const form = document.querySelector("#chatForm");
const promptInput = document.querySelector("#prompt");
const messagesEl = document.querySelector("#messages");
const sendButton = document.querySelector("#sendButton");
const newChatButton = document.querySelector("#newChat");
const historyEl = document.querySelector("#history");
const chatTitleEl = document.querySelector("#chatTitle");
const modelSelect = document.querySelector("#modelSelect");
const ragToggle = document.querySelector("#ragToggle");
const ragStatus = document.querySelector("#ragStatus");
const reindexButton = document.querySelector("#reindexButton");
const metaLine = document.querySelector("#metaLine");

let activeChatId = null;
let messages = [];

function addMessage(role, content, meta = "") {
  const article = document.createElement("article");
  article.className = `message ${role}`;

  const avatar = document.createElement("div");
  avatar.className = "avatar";
  avatar.textContent = role === "user" ? "U" : "L";

  const bubble = document.createElement("div");
  bubble.className = "bubble";
  bubble.textContent = content;

  if (meta) {
    const metaEl = document.createElement("div");
    metaEl.className = "message-meta";
    metaEl.textContent = meta;
    bubble.append(document.createElement("br"), metaEl);
  }

  article.append(avatar, bubble);
  messagesEl.append(article);
  messagesEl.scrollTop = messagesEl.scrollHeight;
  return bubble;
}

function renderMessages() {
  messagesEl.innerHTML = "";

  if (!messages.length) {
    addMessage("assistant", "Local LLM is ready. Ask in Korean or English.");
    return;
  }

  messages.forEach((message) => addMessage(message.role, message.content));
}

function setTitle(title) {
  chatTitleEl.textContent = title || "Local LLM";
}

function selectedModel() {
  return modelSelect.value || "qwen2.5:7b";
}

async function loadModels() {
  const response = await fetch("/api/models");
  const data = await response.json();
  modelSelect.innerHTML = "";

  data.models.forEach((model) => {
    const option = document.createElement("option");
    option.value = model;
    option.textContent = model;
    if (model === data.defaultModel) {
      option.selected = true;
    }
    modelSelect.append(option);
  });
}

async function loadRagStatus() {
  const response = await fetch("/api/rag/status");
  const data = await response.json();
  ragStatus.textContent = `RAG: ${data.files} files, ${data.chunks} chunks`;
}

async function loadHistory() {
  const response = await fetch("/api/chats");
  const data = await response.json();
  historyEl.innerHTML = "";

  data.chats.forEach((chat) => {
    const item = document.createElement("button");
    item.className = `history-item ${chat.id === activeChatId ? "active" : ""}`;
    item.type = "button";
    item.textContent = chat.title;
    item.addEventListener("click", () => loadChat(chat.id));
    historyEl.append(item);
  });
}

async function loadChat(chatId) {
  const response = await fetch(`/api/chats/${chatId}`);
  const data = await response.json();
  activeChatId = data.chat.id;
  messages = data.chat.messages || [];
  modelSelect.value = data.chat.model || selectedModel();
  ragToggle.checked = data.chat.useRag !== false;
  setTitle(data.chat.title);
  renderMessages();
  await loadHistory();
  promptInput.focus();
}

function resetChat() {
  activeChatId = null;
  messages = [];
  setTitle("Local LLM");
  renderMessages();
  loadHistory();
  promptInput.focus();
}

promptInput.addEventListener("input", () => {
  promptInput.style.height = "auto";
  promptInput.style.height = `${promptInput.scrollHeight}px`;
});

promptInput.addEventListener("keydown", (event) => {
  if (event.key === "Enter" && !event.shiftKey) {
    event.preventDefault();
    form.requestSubmit();
  }
});

newChatButton.addEventListener("click", resetChat);

reindexButton.addEventListener("click", async () => {
  reindexButton.disabled = true;
  ragStatus.textContent = "RAG: indexing";
  try {
    const response = await fetch("/api/rag/reindex", { method: "POST" });
    const data = await response.json();
    ragStatus.textContent = `RAG: ${data.files} files, ${data.chunks} chunks`;
  } finally {
    reindexButton.disabled = false;
  }
});

form.addEventListener("submit", async (event) => {
  event.preventDefault();

  const content = promptInput.value.trim();
  if (!content || sendButton.disabled) {
    return;
  }

  promptInput.value = "";
  promptInput.style.height = "auto";
  addMessage("user", content);
  messages.push({ role: "user", content });

  sendButton.disabled = true;
  const pending = addMessage("assistant", "Thinking...");

  try {
    const response = await fetch("/api/chat", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        chatId: activeChatId,
        messages,
        model: selectedModel(),
        useRag: ragToggle.checked,
      }),
    });

    const data = await response.json();
    if (!response.ok) {
      throw new Error(data.error || "Response failed");
    }

    const sourceText = data.sources?.length
      ? `sources: ${data.sources.map((item) => item.source).join(", ")}`
      : "no sources";
    pending.textContent = data.reply;

    const meta = document.createElement("div");
    meta.className = "message-meta";
    meta.textContent = `${data.model} / ${(data.elapsedMs / 1000).toFixed(1)}s / ${sourceText}`;
    pending.append(document.createElement("br"), meta);

    activeChatId = data.chatId;
    messages = data.chat.messages || [...messages, { role: "assistant", content: data.reply }];
    setTitle(data.chat.title);
    metaLine.textContent = `${data.model} with RAG ${ragToggle.checked ? "on" : "off"}`;
    await loadHistory();
  } catch (error) {
    pending.textContent = `Error: ${error.message}`;
  } finally {
    sendButton.disabled = false;
    promptInput.focus();
  }
});

loadModels();
loadRagStatus();
renderMessages();
loadHistory();