export const API_BASE =
  process.env.NEXT_PUBLIC_API_BASE_URL || "http://localhost:8000";

const TOKEN_KEY = "agentic_token";

export function getToken(): string | null {
  if (typeof window === "undefined") return null;
  return window.localStorage.getItem(TOKEN_KEY);
}

export function setToken(token: string | null) {
  if (typeof window === "undefined") return;
  if (token) window.localStorage.setItem(TOKEN_KEY, token);
  else window.localStorage.removeItem(TOKEN_KEY);
}

export class ApiError extends Error {
  status: number;
  constructor(status: number, message: string) {
    super(message);
    this.status = status;
  }
}

export async function api<T = any>(
  path: string,
  options: RequestInit = {}
): Promise<T> {
  const headers = new Headers(options.headers);
  const token = getToken();
  if (token) headers.set("Authorization", `Bearer ${token}`);
  if (!headers.has("Content-Type") && options.body && !(options.body instanceof FormData)) {
    headers.set("Content-Type", "application/json");
  }
  const res = await fetch(`${API_BASE}${path}`, { ...options, headers });
  if (res.status === 401 && typeof window !== "undefined") {
    setToken(null);
    if (!window.location.pathname.startsWith("/login")) {
      window.location.href = "/login";
    }
  }
  if (!res.ok) {
    let detail = res.statusText;
    try {
      const body = await res.json();
      detail = body.detail || detail;
    } catch {}
    throw new ApiError(res.status, typeof detail === "string" ? detail : JSON.stringify(detail));
  }
  if (res.status === 204) return undefined as T;
  return res.json();
}

export async function login(email: string, password: string) {
  const form = new URLSearchParams();
  form.set("username", email);
  form.set("password", password);
  const res = await fetch(`${API_BASE}/api/auth/login`, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: form.toString(),
  });
  if (!res.ok) {
    let detail = "Login failed";
    try {
      detail = (await res.json()).detail || detail;
    } catch {}
    throw new ApiError(res.status, detail);
  }
  return res.json() as Promise<{ access_token: string; role: string; email: string }>;
}

export function wsUrl(path: string): string {
  const base = API_BASE.replace(/^http/, "ws");
  const token = getToken();
  const sep = path.includes("?") ? "&" : "?";
  return `${base}${path}${sep}token=${encodeURIComponent(token || "")}`;
}

export const fetcher = (path: string) => api(path);