(function () {
  "use strict";

  const DICTS = {
    fr: {
      auth: {
        login: "Se connecter",
        register: "S'inscrire",
        logout: "Déconnexion",
        loginTab: "Connexion",
        registerTab: "Inscription",
        identifierLabel: "Pseudo ou email",
        passwordLabel: "Mot de passe",
        submitLogin: "Se connecter",
        pseudoLabel: "Pseudo",
        emailLabel: "Email",
        submitRegister: "Créer mon compte",
        benefit1: "📜 Historique de toutes vos parties",
        benefit2: "⏱️ Suivi de votre vitesse de résolution",
        benefit3: "🏆 Apparition au classement des joueurs",
      },
      banner: {
        html: "Vous jouez en <b>anonyme</b>. Créez un compte gratuit pour sauvegarder votre historique, suivre votre vitesse de résolution et grimper au classement !",
      },
      topbar: { difficulty: "Difficulté", time: "Temps", mistakes: "Erreurs" },
      difficulty: { easy: "Facile", medium: "Moyen", hard: "Difficile", expert: "Expert" },
      board: { ready: "Prêt à jouer ?", start: "▶ Démarrer", paused: "⏸ En pause", resume: "▶ Reprendre" },
      actions: {
        pause: "⏸ Pause", stop: "⏹ Stop", undo: "↩️ Annuler", erase: "🧹 Effacer",
        notes: "✏️ Notes", hint: "💡 Indice", history: "📜 Historique",
        leaderboard: "🏆 Classement", rules: "📖 Règles",
      },
      confirm: { stop: "Abandonner la partie en cours ?" },
      win: {
        title: "🎉 Bravo !",
        subtitle: "Grille {difficulty} résolue.",
        time: "TEMPS",
        mistakesLabel: "ERREURS",
        pointsSaved: "+{points} points enregistrés",
        saveError: "Erreur d'enregistrement : {msg}",
        ctaText: "Connectez-vous pour sauvegarder ce score et apparaître au classement.",
        ctaButton: "Créer un compte gratuit",
        replay: "Rejouer",
      },
      msg: {
        welcome: "Bienvenue, {pseudo} !",
        accountCreated: "Compte créé, bienvenue {pseudo} !",
        loggedOut: "Vous êtes déconnecté.",
        loginRequiredHistory: "Connectez-vous pour consulter votre historique.",
        scoreSaved: "Score enregistré : +{points} points !",
        scoreSaveError: "Impossible d'enregistrer le score : {msg}",
      },
      history: {
        title: "📜 Historique", loading: "Chargement…",
        empty: "Aucune partie enregistrée pour le moment.", error: "Erreur : {msg}",
        colDate: "Date", colDifficulty: "Difficulté", colTime: "Temps",
        colMistakes: "Erreurs", colResult: "Résultat", colPoints: "Points",
      },
      leaderboard: {
        title: "🏆 Classement", tabTimes: "Meilleurs temps", tabPoints: "Points",
        emptyTimes: "Aucun score pour cette difficulté.", emptyPoints: "Aucun classement disponible.",
        colRank: "#", colPlayer: "Joueur", colTime: "Temps", colMistakes: "Erreurs",
        colPoints: "Points", colWins: "Victoires", error: "Erreur : {msg}",
      },
      rules: {
        title: "📖 Règles & guide du débutant",
        objectiveTitle: "Objectif",
        objectiveText: "Remplissez la grille de 9×9 cases avec des chiffres de 1 à 9.",
        goldenRulesTitle: "Les 3 règles d'or",
        rule1: "Chaque ligne doit contenir les chiffres de 1 à 9, sans répétition.",
        rule2: "Chaque colonne doit contenir les chiffres de 1 à 9, sans répétition.",
        rule3: "Chaque bloc de 3×3 doit contenir les chiffres de 1 à 9, sans répétition.",
        howToTitle: "Comment jouer sur ce site",
        how1: "Cliquez sur une case vide puis sur un chiffre (ou utilisez les touches 1-9 du clavier).",
        how2: "✏️ Notes : activez ce mode pour noter les chiffres possibles dans une case, utile pour explorer les hypothèses.",
        how3: "💡 Indice : révèle la bonne valeur dans la case sélectionnée (ou une case au hasard).",
        how4: "↩️ Annuler : revient sur votre dernière action.",
        how5: "⏸ Pause / ⏹ Stop : mettez la partie en pause ou abandonnez-la à tout moment.",
        tipsTitle: "Astuces pour débutants",
        tip1: "Repérez d'abord les chiffres qui apparaissent le plus souvent dans la grille de départ.",
        tip2: "Pour une case donnée, éliminez les chiffres déjà présents dans sa ligne, sa colonne et son bloc.",
        tip3: "Si un chiffre ne peut aller qu'à un seul endroit dans un bloc, une ligne ou une colonne, placez-le.",
        tip4: "Utilisez les notes pour les cases à plusieurs possibilités, puis réduisez au fur et à mesure.",
        tip5: "Ne devinez pas au hasard : chaque grille a une solution logique unique.",
      },
      footer: { text: "Fait maison • servi depuis un conteneur Docker" },
      settings: { language: "Langue", theme: "Thème" },
      theme: { blue: "Bleu", green: "Émeraude", amber: "Ambre", mono: "Noir & blanc" },
      errors: {
        INVALID_PSEUDO: "Pseudo invalide (3 à 20 caractères, lettres/chiffres/_).",
        INVALID_EMAIL: "Adresse email invalide.",
        INVALID_PASSWORD: "Le mot de passe doit contenir au moins 6 caractères.",
        PSEUDO_TAKEN: "Ce pseudo est déjà utilisé.",
        EMAIL_TAKEN: "Cette adresse email est déjà utilisée.",
        REGISTER_FAILED: "Erreur lors de l'inscription.",
        MISSING_CREDENTIALS: "Identifiant et mot de passe requis.",
        INVALID_CREDENTIALS: "Identifiants incorrects.",
        AUTH_REQUIRED: "Authentification requise.",
        RATE_LIMITED: "Trop de tentatives, réessayez plus tard.",
        INVALID_DIFFICULTY: "Difficulté invalide.",
