package com.xuqm.im.service;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.xuqm.common.exception.BusinessException;
import com.xuqm.im.entity.ImGroupEntity;
import com.xuqm.im.repository.ImGroupRepository;
import org.springframework.stereotype.Service;

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

@Service
public class ImGroupService {

    private final ImGroupRepository groupRepository;
    private final ObjectMapper objectMapper;

    public ImGroupService(ImGroupRepository groupRepository, ObjectMapper objectMapper) {
        this.groupRepository = groupRepository;
        this.objectMapper = objectMapper;
    }

    public ImGroupEntity create(String appId, String name, String creatorId, List<String> memberIds) {
        List<String> members = new ArrayList<>(memberIds);
        if (!members.contains(creatorId)) members.add(creatorId);

        ImGroupEntity group = new ImGroupEntity();
        group.setId(UUID.randomUUID().toString());
        group.setAppId(appId);
        group.setName(name);
        group.setCreatorId(creatorId);
        group.setMemberIds(toJson(members));
        group.setAdminIds(toJson(List.of(creatorId)));
        group.setCreatedAt(LocalDateTime.now());
        return groupRepository.save(group);
    }

    public ImGroupEntity addMember(String groupId, String userId) {
        ImGroupEntity group = groupRepository.findById(groupId)
                .orElseThrow(() -> new BusinessException(404, "群组不存在"));
        List<String> members = fromJson(group.getMemberIds());
        if (!members.contains(userId)) {
            members.add(userId);
            group.setMemberIds(toJson(members));
            groupRepository.save(group);
        }
        return group;
    }

    public ImGroupEntity removeMember(String groupId, String userId, String operatorId) {
        ImGroupEntity group = groupRepository.findById(groupId)
                .orElseThrow(() -> new BusinessException(404, "群组不存在"));
        List<String> admins = fromJson(group.getAdminIds());
        if (!admins.contains(operatorId) && !group.getCreatorId().equals(operatorId)) {
            throw new BusinessException(403, "无权操作");
        }
        List<String> members = new ArrayList<>(fromJson(group.getMemberIds()));
        members.remove(userId);
        group.setMemberIds(toJson(members));
        return groupRepository.save(group);
    }

    public List<ImGroupEntity> listByApp(String appId) {
        return groupRepository.findByAppId(appId);
    }

    private String toJson(List<String> list) {
        try { return objectMapper.writeValueAsString(list); } catch (Exception e) { return "[]"; }
    }

    private List<String> fromJson(String json) {
        try { return objectMapper.readValue(json, new TypeReference<>() {}); } catch (Exception e) { return new ArrayList<>(); }
    }
}