src/game/Translator.js

/**
 * Translator — Sinhala (si) + Tamil (ta) with quality validation.
 * Primary: Google Translate unofficial endpoint
 * Fallback: MyMemory
 *
 * Validation rejects: wrong-script responses, Bamini-encoded gibberish,
 * paragraph-length descriptions, English echoes.
 */

const CACHE_PREFIX = 'echo_t3_';   // bumped to ignore old contextual mistakes

const SCRIPT = {
  si: /[඀-෿]/,
  ta: /[஀-௿]/,
};

/**
 * Curated translations for the trickiest short / function words.
 * These ALWAYS win over the translation APIs (which translate "at" as "time",
 * "of" as "of belonging", etc., because there's no sentence context).
 */
const FUNCTION_WORDS = {
  a:    { si: 'එක',         ta: 'ஒரு' },
  i:    { si: 'මම',         ta: 'நான்' },
  an:   { si: 'එක',         ta: 'ஒரு' },
  the:  { si: 'එම',         ta: 'அந்த' },
  at:   { si: 'හි',          ta: 'இல்' },
  in:   { si: 'තුළ',         ta: 'உள்ளே' },
  on:   { si: 'මත',         ta: 'மீது' },
  of:   { si: 'හි',          ta: 'இன்' },
  to:   { si: 'කරා',        ta: 'க்கு' },
  by:   { si: 'විසින්',      ta: 'மூலம்' },
  for:  { si: 'සඳහා',       ta: 'க்காக' },
  from: { si: 'වෙතින්',     ta: 'இருந்து' },
  up:   { si: 'ඉහළ',        ta: 'மேலே' },
  us:   { si: 'අපට',        ta: 'எங்களை' },
  we:   { si: 'අපි',         ta: 'நாம்' },
  he:   { si: 'ඔහු',         ta: 'அவன்' },
  she:  { si: 'ඇය',         ta: 'அவள்' },
  it:   { si: 'එය',          ta: 'அது' },
  me:   { si: 'මට',          ta: 'என்னை' },
  my:   { si: 'මගේ',        ta: 'என்' },
  no:   { si: 'නැහැ',       ta: 'இல்லை' },
  or:   { si: 'හෝ',          ta: 'அல்லது' },
  so:   { si: 'එසේ',         ta: 'அப்படி' },
  if:   { si: 'නම්',          ta: 'என்றால்' },
  is:   { si: 'වේ',           ta: 'உள்ளது' },
  am:   { si: 'වෙමි',         ta: 'இருக்கிறேன்' },
  are:  { si: 'වෙති',         ta: 'உள்ளனர்' },
  was:  { si: 'විය',          ta: 'இருந்தது' },
  be:   { si: 'වෙන්න',        ta: 'இரு' },
  do:   { si: 'කරන්න',        ta: 'செய்' },
  go:   { si: 'යන්න',          ta: 'போ' },
  and:  { si: 'සහ',          ta: 'மற்றும்' },
  but:  { si: 'නමුත්',         ta: 'ஆனால்' },
  not:  { si: 'නැත',         ta: 'இல்லை' },
  yes:  { si: 'ඔව්',          ta: 'ஆம்' },
  you:  { si: 'ඔබ',           ta: 'நீ' },
  who:  { si: 'කවුද',         ta: 'யார்' },
  why:  { si: 'ඇයි',          ta: 'ஏன்' },
  how:  { si: 'කෙසේද',       ta: 'எப்படி' },
  what: { si: 'මොකක්ද',      ta: 'என்ன' },
  when: { si: 'කවදද',         ta: 'எப்போது' },
  where:{ si: 'කොහෙද',       ta: 'எங்கே' },
  this: { si: 'මේ',           ta: 'இந்த' },
  that: { si: 'එම',           ta: 'அந்த' },
  these:{ si: 'මේවා',         ta: 'இவை' },
  those:{ si: 'ඒවා',          ta: 'அவை' },
  with: { si: 'සමඟ',          ta: 'உடன்' },
  out:  { si: 'පිටත',         ta: 'வெளியே' },
  off:  { si: 'ඉවත්',         ta: 'விலகி' },
  one:  { si: 'එක',           ta: 'ஒன்று' },
  two:  { si: 'දෙක',          ta: 'இரண்டு' },
  ten:  { si: 'දහය',          ta: 'பத்து' },
  yes:  { si: 'ඔව්',          ta: 'ஆம்' },
  ok:   { si: 'හරි',           ta: 'சரி' },
  hi:   { si: 'හායි',          ta: 'வணக்கம்' },
  oh:   { si: 'ඕ',             ta: 'ஓ' },
  as:   { si: 'ලෙස',          ta: 'ஆக' },
  all:  { si: 'සියල්ල',        ta: 'அனைத்தும்' },
  any:  { si: 'ඕනෑම',         ta: 'எதேனும்' },
  can:  { si: 'හැකි',           ta: 'முடியும்' },
  will: { si: 'කරයි',          ta: 'செய்யும்' },
  may:  { si: 'පුළුවන්',         ta: 'இருக்கலாம்' },
  her:  { si: 'ඇගේ',          ta: 'அவளுடைய' },
  him:  { si: 'ඔහුට',           ta: 'அவனை' },
  his:  { si: 'ඔහුගේ',          ta: 'அவனது' },
  our:  { si: 'අපේ',            ta: 'எங்கள்' },
  your: { si: 'ඔබේ',            ta: 'உங்கள்' },
  its:  { si: 'එහි',             ta: 'அதன்' },
};

