package com.emotion.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.emotion.dto.response.MessageResponse;
import com.emotion.entity.Conversation;
import com.emotion.entity.EpicScript;
import com.emotion.entity.Message;
import com.emotion.service.ConversationService;
import com.emotion.service.EpicScriptService;
import com.emotion.service.MessageService;
import com.emotion.service.ScriptMessageService;
import com.emotion.util.UserContextHolder;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

/**
 * 剧本消息版本管理服务实现
 */
@Service
public class ScriptMessageServiceImpl implements ScriptMessageService {

    @Autowired
    private MessageService messageService;

    @Autowired
    private ConversationService conversationService;

    @Autowired
    private EpicScriptService epicScriptService;

    @Override
    public List<MessageResponse> listByConversation(String conversationId, boolean includeVersions) {
        String currentUserId = UserContextHolder.getCurrentUserId();
        Conversation conversation = conversationService.getById(conversationId);
        if (conversation == null || !conversation.getUserId().equals(currentUserId)) {
            throw new IllegalStateException("对话不存在或无权限");
        }

        LambdaQueryWrapper<Message> wrapper = new LambdaQueryWrapper<>();
        wrapper.eq(Message::getConversationId, conversationId);
        if (!includeVersions) {
            // 只返回当前生效版本链上的消息：parent_message_id 为空的 script 消息 + 所有 chat 消息
            wrapper.and(w -> w.isNull(Message::getParentMessageId).or().ne(Message::getType, "script"));
        }
        wrapper.orderByAsc(Message::getMessageOrder);
        List<Message> messages = messageService.list(wrapper);
        return messages.stream().map(this::convertToResponse).collect(Collectors.toList());
    }

    @Override
    public List<MessageResponse> getVersions(String messageId) {
        String currentUserId = UserContextHolder.getCurrentUserId();
        Message message = messageService.getById(messageId);
        if (message == null) {
            throw new IllegalStateException("消息不存在");
        }
        Conversation conversation = conversationService.getById(message.getConversationId());
        if (conversation == null || !conversation.getUserId().equals(currentUserId)) {
            throw new IllegalStateException("无权限");
        }

        // 找到根消息
        String rootId = message.getParentMessageId() == null ? message.getId() : message.getParentMessageId();
        Message root = messageService.getById(rootId);

        LambdaQueryWrapper<Message> wrapper = new LambdaQueryWrapper<>();
        wrapper.eq(Message::getParentMessageId, rootId)
                .orderByAsc(Message::getVersionNumber);
        List<Message> versions = messageService.list(wrapper);

        List<MessageResponse> result = new ArrayList<>();
        if (root != null) {
            result.add(convertToResponse(root));
        }
        result.addAll(versions.stream().map(this::convertToResponse).collect(Collectors.toList()));
        return result;
    }

    @Override
    public boolean deleteVersion(String messageId) {
        String currentUserId = UserContextHolder.getCurrentUserId();
        Message message = messageService.getById(messageId);
        if (message == null) {
            throw new IllegalStateException("消息不存在");
        }
        Conversation conversation = conversationService.getById(message.getConversationId());
        if (conversation == null || !conversation.getUserId().equals(currentUserId)) {
            throw new IllegalStateException("无权限");
        }

        EpicScript script = epicScriptService.getById(conversation.getScriptId());
        if (script == null) {
            throw new IllegalStateException("剧本不存在");
        }

        // 不能删除当前生效版本
        if (messageId.equals(script.getCurrentVersionMessageId())) {
            throw new IllegalStateException("不能删除当前生效版本");
        }

        // 不能删除有子版本的父消息
        if (message.getParentMessageId() == null) {
            LambdaQueryWrapper<Message> childWrapper = new LambdaQueryWrapper<>();
            childWrapper.eq(Message::getParentMessageId, messageId);
            long childCount = messageService.count(childWrapper);
            if (childCount > 0) {
                throw new IllegalStateException("不能删除有子版本的父消息");
            }
        }

        String parentId = message.getParentMessageId();
        boolean removed = messageService.removeById(messageId);
        if (!removed) {
            return false;
        }

        // 重新计算同一 parent 下剩余版本的 version_number
        if (StringUtils.hasText(parentId)) {
            LambdaQueryWrapper<Message> wrapper = new LambdaQueryWrapper<>();
            wrapper.eq(Message::getParentMessageId, parentId)
                    .orderByAsc(Message::getMessageOrder);
            List<Message> siblings = messageService.list(wrapper);
            for (int i = 0; i < siblings.size(); i++) {
                Message sibling = siblings.get(i);
                sibling.setVersionNumber(i + 2);
                messageService.updateById(sibling);
            }
        }
        return true;
    }

    private MessageResponse convertToResponse(Message message) {
        MessageResponse response = new MessageResponse();
        BeanUtils.copyProperties(message, response);
        response.setId(message.getId());
        return response;
    }
}