import { authFetchOrThrow, getApiBase } from "./auth";

export type ApiTransport = (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;

export class ApiClientError extends Error {
  readonly status: number;

  constructor(status: number, message: string) {
    super(message);
    this.name = "ApiClientError";
    this.status = status;
  }
}

const errorMessage = (payload: unknown, fallback: string) => {
  if (!payload || typeof payload !== "object") return fallback;
  const record = payload as Record<string, unknown>;
  for (const key of ["detail", "error", "message"]) {
    const value = record[key];
    if (typeof value === "string" && value.trim()) return value.trim();
  }
  return fallback;
};

export const apiUrl = (path: string) => {
  const normalizedPath = path.startsWith("/") ? path : `/${path}`;
  return `${getApiBase()}${normalizedPath}`;
};

export async function requestJson<T>(
  path: string,
  init?: RequestInit,
  transport: ApiTransport = authFetchOrThrow,
): Promise<T> {
  const response = await transport(apiUrl(path), init);
  if (response.status === 204) return undefined as T;

  const text = await response.text();
  let payload: unknown = null;
  if (text) {
    try {
      payload = JSON.parse(text);
    } catch {
      payload = text;
    }
  }

  if (!response.ok) {
    throw new ApiClientError(response.status, errorMessage(payload, text || `Request failed: ${response.status}`));
  }
  return payload as T;
}