const connection = document.querySelector("#connection");
const detectionsEl = document.querySelector("#detections");
const frameIdEl = document.querySelector("#frame-id");
const fpsEl = document.querySelector("#fps");
const errorEl = document.querySelector("#error");
const sourceEl = document.querySelector("#source");
const deviceSelect = document.querySelector("#device-select");
const timingTokenEl = document.querySelector("#timing-token");
const timingSignEl = document.querySelector("#timing-sign");
const timingUrlEl = document.querySelector("#timing-url");
const timingOpenEl = document.querySelector("#timing-open");
const timingFrameEl = document.querySelector("#timing-frame");

let selectedDevice = "";
let pendingDevice = "";
let queuedDevice = "";
let switching = false;
let devicesSignature = "";
let lastWsSignature = "";

function setConnection(online, text) {
  connection.textContent = text;
  connection.classList.toggle("online", online);
  connection.classList.toggle("offline", !online);
}

function formatMs(value) {
  if (value === undefined || value === null || value === 0) {
    return "-";
  }
  return `${Number(value).toFixed(2)} ms`;
}

function renderDevices(devices, currentDeviceNum) {
  if (!devices.length) {
    deviceSelect.innerHTML = '<option value="">未配置摄像头</option>';
    deviceSelect.disabled = true;
    return;
  }

  const displayDevice = pendingDevice || currentDeviceNum;
  const nextSignature = `${displayDevice}|${devices.map((device) => device.device_num).join(",")}`;
  if (nextSignature === devicesSignature) {
    return;
  }

  selectedDevice = displayDevice;
  devicesSignature = nextSignature;
  deviceSelect.innerHTML = devices
    .map((device) => {
      const selected = device.device_num === displayDevice ? "selected" : "";
      return `<option value="${device.device_num}" ${selected}>${device.name} · ${device.device_num}</option>`;
    })
    .join("");
}

function renderTimings(timings) {
  timingTokenEl.textContent = timings?.token_cache ? "缓存" : formatMs(timings?.token_ms);
  timingSignEl.textContent = formatMs(timings?.sign_ms);
  timingUrlEl.textContent = formatMs(timings?.stream_url_ms);
  timingOpenEl.textContent = formatMs(timings?.open_ms);
  timingFrameEl.textContent = formatMs(timings?.first_frame_ms);
}

function renderDetections(detections) {
  if (!detections.length) {
    detectionsEl.className = "detections empty";
    detectionsEl.textContent = "暂无目标";
    return;
  }

  detectionsEl.className = "detections";
  detectionsEl.innerHTML = detections
    .map((det) => {
      const score = `${(det.score * 100).toFixed(1)}%`;
      const box = det.box.join(", ");
      return `
        <div class="det-item">
          <div class="det-title">
            <span>${det.label}</span>
            <span>${score}</span>
          </div>
          <div class="det-box">box: [${box}]</div>
        </div>
      `;
    })
    .join("");
}

async function performSwitch(deviceNum) {
  switching = true;
  pendingDevice = deviceNum;
  devicesSignature = "";
  setConnection(false, "切换中");
  console.log("[device-switch] start", { deviceNum });

  try {
    const response = await fetch(`/devices/${encodeURIComponent(deviceNum)}`, { method: "POST" });
    if (!response.ok) {
      throw new Error("切换摄像头失败");
    }
    const result = await response.json();
    const video = document.querySelector("#video");
    if (video) {
      video.src = `/video?t=${Date.now()}`;
    }
    document.querySelectorAll(".grid-video").forEach((item) => {
      item.src = `${item.dataset.src}?t=${Date.now()}`;
    });
    console.log("[device-switch] requested", { deviceNum, version: result.version });
  } catch (error) {
    pendingDevice = "";
    devicesSignature = "";
    setConnection(false, "切换失败");
    console.error("[device-switch] failed", { deviceNum, error });
  } finally {
    switching = false;
    if (queuedDevice && queuedDevice !== deviceNum) {
      const nextDevice = queuedDevice;
      queuedDevice = "";
      return performSwitch(nextDevice);
    }
    queuedDevice = "";
  }
}

function switchDevice(deviceNum) {
  if (switching) {
    queuedDevice = deviceNum;
    pendingDevice = deviceNum;
    devicesSignature = "";
    setConnection(false, "等待切换");
    console.log("[device-switch] queued", { deviceNum });
    return Promise.resolve();
  }

  return performSwitch(deviceNum);
}

function connectWebSocket() {
  const protocol = window.location.protocol === "https:" ? "wss" : "ws";
  const ws = new WebSocket(`${protocol}://${window.location.host}/ws/detections`);

  ws.addEventListener("open", () => setConnection(true, "已连接"));

  ws.addEventListener("message", (event) => {
    const data = JSON.parse(event.data);
    frameIdEl.textContent = data.frame_id ?? "-";
    fpsEl.textContent = data.fps ?? "-";
    errorEl.textContent = data.error || (data.connected ? "正常" : "未连接");
    sourceEl.textContent = data.source || "-";
    setConnection(Boolean(data.connected), data.connected ? "已连接" : "重连中");
    const wsSignature = `${data.current_device_num}|${data.connected}|${data.frame_id}|${data.error || ""}`;
    if (wsSignature !== lastWsSignature) {
      lastWsSignature = wsSignature;
      console.log("[device-switch] ws", {
        currentDeviceNum: data.current_device_num,
        pendingDevice,
        queuedDevice,
        connected: data.connected,
        frameId: data.frame_id,
        error: data.error,
      });
    }
    if (pendingDevice && data.current_device_num === pendingDevice) {
      pendingDevice = "";
      deviceSelect.disabled = false;
    }
    renderDevices(data.devices || [], data.current_device_num || "");
    renderTimings(data.timings || {});
    renderDetections(data.detections || []);
  });

  ws.addEventListener("close", () => {
    setConnection(false, "已断开");
    setTimeout(connectWebSocket, 1500);
  });

  ws.addEventListener("error", () => {
    setConnection(false, "连接错误");
    ws.close();
  });
}

deviceSelect.addEventListener("change", (event) => {
  selectedDevice = event.target.value;
  switchDevice(event.target.value).catch(() => {
    pendingDevice = "";
    devicesSignature = "";
    setConnection(false, "切换失败");
    deviceSelect.disabled = false;
  });
});

connectWebSocket();