social-media/backend/src/Socialize.Api/Modules/Comments/Handlers/CreateComment.cs

using FastEndpoints;
using Microsoft.EntityFrameworkCore;
using Socialize.Api.Data;
using Socialize.Api.Infrastructure.BlobStorage.Contracts;
using Socialize.Api.Infrastructure.Security;
using Socialize.Api.Modules.ContentItems.Contracts;
using Socialize.Api.Modules.ContentItems.Data;
using Socialize.Api.Modules.Comments.Data;
using Socialize.Api.Modules.Notifications.Contracts;
using System.Text.Json;

namespace Socialize.Api.Modules.Comments.Handlers;

public record CreateCommentRequest(
    Guid WorkspaceId,
    Guid ContentItemId,
    Guid? ParentCommentId,
    string Body,
    IFormFile? Attachment);

public class CreateCommentRequestValidator
    : Validator<CreateCommentRequest>
{
    public CreateCommentRequestValidator()
    {
        RuleFor(x => x.WorkspaceId).NotEmpty();
        RuleFor(x => x.ContentItemId).NotEmpty();
        RuleFor(x => x.Body).MaximumLength(4000);
    }
}

public class CreateCommentHandler(
    AppDbContext dbContext,
    AccessScopeService accessScopeService,
    IBlobStorage blobStorage,
    IContentItemActivityWriter activityWriter,
    INotificationEventWriter notificationEventWriter)
    : Endpoint<CreateCommentRequest, CommentDto>
{
    public override void Configure()
    {
        Post("/api/comments");
        Options(o => o.WithTags("Comments"));
        AllowFileUploads();
    }

    public override async Task HandleAsync(CreateCommentRequest request, CancellationToken ct)
    {
        string body = request.Body?.Trim() ?? string.Empty;
        if (string.IsNullOrWhiteSpace(body) && request.Attachment is null)
        {
            AddError(request => request.Body, "A comment body or attachment is required.");
            await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
            return;
        }

        ContentItem? contentItem = await dbContext.ContentItems
            .SingleOrDefaultAsync(
                candidate => candidate.Id == request.ContentItemId && candidate.WorkspaceId == request.WorkspaceId,
                ct);

        if (contentItem is null)
        {
            AddError(request => request.ContentItemId, "The selected content item does not exist in the active workspace.");
            await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
            return;
        }

        if (!await accessScopeService.CanReviewContentAsync(User, contentItem.WorkspaceId, contentItem.ClientId, contentItem.CampaignId, ct))
        {
            await SendForbiddenAsync(ct);
            return;
        }

        if (request.ParentCommentId.HasValue)
        {
            bool parentExists = await dbContext.Comments
                .AnyAsync(
                    comment => comment.Id == request.ParentCommentId.Value && comment.ContentItemId == request.ContentItemId,
                    ct);

            if (!parentExists)
            {
                AddError(request => request.ParentCommentId, "The selected parent comment does not exist.");
                await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
                return;
            }
        }

        Guid commentId = Guid.NewGuid();
        string? attachmentFileName = null;
        string? attachmentContentType = null;
        long? attachmentSizeBytes = null;
        string? attachmentBlobName = null;
        string? attachmentBlobUrl = null;

        if (request.Attachment is not null)
        {
            string normalizedContentType = request.Attachment.ContentType.Trim().ToLowerInvariant();

            if (request.Attachment.Length <= 0)
            {
                AddError(request => request.Attachment, "The attachment must not be empty.");
                await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
                return;
            }

            if (!IsInlineAttachmentContentType(normalizedContentType))
            {
                AddError(request => request.Attachment, "The attachment must be a PNG or JPEG image.");
                await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
                return;
            }

            attachmentFileName = NormalizeFileName(request.Attachment.FileName, normalizedContentType);
            attachmentContentType = normalizedContentType;
            attachmentSizeBytes = request.Attachment.Length;
            attachmentBlobName =
                $"{contentItem.WorkspaceId}/{SubDirectoryNames.Contents}/{contentItem.Id}/comments/{commentId}/{attachmentFileName}";

            try
            {
                attachmentBlobUrl = await blobStorage.UploadFileAsync(
                    ContainerNames.Workspaces,
                    attachmentBlobName,
                    request.Attachment.OpenReadStream(),
                    normalizedContentType,
                    ct);
            }
            catch (InvalidOperationException)
            {
                AddError(request => request.Attachment, "The attachment file is invalid or unsupported.");
                await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
                return;
            }
        }

