住所オートコンプリートAPI：1つのフィールドがチェックアウトコンバージョンを35%向上させる方法

GET https://api.mapatlas.eu/geocoding/v1/autocomplete?text={query}&key={YOUR_API_KEY}

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": { "type": "Point", "coordinates": [4.9041, 52.3676] },
      "properties": {
        "id": "address:node/1234567",
        "label": "Damrak 1, 1012 LG Amsterdam, Netherlands",
        "name": "Damrak 1",
        "street": "Damrak",
        "housenumber": "1",
        "postalcode": "1012 LG",
        "locality": "Amsterdam",
        "region": "North Holland",
        "country": "Netherlands",
        "country_code": "NL",
        "confidence": 0.98
      }
    }
  ]
}

// hooks/useAddressAutocomplete.js
import { useState, useEffect, useRef } from 'react';

const API_BASE = 'https://api.mapatlas.eu/geocoding/v1/autocomplete';
const API_KEY  = process.env.NEXT_PUBLIC_MAPATLAS_KEY;
const DEBOUNCE_MS = 300;
const MIN_CHARS   = 3;

export function useAddressAutocomplete(countryCode = null) {
  const [query,       setQuery]       = useState('');
  const [suggestions, setSuggestions] = useState([]);
  const [loading,     setLoading]     = useState(false);
  const [error,       setError]       = useState(null);
  const debounceTimer = useRef(null);

  useEffect(() => {
    if (query.length < MIN_CHARS) {
      setSuggestions([]);
      return;
    }

    clearTimeout(debounceTimer.current);

    debounceTimer.current = setTimeout(async () => {
      setLoading(true);
      setError(null);

      try {
        const url = new URL(API_BASE);
        url.searchParams.set('text', query);
        url.searchParams.set('key', API_KEY);
        url.searchParams.set('size', '6');
        url.searchParams.set('layers', 'address');
        if (countryCode) {
          url.searchParams.set('boundary.country', countryCode);
        }

        const res  = await fetch(url.toString());
        if (!res.ok) throw new Error(`API error: ${res.status}`);

        const data = await res.json();
        setSuggestions(data.features ?? []);
      } catch (err) {
        setError(err.message);
        setSuggestions([]);
      } finally {
        setLoading(false);
      }
    }, DEBOUNCE_MS);

    return () => clearTimeout(debounceTimer.current);
  }, [query, countryCode]);

  return { query, setQuery, suggestions, loading, error };
}

// components/AddressAutocomplete.jsx
import { useState, useRef } from 'react';
import { useAddressAutocomplete } from '../hooks/useAddressAutocomplete';

export function AddressAutocomplete({ onSelect, countryCode, placeholder }) {
  const { query, setQuery, suggestions, loading } = useAddressAutocomplete(countryCode);
  const [open,        setOpen]    = useState(false);
  const [highlighted, setHighlighted] = useState(-1);
  const inputRef = useRef(null);

  function handleSelect(feature) {
    const p = feature.properties;
    setQuery(p.label);
    setOpen(false);
    setHighlighted(-1);
    onSelect({
      label:       p.label,
      street:      p.street      ?? '',
      housenumber: p.housenumber ?? '',
      postalcode:  p.postalcode  ?? '',
      locality:    p.locality    ?? '',
      region:      p.region      ?? '',
      country:     p.country     ?? '',
      country_code: p.country_code ?? '',
      coordinates: feature.geometry.coordinates, // [lng, lat]
    });
  }

  function handleKeyDown(e) {
    if (!open || suggestions.length === 0) return;
    if (e.key === 'ArrowDown')  setHighlighted(h => Math.min(h + 1, suggestions.length - 1));
    if (e.key === 'ArrowUp')    setHighlighted(h => Math.max(h - 1, 0));
    if (e.key === 'Enter' && highlighted >= 0) handleSelect(suggestions[highlighted]);
    if (e.key === 'Escape')     setOpen(false);
  }

  return (
    <div style={{ position: 'relative' }}>
      <input
        ref={inputRef}
        type="text"
        value={query}
        placeholder={placeholder ?? 'Start typing your address...'}
        onChange={e => { setQuery(e.target.value); setOpen(true); setHighlighted(-1); }}
        onKeyDown={handleKeyDown}
        onBlur={() => setTimeout(() => setOpen(false), 150)}
        style={{ width: '100%', padding: '10px 12px', fontSize: 16, borderRadius: 6, border: '1px solid #ccc' }}
        autoComplete="off"
        aria-autocomplete="list"
        aria-haspopup="listbox"
        aria-expanded={open && suggestions.length > 0}
      />

