// rony-chat-widget — drop-in vanilla JS chat widget.
//
// Usage (HTML):
//   <link rel="stylesheet" href="/path/to/chat-widget.css">
//   <script src="/path/to/chat-widget.js"
//           data-api-url="http://localhost:7331"
//           data-title="Ask me anything"
//           data-position="bottom-right"
//           data-theme="auto"
//           defer></script>
//
// All options are read from <script data-*="..."> attributes; everything is
// optional except data-api-url. The widget is self-contained: no build step,
// no runtime dependencies, no global CSS pollution.

(function () {
  "use strict";

  // ---- i18n -----------------------------------------------------------------
  // The widget UI is bilingual. The conversation language (what the LLM
  // answers in) is decided by the user query and is unaffected by this toggle.

  var STRINGS = {
    en: {
      placeholder: "Type a message...",
      send: "Send",
      online: "online",
      offline: "offline",
      error: "error",
      errorConnect: "Could not reach the server: ",
      errorGeneric: "Unknown error",
      ariaOpen: "Open chat",
      ariaClose: "Close",
      ariaLang: "Language",
      ariaSend: "Send",
    },
    es: {
      placeholder: "Escribe un mensaje...",
      send: "Enviar",
      online: "conectado",
      offline: "desconectado",
      error: "error",
      errorConnect: "No se pudo conectar al servidor: ",
      errorGeneric: "Error desconocido",
      ariaOpen: "Abrir chat",
      ariaClose: "Cerrar",
      ariaLang: "Idioma",
      ariaSend: "Enviar",
    },
  };

  var LANG_KEY = "rony-chat-lang";
  var CONV_KEY = "rony-chat-conv";

  function pickInitialLang() {
    var saved = null;
    try { saved = localStorage.getItem(LANG_KEY); } catch (e) {}
    if (saved === "en" || saved === "es") return saved;
    var nav = (navigator.language || "en").toLowerCase();
    return nav.indexOf("es") === 0 ? "es" : "en";
  }

  function saveLang(lang) {
    try { localStorage.setItem(LANG_KEY, lang); } catch (e) {}
  }

  // ---- Conversation persistence -------------------------------------------
  // The conversation_id is a server-issued UUID-ish string. We store it in
  // localStorage so the same browser keeps its thread across reloads. A
  // different browser (or cleared storage) starts a fresh thread.

  function loadConvID() {
    try { return localStorage.getItem(CONV_KEY) || ""; } catch (e) { return ""; }
  }
  function saveConvID(id) {
    try { localStorage.setItem(CONV_KEY, id); } catch (e) {}
  }
  function clearConvID() {
    try { localStorage.removeItem(CONV_KEY); } catch (e) {}
  }

  // Restore conversation history from the server, if any. On 404 the
  // stored ID is dead (e.g. server DB was wiped) — clear it and start fresh.
  function restoreHistory(convID, onDone) {
    fetch(cfg.apiUrl + "/api/conversations/" + encodeURIComponent(convID))
      .then(function (resp) {
        if (resp.status === 404) { clearConvID(); onDone(null); return null; }
        if (!resp.ok) { onDone(null); return null; }
        return resp.json();
      })
      .then(function (conv) {
        if (!conv) { onDone(null); return; }
        onDone(conv);
      })
      .catch(function () { onDone(null); });
  }

  // ---- Config ----------------------------------------------------------------

  function readConfig() {
    var scripts = document.querySelectorAll("script[data-api-url], script[data-rony-chat]");
    var tag = scripts[scripts.length - 1] || document.currentScript || {};
    var ds = tag.dataset || {};
    return {
      apiUrl: (ds.apiUrl || "").replace(/\/+$/, ""),
      title: ds.title || "Chat",
      greeting: ds.greeting || "",
      position: ds.position || "bottom-right",
      theme: ds.theme || "auto",
    };
  }

  // ---- Tiny markdown subset (no dependency) ----------------------------------
  // Covers: **bold**, *italic*, `code`, ```fences```, lists, [links], paragraphs.

