const SESSION_TIMEOUT_MS = 30 * 60 * 1000;

export const API_URL = import.meta.env.VITE_API_URL || "http://localhost:8000";

interface SessionData {
  token?: string;
  username?: string;
  company?: string;
  lastActivity?: number;
}

function getSession(): SessionData {
  try {
    return JSON.parse(localStorage.getItem("sap_session") || "{}");
  } catch {
    return {};
  }
}

function saveSession(data: SessionData): void {
  localStorage.setItem("sap_session", JSON.stringify(data));
}

function clearSession(): void {
  localStorage.removeItem("sap_session");
}

export function getToken(): string | null {
  return getSession().token || null;
}

export function getUsername(): string | null {
  return getSession().username || null;
}

export function getCompany(): string | null {
  return getSession().company || null;
}

export function setSession(token: string, username: string, company?: string): void {
  saveSession({ token, username, company, lastActivity: Date.now() });
}

function hasTimedOut(): boolean {
  const session = getSession();
  if (!session.lastActivity) return false;
  return Date.now() - session.lastActivity > SESSION_TIMEOUT_MS;
}

function updateLastActivity(): void {
  const session = getSession();
  if (session.token) {
    session.lastActivity = Date.now();
    saveSession(session);
  }
}

function expireSession(): void {
  clearSession();
  window.location.href = "/login";
}

export async function apiFetch(url: string, options: RequestInit = {}): Promise<Response> {
  if (hasTimedOut()) {
    expireSession();
    throw new Error("Sesión expirada");
  }

  const token = getToken();
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
    ...(token ? { "X-Session-Token": token } : {}),
  };

  const customHeaders = options.headers as Record<string, string> | undefined;
  if (customHeaders) {
    for (const key of Object.keys(customHeaders)) {
      headers[key] = customHeaders[key];
    }
  }

  const response = await fetch(url, { ...options, headers });

  if (response.status === 401) {
    expireSession();
    throw new Error("Sesión expirada");
  }

  updateLastActivity();
  return response;
}