export function validateTranslation(text, lang, sourceWord) {
  if (!text) return false;
  const t = String(text).trim();
  if (!t) return false;
  if (t.toLowerCase() === sourceWord.toLowerCase()) return false;
  if (t.length > Math.max(40, sourceWord.length * 6)) return false;
  const re = SCRIPT[lang];
  if (!re) return true;
  const scriptChars = (t.match(new RegExp(re.source, 'g')) || []).length;
  const latinChars = (t.match(/[a-zA-Z]/g) || []).length;
  if (scriptChars < 1) return false;
  if (latinChars > scriptChars) return false;
  const garbage = (t.match(/[;>\/\\\[\]{}|`~]/g) || []).length;
  if (garbage > 1 && scriptChars < 3) return false;
  return true;
}

async function tryGoogle(word, lang) {
  try {
    const url = `https://translate.googleapis.com/translate_a/single?client=gtx&sl=en&tl=${lang}&dt=t&q=${encodeURIComponent(word)}`;
    const r = await fetch(url);
    if (!r.ok) return null;
    const j = await r.json();
    if (j?.[0]?.[0]?.[0]) {
      const t = String(j[0][0][0]).trim();
      if (validateTranslation(t, lang, word)) return t;
    }
  } catch (e) {}
  return null;
}

async function tryMyMemory(word, lang) {
  try {
    const url = `https://api.mymemory.translated.net/get?q=${encodeURIComponent(word)}&langpair=en|${lang}`;
    const r = await fetch(url);
    if (!r.ok) return null;
    const j = await r.json();
    if (j?.responseData?.translatedText) {
      const t = String(j.responseData.translatedText).trim();
      if (validateTranslation(t, lang, word)) return t;
    }
  } catch (e) {}
  return null;
}

async function translateOne(word, lang) {
  return (await tryGoogle(word, lang)) || (await tryMyMemory(word, lang));
}

export async function getMeaning(word) {
  // 1. Curated function-word dictionary ALWAYS wins (context-dependent words)
  if (FUNCTION_WORDS[word]) {
    return { si: FUNCTION_WORDS[word].si, ta: FUNCTION_WORDS[word].ta };
  }

  // 2. Validated cache
  try {
    const cached = JSON.parse(localStorage.getItem(CACHE_PREFIX + word) || 'null');
    if (cached) {
      const siOK = cached.si === '—' || validateTranslation(cached.si, 'si', word);
      const taOK = cached.ta === '—' || validateTranslation(cached.ta, 'ta', word);
      if (siOK && taOK) return cached;
    }
  } catch (e) {}

  // 3. Live API
  const [si, ta] = await Promise.all([translateOne(word, 'si'), translateOne(word, 'ta')]);
  const out = { si: si || '—', ta: ta || '—' };
  try { localStorage.setItem(CACHE_PREFIX + word, JSON.stringify(out)); } catch (e) {}
  return out;
}