const translations = {
  en: {
    "lang.label": "Language",
    "lang.en": "English",
    "lang.de": "Deutsch",

    "auth.loginTab": "Log in",
    "auth.registerTab": "Register",
    "auth.username": "Username",
    "auth.password": "Password",
    "auth.displayName": "Display name (shows to group)",
    "auth.adminKey": "Admin key (optional)",
    "auth.loginSubmit": "Log in",
    "auth.registerSubmit": "Create account",
    "auth.logout": "Logout",
    "auth.welcome": "Welcome, {name}!",
    "auth.defaultName": "Player",
    "auth.loading": "Loading…",
    "auth.needCredentials": "Username and password required",
    "auth.invalidCredentials": "Invalid username or password",

    "phase.suggest": "Suggest",
    "phase.reveal": "Reveal",
    "phase.vote": "Vote",
    "phase.results": "Results",
    "phase.loading": "Loading…",

    "counts.format": "Players: {players} • Suggestions: {suggestions} • Votes: {votes}",

    "suggest.title": "Suggest (up to 5)",
    "suggest.hint": "Only you can see your suggestions until Reveal.",
    "form.gameName": "Game name *",
    "form.genre": "Genre",
    "form.description": "Description",
    "form.players": "Players",
    "form.min": "Min",
    "form.max": "Max",
    "form.screenshot": "Screenshot URL",
    "form.youtube": "YouTube URL",
    "form.gameUrl": "Game website URL",
    "form.submit": "Submit",
    "form.placeholder.description": "Short description",
    "form.placeholder.gameName": "Game name *",
    "form.placeholder.genre": "Genre",
    "form.placeholder.screenshot": "Screenshot URL",
    "form.placeholder.youtube": "YouTube URL",
    "form.placeholder.gameUrl": "Game website URL",

    "section.mySuggestions": "Your suggestions",
    "section.allSuggestions": "All Suggestions",
    "section.allSuggestions.count": "All {count} suggestions",
    "section.vote": "Vote 0-10",
    "section.vote.count": "Vote for all {count} games",
    "section.results": "Results",

    "card.edit": "Edit",
    "card.delete": "Delete",
    "card.players": "Players: {min}–{max}",
    "card.site": "Site ↗",
    "card.youtube": "YouTube ↗",
    "card.openScreenshot": "Open screenshot",

    "vote.saved": "Saved vote",

    "results.rank": "Rank",
    "results.game": "Game",
    "results.author": "Author",
    "results.votes": "Votes",
    "results.avg": "Avg",
    "results.total": "Total",
    "results.links": "Links",
    "results.link.site": "Site ↗",
    "results.link.youtube": "YouTube ↗",

    "admin.title": "Admin",
    "admin.tools": "Admin tools",
    "admin.setPhase": "Set phase",
    "admin.reset": "Reset (keep players)",
    "admin.factoryReset": "Factory reset",
    "admin.phaseUpdated": "Phase updated",
    "admin.resetDone": "Reset complete",
    "admin.factoryResetDone": "Factory reset complete",

    "toast.unexpected": "Unexpected error",
    "toast.registered": "Registered",
    "toast.loggedIn": "Logged in",
    "toast.suggestionAdded": "Suggestion added",
    "toast.suggestionDeleted": "Suggestion deleted",
    "toast.savedChanges": "Saved changes",
    "toast.nameRequired": "Name required",
    "toast.invalidImageUrl": "Screenshot URL must be http(s) and end with an image file.",

    "modal.editTitle": "Edit game",
    "modal.save": "Save changes",
    "modal.cancel": "Cancel",
    "modal.close": "Close",

    "lightbox.close": "Close",
  },
  de: {
    "lang.label": "Sprache",
    "lang.en": "Englisch",
    "lang.de": "Deutsch",

    "auth.loginTab": "Anmelden",
    "auth.registerTab": "Registrieren",
    "auth.username": "Benutzername",
    "auth.password": "Passwort",
    "auth.displayName": "Anzeigename (für die Gruppe sichtbar)",
    "auth.adminKey": "Admin-Schlüssel (optional)",
    "auth.loginSubmit": "Anmelden",
    "auth.registerSubmit": "Konto erstellen",
    "auth.logout": "Abmelden",
    "auth.welcome": "Willkommen, {name}!",
    "auth.defaultName": "Spieler",
    "auth.loading": "Lädt…",
    "auth.needCredentials": "Benutzername und Passwort erforderlich",
    "auth.invalidCredentials": "Ungültiger Benutzername oder Passwort",

    "phase.suggest": "Vorschlagen",
    "phase.reveal": "Enthüllen",
    "phase.vote": "Bewerten",
    "phase.results": "Ergebnisse",
    "phase.loading": "Lädt…",

    "counts.format": "Spieler: {players} • Vorschläge: {suggestions} • Stimmen: {votes}",

