using BuildFlow.Shared.Domain.Common;
using File.Application.Features.Folders.Commands;
using File.Domain.Exceptions;
using File.Infrastructure.Persistence;
using MediatR;

namespace File.Application.Features.Folders.Handlers;

/// <summary>移动文件命令处理器。校验目标文件夹归属与文件归属后改挂。</summary>

public class MoveFileCommandHandler(FileDbContext db, ICurrentUserContext currentUser)
    : IRequestHandler<MoveFileCommand, Unit>
{
    public async Task<Unit> Handle(MoveFileCommand req, CancellationToken ct)
    {
        var owner = currentUser.GetRequiredUserId();

        if (req.TargetFolderId is not null)
        {
            var target = await db.Folders.FirstOrDefaultAsync(f => f.Id == req.TargetFolderId, ct);
            if (target is null) throw new NotFoundException("目标文件夹不存在");
            if (target.OwnerId != owner) throw new ForbiddenException("无权访问目标文件夹");
        }

        var file = await db.Files.FirstOrDefaultAsync(f => f.Id == req.Id && f.OwnerId == owner, ct)
            ?? throw new NotFoundException("文件不存在或无权操作");

        file.FolderId = req.TargetFolderId;
        await db.SaveChangesAsync(ct);
        return Unit.Value;
    }
}