package com.vincent.rsf.server.ai.service;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.vincent.rsf.server.ai.config.AiProperties;
import com.vincent.rsf.server.ai.dto.GatewayChatRequest;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;

@Component
public class AiGatewayClient {

    @Resource
    private AiProperties aiProperties;
    @Resource
    private ObjectMapper objectMapper;

    public interface StreamCallback {
        /**
         * 处理网关返回的一条 NDJSON 事件。
         * 返回 true 表示继续消费后续事件，返回 false 表示主动停止本次流读取。
         */
        boolean handle(JsonNode event) throws Exception;
    }

    /**
     * 调用 AI 网关的内部流式接口，并将网关返回的事件逐条回调给上层编排逻辑。
     * 这里屏蔽了 HTTP 细节，调用方只需要关注 delta / done / error 事件本身。
     */
    public void stream(GatewayChatRequest request, StreamCallback callback) throws Exception {
        HttpURLConnection connection = null;
        boolean terminalEventReceived = false;
        try {
            String url = aiProperties.getGatewayBaseUrl() + "/internal/chat/stream";
            connection = (HttpURLConnection) new URL(url).openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setConnectTimeout(10000);
            connection.setReadTimeout(0);
            connection.setRequestProperty("Content-Type", "application/json");
            connection.setRequestProperty("Accept", "application/x-ndjson");
            try (OutputStream outputStream = connection.getOutputStream()) {
                outputStream.write(objectMapper.writeValueAsBytes(request));
                outputStream.flush();
            }
            InputStream inputStream = connection.getResponseCode() >= 400 ? connection.getErrorStream() : connection.getInputStream();
            if (inputStream == null) {
                return;
            }
            try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8))) {
                String line;
                while ((line = reader.readLine()) != null) {
                    if (line.trim().isEmpty()) {
                        continue;
                    }
                    JsonNode event = objectMapper.readTree(line);
                    String type = event.path("type").asText();
                    if ("done".equals(type) || "error".equals(type)) {
                        terminalEventReceived = true;
                    }
                    if (!callback.handle(event)) {
                        break;
                    }
                }
            }
            if (!terminalEventReceived) {
                throw new IOException("AI网关流异常中断");
            }
        } finally {
            if (connection != null) {
                connection.disconnect();
            }
        }
    }

}