mws.backend.dotnet/mws.application/Documents/Commands/CreateDocument.cs

using AutoMapper;
using MediatR;
using Mws.Application.Common;
using Mws.Application.Permissions;
using Mws.Domain.Documents;

namespace Mws.Application.Documents;

public record CreateDocumentCommand(Guid UserId, Guid ProjectId, CreateDocumentRequest Request) : IRequest<DocumentDto>;

public class CreateDocumentHandler(IUnitOfWork uow, IMapper mapper) : IRequestHandler<CreateDocumentCommand, DocumentDto>
{
    public async Task<DocumentDto> Handle(CreateDocumentCommand command, CancellationToken ct)
    {
        await DocumentAccess.EnsureDocumentPermissionAsync(uow, command.UserId, command.ProjectId, PermissionAction.Create, ct);

        var request = command.Request;
        if (string.IsNullOrWhiteSpace(request.Title))
        {
            throw new BadRequestException("Title is required");
        }

        if (request.ParentId is { } parentId)
        {
            var parent = await uow.Documents.GetInProjectAsync(parentId, command.ProjectId, ct)
                ?? throw new BadRequestException("Parent document not found");
            if (parent.Type != DocumentType.Folder)
            {
                throw new BadRequestException("Parent must be a folder");
            }
        }

        if (request.Type == DocumentType.Folder && !string.IsNullOrWhiteSpace(request.Content))
        {
            throw new BadRequestException("Folders cannot have content");
        }

        var now = DateTime.UtcNow;
        var doc = new Document
        {
            Id = Guid.NewGuid(),
            ProjectId = command.ProjectId,
            ParentId = request.ParentId,
            Title = request.Title.Trim(),
            Type = request.Type,
            Content = request.Type == DocumentType.Document ? request.Content : null,
            CreatedBy = command.UserId,
            CreatedAt = now,
            UpdatedBy = command.UserId,
            UpdatedAt = now,
        };

        uow.Documents.Add(doc);
        await uow.SaveChangesAsync(ct);
        return mapper.Map<DocumentDto>(doc);
    }
}