import { getStoredToken } from './auth-context';
import { getTenantFromPath } from './tenant-context';

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:8000';

function getHeaders(): HeadersInit {
  const token = getStoredToken();
  return {
    'Content-Type': 'application/json',
    ...(token ? { 'Authorization': `Bearer ${token}` } : {}),
  };
}

async function parseErrorDetail(res: Response): Promise<string> {
  try {
    const body = await res.json();
    return body.detail || body.message || 'API request failed';
  } catch {
    return 'API request failed';
  }
}

export async function fetcher<T>(url: string): Promise<T> {
  const res = await fetch(`${API_BASE_URL}${url}`, {
    headers: getHeaders(),
  });
  if (!res.ok) {
    const detail = await parseErrorDetail(res);
    throw new Error(detail);
  }
  return res.json();
}

export function getTenantUrl(path: string, tenantId?: string): string {
  const tenant = tenantId || getTenantFromPath();
  if (!tenant) {
    throw new Error('Tenant ID not found');
  }
  return `/api/${tenant}${path}`;
}

export const api = {
  get: <T>(url: string) => fetcher<T>(url),

  post: async <T>(url: string, data: unknown): Promise<T> => {
    const res = await fetch(`${API_BASE_URL}${url}`, {
      method: 'POST',
      headers: getHeaders(),
      body: JSON.stringify(data),
    });
    if (!res.ok) throw new Error(await parseErrorDetail(res));
    return res.json();
  },

  put: async <T>(url: string, data: unknown): Promise<T> => {
    const res = await fetch(`${API_BASE_URL}${url}`, {
      method: 'PUT',
      headers: getHeaders(),
      body: JSON.stringify(data),
    });
    if (!res.ok) throw new Error(await parseErrorDetail(res));
    return res.json();
  },

  patch: async <T>(url: string, data: unknown): Promise<T> => {
    const res = await fetch(`${API_BASE_URL}${url}`, {
      method: 'PATCH',
      headers: getHeaders(),
      body: JSON.stringify(data),
    });
    if (!res.ok) throw new Error(await parseErrorDetail(res));
    return res.json();
  },

  delete: async <T>(url: string): Promise<T> => {
    const res = await fetch(`${API_BASE_URL}${url}`, {
      method: 'DELETE',
      headers: getHeaders(),
    });
    if (!res.ok) throw new Error(await parseErrorDetail(res));
    return res.json();
  },
};