        Comment comment = new()
        {
            Id = commentId,
            WorkspaceId = request.WorkspaceId,
            ContentItemId = request.ContentItemId,
            ParentCommentId = request.ParentCommentId,
            AuthorUserId = User.GetUserId(),
            AuthorDisplayName = User.GetAlias() ?? User.GetName(),
            AuthorEmail = User.GetEmail(),
            Body = body,
            AttachmentFileName = attachmentFileName,
            AttachmentContentType = attachmentContentType,
            AttachmentSizeBytes = attachmentSizeBytes,
            AttachmentBlobContainerName = attachmentBlobName is not null ? ContainerNames.Workspaces : null,
            AttachmentBlobName = attachmentBlobName,
            AttachmentBlobUrl = attachmentBlobUrl,
            CreatedAt = DateTimeOffset.UtcNow,
        };

        dbContext.Comments.Add(comment);
        await dbContext.SaveChangesAsync(ct);

        string? authorPortraitUrl = await dbContext.Users
            .Where(candidate => candidate.Id == comment.AuthorUserId)
            .Select(candidate => candidate.PortraitUrl)
            .SingleOrDefaultAsync(ct);

        await activityWriter.WriteAsync(
            new ContentItemActivityWriteModel(
                comment.WorkspaceId,
                comment.ContentItemId,
                "comment.created",
                "Comment",
                comment.Id,
                $"{comment.AuthorDisplayName} commented on {contentItem.Title}.",
                comment.AuthorUserId,
                comment.AuthorEmail,
                JsonSerializer.Serialize(new
                {
                    parentCommentId = comment.ParentCommentId,
                    attachmentFileName = comment.AttachmentFileName,
                })),
            ct);

        await notificationEventWriter.WriteAsync(
            new NotificationEventWriteModel(
                comment.WorkspaceId,
                comment.ContentItemId,
                "comment.created",
                "Comment",
                comment.Id,
                $"{comment.AuthorDisplayName} commented on {contentItem.Title}.",
                null,
                null,
                $$"""{"parentCommentId":"{{comment.ParentCommentId}}"}"""),
            ct);

        CommentDto dto = new(
            comment.Id,
            comment.WorkspaceId,
            comment.ContentItemId,
            comment.ParentCommentId,
            comment.AuthorUserId,
            comment.AuthorDisplayName,
            comment.AuthorEmail,
            authorPortraitUrl,
            comment.Body,
            comment.AttachmentFileName,
            comment.AttachmentContentType,
            comment.AttachmentSizeBytes,
            comment.AttachmentBlobUrl,
            comment.CreatedAt);

        await SendAsync(dto, StatusCodes.Status201Created, ct);
    }

    private static bool IsInlineAttachmentContentType(string contentType)
    {
        return contentType.Trim().ToLowerInvariant() is "image/png" or "image/jpeg" or "image/jpg";
    }

    private static string NormalizeFileName(string? fileName, string contentType)
    {
        string extension = contentType.Trim().ToLowerInvariant() switch
        {
            "image/png" => ".png",
            "image/jpeg" or "image/jpg" => ".jpg",
            _ => string.Empty,
        };
        string normalized = Path.GetFileName(fileName ?? string.Empty).Trim();
        if (string.IsNullOrWhiteSpace(normalized))
        {
            return $"comment-attachment{extension}";
        }

        return normalized.Length > 256 ? normalized[..256] : normalized;
    }
}