// Single source of truth for all backend communication.

async function http(path, { method = 'GET', body } = {}) {
  const headers = { 'Content-Type': 'application/json' };

  const res = await fetch(path, {
    method,
    headers,
    credentials: 'include',
    body: body ? JSON.stringify(body) : undefined,
  });

  if (!res.ok) {
    let message = res.statusText;
    let data;
    try {
      data = await res.json();
      message = data.error || data.message || message;
    } catch {
      message = (await res.text().catch(() => message)) || message;
    }
    const err = new Error(message || `Request failed (${res.status})`);
    err.status = res.status;
    err.data = data;
    throw err;
  }
  if (res.status === 204) return null;
  return res.json();
}

export const auth = {
  async me() {
    try {
      const data = await http('/api/auth/me');
      return {
        user: data.user ?? null,
        googleClientId: data.googleClientId ?? null,
      };
    } catch (err) {
      if (err.status === 401 || err.status === 403) {
        return {
          user: null,
          googleClientId: err.data?.googleClientId ?? null,
          forbidden: err.status === 403,
          message: err.message,
        };
      }
      throw err;
    }
  },

  async loginWithGoogle(idToken) {
    const data = await http('/api/auth/login', {
      method: 'POST',
      body: { idToken },
    });
    return { user: data.user };
  },

  async logout() {
    try {
      await http('/api/auth/logout', { method: 'POST' });
    } catch (err) {
      if (err.status !== 401) throw err;
    }
  },
};

export default { auth };