    "suggest.title": "Vorschlagen (bis zu 5)",
    "suggest.hint": "Nur du siehst deine Vorschläge bis zur Enthüllung.",
    "form.gameName": "Spielname *",
    "form.genre": "Genre",
    "form.description": "Beschreibung",
    "form.players": "Spieler",
    "form.min": "Min",
    "form.max": "Max",
    "form.screenshot": "Screenshot-URL",
    "form.youtube": "YouTube-URL",
    "form.gameUrl": "Spiel-Webseite",
    "form.submit": "Absenden",
    "form.placeholder.description": "Kurze Beschreibung",
    "form.placeholder.gameName": "Spielname *",
    "form.placeholder.genre": "Genre",
    "form.placeholder.screenshot": "Screenshot-URL",
    "form.placeholder.youtube": "YouTube-URL",
    "form.placeholder.gameUrl": "Spiel-Webseite",

    "section.mySuggestions": "Deine Vorschläge",
    "section.allSuggestions": "Alle Vorschläge",
    "section.allSuggestions.count": "Alle {count} Vorschläge",
    "section.vote": "Bewerten 0-10",
    "section.vote.count": "Bewerte alle {count} Spiele",
    "section.results": "Ergebnisse",

    "card.edit": "Bearbeiten",
    "card.delete": "Löschen",
    "card.players": "Spieler: {min}–{max}",
    "card.site": "Website ↗",
    "card.youtube": "YouTube ↗",
    "card.openScreenshot": "Screenshot öffnen",

    "vote.saved": "Stimme gespeichert",

    "results.rank": "Rang",
    "results.game": "Spiel",
    "results.author": "Autor",
    "results.votes": "Stimmen",
    "results.avg": "Durchschn.",
    "results.total": "Gesamt",
    "results.links": "Links",
    "results.link.site": "Website ↗",
    "results.link.youtube": "YouTube ↗",

    "admin.title": "Admin",
    "admin.tools": "Admin-Werkzeuge",
    "admin.setPhase": "Phase setzen",
    "admin.reset": "Zurücksetzen (Spieler behalten)",
    "admin.factoryReset": "Werkseinstellung",
    "admin.phaseUpdated": "Phase aktualisiert",
    "admin.resetDone": "Zurücksetzen abgeschlossen",
    "admin.factoryResetDone": "Werkseinstellung abgeschlossen",

    "toast.unexpected": "Unerwarteter Fehler",
    "toast.registered": "Registriert",
    "toast.loggedIn": "Angemeldet",
    "toast.suggestionAdded": "Vorschlag hinzugefügt",
    "toast.suggestionDeleted": "Vorschlag gelöscht",
    "toast.savedChanges": "Änderungen gespeichert",
    "toast.nameRequired": "Name erforderlich",
    "toast.invalidImageUrl": "Screenshot-URL muss mit http(s) beginnen und auf eine Bilddatei enden.",

    "modal.editTitle": "Spiel bearbeiten",
    "modal.save": "Änderungen speichern",
    "modal.cancel": "Abbrechen",
    "modal.close": "Schließen",

    "lightbox.close": "Schließen",
  }
};

const storageKey = "app_lang";
const defaultLang = "en";
let currentLang = defaultLang;
const listeners = [];

function interpolate(template, params = {}) {
  return template.replace(/\{(\w+)\}/g, (_, key) => (params[key] ?? `{${key}}`));
}

function t(key, params) {
  const fallback = translations[defaultLang][key] ?? key;
  const phrase = translations[currentLang]?.[key] ?? fallback;
  return interpolate(phrase, params);
}

function detectLanguage() {
  const stored = localStorage.getItem(storageKey);
  if (stored && translations[stored]) return stored;
  const nav = navigator.language?.slice(0, 2);
  if (nav && translations[nav]) return nav;
  return defaultLang;
}

function applyTranslations(root = document) {
  root.querySelectorAll("[data-i18n]").forEach((el) => {
    const key = el.dataset.i18n;
    const attrs = (el.dataset.i18nAttr || "")
      .split(",")
      .map((a) => a.trim())
      .filter(Boolean);
    const text = t(key);
    if (attrs.length === 0) {
      el.textContent = text;
    } else {
      attrs.forEach((attr) => el.setAttribute(attr, text));
    }
  });
}

function notify() {
  listeners.forEach((fn) => fn(currentLang));
}

function setLanguage(lang) {
  if (!translations[lang]) lang = defaultLang;
  currentLang = lang;
  localStorage.setItem(storageKey, lang);
  document.documentElement.lang = lang;
  applyTranslations();
  notify();
}

function getLanguage() {
  return currentLang;
}

function initI18n() {
  currentLang = detectLanguage();
  document.documentElement.lang = currentLang;
  applyTranslations();
  notify();
  return currentLang;
}

function onLanguageChange(fn) {
  listeners.push(fn);
}

export { t, setLanguage, getLanguage, initI18n, applyTranslations, onLanguageChange, translations };