink
            end

            table.insert(items, string.format('<li class="%s">%s</li>', liClass, content))
        end
    end

    if #items == 0 then
        return ""
    end

    local iconHtml = icon ~= "" and string.format('<span class="lang-icon">%s</span>', escapeHtml(icon)) or ""
    local html = {}
    table.insert(html, string.format('<nav class="%s" role="navigation" aria-label="Languages">', wrapperClass))
    table.insert(html, iconHtml)
    table.insert(html, '<ul class="lang-list">')
    table.insert(html, table.concat(items))
    table.insert(html, '</ul>')
    table.insert(html, '</nav>')

    return table.concat(html)
end

return p