// 商品實體類
@Document(indexName = "products")
public class Product {
    @Id
    private String id;
    
    // 使用ik_max_word分詞器
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String title; 
    
    private Double price;
    private Long sales;
    // getters/setters
}
// 搜索服務
@Service 
public class ProductService {
    @Autowired
    private ElasticsearchOperations esOperations;
    public List<Product> search(String keyword) {
        Query query = NativeQuery.builder()
            .withQuery(q -> q
                .match(m -> m      // 多字段匹配
                    .field("title")
                    .field("description")
                    .query(keyword)
                )
            )
            .withSort(s -> s     // 綜合排序：銷量倒序 > 價格升序
                .field(f -> f.field("sales").order(SortOrder.Desc))
                .field(f -> f.field("price").order(SortOrder.Asc))
            )
            .build();
        return esOperations.search(query, Product.class)
            .stream().map(SearchHit::getContent).collect(Collectors.toList());
    }
}

// 用戶畫像實體
@Document(indexName = "user_profiles")
public class UserProfile {
    @Field(type = FieldType.Keyword)
    private String userId;
    
    // 用戶興趣標簽（可動態更新）
    @Field(type = FieldType.Keyword)
    private List<String> tags;
    
    @GeoPointField
    private GeoPoint lastLocation;
}
// 附近相似用戶推薦
public List<UserProfile> recommendUsers(String userId, int radiusKm) {
    UserProfile current = getUserById(userId); // 獲取當前用戶
    
    Query query = NativeQuery.builder()
        .withQuery(q -> q
            .bool(b -> b
                .must(m -> m.geoDistance(g -> g // 地理過濾
                    .field("lastLocation")
                    .distance(radiusKm + "km")
                    .location(l -> l.latlon(ll -> 
                        ll.lat(current.getLastLocation().lat())
                          .lon(current.getLastLocation().lon())
                    ))
                ))
                .must(m -> m.terms(t -> t // 標簽匹配
                    .field("tags")
                    .terms(t2 -> t2.value(current.getTags()))
                )
            )
        )
        .build();
    return esOperations.search(query, UserProfile.class)
        .stream().map(SearchHit::getContent)
        .collect(Collectors.toList());
}

// 商家實體（含地理位置）
@Document(indexName = "shops")
public class Shop {
    @Id
    private String id;
    
    @GeoPointField // 關鍵注解！
    private GeoPoint location;
    
    @Field(type = FieldType.Text)
    private String name;
}
// 附近商家服務
@Service
public class ShopService {
    public List<Shop> findNearby(double lat, double lon, double radiusKm) {
        Query query = NativeQuery.builder()
            .withQuery(q -> q
                .geoDistance(g -> g
                    .field("location")
                    .distance(radiusKm + "km")
                    .location(gl -> gl.latlon(l -> l.lat(lat).lon(lon)))
            )
            .withSort(s -> s // 按距離排序
                .geoDistance(g -> g
                    .field("location")
                    .location(l -> l.latlon(ll -> ll.lat(lat).lon(lon))
                    .order(SortOrder.Asc))
            )
            .build();
        return esOperations.search(query, Shop.class)
            .stream().map(SearchHit::getContent)
            .collect(Collectors.toList());
    }
}
// 接口調用示例
@RestController
@RequestMapping("/shops")
public class ShopController {
    @GetMapping("/nearby")
    public List<Shop> getNearby(
        @RequestParam double lat, 
        @RequestParam double lon,
        @RequestParam(defaultValue = "3") double radius) {
        return shopService.findNearby(lat, lon, radius);
    }
}