package com.oms.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.oms.converter.ChatSessionConverter;
import com.oms.dto.ChatSessionDTO;
import com.oms.entity.ChatSession;
import com.oms.enums.ChatStatus;
import com.oms.mapper.ChatSessionMapper;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.List;

@Service
@RequiredArgsConstructor
public class ChatSessionService {
    private final ChatSessionMapper mapper;
    private final ChatSessionConverter converter;

    public Page<ChatSession> getPage(int page, int size) {
        Page<ChatSession> pageParam = new Page<>(page, size);
        return mapper.selectPage(pageParam, new LambdaQueryWrapper<ChatSession>()
                .orderByDesc(ChatSession::getCreatedAt));
    }

    public List<ChatSession> getAll() {
        return mapper.selectList(new LambdaQueryWrapper<ChatSession>()
                .orderByDesc(ChatSession::getCreatedAt));
    }

    public ChatSession getById(Long id) {
        return mapper.selectById(id);
    }

    public ChatSessionDTO getDtoById(Long id) {
        ChatSession entity = mapper.selectById(id);
        return entity == null ? null : converter.toDto(entity);
    }

    public List<ChatSession> getByStatus(String status) {
        return mapper.selectList(new LambdaQueryWrapper<ChatSession>()
                .eq(ChatSession::getStatus, status)
                .orderByDesc(ChatSession::getCreatedAt));
    }

    public List<ChatSession> getWaitingSessions() {
        return mapper.selectList(new LambdaQueryWrapper<ChatSession>()
                .eq(ChatSession::getStatus, ChatStatus.WAITING.getCode())
                .orderByAsc(ChatSession::getCreatedAt));
    }

    @Transactional
    public Long save(ChatSession entity) {
        if (entity.getStatus() == null) {
            entity.setStatus(ChatStatus.WAITING.getCode());
        }
        if (entity.getAiHandled() == null) {
            entity.setAiHandled(1);
        }
        entity.setLastMessageAt(LocalDateTime.now());
        mapper.insert(entity);
        return entity.getId();
    }

    @Transactional
    public void update(ChatSession entity) {
        mapper.updateById(entity);
    }

    @Transactional
    public void delete(Long id) {
        mapper.deleteById(id);
    }

    @Transactional
    public void closeSession(Long id) {
        ChatSession cs = mapper.selectById(id);
        if (cs == null) throw new IllegalArgumentException("Session not found");
        cs.setStatus(ChatStatus.CLOSED.getCode());
        cs.setEndedAt(LocalDateTime.now());
        mapper.updateById(cs);
    }

    @Transactional
    public void assignAgent(Long sessionId, Long agentId, String agentName) {
        ChatSession cs = mapper.selectById(sessionId);
        if (cs == null) throw new IllegalArgumentException("Session not found");
        cs.setAgentId(agentId);
        cs.setAgentName(agentName);
        cs.setStatus(ChatStatus.ASSIGNED.getCode());
        mapper.updateById(cs);
    }

    @Transactional
    public void updateLastMessage(Long sessionId) {
        ChatSession cs = mapper.selectById(sessionId);
        if (cs != null) {
            cs.setLastMessageAt(LocalDateTime.now());
            mapper.updateById(cs);
        }
    }

    @Transactional
    public void rateSession(Long sessionId, int rating) {
        ChatSession cs = mapper.selectById(sessionId);
        if (cs == null) throw new IllegalArgumentException("Session not found");
        cs.setSatisfaction(rating);
        cs.setStatus(ChatStatus.CLOSED.getCode());
        cs.setEndedAt(LocalDateTime.now());
        mapper.updateById(cs);
    }

    @Transactional
    public void transferToAgent(Long sessionId, Long agentId, String agentName) {
        ChatSession cs = mapper.selectById(sessionId);
        if (cs == null) throw new IllegalArgumentException("Session not found");
        cs.setAgentId(agentId);
        cs.setAgentName(agentName);
        cs.setStatus(ChatStatus.ASSIGNED.getCode());
        mapper.updateById(cs);
    }
}