frontend/src/api/client.js

const DEFAULT_API_BASE_URL = '';

const normalizedBase = (import.meta.env?.VITE_API_BASE_URL ?? DEFAULT_API_BASE_URL).trim();
const API_BASE_URL = normalizedBase ? normalizedBase.replace(/\/+$/, '') : '';

async function request(path, { method = 'GET', params, body } = {}) {
  const basePath = path.startsWith('/') ? path : `/${path}`;
  const url = API_BASE_URL
    ? new URL(`${API_BASE_URL}${basePath}`)
    : new URL(basePath, window.location.origin);
  if (params) {
    Object.entries(params).forEach(([key, value]) => {
      if (value !== undefined && value !== null) {
        url.searchParams.set(key, value);
      }
    });
  }

  const headers = {};
  let payload;
  if (body !== undefined) {
    headers['Content-Type'] = 'application/json';
    payload = JSON.stringify(body);
  }

  const response = await fetch(url.toString(), {
    method,
    headers,
    body: payload,
  });

  if (!response.ok) {
    let errorMessage = `Request failed with status ${response.status}`;
    try {
      const errorBody = await response.json();
      errorMessage = errorBody.detail || errorBody.error || errorMessage;
    } catch {
      // ignore JSON parsing errors
    }
    throw new Error(errorMessage);
  }

  return response.json();
}

export function fetchProviders() {
  return request('/api/providers');
}

export function fetchSessions() {
  return request('/api/sessions');
}

export function fetchHistory(sessionId) {
  return request('/api/history', {
    params: { session_id: sessionId },
  });
}

export function sendQuery({ sessionId, question, provider }) {
  return request('/api/query', {
    method: 'POST',
    body: {
      session_id: sessionId,
      question,
      provider,
    },
  });
}