import { API_BASE_URL } from "@config/config_frontend";
import { renderHelpMarkdown } from "@ui/ui_template_help";
import { openModal } from "@ui/ui_template_modal";

type Source = { path: string; excerpt: string };
type ChatAnswer = { answer: string; sources: Source[]; detail?: string };
type ChatTurn = { role: "user" | "assistant"; content: string };
const chatIcon = `<svg viewBox="0 0 32 32" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M8 5h16a5 5 0 0 1 5 5v10a5 5 0 0 1-5 5H13l-7 4v-5a5 5 0 0 1-3-4V10a5 5 0 0 1 5-5Z"/><path d="M11 19c0-5 4-8 10-8 0 6-3 10-8 10"/><path d="M11 22c2-3 5-5 9-7"/></svg>`;

export function buildKnowledgeChat(): HTMLElement {
  const wrap = document.createElement("div");
  wrap.className = "b01-knowledge-chat";
  const toggle = document.createElement("button");
  toggle.type = "button";
  toggle.className = "b01-knowledge-chat__toggle";
  toggle.innerHTML = chatIcon;
  toggle.setAttribute("aria-label", "챗봇 열기");
  toggle.title = "챗봇";
  toggle.setAttribute("aria-expanded", "false");
  const panel = document.createElement("section");
  panel.className = "b01-knowledge-chat__panel";
  panel.hidden = true;
  panel.id = "b01-knowledge-chat-panel";
  panel.setAttribute("aria-label", "챗봇");
  panel.addEventListener(
    "wheel",
    (event) => {
      if (!messages.contains(event.target as Node)) event.preventDefault();
    },
    { passive: false },
  );
  toggle.setAttribute("aria-controls", panel.id);
  const header = document.createElement("header");
  const avatar = document.createElement("span");
  avatar.className = "b01-knowledge-chat__avatar";
  avatar.innerHTML = chatIcon;
  const title = document.createElement("strong");
  title.textContent = "챗봇";
  const close = document.createElement("button");
  close.type = "button";
  close.className = "b01-knowledge-chat__close";
  close.textContent = "×";
  close.setAttribute("aria-label", "챗봇 닫기");
  header.append(avatar, title, close);
  const messages = document.createElement("div");
  let history: ChatTurn[] = [];
  messages.className = "b01-knowledge-chat__messages";
  messages.setAttribute("role", "log");
  messages.setAttribute("aria-live", "polite");
  const welcome = document.createElement("p");
  welcome.className = "b01-knowledge-chat__reply";
  welcome.textContent =
    "안녕하세요! 법령이나 지침에 대해 질문해 주세요. 근거 문서도 함께 보여드릴게요.";
  messages.append(welcome);
  const form = document.createElement("form");
  form.className = "b01-knowledge-chat__form";
  const input = document.createElement("textarea");
  input.rows = 2;
  input.required = true;
  input.maxLength = 500;
  input.placeholder = "메시지를 입력하세요";
  input.setAttribute("aria-label", "질문");
  const submit = document.createElement("button");
  submit.type = "submit";
  submit.textContent = "보내기";
  form.append(input, submit);
  panel.append(header, messages, form);
  wrap.append(toggle, panel);

  const setOpen = (open: boolean): void => {
    panel.hidden = !open;
    toggle.setAttribute("aria-expanded", String(!panel.hidden));
    toggle.setAttribute("aria-label", open ? "챗봇 닫기" : "챗봇 열기");
    if (open) input.focus();
    else toggle.focus();
  };
  toggle.addEventListener("click", () => setOpen(Boolean(panel.hidden)));
  close.addEventListener("click", () => setOpen(false));

  form.addEventListener("submit", async (event) => {
    event.preventDefault();
    const question = input.value.trim();
    if (question.length < 2) return;
    const userLine = document.createElement("p");
    userLine.className = "b01-knowledge-chat__user";
    userLine.textContent = question;
    messages.append(userLine);
    input.value = "";
    input.disabled = submit.disabled = true;
    const reply = document.createElement("div");
    reply.className = "b01-knowledge-chat__reply";
    reply.textContent = "원문을 찾는 중입니다…";
    messages.append(reply);
    messages.scrollTop = messages.scrollHeight;
    try {
      const response = await fetch(`${API_BASE_URL}/dashboard/knowledge-chat`, {
        method: "POST",
        credentials: "include",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ question, history }),
      });
      const result = (await response.json()) as ChatAnswer;
      if (!response.ok) throw new Error(result.detail || "답변을 받지 못했습니다.");
      reply.textContent = result.answer;
      history = [
        ...history,
        { role: "user", content: question },
        { role: "assistant", content: result.answer },
      ].slice(-6) as ChatTurn[];
      if (result.sources.length) {
        const sources = document.createElement("details");
        sources.className = "b01-knowledge-chat__sources";
        const summary = document.createElement("summary");
        summary.textContent = `근거 원문 ${result.sources.length}건`;
        sources.append(summary);
        result.sources.forEach((source, index) => {
          const item = document.createElement("button");
          item.type = "button";
          item.className = "b01-knowledge-chat__source";
          const filename = source.path.split("/").pop()?.replace(/\.md$/i, "") ?? source.path;
          const name = document.createElement("strong");
          name.textContent = `[${index + 1}] ${filename}`;
          const location = document.createElement("span");
          location.textContent = `원문 · ${source.path.replace(/^original\//, "")}`;
          item.append(name, location);
          item.addEventListener("click", () => void openSource(source.path, filename));
          sources.append(item);
        });
        reply.append(sources);
      }
    } catch (error) {
      reply.textContent = error instanceof Error ? error.message : "답변을 받지 못했습니다.";
    } finally {
      input.disabled = submit.disabled = false;
      input.focus();
      messages.scrollTop = messages.scrollHeight;
    }
  });
  return wrap;
}

async function openSource(path: string, title: string): Promise<void> {
  openModal({
    title,
    closeLabel: "닫기",
    dialogClass: "b01-knowledge-source-modal",
    mount: (body) => {
      const article = document.createElement("article");
      article.className = "b01-knowledge-source-modal__content";
      article.textContent = "원문을 불러오는 중입니다…";
      body.append(article);
      void fetch(`${API_BASE_URL}/dashboard/knowledge-chat/source`, {
        method: "POST",
        credentials: "include",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ path }),
      })
        .then(async (response) => {
          const result = (await response.json()) as { content?: string; detail?: string };
          if (!response.ok) throw new Error(result.detail || "원문을 불러오지 못했습니다.");
          article.innerHTML = renderHelpMarkdown(result.content ?? "");
        })
        .catch((error: unknown) => {
          article.textContent =
            error instanceof Error ? error.message : "원문을 불러오지 못했습니다.";
        });
    },
  });
}