// src/utils/apiUtils.js
import axios from 'axios';

/* ------------------------------------------------------------------
   Single authority for “baseURL + path” so we never worry
   about trailing slashes again.
 ------------------------------------------------------------------*/
const BASE = (
  import.meta.env.VITE_API_BASE ||
  process.env.REACT_APP_API_URL ||
  ''
).replace(/\/+$/, '');               // trim *all* trailing “/”

export const api = (path = '') =>
  `${BASE}${path.startsWith('/') ? '' : '/'}${path}`;

/* ------------------------------------------------------------------
   Fetch areas-by-state (static JSON in public/ or served by nginx)
 ------------------------------------------------------------------*/
export const fetchAreasByState = async (state) => {
  try {
    // NOTE: if Institution_data.json is in /public, nginx serves it
    const res = await fetch(api('/Institution_data.json'));
    if (!res.ok) throw new Error(`HTTP ${res.status}`);
    // Adjust this part if your JSON structure is different
    const json = await res.json();
    return json[state]?.areas || [];
  } catch (err) {
    console.error('Error fetching areas:', err.message);
    return [];
  }
};

/* ------------------------------------------------------------------
   Client-side Google Maps geocode
 ------------------------------------------------------------------*/
export async function clientGeocodeZip(zip) {
  const apiKey = import.meta.env.VITE_GOOGLE_MAPS_API_KEY ??
                 process.env.REACT_APP_GOOGLE_MAPS_API_KEY;
  const url = `https://maps.googleapis.com/maps/api/geocode/json` +
              `?address=${encodeURIComponent(zip)}&key=${apiKey}`;

  const resp = await axios.get(url);
  const { status, results } = resp.data;
  if (status === 'OK' && results.length) {
    return results[0].geometry.location;   // { lat, lng }
  }
  throw new Error('Geocoding failed.');
}

/* ------------------------------------------------------------------
   Haversine distance helper (miles)
 ------------------------------------------------------------------*/
export function haversineDistance(lat1, lon1, lat2, lon2) {
  const R = 3959; // earth radius in miles
  const toRad = (v) => (v * Math.PI) / 180;

  const dLat = toRad(lat2 - lat1);
  const dLon = toRad(lon2 - lon1);

  const a = Math.sin(dLat / 2) ** 2 +
            Math.cos(toRad(lat1)) *
            Math.cos(toRad(lat2)) *
            Math.sin(dLon / 2) ** 2;

  return 2 * R * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
}

/* ------------------------------------------------------------------
   Fetch schools for one or many CIP prefixes
 ------------------------------------------------------------------*/
export async function fetchSchools(cipCodes) {
  try {
    // 1) Ensure array-ness, then join with commas
    const codes = Array.isArray(cipCodes) ? cipCodes : [cipCodes];
    const cipParam = codes.join(',');

    // 2) Hit backend
    const res = await axios.get(api('/api/schools'), {
      params: { cipCodes: cipParam },
    });
    return res.data;
  } catch (err) {
    console.error('Error fetching schools:', err.message);
    return [];
  }
}