package club.mydlq.demo;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.netflix.hystrix.exception.HystrixTimeoutException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.stereotype.Component;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * 服务降级
 */
@Slf4j
@Component
public class ServiceFallbackProvider implements FallbackProvider {

    private static final ObjectMapper objectMapper = new ObjectMapper();

    @Override
    public String getRoute() {
        // 可以单独指定 ServiceID，也可以设置“*”即为设置全部服务
        return "SPRINGBOOT-ADMIN-DEMO";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        if (cause instanceof HystrixTimeoutException) {
            return response(HttpStatus.GATEWAY_TIMEOUT);
        } else {
            return response(HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    private ClientHttpResponse response(final HttpStatus status) {
        return new ClientHttpResponse() {
            @Override
            public HttpStatus getStatusCode() {
                return status;
            }

            @Override
            public int getRawStatusCode() {
                return status.value();
            }

            @Override
            public String getStatusText() {
                return status.getReasonPhrase();
            }

            @Override
            public void close() {
            }

            @Override
            public InputStream getBody() throws JsonProcessingException {
                Map<String,String> map = new HashMap<>();
                map.put("code", "501");
                map.put("message", "后台服务异常");
                String json = objectMapper.writeValueAsString(map);
                return new ByteArrayInputStream(json.getBytes(StandardCharsets.UTF_8));
            }

            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders headers = new HttpHeaders();
                headers.setContentType(MediaType.APPLICATION_JSON);
                return headers;
            }
        };
    }
}