CurrenciCombo/src/services/http.ts

/**
 * Thin fetch wrapper with timeout + JSON handling + typed errors.
 * Keep this dependency-free so every service can share it.
 */

export class HttpError extends Error {
  readonly status: number;
  readonly statusText: string;
  readonly url: string;
  readonly body?: unknown;
  constructor(status: number, statusText: string, url: string, body?: unknown) {
    super(`HTTP ${status} ${statusText} (${url})`);
    this.name = 'HttpError';
    this.status = status;
    this.statusText = statusText;
    this.url = url;
    this.body = body;
  }
}

export interface HttpOptions extends Omit<RequestInit, 'body'> {
  /** Request body — automatically JSON-stringified when an object. */
  body?: unknown;
  /** Abort the request after N ms. Default 10000. */
  timeoutMs?: number;
}

export async function httpJson<T>(url: string, opts: HttpOptions = {}): Promise<T> {
  const { body, timeoutMs = 10_000, headers, ...rest } = opts;
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), timeoutMs);

  try {
    const res = await fetch(url, {
      ...rest,
      signal: controller.signal,
      headers: {
        Accept: 'application/json',
        ...(body !== undefined ? { 'Content-Type': 'application/json' } : {}),
        ...headers,
      },
      body: body === undefined ? undefined : typeof body === 'string' ? body : JSON.stringify(body),
    });

    if (!res.ok) {
      let parsed: unknown;
      try { parsed = await res.json(); } catch { parsed = await res.text().catch(() => undefined); }
      throw new HttpError(res.status, res.statusText, url, parsed);
    }

    const ct = res.headers.get('content-type') ?? '';
    if (ct.includes('application/json')) return (await res.json()) as T;
    return (await res.text()) as unknown as T;
  } finally {
    clearTimeout(timer);
  }
}