  function escapeHTML(s) {
    return s.replace(/[&<>"']/g, function (c) {
      return { "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" }[c];
    });
  }

  function renderMarkdown(src) {
    var fences = [];
    src = src.replace(/```([\s\S]*?)```/g, function (_, code) {
      fences.push(code.replace(/^\n/, ""));
      return "\u0000F" + (fences.length - 1) + "\u0000";
    });
    var inlines = [];
    src = src.replace(/`([^`\n]+)`/g, function (_, code) {
      inlines.push(code);
      return "\u0000I" + (inlines.length - 1) + "\u0000";
    });
    src = escapeHTML(src);
    src = src.replace(/\u0000I(\d+)\u0000/g, function (_, i) {
      return "<code>" + escapeHTML(inlines[+i]) + "</code>";
    });
    src = src.replace(/\u0000F(\d+)\u0000/g, function (_, i) {
      return "<pre><code>" + escapeHTML(fences[+i]) + "</code></pre>";
    });
    src = src.replace(/\*\*([^*]+)\*\*/g, "<strong>$1</strong>");
    src = src.replace(/\*([^*]+)\*/g, "<em>$1</em>");
    src = src.replace(/\[([^\]]+)\]\(([^)]+)\)/g, function (_, t, u) {
      var safe = /^(https?:|mailto:|#|\/)/i.test(u) ? u : "#";
      return '<a href="' + safe + '" target="_blank" rel="noopener noreferrer">' + t + "</a>";
    });
    src = src.replace(/(^|\n)((?:[-*] |\d+\. ).+(?:\n(?:[-*] |\d+\. ).+)*)/g, function (m, lead, block) {
      var lines = block.split("\n");
      var isOrdered = /^\d+\. /.test(lines[0]);
      var tag = isOrdered ? "ol" : "ul";
      var items = lines.map(function (l) {
        return "<li>" + l.replace(/^[-*] |\d+\. /, "") + "</li>";
      }).join("");
      return lead + "<" + tag + ">" + items + "</" + tag + ">";
    });
    src = src
      .split(/\n{2,}/)
      .map(function (p) {
        if (/^\s*<(pre|ul|ol|h\d|blockquote)/.test(p)) return p;
        return "<p>" + p.replace(/\n/g, "<br>") + "</p>";
      })
      .join("\n");
    return src;
  }

  // ---- SSE parsing -----------------------------------------------------------

  function readSSE(response, onEvent, signal) {
    var reader = response.body.getReader();
    var decoder = new TextDecoder("utf-8");
    var buffer = "";
    var aborted = false;

    if (signal) {
      signal.addEventListener("abort", function () {
        aborted = true;
        try { reader.cancel(); } catch (e) {}
      });
    }

    function pump() {
      if (aborted) return;
      return reader.read().then(function (r) {
        if (r.done) return;
        buffer += decoder.decode(r.value, { stream: true });
        var idx;
        while ((idx = buffer.indexOf("\n\n")) !== -1) {
          var raw = buffer.slice(0, idx);
          buffer = buffer.slice(idx + 2);
          var ev = { event: "message", data: "" };
          raw.split("\n").forEach(function (line) {
            if (line.indexOf("event: ") === 0) ev.event = line.slice(7).trim();
            else if (line.indexOf("data: ") === 0) ev.data += (ev.data ? "\n" : "") + line.slice(6);
          });
          if (ev.data) onEvent(ev.event, ev.data);
        }
        return pump();
      });
    }
    return pump();
  }

