import { API_BASE_URL } from "./config";

const TOKEN_KEY = "classlens_token";

export function getToken(): string | null {
  return localStorage.getItem(TOKEN_KEY);
}

export function setToken(token: string) {
  localStorage.setItem(TOKEN_KEY, token);
}

export function clearToken() {
  localStorage.removeItem(TOKEN_KEY);
}

function authHeaders(): Record<string, string> {
  const token = getToken();
  return token ? { Authorization: `Bearer ${token}` } : {};
}

async function handleResponse<T>(res: Response): Promise<T> {
  if (res.status === 401) {
    clearToken();
    window.location.reload();
    throw new Error("Unauthorized");
  }
  if (!res.ok) {
    const text = await res.text();
    let msg = text;
    try {
      const j = JSON.parse(text);
      msg = j.detail || j.message || text;
    } catch {}
    throw new Error(msg);
  }
  return res.json();
}

export async function apiGet<T>(path: string): Promise<T> {
  const res = await fetch(`${API_BASE_URL}${path}`, {
    headers: { ...authHeaders() },
  });
  return handleResponse<T>(res);
}

export async function apiPost<T>(path: string, body?: unknown): Promise<T> {
  const res = await fetch(`${API_BASE_URL}${path}`, {
    method: "POST",
    headers: { "Content-Type": "application/json", ...authHeaders() },
    body: body ? JSON.stringify(body) : undefined,
  });
  return handleResponse<T>(res);
}

export async function apiPut<T>(path: string, body: unknown): Promise<T> {
  const res = await fetch(`${API_BASE_URL}${path}`, {
    method: "PUT",
    headers: { "Content-Type": "application/json", ...authHeaders() },
    body: JSON.stringify(body),
  });
  return handleResponse<T>(res);
}

export async function apiDelete(path: string): Promise<void> {
  const res = await fetch(`${API_BASE_URL}${path}`, {
    method: "DELETE",
    headers: { ...authHeaders() },
  });
  if (res.status === 401) {
    clearToken();
    window.location.reload();
    throw new Error("Unauthorized");
  }
  if (!res.ok) {
    const text = await res.text();
    throw new Error(text);
  }
}

export async function apiUpload<T>(path: string, formData: FormData): Promise<T> {
  const res = await fetch(`${API_BASE_URL}${path}`, {
    method: "POST",
    headers: { ...authHeaders() },
    body: formData,
  });
  return handleResponse<T>(res);
}