/*
 * translate.js
 * A HexDroid script
 *
 * Auto-translates incoming messages and adds a /tr command for manual one-off translation.
 *
 * Backend: a LibreTranslate instance (https://libretranslate.com or self-hosted).
 * LibreTranslate is FOSS and has a /detect + /translate JSON API
 * Point TR_ENDPOINT at your own instance for privacy + no rate limits. If your instance needs a key, set TR_KEY.
 *
 * The host must permit network to TR_ENDPOINT (ScriptHost.isNetworkAllowed).
 */

var TR_ENDPOINT = "https://libretranslate.com";
var TR_KEY      = "";          // API key for your instance
var SHOW_ORIGINAL_LANG = true; // prefix the translated line with the detected lang

function appLang() {
  // e.g. "en". Falls back to English if the host doesn't expose the setting.
  return (setting("appLanguage") || "en").toLowerCase().slice(0, 2);
}

// POST JSON and parse the reply. cb(err, obj).
function postJson(path, payload, cb) {
  http.post(TR_ENDPOINT + path, JSON.stringify(payload), function (res) {
    if (!res.ok) { cb(res.error || ("HTTP " + res.status), null); return; }
    try { cb(null, JSON.parse(res.body)); }
    catch (e) { cb("bad JSON from server", null); }
  });
}

function detect(text, cb) {
  postJson("/detect", { q: text, api_key: TR_KEY }, function (err, arr) {
    if (err) { cb(err, null); return; }
    // /detect returns [{ confidence, language }], best first.
    if (arr && arr.length && arr[0].language) cb(null, arr[0].language);
    else cb("no language detected", null);
  });
}

function translate(text, source, target, cb) {
  postJson("/translate", {
    q: text, source: source, target: target, format: "text", api_key: TR_KEY
  }, function (err, obj) {
    if (err) { cb(err, null); return; }
    if (obj && obj.translatedText) cb(null, obj.translatedText);
    else cb("no translation returned", null);
  });
}

// auto-translate incoming foreign messages

on("TEXT", function (e) {
  if (e.isMine) return; // don't translate our own echo
  var text = e.text;
  if (!text || text.length < 2) return;

  var want = appLang();

  detect(text, function (err, src) {
    if (err) { log("detect failed:", err); return; }
    src = src.toLowerCase().slice(0, 2);
    if (src === want) return;

    translate(text, src, want, function (err2, out) {
      if (err2) { log("translate failed:", err2); return; }
      if (!out || out === text) return;
      var prefix = SHOW_ORIGINAL_LANG ? ("\u0002[" + src + "\u2192" + want + "]\u0002 ") : "";
      // Inject a line under the original, attributed to the same nick.
      echo(e.buffer, e.from, prefix + out);
    });
  });
});

// /tr <text> translate something manually

command("tr", function (args, e) {
  var text = (args || "").trim();
  if (!text) { echo(e.buffer, "*** Usage: /tr <text to translate>"); return; }
  var want = appLang();
  detect(text, function (err, src) {
    src = (err ? want : src).toLowerCase().slice(0, 2);
    translate(text, src === want ? "auto" : src, want, function (err2, out) {
      if (err2) { echo(e.buffer, "*** /tr failed: " + err2); return; }
      echo(e.buffer, "*** (" + src + "\u2192" + want + ") " + out);
    });
  });
});

log("translate.js loaded (endpoint " + TR_ENDPOINT + ")");