(function () {
  const sessionId = window.location.pathname.split("/").pop();
  const canvas = document.getElementById("screen");
  const ctx = canvas.getContext("2d");
  const addressBar = document.getElementById("address-bar");
  const statusEl = document.getElementById("status");
  const overlay = document.getElementById("overlay");
  const overlayMsg = document.getElementById("overlay-msg");

  let ws = null;
  let viewportWidth = 1024;
  let viewportHeight = 576;
  let scaleX = 1;
  let scaleY = 1;
  let pingTimer = null;
  let pendingFrame = null;
  let frameScheduled = false;
  let frameCount = 0;
  let lastFpsTime = performance.now();
  const frameImage = new Image();

  const wsProtocol = window.location.protocol === "https:" ? "wss:" : "ws:";
  const wsUrl = `${wsProtocol}//${window.location.host}/ws/${sessionId}`;

  function setStatus(text) {
    statusEl.textContent = text;
  }

  function showOverlay(message) {
    overlayMsg.textContent = message;
    overlay.classList.remove("hidden");
  }

  function mapCoords(clientX, clientY) {
    const rect = canvas.getBoundingClientRect();
    const x = (clientX - rect.left) / scaleX;
    const y = (clientY - rect.top) / scaleY;
    return { x, y };
  }

  function send(payload) {
    if (ws && ws.readyState === WebSocket.OPEN) {
      ws.send(JSON.stringify(payload));
    }
  }

  function drawDecodedFrame() {
    if (canvas.width !== frameImage.width || canvas.height !== frameImage.height) {
      canvas.width = frameImage.width;
      canvas.height = frameImage.height;
      viewportWidth = frameImage.width;
      viewportHeight = frameImage.height;
      updateScale();
    }
    ctx.drawImage(frameImage, 0, 0);
    frameCount += 1;
    const now = performance.now();
    if (now - lastFpsTime >= 2000) {
      const fps = Math.round((frameCount * 1000) / (now - lastFpsTime));
      setStatus(`已连接 · ${fps} fps`);
      frameCount = 0;
      lastFpsTime = now;
    }
  }

  function scheduleFrame(arrayBuffer) {
    pendingFrame = arrayBuffer;
    if (frameScheduled) {
      return;
    }
    frameScheduled = true;
    requestAnimationFrame(() => {
      frameScheduled = false;
      if (!pendingFrame) {
        return;
      }
      const blob = new Blob([pendingFrame], { type: "image/jpeg" });
      pendingFrame = null;
      const url = URL.createObjectURL(blob);
      frameImage.onload = () => {
        URL.revokeObjectURL(url);
        drawDecodedFrame();
      };
      frameImage.src = url;
    });
  }

  function updateScale() {
    const rect = canvas.getBoundingClientRect();
    scaleX = rect.width / viewportWidth;
    scaleY = rect.height / viewportHeight;
  }

  function connect() {
    ws = new WebSocket(wsUrl);
    ws.binaryType = "arraybuffer";

    ws.onopen = () => {
      setStatus("已连接");
      pingTimer = setInterval(() => send({ type: "ping" }), 60000);
    };

    ws.onmessage = (event) => {
      if (event.data instanceof ArrayBuffer) {
        scheduleFrame(event.data);
        return;
      }

      try {
        const msg = JSON.parse(event.data);
        if (msg.type === "init") {
          viewportWidth = msg.width;
          viewportHeight = msg.height;
          addressBar.value = msg.url || "";
          updateScale();
        } else if (msg.type === "url" || msg.type === "url_update") {
          addressBar.value = msg.url || "";
        } else if (msg.type === "closed") {
          showOverlay("会话已结束");
          ws.close();
        } else if (msg.type === "error") {
          setStatus(msg.message);
        }
      } catch (_) {
        /* ignore */
      }
    };

    ws.onclose = () => {
      setStatus("已断开");
      clearInterval(pingTimer);
    };

    ws.onerror = () => {
      setStatus("连接错误");
    };
  }

  canvas.addEventListener("click", (e) => {
    canvas.focus();
    const { x, y } = mapCoords(e.clientX, e.clientY);
    send({ action: "click", x, y, button: "left" });
  });

  canvas.addEventListener("dblclick", (e) => {
    e.preventDefault();
    const { x, y } = mapCoords(e.clientX, e.clientY);
    send({ action: "dblclick", x, y });
  });

  canvas.addEventListener("wheel", (e) => {
    e.preventDefault();
    send({ action: "wheel", deltaX: e.deltaX, deltaY: e.deltaY });
  }, { passive: false });

  const specialKeys = new Set([
    "Enter", "Backspace", "Delete", "Tab", "Escape",
    "ArrowUp", "ArrowDown", "ArrowLeft", "ArrowRight",
    "Home", "End", "PageUp", "PageDown",
  ]);

  canvas.addEventListener("keydown", (e) => {
    e.preventDefault();
    if (e.key.length === 1 && !e.ctrlKey && !e.metaKey && !e.altKey) {
      send({ action: "type", text: e.key });
    } else if (specialKeys.has(e.key)) {
      send({ action: "press", key: e.key });
    } else {
      send({ action: "keydown", key: e.key });
    }
  });

  canvas.addEventListener("keyup", (e) => {
    e.preventDefault();
    if (e.key.length > 1 || e.ctrlKey || e.metaKey || e.altKey) {
      send({ action: "keyup", key: e.key });
    }
  });

  window.addEventListener("resize", updateScale);

  async function apiPost(path) {
    const res = await fetch(path, { method: "POST", credentials: "include" });
    if (res.status === 401) {
      window.location.href = "/";
      return null;
    }
    return res.json();
  }

  async function ensureAuth() {
    const res = await fetch("/api/auth/me", { credentials: "include" });
    if (!res.ok) {
      window.location.href = "/";
      return false;
    }
    return true;
  }

  document.getElementById("btn-back").addEventListener("click", async () => {
    const data = await apiPost(`/api/session/${sessionId}/back`);
    if (data) addressBar.value = data.url;
  });

  document.getElementById("btn-forward").addEventListener("click", async () => {
    const data = await apiPost(`/api/session/${sessionId}/forward`);
    if (data) addressBar.value = data.url;
  });

  document.getElementById("btn-reload").addEventListener("click", async () => {
    const data = await apiPost(`/api/session/${sessionId}/reload`);
    if (data) addressBar.value = data.url;
  });

  function navigateTo(url) {
    send({ type: "navigate", url });
  }

  document.getElementById("btn-go").addEventListener("click", () => {
    navigateTo(addressBar.value.trim());
  });

  addressBar.addEventListener("keydown", (e) => {
    if (e.key === "Enter") {
      navigateTo(addressBar.value.trim());
    }
  });

  document.getElementById("btn-close").addEventListener("click", async () => {
    await fetch(`/api/session/${sessionId}`, { method: "DELETE", credentials: "include" });
    showOverlay("会话已关闭");
    if (ws) ws.close();
  });

  ensureAuth().then((ok) => {
    if (ok) {
      connect();
      canvas.focus();
    }
  });
})();