using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using MediatR;
using Knot.Shared.Kernel;
using Knot.Modules.Chats.Application.DTOs;
using Knot.Modules.Chats.Domain;

namespace Knot.Modules.Chats.Application.Messages.SearchMessages;

public record SearchMessagesQuery(Guid UserId, string Query, Guid? ChatId) : IQuery<List<SearchMessageDto>>;

internal sealed class SearchMessagesQueryHandler : IQueryHandler<SearchMessagesQuery, List<SearchMessageDto>>
{
    private readonly IMessageRepository _messageRepository;
    private readonly IUserDisplayNameProvider _userProvider;

    public SearchMessagesQueryHandler(IMessageRepository messageRepository, IUserDisplayNameProvider userProvider)
    {
        _messageRepository = messageRepository;
        _userProvider = userProvider;
    }

    public async Task<Result<List<SearchMessageDto>>> Handle(SearchMessagesQuery request, CancellationToken cancellationToken)
    {
        var messages = await _messageRepository.SearchMessagesAsync(request.Query, request.ChatId, request.UserId, cancellationToken);
        messages = messages.Where(message => !message.IsDeletedForUser(request.UserId)).ToList();

        var userIds = messages.Select(message => message.SenderId).ToList();
        userIds.AddRange(messages.Where(message => message.ForwardedFromId.HasValue).Select(message => message.ForwardedFromId!.Value));

        var senders = await _userProvider.GetUsersInfoAsync(userIds.Distinct(), cancellationToken);

        var result = messages.Select(message => new SearchMessageDto(
            message.Id,
            message.ChatId,
            message.SenderId,
                message.Content,
                message.Type,
                message.ReplyToId,
                message.Quote,
                message.IsEdited,
                message.IsDeleted,
                message.CreatedAt,
                message.ForwardedFromId,
                null, 
                message.StoryId,
                message.StoryMediaUrl,
                message.StoryMediaType,
                message.Media.Select(media => new MediaDto(media.Id, media.Type, media.Url, media.Filename, media.Size)).ToList(),
            senders.TryGetValue(message.SenderId, out var senderUser) ? new MessageSenderDto(senderUser.Id, senderUser.Username, senderUser.DisplayName, senderUser.Avatar) : new MessageSenderDto(message.SenderId, "unknown", "Unknown", null),
            message.Reactions.Select(reaction => new SimpleReactionDto(reaction.UserId, reaction.Emoji)).ToList(),
            message.ReadBy.Select(readReceipt => new ReadByDto(readReceipt.UserId)).ToList()
        )).ToList();

        return Result.Success(result);
    }
}