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 CreateDocumentCommand(Guid UserId, Guid ProjectId, CreateDocumentRequest Request) : IRequest<DocumentDto>, IAuditableRequest
{
    public string Action => "Document.Create";
    public string EntityType => "Document";
    public string? EntityName => Request.Title;
}

public class CreateDocumentHandler(IUnitOfWork uow, IMapper mapper, IDocumentContentStore contentStore)
    : 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,
            CreatedBy = command.UserId,
            CreatedAt = now,
            UpdatedBy = command.UserId,
            UpdatedAt = now,
        };

        uow.Documents.Add(doc);
        await uow.SaveChangesAsync(ct);

        if (request.Type == DocumentType.Document && !string.IsNullOrEmpty(request.Content))
        {
            var projectName = (await uow.Projects.GetByIdAsync(doc.ProjectId, ct))?.Name ?? doc.ProjectId.ToString();
            var bytes = Encoding.UTF8.GetBytes(request.Content);
            using (var ms = new MemoryStream(bytes))
            {
                doc.StorageKey = await contentStore.UploadAsync(projectName, doc.Title, "text/html; charset=utf-8", ms, ct);
            }

            doc.ContentSize = bytes.Length;
            doc.UpdatedContentAt = now;
            await uow.SaveChangesAsync(ct);
        }

        return mapper.Map<DocumentDto>(doc);
    }
}