using AutoMapper;
using AutoMapper.QueryableExtensions;
using IM_API.Domain.Events;
using IM_API.Dtos.Group;
using IM_API.Exceptions;
using IM_API.Interface.Services;
using IM_API.Models;
using IM_API.Tools;
using MassTransit;
using Microsoft.EntityFrameworkCore;
using System;

namespace IM_API.Services
{
    public class GroupService : IGroupService
    {
        private readonly ImContext _context;
        private readonly IMapper _mapper;
        private readonly ILogger<GroupService> _logger;
        private readonly IPublishEndpoint _endPoint;
        public GroupService(ImContext context, IMapper mapper, ILogger<GroupService> logger, IPublishEndpoint publishEndpoint)
        {
            _context = context;
            _mapper = mapper;
            _logger = logger;
            _endPoint = publishEndpoint;
        }

        private async Task<List<GroupInvite>> GetGroupInvites(int userId, int groupId, List<int> ids)
        {
            DateTime dateTime = DateTime.Now;
            //验证被邀请用户是否为好友
            var validFriendIds = await _context.Friends
            .Where(f => f.UserId == userId && ids.Contains(f.FriendId))
            .Select(f => f.FriendId)
            .ToListAsync();
            //创建群成员对象
            return validFriendIds.Select(fid => new GroupInvite
            {
                Created = dateTime,
                GroupId = groupId,
                InvitedUser = fid,
                StateEnum = GroupInviteState.Pending,
                InviteUser = userId
            }).ToList();
        }

        public async Task<GroupInfoDto> CreateGroupAsync(int userId, GroupCreateDto groupCreateDto)
        {
            List<int> userIds = groupCreateDto.UserIDs ?? [];
            using var transaction = await _context.Database.BeginTransactionAsync();
            try
            {
                //先创建群
                DateTime dateTime = DateTime.Now;
                Group group = _mapper.Map<Group>(groupCreateDto);
                group.GroupMaster = userId;
                _context.Groups.Add(group);
                await _context.SaveChangesAsync();
                var groupInvites = new List<GroupInvite>();
                if (userIds.Count > 0)
                {
                    groupInvites = await GetGroupInvites(userId,group.Id, userIds);
                    _context.GroupInvites.AddRange(groupInvites);
                }
                var groupMember = new GroupMember
                {
                    UserId = userId,
                    Created = dateTime,
                    RoleEnum = GroupMemberRole.Master,
                    GroupId = group.Id
                };
                _context.GroupMembers.Add(groupMember);
                await _context.SaveChangesAsync();
                await transaction.CommitAsync();
                await _endPoint.Publish(new GroupInviteEvent
                {
                    AggregateId = userId.ToString(),
                    GroupId = group.Id,
                    EventId = Guid.NewGuid(),
                    OccurredAt = dateTime,
                    Ids = groupInvites.Select(x => x.Id).ToList(),
                    OperatorId = userId,
                    UserId = userId
                });
                return _mapper.Map<GroupInfoDto>(group);
            }
            catch
            {
                await transaction.RollbackAsync();
                throw;
            }
        }

        public Task DeleteGroupAsync(int userId, int groupId)
        {
            throw new NotImplementedException();
        }

        public async Task InviteUsersAsync(int userId, int groupId, List<int> userIds)
        {
            var group = await _context.Groups.FirstOrDefaultAsync(
                x => x.Id == groupId) ?? throw new BaseException(CodeDefine.GROUP_NOT_FOUND);
            
        }

        public Task JoinGroupAsync(int userId, int groupId)
        {
            throw new NotImplementedException();
        }

        public async Task<List<GroupInfoDto>> GetGroupListAsync(int userId, int page, int limit, bool desc)
        {
            var query = _context.GroupMembers
                .Where(x => x.UserId == userId)
                .Select(s => s.Group);
            if (desc)
            {
                query = query.OrderByDescending(x => x.Id);
            }
            var list = await query
                .Skip((page - 1) * limit)
                .Take(limit)
                .ProjectTo<GroupInfoDto>(_mapper.ConfigurationProvider)
                .ToListAsync();
            return list;
        }
    }
}