(function () {
  const realtime = {
    match: null,
    socket: null,
    pollTimer: null,
    clockTimer: null,
    opponentProgress: 0,
    reconnectTimer: null,
  };

  function stopTimers() {
    if (realtime.pollTimer) window.clearInterval(realtime.pollTimer);
    if (realtime.clockTimer) window.clearInterval(realtime.clockTimer);
    realtime.pollTimer = null;
    realtime.clockTimer = null;
  }

  function closeSocket() {
    if (realtime.reconnectTimer) window.clearTimeout(realtime.reconnectTimer);
    realtime.reconnectTimer = null;
    if (realtime.socket) {
      realtime.socket.onclose = null;
      realtime.socket.close();
    }
    realtime.socket = null;
  }

  function websocketUrl(path) {
    const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
    return `${protocol}//${window.location.host}${path}`;
  }

  function connectSocket() {
    closeSocket();
    if (!realtime.match?.websocket_path) return;
    const socket = new WebSocket(websocketUrl(realtime.match.websocket_path));
    realtime.socket = socket;
    socket.addEventListener("open", () => {
      updateConnectionStatus("实时连接已建立");
      socket.send(JSON.stringify({ type: "ping" }));
    });
    socket.addEventListener("message", async (event) => {
      let message;
      try {
        message = JSON.parse(event.data);
      } catch {
        return;
      }
      if (message.type === "state") {
        await refreshMatch();
      } else if (
        message.type === "progress" &&
        message.user_id !== String(state.user?.id)
      ) {
        realtime.opponentProgress = message.answered_count;
        updateProgressUI();
      }
    });
    socket.addEventListener("close", () => {
      updateConnectionStatus("实时连接中断，正在使用轮询");
      if (["waiting", "active"].includes(realtime.match?.status)) {
        realtime.reconnectTimer = window.setTimeout(connectSocket, 2000);
      }
    });
    socket.addEventListener("error", () => {
      updateConnectionStatus("WebSocket 不可用，轮询仍在工作");
    });
  }

  function updateConnectionStatus(message) {
    const node = document.querySelector("#realtime-connection");
    if (node) node.textContent = message;
  }

  async function refreshMatch() {
    if (!realtime.match?.match_id) return;
    try {
      const match = await api(`contests/matches/${realtime.match.match_id}/`);
      const previous = realtime.match;
      const previousStatus = previous.status;
      realtime.match = match;
      const shouldRender =
        previous.status !== match.status ||
        previous.attempt?.status !== match.attempt?.status;
      if (shouldRender) renderMatch();
      else {
        updateClock();
        if (
          previous.opponent?.status !== match.opponent?.status &&
          match.opponent?.status &&
          match.opponent.status !== "active"
        ) {
          realtime.opponentProgress = match.attempt?.questions.length || 0;
          updateProgressUI();
          updateConnectionStatus("对手已提交，完成后将立即结算");
        }
      }
      if (previousStatus === "waiting" && match.status === "active") {
        showToast(`已匹配到 ${match.opponent.nickname}`);
      }
      if (!["waiting", "active"].includes(match.status)) {
        stopTimers();
        closeSocket();
      }
    } catch (error) {
      if (error.status === 404) {
        stopTimers();
        closeSocket();
      }
    }
  }

  function startPolling() {
    stopTimers();
    realtime.pollTimer = window.setInterval(refreshMatch, 2000);
    realtime.clockTimer = window.setInterval(updateClock, 250);
  }

  function openMatch(match) {
    realtime.match = match;
    realtime.opponentProgress = 0;
    renderMatch();
    const dialog = document.querySelector("#experience-dialog");
    if (!dialog.open) dialog.showModal();
    connectSocket();
    if (["waiting", "active"].includes(match.status)) startPolling();
  }

  function header(root, match) {
    const label = document.createElement("span");
    label.className = "kicker";
    label.textContent =
      `${match.match_type === "challenge" ? "联机码约战" : "随机匹配"} · REALTIME`;
    const title = document.createElement("h2");
    title.textContent = match.contest;
    const status = document.createElement("div");
    status.className = "realtime-status-line";
    const connection = document.createElement("span");
    connection.id = "realtime-connection";
    connection.textContent = "正在建立实时连接…";
    const clock = document.createElement("strong");
    clock.id = "realtime-clock";
    status.append(connection, clock);
    root.append(label, title, status);
  }

  function updateClock() {
    const clock = document.querySelector("#realtime-clock");
    if (!clock || !realtime.match) return;
    if (realtime.match.status === "waiting") {
      const expiresAt = new Date(realtime.match.expires_at).getTime();
      const seconds = Math.max(0, Math.ceil((expiresAt - Date.now()) / 1000));
      clock.textContent = `联机码 ${Math.floor(seconds / 60)}:${String(seconds % 60).padStart(2, "0")} 后失效`;
      return;
    }
    if (realtime.match.status === "active") {
      const startedAt = new Date(realtime.match.started_at).getTime();
      const elapsed = (Date.now() - startedAt) / 1000;
      const remaining = Math.max(0, Math.ceil(realtime.match.duration_seconds - elapsed));
      clock.textContent = `剩余 ${remaining} 秒`;
      if (remaining === 0) refreshMatch();
      return;
    }
    clock.textContent = "";
  }

