package com.zy.ai.service;

import com.zy.ai.entity.ChatCompletionRequest;
import com.zy.ai.entity.ChatCompletionResponse;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Mono;
import reactor.core.publisher.Flux;

import java.util.List;
import java.util.function.Consumer;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

@Slf4j
@Service
@RequiredArgsConstructor
public class LlmChatService {

    private final WebClient llmWebClient;

    @Value("${llm.api-key}")
    private String apiKey;

    @Value("${llm.model}")
    private String model;

    /**
     * 通用对话方法：传入 messages，返回大模型文本回复
     */
    public String chat(List<ChatCompletionRequest.Message> messages,
                       Double temperature,
                       Integer maxTokens) {

        ChatCompletionRequest req = new ChatCompletionRequest();
        req.setModel(model);
        req.setMessages(messages);
        req.setTemperature(temperature != null ? temperature : 0.3);
        req.setMax_tokens(maxTokens != null ? maxTokens : 1024);
        req.setStream(false);

        ChatCompletionResponse response = llmWebClient.post()
                .uri("/chat/completions")
                .header(HttpHeaders.AUTHORIZATION, "Bearer " + apiKey)
                .contentType(MediaType.APPLICATION_JSON)
                .accept(MediaType.APPLICATION_JSON, MediaType.TEXT_EVENT_STREAM)
                .bodyValue(req)
                .exchangeToMono(resp -> resp.bodyToFlux(String.class)
                        .collectList()
                        .map(list -> {
                            String payload = String.join("\n\n", list);
                            return parseCompletion(payload);
                        }))
                .doOnError(ex -> log.error("调用 LLM 失败", ex))
                .onErrorResume(ex -> Mono.empty())
                .block();

        if (response == null ||
                response.getChoices() == null ||
                response.getChoices().isEmpty() ||
                response.getChoices().get(0).getMessage() == null ||
                response.getChoices().get(0).getMessage().getContent() == null ||
                response.getChoices().get(0).getMessage().getContent().isEmpty()) {
            return null;
        }

        return response.getChoices().get(0).getMessage().getContent();
    }

    public void chatStream(List<ChatCompletionRequest.Message> messages,
                           Double temperature,
                           Integer maxTokens,
                           Consumer<String> onChunk,
                           Runnable onComplete,
                           Consumer<Throwable> onError) {

        ChatCompletionRequest req = new ChatCompletionRequest();
        req.setModel(model);
        req.setMessages(messages);
        req.setTemperature(temperature != null ? temperature : 0.3);
        req.setMax_tokens(maxTokens != null ? maxTokens : 1024);
        req.setStream(true);


        Flux<String> flux = llmWebClient.post()
                .uri("/chat/completions")
                .header(HttpHeaders.AUTHORIZATION, "Bearer " + apiKey)
                .contentType(MediaType.APPLICATION_JSON)
                .accept(MediaType.TEXT_EVENT_STREAM)
                .bodyValue(req)
                .retrieve()
                .bodyToFlux(String.class)
                .doOnError(ex -> log.error("调用 LLM 流式失败", ex));

        AtomicBoolean doneSeen = new AtomicBoolean(false);
        AtomicBoolean errorSeen = new AtomicBoolean(false);
        LinkedBlockingQueue<String> queue = new LinkedBlockingQueue<>();

        Thread drain = new Thread(() -> {
            try {
                while (true) {
                    String s = queue.poll(2, TimeUnit.SECONDS);
                    if (s != null) {
                        try { onChunk.accept(s); } catch (Exception ignore) {}
                    }
                    if (doneSeen.get() && queue.isEmpty()) {
                        if (!errorSeen.get()) {
                            try { if (onComplete != null) onComplete.run(); } catch (Exception ignore) {}
                        }
                        break;
                    }
                }
            } catch (InterruptedException ignore) {
                ignore.printStackTrace();
            }
        });
        drain.setDaemon(true);
        drain.start();

        flux.subscribe(payload -> {
            if (payload == null || payload.isEmpty()) return;
            String[] events = payload.split("\\r?\\n\\r?\\n");
            for (String part : events) {
                String s = part;
                if (s == null || s.isEmpty()) continue;
                if (s.startsWith("data:")) {
                    s = s.substring(5);
                    if (s.startsWith(" ")) s = s.substring(1);
                }
                if ("[DONE]".equals(s.trim())) {
                    doneSeen.set(true);
                    continue;
                }
                try {
                    JSONObject obj = JSON.parseObject(s);
                    JSONArray choices = obj.getJSONArray("choices");
                    if (choices != null && !choices.isEmpty()) {
                        JSONObject c0 = choices.getJSONObject(0);
                        JSONObject delta = c0.getJSONObject("delta");
                        if (delta != null) {
                            String content = delta.getString("content");
                            if (content != null) {
                                try { queue.offer(content); } catch (Exception ignore) {}
                            }
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, err -> {
            errorSeen.set(true);
            doneSeen.set(true);
            if (onError != null) onError.accept(err);
        }, () -> {
            if (!doneSeen.get()) {
                errorSeen.set(true);
                doneSeen.set(true);
                if (onError != null) onError.accept(new RuntimeException("LLM 流意外完成"));
            } else {
                doneSeen.set(true);
            }
        });
    }

