package jnpf.handler;

import com.alibaba.csp.sentinel.adapter.gateway.sc.callback.GatewayCallbackManager;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import jnpf.constant.MsgCode;
import jnpf.util.JsonUtil;
import jnpf.base.ActionResult;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebExceptionHandler;
import reactor.core.publisher.Mono;

/**
 * 自定义限流异常处理
 *
 * @author JNPF开发平台组
 * @version V3.1.0
 * @copyright 引迈信息技术有限公司（https://www.jnpfsoft.com）
 * @date 2021-03-24
 */
public class SentinelHandler implements WebExceptionHandler {

    private Mono<Void> writeResponse(ServerResponse response, ServerWebExchange exchange) {
        ServerHttpResponse serverHttpResponse = exchange.getResponse();
        ActionResult result = ActionResult.fail(MsgCode.GT108.get());
        DataBuffer buffer = serverHttpResponse.bufferFactory().wrap(JsonUtil.getObjectToString(result).getBytes());
        return serverHttpResponse.writeWith(Mono.just(buffer));
    }

    @Override
    public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
        if (exchange.getResponse().isCommitted()) {
            return Mono.error(ex);
        }
        if (!BlockException.isBlockException(ex)) {
            return Mono.error(ex);
        }
        return handleBlockedRequest(exchange, ex).flatMap(response -> writeResponse(response, exchange));
    }

    private Mono<ServerResponse> handleBlockedRequest(ServerWebExchange exchange, Throwable throwable) {
        return GatewayCallbackManager.getBlockHandler().handleRequest(exchange, throwable);
    }
}