  async function copyCode(code) {
    try {
      await navigator.clipboard.writeText(code);
      showToast(`联机码 ${code} 已复制`);
    } catch {
      showToast(`联机码：${code}`);
    }
  }

  function renderWaiting(root, match) {
    const panel = document.createElement("div");
    panel.className = "realtime-waiting";
    const pulse = document.createElement("span");
    pulse.className = "realtime-pulse";
    const message = document.createElement("p");
    message.textContent =
      match.match_type === "challenge"
        ? "把联机码发给朋友。对方加入后会自动开始，无需再次点击。"
        : "正在寻找同赛道、相近 Rating 的玩家。";
    panel.append(pulse, message);
    if (match.challenge_code) {
      const code = document.createElement("button");
      code.className = "challenge-code";
      code.textContent = match.challenge_code;
      code.title = "点击复制联机码";
      code.addEventListener("click", () => copyCode(match.challenge_code));
      panel.append(code);
    }
    if (match.is_owner) {
      const cancel = document.createElement("button");
      cancel.className = "ghost-button";
      cancel.textContent = "取消等待";
      cancel.addEventListener("click", async () => {
        cancel.disabled = true;
        try {
          realtime.match = await api(`contests/matches/${match.match_id}/cancel/`, {
            method: "POST",
            body: {},
          });
          renderMatch();
          stopTimers();
          closeSocket();
        } catch (error) {
          showToast(error.message);
          cancel.disabled = false;
        }
      });
      panel.append(cancel);
    }
    root.append(panel);
    updateClock();
  }

  function progressPanel(root, match) {
    const panel = document.createElement("div");
    panel.className = "realtime-progress-panel";
    const self = document.createElement("div");
    self.innerHTML = `<span>你</span><b id="self-progress">0 / ${match.attempt.questions.length}</b>`;
    const opponent = document.createElement("div");
    opponent.innerHTML =
      `<span>${match.opponent?.nickname || "对手"}</span>` +
      `<b id="opponent-progress">${realtime.opponentProgress} / ${match.attempt.questions.length}</b>`;
    panel.append(self, opponent);
    root.append(panel);
  }

  function updateProgressUI(selfCount) {
    if (Number.isInteger(selfCount)) {
      const self = document.querySelector("#self-progress");
      if (self && realtime.match?.attempt) {
        self.textContent = `${selfCount} / ${realtime.match.attempt.questions.length}`;
      }
    }
    const opponent = document.querySelector("#opponent-progress");
    if (opponent && realtime.match?.attempt) {
      opponent.textContent =
        `${realtime.opponentProgress} / ${realtime.match.attempt.questions.length}`;
    }
  }

  function sendProgress(answeredCount) {
    if (realtime.socket?.readyState === WebSocket.OPEN) {
      realtime.socket.send(
        JSON.stringify({ type: "progress", answered_count: answeredCount })
      );
    }
  }

  function renderActive(root, match) {
    progressPanel(root, match);
    const attempt = match.attempt;
    if (attempt.status !== "active") {
      const waiting = document.createElement("div");
      waiting.className = "realtime-submitted";
      waiting.innerHTML =
        "<strong>答案已锁定</strong><p>等待对手提交。双方完成后才会公开答案和 Rating 变化。</p>";
      root.append(waiting);
      updateClock();
      return;
    }
    const form = document.createElement("form");
    form.className = "choice-list realtime-answer-form";
    attempt.questions.forEach((question) => {
      const field = document.createElement("label");
      field.textContent = `${question.order}. ${question.prompt}`;
      const input = document.createElement("input");
      input.name = String(question.order);
      input.inputMode = "decimal";
      input.autocomplete = "off";
      input.addEventListener("input", () => {
        const answered = [...form.querySelectorAll("input")].filter(
          (item) => item.value.trim()
        ).length;
        updateProgressUI(answered);
        sendProgress(answered);
      });
      field.append(input);
      form.append(field);
    });
    const submit = document.createElement("button");
    submit.className = "primary-button";
    submit.type = "submit";
    submit.textContent = "提交并等待对手";
    form.append(submit);
    form.addEventListener("submit", async (event) => {
      event.preventDefault();
      submit.disabled = true;
      const data = new FormData(form);
      try {
        realtime.match = await api(
          `contests/attempts/${attempt.attempt_id}/submit/`,
          {
            method: "POST",
            headers: { "Idempotency-Key": createIdempotencyKey() },
            body: {
              answers: attempt.questions.map((question) => ({
                order: question.order,
                answer: data.get(String(question.order)) || "",
              })),
            },
          },
        );
        renderMatch();
      } catch (error) {
        showToast(error.message);
        submit.disabled = false;
      }
    });
    root.append(form);
    updateClock();
  }

