const KEYS = ["token", "role", "wallet", "username"];

export function session() {
  return {
    token: localStorage.getItem("token") || "",
    role: localStorage.getItem("role") || "",
    wallet: localStorage.getItem("wallet") || "",
    username: localStorage.getItem("username") || "",
  };
}

export function saveSession(payload) {
  localStorage.setItem("token", payload.access_token);
  localStorage.setItem("role", payload.role);
  localStorage.setItem("wallet", payload.wallet_address);
  localStorage.setItem("username", payload.username || "");
}

export function clearSession() {
  KEYS.forEach((key) => localStorage.removeItem(key));
}

export async function api(path, options = {}) {
  const headers = { ...(options.headers || {}) };
  if (options.body && !headers["Content-Type"]) headers["Content-Type"] = "application/json";
  const token = localStorage.getItem("token");
  if (token) headers.Authorization = `Bearer ${token}`;
  const response = await fetch(`/api/v1${path}`, { ...options, headers });
  const text = await response.text();
  const data = text ? JSON.parse(text) : null;
  if (response.status === 401) {
    clearSession();
    if (location.pathname !== "/login") location.assign("/login");
    throw new Error(messageOf(data) || "登录已失效");
  }
  if (!response.ok) throw new Error(messageOf(data) || "请求失败");
  return data;
}

export async function download(path, filename) {
  const headers = {};
  const token = localStorage.getItem("token");
  if (token) headers.Authorization = `Bearer ${token}`;
  const response = await fetch(`/api/v1${path}`, { headers });
  if (response.status === 401) {
    clearSession();
    if (location.pathname !== "/login") location.assign("/login");
    throw new Error("登录已失效");
  }
  if (!response.ok) {
    const text = await response.text();
    const data = text ? JSON.parse(text) : null;
    throw new Error(messageOf(data) || "下载失败");
  }
  const blob = await response.blob();
  const url = URL.createObjectURL(blob);
  const link = document.createElement("a");
  link.href = url;
  link.download = filename;
  link.click();
  URL.revokeObjectURL(url);
}

function messageOf(data) {
  if (!data) return "";
  if (typeof data.detail === "string") return data.detail;
  if (Array.isArray(data.detail)) return data.detail.map((item) => item.msg).filter(Boolean).join("；");
  return "";
}