      {loading && (
        <span style={{ position: 'absolute', right: 12, top: '50%', transform: 'translateY(-50%)', fontSize: 12, color: '#888' }}>
          Searching…
        </span>
      )}

      {open && suggestions.length > 0 && (
        <ul
          role="listbox"
          style={{
            position: 'absolute', top: '100%', left: 0, right: 0, zIndex: 999,
            background: '#fff', border: '1px solid #ccc', borderTop: 'none',
            borderRadius: '0 0 6px 6px', listStyle: 'none', margin: 0, padding: 0,
            boxShadow: '0 4px 12px rgba(0,0,0,0.1)',
          }}
        >
          {suggestions.map((feature, i) => (
            <li
              key={feature.properties.id}
              role="option"
              aria-selected={i === highlighted}
              onMouseDown={() => handleSelect(feature)}
              onMouseEnter={() => setHighlighted(i)}
              style={{
                padding: '10px 12px',
                cursor: 'pointer',
                fontSize: 14,
                background: i === highlighted ? '#f0f7e6' : '#fff',
                borderBottom: i < suggestions.length - 1 ? '1px solid #f0f0f0' : 'none',
              }}
            >
              {feature.properties.label}
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}

// pages/checkout.jsx
import { useState } from 'react';
import { AddressAutocomplete } from '../components/AddressAutocomplete';

export default function CheckoutPage() {
  const [address, setAddress] = useState({
    street: '', housenumber: '', postalcode: '',
    locality: '', country: '', coordinates: null,
  });

  function handleAddressSelect(selected) {
    setAddress(selected);
    // Coordinates are available for routing/delivery estimation
    console.log('Delivery coordinates:', selected.coordinates);
  }

  return (
    <form>
      <h2>Delivery address</h2>

      <AddressAutocomplete
        onSelect={handleAddressSelect}
        countryCode="NLD"  // Restrict to Netherlands, remove for EU-wide
        placeholder="Start typing your street address..."
      />

      {/* Show structured fields after selection, allow manual edits */}
      {address.street && (
        <div style={{ display: 'grid', gridTemplateColumns: '1fr auto', gap: 8, marginTop: 12 }}>
          <input value={address.street}      onChange={e => setAddress(a => ({ ...a, street: e.target.value }))}      placeholder="Street" />
          <input value={address.housenumber} onChange={e => setAddress(a => ({ ...a, housenumber: e.target.value }))} placeholder="No." style={{ width: 80 }} />
          <input value={address.postalcode}  onChange={e => setAddress(a => ({ ...a, postalcode: e.target.value }))}  placeholder="Postal code" />
          <input value={address.locality}    onChange={e => setAddress(a => ({ ...a, locality: e.target.value }))}    placeholder="City" />
        </div>
      )}

      <button type="submit" style={{ marginTop: 16 }}>
        Continue to payment
      </button>
    </form>
  );
}

// pages/api/autocomplete.js (Next.js API route)
export default async function handler(req, res) {
  const { text, countryCode } = req.query;
  const url = new URL('https://api.mapatlas.eu/geocoding/v1/autocomplete');
  url.searchParams.set('text',  text);
  url.searchParams.set('key',   process.env.MAPATLAS_KEY); // Server-side env var
  url.searchParams.set('size',  '6');
  url.searchParams.set('layers', 'address');
  if (countryCode) url.searchParams.set('boundary.country', countryCode);

  const response = await fetch(url.toString());
  const data     = await response.json();
  res.json(data);
}