using System.Collections.Generic;
using System.Linq;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Options;
using Microsoft.Extensions.Primitives;
using Volo.Abp.DependencyInjection;

namespace Volo.Abp.VirtualFileSystem;

public class VirtualFileProvider : IVirtualFileProvider, ISingletonDependency
{
    private readonly IFileProvider _hybridFileProvider;
    private readonly AbpVirtualFileSystemOptions _options;

    public VirtualFileProvider(
        IOptions<AbpVirtualFileSystemOptions> options,
        IDynamicFileProvider dynamicFileProvider)
    {
        _options = options.Value;
        _hybridFileProvider = CreateHybridProvider(dynamicFileProvider);
    }

    public virtual IFileInfo GetFileInfo(string subpath)
    {
        return _hybridFileProvider.GetFileInfo(subpath);
    }

    public virtual IDirectoryContents GetDirectoryContents(string subpath)
    {
        if (subpath == "")
        {
            subpath = "/";
        }

        return _hybridFileProvider.GetDirectoryContents(subpath);
    }

    public virtual IChangeToken Watch(string filter)
    {
        return _hybridFileProvider.Watch(filter);
    }

    protected virtual IFileProvider CreateHybridProvider(IDynamicFileProvider dynamicFileProvider)
    {
        var fileProviders = new List<IFileProvider>();

        fileProviders.Add(dynamicFileProvider);

        foreach (var fileSet in _options.FileSets.AsEnumerable().Reverse())
        {
            fileProviders.Add(fileSet.FileProvider);
        }

        return new CompositeFileProvider(fileProviders);
    }
}