const DEFAULT_GANTT_API_BASE_URL = "http://localhost:3000/api";

function normalizeBaseUrl(url: string): string {
  return url.replace(/\/+$/, "");
}

export function getGanttApiBaseUrl(): string {
  const configured =
    process.env.GANTT_API_BASE_URL ||
    process.env.NEXT_PUBLIC_GANTT_API_BASE_URL ||
    DEFAULT_GANTT_API_BASE_URL;
  return normalizeBaseUrl(configured);
}

function buildAuthHeaders(): HeadersInit {
  const headers: Record<string, string> = {};

  if (process.env.GANTT_API_BEARER_TOKEN) {
    headers.Authorization = `Bearer ${process.env.GANTT_API_BEARER_TOKEN}`;
  }

  if (process.env.GANTT_API_COOKIE) {
    headers.Cookie = process.env.GANTT_API_COOKIE;
  }

  return headers;
}

export async function fetchGanttApi<T>(endpoint: string): Promise<T> {
  const baseUrl = getGanttApiBaseUrl();
  const response = await fetch(`${baseUrl}${endpoint}`, {
    method: "GET",
    cache: "no-store",
    headers: {
      Accept: "application/json",
      ...buildAuthHeaders(),
    },
  });

  const payload = (await response.json().catch(() => null)) as
    | { error?: string; message?: string }
    | null;

  if (!response.ok) {
    const details = payload?.error || payload?.message || response.statusText;
    throw new Error(`gantt-board API request failed (${response.status} ${endpoint}): ${details}`);
  }

  return payload as T;
}