forkmessager/backend/src/Modules/Conversations/Application/Chats/Avatar/Avatar.cs

using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Knot.Shared.Kernel;
using Knot.Shared.Kernel.Storage;
using Knot.Contracts.Conversations.Domain;
using Knot.Contracts.Conversations.Application.Abstractions;
using MediatR;
using System.Linq;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

namespace Knot.Modules.Conversations.Application.Chats.Avatar;

public record UploadGroupAvatarCommand(Guid ChatId, Guid UserId, string FileName, string ContentType, Stream FileStream) : ICommand<Guid>;

internal sealed class UploadGroupAvatarCommandHandler : ICommandHandler<UploadGroupAvatarCommand, Guid>
{
    private readonly IChatRepository _chatRepository;
    private readonly IChatsUnitOfWork _uow;
    private readonly IFileStorageService _fileStorage;

    public UploadGroupAvatarCommandHandler(IChatRepository chatRepository, IChatsUnitOfWork uow, IFileStorageService fileStorage)
    {
        _chatRepository = chatRepository;
        _uow = uow;
        _fileStorage = fileStorage;
    }

    public async Task<Result<Guid>> Handle(UploadGroupAvatarCommand request, CancellationToken cancellationToken)
    {
        var chat = await _chatRepository.GetByIdAsync(request.ChatId, cancellationToken);
        if (chat == null || !chat.Members.Any(m => m.UserId == request.UserId))
        {
            return Result.Failure<Guid>(ChatErrors.ChatNotFound);
        }

        var fileId = await _fileStorage.UploadFileAsync(request.FileStream, request.FileName, request.ContentType);
        var url = $"/api/files/{fileId}";

        chat.UpdateAvatar(url);
        _chatRepository.Update(chat);
        await _uow.SaveChangesAsync(cancellationToken);

        return Result.Success(request.ChatId);
    }
}

public record CropGroupAvatarCommand(Guid ChatId, Guid UserId, string FileName, string ContentType, Stream FileStream, int X, int Y, int Width, int Height) : ICommand<Guid>;

internal sealed class CropGroupAvatarCommandHandler : ICommandHandler<CropGroupAvatarCommand, Guid>
{
    private readonly IChatRepository _chatRepository;
    private readonly IChatsUnitOfWork _uow;
    private readonly IFileStorageService _fileStorage;

    public CropGroupAvatarCommandHandler(IChatRepository chatRepository, IChatsUnitOfWork uow, IFileStorageService fileStorage)
    {
        _chatRepository = chatRepository;
        _uow = uow;
        _fileStorage = fileStorage;
    }

    public async Task<Result<Guid>> Handle(CropGroupAvatarCommand request, CancellationToken cancellationToken)
    {
        var chat = await _chatRepository.GetByIdAsync(request.ChatId, cancellationToken);
        if (chat == null || !chat.Members.Any(m => m.UserId == request.UserId))
        {
            return Result.Failure<Guid>(ChatErrors.ChatNotFound);
        }

        string url;

        using (var image = await SixLabors.ImageSharp.Image.LoadAsync(request.FileStream))
        {
            int startX = Math.Max(0, Math.Min(request.X, image.Width - 1));
            int startY = Math.Max(0, Math.Min(request.Y, image.Height - 1));
            int rectWidth = Math.Max(1, Math.Min(request.Width, image.Width - startX));
            int rectHeight = Math.Max(1, Math.Min(request.Height, image.Height - startY));

            image.Mutate(ctx => ctx.Crop(new SixLabors.ImageSharp.Rectangle(startX, startY, rectWidth, rectHeight)));
            image.Mutate(ctx => ctx.Resize(400, 400));

            using var outStream = new MemoryStream();
            await image.SaveAsJpegAsync(outStream, cancellationToken);
            outStream.Position = 0;

            var fileName = request.FileName ?? "avatar.jpg";
            var fileId = await _fileStorage.UploadFileAsync(outStream, fileName, "image/jpeg");
            url = $"/api/files/{fileId}";
        }

        chat.UpdateAvatar(url);
        _chatRepository.Update(chat);
        await _uow.SaveChangesAsync(cancellationToken);

        return Result.Success(request.ChatId);
    }
}

public record RemoveGroupAvatarCommand(Guid ChatId, Guid UserId) : ICommand<Guid>;

internal sealed class RemoveGroupAvatarCommandHandler : ICommandHandler<RemoveGroupAvatarCommand, Guid>
{
    private readonly IChatRepository _chatRepository;
    private readonly IChatsUnitOfWork _uow;

    public RemoveGroupAvatarCommandHandler(IChatRepository chatRepository, IChatsUnitOfWork uow)
    {
        _chatRepository = chatRepository;
        _uow = uow;
    }

    public async Task<Result<Guid>> Handle(RemoveGroupAvatarCommand request, CancellationToken cancellationToken)
    {
        var chat = await _chatRepository.GetByIdAsync(request.ChatId, cancellationToken);
        if (chat == null || !chat.Members.Any(m => m.UserId == request.UserId))
        {
            return Result.Failure<Guid>(ChatErrors.ChatNotFound);
        }

        chat.UpdateAvatar(null);
        _chatRepository.Update(chat);
        await _uow.SaveChangesAsync(cancellationToken);

        return Result.Success(request.ChatId);
    }
}