ErsatzTV/ErsatzTV.Core.Tests/Fakes/FakeLocalFileSystem.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Metadata;
using LanguageExt;
using static LanguageExt.Prelude;

namespace ErsatzTV.Core.Tests.Fakes
{
    public class FakeLocalFileSystem : ILocalFileSystem
    {
        public static readonly byte[] TestBytes = { 1, 2, 3, 4, 5 };

        private readonly List<FakeFileEntry> _files;
        private readonly List<FakeFolderEntry> _folders;

        public FakeLocalFileSystem(List<FakeFileEntry> files) : this(files, new List<FakeFolderEntry>())
        {
        }

        public FakeLocalFileSystem(List<FakeFileEntry> files, List<FakeFolderEntry> folders)
        {
            _files = files;

            var allFolders = new List<string>(folders.Map(f => f.Path));
            foreach (FakeFileEntry file in _files)
            {
                List<DirectoryInfo> moreFolders =
                    Split(new DirectoryInfo(Path.GetDirectoryName(file.Path) ?? string.Empty));
                allFolders.AddRange(moreFolders.Map(i => i.FullName));
            }

            _folders = allFolders.Distinct().Map(f => new FakeFolderEntry(f)).ToList();
        }

        public Unit EnsureFolderExists(string folder) => Unit.Default;

        public DateTime GetLastWriteTime(string path) =>
            Optional(_files.SingleOrDefault(f => f.Path == path))
                .Map(f => f.LastWriteTime)
                .IfNone(SystemTime.MinValueUtc);

        public bool IsLibraryPathAccessible(LibraryPath libraryPath) =>
            _files.Any(f => f.Path.StartsWith(libraryPath.Path + Path.DirectorySeparatorChar));

        public IEnumerable<string> ListSubdirectories(string folder) =>
            _folders.Map(f => f.Path).Filter(f => f.StartsWith(folder) && Directory.GetParent(f)?.FullName == folder);

        public IEnumerable<string> ListFiles(string folder) =>
            _files.Map(f => f.Path).Filter(f => Path.GetDirectoryName(f) == folder);

        public bool FileExists(string path) => _files.Any(f => f.Path == path);

        public Task<byte[]> ReadAllBytes(string path) => TestBytes.AsTask();

        public Task<Either<BaseError, Unit>> CopyFile(string source, string destination) =>
            Task.FromResult(Right<BaseError, Unit>(Unit.Default));

        private static List<DirectoryInfo> Split(DirectoryInfo path)
        {
            var result = new List<DirectoryInfo>();
            if (path == null || string.IsNullOrWhiteSpace(path.FullName))
            {
                return result;
            }

            if (path.Parent != null)
            {
                result.AddRange(Split(path.Parent));
            }

            result.Add(path);

            return result;
        }
    }
}