        INVALID_TIME: "Temps invalide.",
        INVALID_MISTAKES: "Nombre d'erreurs invalide.",
        TIME_TOO_SHORT: "Temps trop court pour cette difficulté.",
        UNKNOWN: "Une erreur est survenue.",
      },
    },
    en: {
      auth: {
        login: "Log in",
        register: "Sign up",
        logout: "Log out",
        loginTab: "Login",
        registerTab: "Sign up",
        identifierLabel: "Username or email",
        passwordLabel: "Password",
        submitLogin: "Log in",
        pseudoLabel: "Username",
        emailLabel: "Email",
        submitRegister: "Create my account",
        benefit1: "📜 History of all your games",
        benefit2: "⏱️ Track your solving speed",
        benefit3: "🏆 Appear on the player leaderboard",
      },
      banner: {
        html: "You're playing as a <b>guest</b>. Create a free account to save your history, track your solving speed and climb the leaderboard!",
      },
      topbar: { difficulty: "Difficulty", time: "Time", mistakes: "Mistakes" },
      difficulty: { easy: "Easy", medium: "Medium", hard: "Hard", expert: "Expert" },
      board: { ready: "Ready to play?", start: "▶ Start", paused: "⏸ Paused", resume: "▶ Resume" },
      actions: {
        pause: "⏸ Pause", stop: "⏹ Stop", undo: "↩️ Undo", erase: "🧹 Erase",
        notes: "✏️ Notes", hint: "💡 Hint", history: "📜 History",
        leaderboard: "🏆 Leaderboard", rules: "📖 Rules",
      },
      confirm: { stop: "Abandon the current game?" },
      win: {
        title: "🎉 Well done!",
        subtitle: "{difficulty} grid solved.",
        time: "TIME",
        mistakesLabel: "MISTAKES",
        pointsSaved: "+{points} points saved",
        saveError: "Save error: {msg}",
        ctaText: "Log in to save this score and appear on the leaderboard.",
        ctaButton: "Create a free account",
        replay: "Play again",
      },
      msg: {
        welcome: "Welcome, {pseudo}!",
        accountCreated: "Account created, welcome {pseudo}!",
        loggedOut: "You are logged out.",
        loginRequiredHistory: "Log in to view your history.",
        scoreSaved: "Score saved: +{points} points!",
        scoreSaveError: "Could not save the score: {msg}",
      },
      history: {
        title: "📜 History", loading: "Loading…",
        empty: "No games recorded yet.", error: "Error: {msg}",
        colDate: "Date", colDifficulty: "Difficulty", colTime: "Time",
        colMistakes: "Mistakes", colResult: "Result", colPoints: "Points",
      },
      leaderboard: {
        title: "🏆 Leaderboard", tabTimes: "Best times", tabPoints: "Points",
        emptyTimes: "No scores for this difficulty.", emptyPoints: "No leaderboard available.",
        colRank: "#", colPlayer: "Player", colTime: "Time", colMistakes: "Mistakes",
        colPoints: "Points", colWins: "Wins", error: "Error: {msg}",
      },
      rules: {
        title: "📖 Rules & beginner's guide",
        objectiveTitle: "Objective",
        objectiveText: "Fill the 9×9 grid with numbers from 1 to 9.",
        goldenRulesTitle: "The 3 golden rules",
        rule1: "Each row must contain the numbers 1 to 9, without repetition.",
        rule2: "Each column must contain the numbers 1 to 9, without repetition.",
        rule3: "Each 3×3 block must contain the numbers 1 to 9, without repetition.",
        howToTitle: "How to play on this site",
        how1: "Click an empty cell then a number (or use the 1-9 keyboard keys).",
        how2: "✏️ Notes: turn this on to jot down candidate numbers in a cell — handy for exploring possibilities.",
        how3: "💡 Hint: reveals the correct value in the selected cell (or a random one).",
        how4: "↩️ Undo: reverts your last action.",
        how5: "⏸ Pause / ⏹ Stop: pause the game or abandon it at any time.",
        tipsTitle: "Tips for beginners",
        tip1: "Start by spotting the numbers that appear most often in the starting grid.",
        tip2: "For a given cell, eliminate numbers already present in its row, column and block.",
        tip3: "If a number can only go in one spot within a block, row or column, place it there.",
        tip4: "Use notes for cells with several possibilities, then narrow them down as you go.",
        tip5: "Don't guess randomly: every grid has a unique logical solution.",
      },
      footer: { text: "Homemade • served from a Docker container" },
      settings: { language: "Language", theme: "Theme" },
      theme: { blue: "Blue", green: "Emerald", amber: "Amber", mono: "Black & white" },
      errors: {
        INVALID_PSEUDO: "Invalid username (3 to 20 characters, letters/digits/_).",
        INVALID_EMAIL: "Invalid email address.",
        INVALID_PASSWORD: "Password must be at least 6 characters.",
        PSEUDO_TAKEN: "This username is already taken.",
        EMAIL_TAKEN: "This email address is already in use.",
        REGISTER_FAILED: "An error occurred during registration.",
        MISSING_CREDENTIALS: "Username/email and password required.",
        INVALID_CREDENTIALS: "Incorrect credentials.",
        AUTH_REQUIRED: "Authentication required.",
        RATE_LIMITED: "Too many attempts, please try again later.",
        INVALID_DIFFICULTY: "Invalid difficulty.",
        INVALID_TIME: "Invalid time.",
        INVALID_MISTAKES: "Invalid number of mistakes.",
        TIME_TOO_SHORT: "Time too short for this difficulty.",
        UNKNOWN: "An error occurred.",
      },
    },
  };

