export const apiBaseUrl = import.meta.env.VITE_API_URL ?? "http://localhost:3001";

export function extractErrorMessage(payload, status) {
  if (payload?.msg) return payload.msg;
  if (payload?.error) return payload.error;
  if (payload?.message) return payload.message;
  return `http_error:${status}`;
}


export class ApiError extends Error {
  constructor(category, message, extra = {}) {
    super(message || category);
    this.category = category;
    Object.assign(this, extra);
  }
}

export function categorizeHttpStatus(status) {
  if (status === 401) return "invalid_credentials";
  if (status === 429) return "locked";
  return "server";
}

let _accessToken = null;
let _refreshFn = null;
let _authErrorFn = null;
let _refreshPromise = null;

export function setAccessToken(token) {
  _accessToken = token ?? null;
}

export function setRefreshCallback(fn) {
  _refreshFn = fn ?? null;
}

export function setAuthErrorCallback(fn) {
  _authErrorFn = fn ?? null;
}

export function buildAuthHeaders(extra = {}) {
  const headers = { "content-type": "application/json", ...extra };
  if (_accessToken) headers["Authorization"] = `Bearer ${_accessToken}`;
  return headers;
}


export async function refreshAccessToken() {
  if (!_refreshFn) return null;
  if (!_refreshPromise) {
    _refreshPromise = _refreshFn().finally(() => { _refreshPromise = null; });
  }
  return _refreshPromise;
}

export function notifyAuthError() {
  _authErrorFn?.();
}

export async function apiFetch(path, { method = "GET", body } = {}) {
  const headers = { "content-type": "application/json" };
  if (_accessToken) headers["Authorization"] = `Bearer ${_accessToken}`;

  let res;
  try {
    res = await fetch(`${apiBaseUrl}${path}`, {
      method,
      headers,
      body: body ? JSON.stringify(body) : undefined
    });
  } catch {
    throw new ApiError("network", "network_error");
  }

  if (res.status === 401 && _refreshFn) {
    let newToken;
    try {
      newToken = await refreshAccessToken();
    } catch {
      _authErrorFn?.();
      throw new Error("session_expired");
    }
    if (newToken) {
      headers["Authorization"] = `Bearer ${newToken}`;
      try {
        res = await fetch(`${apiBaseUrl}${path}`, {
          method,
          headers,
          body: body ? JSON.stringify(body) : undefined
        });
      } catch {
        throw new ApiError("network", "network_error");
      }
    }
  }

  if (res.status === 401) {
    _authErrorFn?.();
    throw new Error("session_expired");
  }

  if (!res.ok) {
    const text = await res.text().catch(() => "");
    let payload = null;
    try { payload = JSON.parse(text); } catch {}
    throw new Error(extractErrorMessage(payload, res.status) || text || `http_error:${res.status}`);
  }

  const contentType = res.headers.get("content-type") ?? "";
  if (contentType.includes("application/json")) return res.json();
  return res.text();
}