export class ApiError extends Error {
  constructor(message, status = 0, code = "error") {
    super(message);
    this.name = "ApiError";
    this.status = status;
    this.code = code;
  }
}

function buildUrl(path, params) {
  const url = new URL(path, window.location.origin);
  if (params) {
    for (const [key, value] of Object.entries(params)) {
      if (value === null || value === undefined || value === "") continue;
      url.searchParams.set(key, String(value));
    }
  }
  return url;
}

export async function api(path, params) {
  const response = await fetch(buildUrl(path, params), {
    headers: { Accept: "application/json" },
    credentials: "same-origin",
  });
  if (response.status === 401) {
    window.location.href = "/login";
    throw new ApiError("登录已失效，请重新登录", 401, "unauthorized");
  }
  let payload;
  try {
    payload = await response.json();
  } catch {
    throw new ApiError(`接口返回异常（HTTP ${response.status}）`, response.status);
  }
  if (!response.ok || !payload.ok) {
    const error = payload.error || {};
    throw new ApiError(
      error.message || `请求失败（HTTP ${response.status}）`,
      response.status,
      error.code || "error",
    );
  }
  return payload.data;
}

export async function health() {
  const response = await fetch("/api/health", { credentials: "same-origin" });
  if (!response.ok) throw new ApiError("无法连接看板服务", response.status);
  const payload = await response.json();
  return payload?.data ?? payload;
}

export async function session() {
  const response = await fetch("/api/session", { credentials: "same-origin" });
  if (!response.ok) throw new ApiError("无法连接看板服务", response.status);
  const payload = await response.json();
  return payload?.data ?? payload;
}

export async function stats(params) {
  return api("/api/stats", params);
}

export function visit(path) {
  // 访问统计埋点：优先 sendBeacon（不阻塞导航），失败时用 keepalive fetch 兜底。
  const body = JSON.stringify({ path });
  try {
    if (typeof navigator !== "undefined" && typeof navigator.sendBeacon === "function") {
      const blob = new Blob([body], { type: "application/json" });
      if (navigator.sendBeacon("/api/visit", blob)) return;
    }
  } catch {
    // 忽略，走 fetch 兜底
  }
  fetch("/api/visit", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body,
    credentials: "same-origin",
    keepalive: true,
  }).catch(() => {});
}