  function detectInitialLang() {
    try {
      const saved = localStorage.getItem('sudoku-lang');
      if (saved === 'fr' || saved === 'en') return saved;
    } catch (e) {}
    return 'fr';
  }

  let lang = detectInitialLang();

  function get(dict, path) {
    return path.split('.').reduce((o, k) => (o && o[k] !== undefined ? o[k] : undefined), dict);
  }

  function t(key, vars) {
    let str = get(DICTS[lang], key);
    if (str === undefined) str = get(DICTS.fr, key);
    if (str === undefined) return key;
    if (vars) {
      Object.keys(vars).forEach(k => {
        str = str.replace(new RegExp('\\{' + k + '\\}', 'g'), vars[k]);
      });
    }
    return str;
  }

  function applyTranslations() {
    document.documentElement.lang = lang;
    document.querySelectorAll('[data-i18n]').forEach(el => {
      el.textContent = t(el.getAttribute('data-i18n'));
    });
    document.querySelectorAll('[data-i18n-html]').forEach(el => {
      el.innerHTML = t(el.getAttribute('data-i18n-html'));
    });
  }

  function setLang(l) {
    if (l !== 'fr' && l !== 'en') return;
    lang = l;
    try { localStorage.setItem('sudoku-lang', l); } catch (e) {}
    applyTranslations();
    if (typeof window.onLangChange === 'function') window.onLangChange(l);
  }

  window.I18N = { t, setLang, getLang: () => lang, applyTranslations };

  applyTranslations();
})();