  // ---- Widget construction --------------------------------------------------

  function buildWidget(cfg) {
    var root = document.createElement("div");
    root.className = "rony-chat-widget-root";
    root.setAttribute("data-position", cfg.position);
    root.setAttribute("data-theme", cfg.theme);
    root.setAttribute("data-open", "false");
    root.innerHTML = [
      '<div class="rony-chat-widget-panel" role="dialog" aria-label="' + escapeHTML(cfg.title) + '">',
      '  <div class="rony-chat-widget-header">',
      '    <span class="rony-chat-widget-title">' + escapeHTML(cfg.title) + '</span>',
      '    <div class="rony-chat-widget-lang" role="group" aria-label="Language">',
      '      <button type="button" data-lang-btn="en" aria-pressed="false">EN</button>',
      '      <button type="button" data-lang-btn="es" aria-pressed="false">ES</button>',
      '    </div>',
      '    <span class="rony-chat-widget-status" data-status>online</span>',
      '    <button class="rony-chat-widget-close" aria-label="Close" data-close>×</button>',
      '  </div>',
      '  <div class="rony-chat-widget-messages" data-messages></div>',
      '  <form class="rony-chat-widget-form" data-form>',
      '    <textarea class="rony-chat-widget-input" data-input rows="1" placeholder="Type a message..."></textarea>',
      '    <button class="rony-chat-widget-send" type="submit" data-send>Send</button>',
      '  </form>',
      '</div>',
      '<button class="rony-chat-widget-bubble" aria-label="Open chat" data-bubble>',
      '  <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">',
      '    <path d="M21 15a2 2 0 0 1-2 2H7l-4 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2z"/>',
      '  </svg>',
      '</button>',
    ].join("\n");
    return root;
  }

  function init() {
    var cfg = readConfig();
    if (!cfg.apiUrl) {
      console.error("[rony-chat-widget] missing data-api-url on <script> tag");
      return;
    }
    var widget = buildWidget(cfg);
    document.body.appendChild(widget);

    var $messages = widget.querySelector("[data-messages]");
    var $input = widget.querySelector("[data-input]");
    var $form = widget.querySelector("[data-form]");
    var $send = widget.querySelector("[data-send]");
    var $bubble = widget.querySelector("[data-bubble]");
    var $close = widget.querySelector("[data-close]");
    var $status = widget.querySelector("[data-status]");
    var $langBtns = widget.querySelectorAll("[data-lang-btn]");
    var $title = widget.querySelector(".rony-chat-widget-title");
    var $panel = widget.querySelector(".rony-chat-widget-panel");
    var $langGroup = widget.querySelector(".rony-chat-widget-lang");

    var history = [];
    var busy = false;
    var abortCtrl = null;
    var lang = pickInitialLang();
    var convID = loadConvID();

    // ---- Language handling -----------------------------------------------

    function applyLang(next) {
      lang = next;
      saveLang(next);
      var t = STRINGS[next];
      $input.placeholder = t.placeholder;
      $send.textContent = t.send;
      $send.setAttribute("aria-label", t.ariaSend);
      $close.setAttribute("aria-label", t.ariaClose);
      $bubble.setAttribute("aria-label", t.ariaOpen);
      $langGroup.setAttribute("aria-label", t.ariaLang);
      $panel.setAttribute("lang", next);
      widget.setAttribute("data-lang", next);
      for (var i = 0; i < $langBtns.length; i++) {
        var active = $langBtns[i].getAttribute("data-lang-btn") === next;
        $langBtns[i].setAttribute("aria-pressed", active ? "true" : "false");
        $langBtns[i].classList.toggle("is-active", active);
      }
      // Refresh the visible status text with the new language
      $status.textContent = t[lastStatusKey] || t.online;
    }

    applyLang(lang);
    for (var j = 0; j < $langBtns.length; j++) {
      $langBtns[j].addEventListener("click", function (e) {
        var next = e.currentTarget.getAttribute("data-lang-btn");
        if (next && next !== lang) applyLang(next);
      });
    }

    // Restore conversation history from the server on first load. The
    // convID came from localStorage; if the server doesn't know it
    // (404), we wipe it and start a fresh thread on next send.
    if (convID) {
      restoreHistory(convID, function (conv) {
        if (conv && conv.messages) {
          for (var i = 0; i < conv.messages.length; i++) {
            var m = conv.messages[i];
            appendMessage(m.role, m.content);
            history.push({ role: m.role, content: m.content });
          }
        }
      });
    }

