using System.Text;
using AutoMapper;
using MediatR;
using mws.backend.dotnet.application.Audit;
using mws.backend.dotnet.application.Common;
using mws.backend.dotnet.application.Permissions;
using mws.backend.dotnet.domain.Documents;

namespace mws.backend.dotnet.application.Documents;

public record UpdateDocumentCommand(Guid UserId, Guid DocumentId, UpdateDocumentRequest Request) : IRequest<DocumentDto>, IAuditableRequest
{
    public string Action => "Document.Update";
    public string EntityType => "Document";
    public Guid? EntityId => DocumentId;
    public string? EntityName => Request.Title;
}

public class UpdateDocumentHandler(IUnitOfWork uow, IMapper mapper, IDocumentContentStore contentStore)
    : IRequestHandler<UpdateDocumentCommand, DocumentDto>
{
    public async Task<DocumentDto> Handle(UpdateDocumentCommand command, CancellationToken ct)
    {
        var doc = await DocumentAccess.GetDocumentForUserAsync(uow, command.UserId, command.DocumentId, ct);
        await DocumentAccess.EnsureDocumentPermissionAsync(uow, command.UserId, doc.ProjectId, PermissionAction.Edit, ct);

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

        doc.Title = request.Title.Trim();
        doc.UpdatedAt = DateTime.UtcNow;
        doc.UpdatedBy = command.UserId;

        await uow.SaveChangesAsync(ct);

        if (doc.Type == DocumentType.Document)
        {
            var previousKey = doc.StorageKey;
            var bytes = Encoding.UTF8.GetBytes(request.Content ?? "");
            using (var ms = new MemoryStream(bytes))
            {
                doc.StorageKey = await contentStore.UploadAsync(doc.ProjectId, doc.Title, "text/html; charset=utf-8", ms, ct);
            }

            if (!string.IsNullOrEmpty(previousKey) && previousKey != doc.StorageKey)
            {
                await contentStore.DeleteAsync(previousKey, ct);
            }

            doc.ContentSize = bytes.Length;
            doc.UpdatedContentAt = DateTime.UtcNow;
            doc.ContentHash = null;
            await uow.SaveChangesAsync(ct);
        }

        var dto = mapper.Map<DocumentDto>(doc);
        if (doc.Type == DocumentType.Document)
        {
            dto.Content = request.Content;
        }
        return dto;
    }
}