Module:LangSwitcher

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

-- Module:LangSwitcher
-- Language subpage switcher that outputs wikitext (no raw HTML).
-- Usage:
--   {{#invoke:LangSwitcher|render
--      | langs  = en,sv,da
--      | labels = en=English,sv=Svenska,da=Dansk
--      | default = en
--      | show_missing = yes
--      | icon = 🌐
--   }}
--
-- Behavior:
-- * Base page (no suffix) represents the default language (e.g., 'en').
-- * Subpages at Base/xx (e.g., /sv, /da) are translations.
-- * Lists languages from |langs=, bolds the active language, links to each page.
-- * If show_missing = yes, includes languages whose page doesn’t exist yet (redlinks).
-- * Supports hyphenated codes like pt-br.

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)
        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 Base/xx or Base/pt-br (2+ 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 pageExists(page)
    local t = mw.title.new(page)
    return t and t.exists
end

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

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

    -- Inputs
    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 icon = args.icon or ""

    -- Detect base/current
    local base, currentLang = getTitleParts()

    -- Default language: code that maps to the base page (no suffix)
    local defaultLang = trim(args.default or (langs[1] or "en")):lower()

    -- Label lookup with fallback to code
    local function labelFor(code)
        return labels[code] or code
    end

    -- Build ordered list, starting with defaultLang, then rest
    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

    -- Build wikitext pieces: "🌐 English • Svenska • Dansk"
    local pieces = {}
    if icon ~= "" then
        table.insert(pieces, "''" .. icon .. "'' ")
    end

    local links = {}
    for _, code in ipairs(ordered) do
        local target = (code == defaultLang) and base or (base .. "/" .. code)
        local exists = pageExists(target)
        if exists or showMissing then
            local link = wikilink(target, labelFor(code))
            local isActive
            if currentLang then
                isActive = (currentLang == code)
            else
                isActive = (code == defaultLang)
            end
            if isActive then
                link = "'''" .. link .. "'''"
            end
            table.insert(links, link)
        end
    end

    if #links == 0 then
        return ""
    end

    table.insert(pieces, table.concat(links, " • "))
    return table.concat(pieces)
end

return p