  function renderCompleted(root, match) {
    const result = document.createElement("section");
    result.className = `realtime-result result-${match.result.winner}`;
    const outcome = document.createElement("strong");
    outcome.textContent =
      match.result.winner === "self"
        ? "获胜"
        : match.result.winner === "opponent"
        ? "本局惜败"
        : "平局";
    const score = document.createElement("p");
    score.textContent =
      `你 ${match.attempt.score} 分 · ${match.opponent.score} 分 ${match.opponent.nickname}`;
    const timeLine = document.createElement("p");
    timeLine.className = "realtime-time-line";
    const selfMs = match.attempt.duration_ms || 0;
    const opponentMs = match.opponent.duration_ms || 0;
    const selfSec = (selfMs / 1000).toFixed(1);
    const opponentSec = (opponentMs / 1000).toFixed(1);
    timeLine.textContent = `你 ${selfSec}s · ${match.opponent.nickname} ${opponentSec}s`;
    if (match.attempt.score === match.opponent.score && match.result.winner !== "draw") {
      const faster = selfMs < opponentMs ? "你" : match.opponent.nickname;
      const tiebreak = document.createElement("small");
      tiebreak.className = "realtime-tiebreak";
      tiebreak.textContent = `同分，${faster}更快完成，快者胜`;
      timeLine.append(tiebreak);
    }
    const rating = document.createElement("b");
    const sign = match.result.rating_delta > 0 ? "+" : "";
    rating.textContent =
      `Rating ${sign}${match.result.rating_delta} → ${match.result.rating_after}`;
    result.append(outcome, score, timeLine, rating);
    root.append(result);

    // 刷新右上角用户 Rating 显示
    if (typeof loadUser === "function") loadUser();

    const review = document.createElement("div");
    review.className = "realtime-review";
    match.attempt.questions.forEach((question) => {
      const item = document.createElement("article");
      const title = document.createElement("b");
      title.textContent = `${question.order}. ${question.prompt}`;
      const answer = document.createElement("p");
      answer.textContent =
        `你的答案：${question.submitted_answer || "未作答"} · 正确答案：${question.correct_answer}`;
      const explanation = document.createElement("small");
      explanation.textContent = question.explanation || "";
      item.className = question.is_correct ? "correct" : "incorrect";
      item.append(title, answer, explanation);
      review.append(item);
    });
    root.append(review);
  }

  function renderMatch() {
    const root = document.querySelector("#experience-content");
    const match = realtime.match;
    root.replaceChildren();
    header(root, match);
    if (match.status === "waiting") renderWaiting(root, match);
    else if (match.status === "active") renderActive(root, match);
    else if (match.status === "completed") renderCompleted(root, match);
    else {
      const message = document.createElement("p");
      message.className = "scene";
      message.textContent = "这场匹配已取消或联机码已过期。";
      root.append(message);
    }
  }

  function currentRealtimeContest() {
    return state.contests.find(
      (contest) => contest.kind === "realtime" && contest.track === state.track
    );
  }

  async function startRandom(contest) {
    const match = await api(`contests/${contest.slug}/matchmaking/`, {
      method: "POST",
      body: {},
    });
    openMatch(match);
  }

  async function createChallenge() {
    if (!requireAuth()) return;
    const contest = currentRealtimeContest();
    if (!contest) {
      showToast("当前赛道没有可用的实时比赛");
      return;
    }
    try {
      const match = await api(`contests/${contest.slug}/challenges/`, {
        method: "POST",
        body: {},
      });
      openMatch(match);
    } catch (error) {
      showToast(error.message);
    }
  }

  async function joinChallenge(event) {
    event.preventDefault();
    if (!requireAuth()) return;
    const input = document.querySelector("#challenge-code-input");
    const challengeCode = input.value.trim().toUpperCase();
    if (challengeCode.length !== 6) {
      showToast("请输入 6 位联机码");
      return;
    }
    try {
      const match = await api("contests/challenges/join/", {
        method: "POST",
        body: { challenge_code: challengeCode },
      });
      input.value = "";
      openMatch(match);
    } catch (error) {
      showToast(error.message);
    }
  }

  function init() {
    document
      .querySelector("#challenge-create")
      .addEventListener("click", createChallenge);
    document
      .querySelector("#challenge-join-form")
      .addEventListener("submit", joinChallenge);
    document
      .querySelector("#challenge-code-input")
      .addEventListener("input", (event) => {
        event.target.value = event.target.value
          .toUpperCase()
          .replace(/[^ABCDEFGHJKLMNPQRSTUVWXYZ23456789]/g, "")
          .slice(0, 6);
      });
  }

  function reset() {
    stopTimers();
    closeSocket();
    realtime.match = null;
    realtime.opponentProgress = 0;
  }

  window.HuluRealtime = { init, startRandom, refreshMatch, reset };
})();