    // ---- Chat behavior --------------------------------------------------

    var lastStatusKey = "online";

    function setStatus(key) {
      lastStatusKey = key;
      $status.textContent = STRINGS[lang][key] || key;
    }

    function setOpen(open) {
      widget.setAttribute("data-open", open ? "true" : "false");
      // Greeting only fires on a brand-new thread. If history was
      // restored from the server we don't want to prepend a greeting on
      // top of the user's previous messages.
      if (open && !history.length && cfg.greeting) {
        appendMessage("assistant", cfg.greeting);
        history.push({ role: "assistant", content: cfg.greeting });
      }
      if (open) $input.focus();
    }

    function appendMessage(role, content) {
      var div = document.createElement("div");
      div.className = "rony-chat-widget-msg rony-chat-widget-msg-" + role;
      if (role === "assistant") {
        div.innerHTML = renderMarkdown(content);
      } else {
        div.textContent = content;
      }
      $messages.appendChild(div);
      $messages.scrollTop = $messages.scrollHeight;
      return div;
    }

    function appendError(msg) {
      var div = document.createElement("div");
      div.className = "rony-chat-widget-msg rony-chat-widget-msg-error";
      div.textContent = msg;
      $messages.appendChild(div);
      $messages.scrollTop = $messages.scrollHeight;
    }

    function send(userText) {
      if (busy || !userText.trim()) return;
      busy = true;
      $send.disabled = true;
      $input.value = "";
      autoSize();

      history.push({ role: "user", content: userText });
      appendMessage("user", userText);
      var assistantDiv = appendMessage("assistant", "");
      var caret = document.createElement("span");
      caret.className = "rony-chat-widget-caret";
      assistantDiv.appendChild(caret);

      abortCtrl = new AbortController();
      var collectedSources = [];

      fetch(cfg.apiUrl + "/api/chat", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          messages: history,
          stream: true,
          conversation_id: convID || undefined,
        }),
        signal: abortCtrl.signal,
      }).then(function (resp) {
        if (!resp.ok) {
          throw new Error("HTTP " + resp.status);
        }
        return readSSE(resp, function (type, data) {
          try {
            var payload = JSON.parse(data);
          } catch (e) {
            return;
          }
          if (type === "start" && payload.conversation_id) {
            // Server may have minted a new id; persist it.
            if (payload.conversation_id !== convID) {
              convID = payload.conversation_id;
              saveConvID(convID);
            }
          } else if (type === "chunk" && payload.content) {
            assistantDiv.insertBefore(document.createTextNode(payload.content), caret);
            $messages.scrollTop = $messages.scrollHeight;
          } else if (type === "sources" && Array.isArray(payload.documents)) {
            collectedSources = payload.documents;
          } else if (type === "done") {
            var finalText = assistantDiv.textContent.replace(/\s+$/, "");
            history.push({ role: "assistant", content: finalText });
            if (caret.parentNode) caret.parentNode.removeChild(caret);
            assistantDiv.innerHTML = renderMarkdown(finalText);
            if (collectedSources.length) {
              var row = document.createElement("div");
              row.className = "rony-chat-widget-sources";
              collectedSources.forEach(function (s) {
                var chip = document.createElement("span");
                chip.className = "rony-chat-widget-source";
                chip.textContent = s;
                row.appendChild(chip);
              });
              assistantDiv.appendChild(row);
            }
            setStatus("online");
          } else if (type === "error") {
            if (caret.parentNode) caret.parentNode.removeChild(caret);
            appendError(payload.error || STRINGS[lang].errorGeneric);
            setStatus("error");
          }
        }, abortCtrl.signal);
      }).catch(function (err) {
        if (err.name === "AbortError") return;
        if (caret.parentNode) caret.parentNode.removeChild(caret);
        appendError(STRINGS[lang].errorConnect + err.message);
        setStatus("offline");
      }).then(function () {
        busy = false;
        $send.disabled = false;
        abortCtrl = null;
      });
    }

    function autoSize() {
      $input.style.height = "auto";
      $input.style.height = Math.min($input.scrollHeight, 100) + "px";
    }

    $bubble.addEventListener("click", function () { setOpen(true); });
    $close.addEventListener("click", function () { setOpen(false); });
    $input.addEventListener("input", autoSize);
    $input.addEventListener("keydown", function (e) {
      if (e.key === "Enter" && !e.shiftKey) {
        e.preventDefault();
        $form.requestSubmit();
      }
    });
    $form.addEventListener("submit", function (e) {
      e.preventDefault();
      send($input.value);
    });
  }

  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", init);
  } else {
    init();
  }
})();