/**
 * DC-077: i18n Frontend — Language selector and translation system
 * 
 * Provides window.DCI18n.t(key) for the dashboard frontend.
 * Loads translations from /api/v1/i18n/translations/:lang
 * Language preference stored in localStorage.
 * Handles RTL for Arabic.
 */
(function () {
  'use strict';

  const STORAGE_KEY = 'dashcaddy-language';
  const DEFAULT_LANG = 'en';
  const SUPPORTED_LANGS = ['en', 'es', 'fr', 'de', 'ar'];
  const LANG_NAMES = {
    en: 'English', es: 'Español', fr: 'Français', de: 'Deutsch', ar: 'العربية',
  };

  let currentLang = localStorage.getItem(STORAGE_KEY) || DEFAULT_LANG;
  let translations = {};
  let loaded = false;

  async function loadTranslations(lang) {
    if (lang === DEFAULT_LANG) {
      translations = {}; // English is the default — no translation needed
      loaded = true;
      return;
    }
    try {
      const res = await fetch(`/api/v1/i18n/translations/${lang}`);
      if (res.ok) {
        const data = await res.json();
        translations = data.translations || {};
        loaded = true;
      }
    } catch (e) {
      console.warn('[i18n] Failed to load translations for', lang, e);
    }
  }

  function t(key) {
    if (currentLang === DEFAULT_LANG) return key;
    return translations[key] || key;
  }

  function setLanguage(lang) {
    if (!SUPPORTED_LANGS.includes(lang)) return;
    currentLang = lang;
    localStorage.setItem(STORAGE_KEY, lang);

    // RTL handling
    const isRtl = lang === 'ar';
    document.documentElement.dir = isRtl ? 'rtl' : 'ltr';
    document.documentElement.lang = lang;

    loadTranslations(lang).then(() => {
      applyTranslations();
    });
  }

  function getLanguage() {
    return currentLang;
  }

  function applyTranslations() {
    // Apply translations to elements with data-i18n attributes
    document.querySelectorAll('[data-i18n]').forEach(el => {
      const key = el.getAttribute('data-i18n');
      const translated = t(key);
      if (translated && translated !== key) {
        el.textContent = translated;
      }
    });
    // Apply to placeholders
    document.querySelectorAll('[data-i18n-placeholder]').forEach(el => {
      const key = el.getAttribute('data-i18n-placeholder');
      const translated = t(key);
      if (translated && translated !== key) {
        el.placeholder = translated;
      }
    });
    // Apply to titles
    document.querySelectorAll('[data-i18n-title]').forEach(el => {
      const key = el.getAttribute('data-i18n-title');
      const translated = t(key);
      if (translated && translated !== key) {
        el.title = translated;
      }
    });
  }

  function createLanguageSelector() {
    // Find the top bar area to insert the selector
    // Look for the auth-settings area or the header actions
    const targetContainer = document.querySelector('.header-actions') ||
                            document.querySelector('#auth-settings-btn')?.parentElement ||
                            document.querySelector('.top-bar-actions');

    if (!targetContainer) {
      // If we can't find a target, try to add it near the settings button
      const settingsBtn = document.getElementById('auth-settings-btn');
      if (settingsBtn && settingsBtn.parentElement) {
        return createDropdown(settingsBtn.parentElement);
      }
      return null;
    }

    return createDropdown(targetContainer);
  }

  function createDropdown(container) {
    // Check if selector already exists
    if (document.getElementById('dc-lang-selector')) return;

    const wrapper = document.createElement('div');
    wrapper.id = 'dc-lang-selector';
    wrapper.style.cssText = 'display: inline-flex; align-items: center; gap: 4px; margin: 0 8px; position: relative;';

    const btn = document.createElement('button');
    btn.id = 'dc-lang-btn';
    btn.className = 'lang-selector-btn';
    btn.style.cssText = 'background: var(--card-base, #2a2a3e); border: 1px solid var(--border, #3a3a4e); color: var(--text-primary, #e0e0e0); padding: 6px 10px; border-radius: 6px; cursor: pointer; font-size: 0.8rem; display: flex; align-items: center; gap: 4px;';
    btn.innerHTML = `🌐 <span class="lang-current">${currentLang.toUpperCase()}</span>`;
    btn.title = 'Language / Idioma / Langue / Sprache / اللغة';

    const dropdown = document.createElement('div');
    dropdown.id = 'dc-lang-dropdown';
    dropdown.style.cssText = 'display: none; position: absolute; top: 100%; right: 0; margin-top: 4px; background: var(--card-base, #2a2a3e); border: 1px solid var(--border, #3a3a4e); border-radius: 8px; box-shadow: 0 4px 12px rgba(0,0,0,0.3); z-index: 9999; min-width: 140px; overflow: hidden;';

    SUPPORTED_LANGS.forEach(lang => {
      const item = document.createElement('div');
      item.className = 'lang-option';
      item.style.cssText = 'padding: 8px 14px; cursor: pointer; display: flex; align-items: center; gap: 8px; font-size: 0.85rem; color: var(--text-primary, #e0e0e0);';
      item.onmouseenter = () => item.style.background = 'var(--card-hover, rgba(255,255,255,0.05))';
      item.onmouseleave = () => item.style.background = 'transparent';

      const flag = document.createElement('span');
      flag.textContent = lang === currentLang ? '✓' : '';
      flag.style.cssText = 'width: 16px; color: var(--ok-fg, #4ade80);';

      const name = document.createElement('span');
      name.textContent = LANG_NAMES[lang];

      item.appendChild(flag);
      item.appendChild(name);
      item.onclick = () => {
        setLanguage(lang);
        dropdown.style.display = 'none';
        // Update button text
        btn.querySelector('.lang-current').textContent = lang.toUpperCase();
        // Update checkmarks
        dropdown.querySelectorAll('.lang-option').forEach((opt, i) => {
          opt.querySelector('span').textContent = SUPPORTED_LANGS[i] === lang ? '✓' : '';
        });
        // Show notification
        if (window.showNotification) {
          window.showNotification(`Language: ${LANG_NAMES[lang]}`, 'info');
        }
      };
      dropdown.appendChild(item);
    });

    btn.onclick = (e) => {
      e.stopPropagation();
      dropdown.style.display = dropdown.style.display === 'none' ? 'block' : 'none';
    };

    // Close on outside click
    document.addEventListener('click', (e) => {
      if (!wrapper.contains(e.target)) {
        dropdown.style.display = 'none';
      }
    });

    wrapper.appendChild(btn);
    wrapper.appendChild(dropdown);
    container.insertBefore(wrapper, container.firstChild);

    return wrapper;
  }

  // Initialize on page load
  function init() {
    // Set initial RTL if needed
    if (currentLang === 'ar') {
      document.documentElement.dir = 'rtl';
      document.documentElement.lang = 'ar';
    }

    // Create the language selector after DOM is ready
    if (document.readyState === 'loading') {
      document.addEventListener('DOMContentLoaded', () => {
        createLanguageSelector();
        if (currentLang !== DEFAULT_LANG) loadTranslations(currentLang).then(applyTranslations);
      });
    } else {
      createLanguageSelector();
      if (currentLang !== DEFAULT_LANG) loadTranslations(currentLang).then(applyTranslations);
    }
  }

  // Expose globally
  window.DCI18n = { t, setLanguage, getLanguage, applyTranslations, loadTranslations };

  // Auto-init
  init();
})();