    private ChatCompletionResponse mergeSseChunk(ChatCompletionResponse acc, String payload) {
        if (payload == null || payload.isEmpty()) return acc;
        String[] events = payload.split("\\r?\\n\\r?\\n");
        for (String part : events) {
            String s = part;
            if (s == null || s.isEmpty()) continue;
            if (s.startsWith("data:")) {
                s = s.substring(5);
                if (s.startsWith(" ")) s = s.substring(1);
            }
            if ("[DONE]".equals(s.trim())) {
                continue;
            }
            try {
                JSONObject obj = JSON.parseObject(s);
                if (obj == null) continue;
                JSONArray choices = obj.getJSONArray("choices");
                if (choices != null && !choices.isEmpty()) {
                    JSONObject c0 = choices.getJSONObject(0);
                    if (acc.getChoices() == null || acc.getChoices().isEmpty()) {
                        ChatCompletionResponse.Choice choice = new ChatCompletionResponse.Choice();
                        ChatCompletionRequest.Message msg = new ChatCompletionRequest.Message();
                        choice.setMessage(msg);
                        java.util.ArrayList<ChatCompletionResponse.Choice> list = new java.util.ArrayList<>();
                        list.add(choice);
                        acc.setChoices(list);
                    }
                    ChatCompletionResponse.Choice choice = acc.getChoices().get(0);
                    ChatCompletionRequest.Message msg = choice.getMessage();
                    if (msg.getRole() == null || msg.getRole().isEmpty()) {
                        msg.setRole("assistant");
                    }
                    JSONObject delta = c0.getJSONObject("delta");
                    if (delta != null) {
                        String c = delta.getString("content");
                        if (c != null) {
                            String prev = msg.getContent();
                            msg.setContent(prev == null ? c : prev + c);
                        }
                        String role = delta.getString("role");
                        if (role != null && !role.isEmpty()) msg.setRole(role);
                    }
                    JSONObject message = c0.getJSONObject("message");
                    if (message != null) {
                        String c = message.getString("content");
                        if (c != null) {
                            String prev = msg.getContent();
                            msg.setContent(prev == null ? c : prev + c);
                        }
                        String role = message.getString("role");
                        if (role != null && !role.isEmpty()) msg.setRole(role);
                    }
                    String fr = c0.getString("finish_reason");
                    if (fr != null && !fr.isEmpty()) choice.setFinishReason(fr);
                }
                String id = obj.getString("id");
                if (id != null && !id.isEmpty()) acc.setId(id);
                Long created = obj.getLong("created");
                if (created != null) acc.setCreated(created);
                String object = obj.getString("object");
                if (object != null && !object.isEmpty()) acc.setObjectName(object);
            } catch (Exception ignore) {}
        }
        return acc;
    }

    private ChatCompletionResponse parseCompletion(String payload) {
        if (payload == null) return null;
        try {
            ChatCompletionResponse r = JSON.parseObject(payload, ChatCompletionResponse.class);
            if (r != null && r.getChoices() != null && !r.getChoices().isEmpty() && r.getChoices().get(0).getMessage() != null) {
                return r;
            }
        } catch (Exception ignore) {}
        ChatCompletionResponse sse = mergeSseChunk(new ChatCompletionResponse(), payload);
        if (sse.getChoices() != null && !sse.getChoices().isEmpty() && sse.getChoices().get(0).getMessage() != null && sse.getChoices().get(0).getMessage().getContent() != null) {
            return sse;
        }
        ChatCompletionResponse r = new ChatCompletionResponse();
        ChatCompletionResponse.Choice choice = new ChatCompletionResponse.Choice();
        ChatCompletionRequest.Message msg = new ChatCompletionRequest.Message();
        msg.setRole("assistant");
        msg.setContent(payload);
        choice.setMessage(msg);
        java.util.ArrayList<ChatCompletionResponse.Choice> list = new java.util.ArrayList<>();
        list.add(choice);
        r.setChoices(list);
        return r;
    }
}