CloudMusic/FNZCM2/FNZCM2.Abstractions/Utility/FolderScan.cs

using System.IO.Enumeration;
using FNZCM2.Abstractions.Models.Fs;

namespace FNZCM2.Abstractions.Utility;

using FSE = (bool isDir, string path, long size, DateTimeOffset lastWrited);

public static class FolderScan
{
    public static FolderScanResult Scan(string folderPath)
    {
        //List<IFsEntry> allEntries = new();
        List<FolderEntry> allFolders = new();
        List<FileEntry> allFiles = new();

        Dictionary<string, long> folderPathToIdCache = new();
        long GetFolderId(string path)
        {
            if (folderPathToIdCache.TryGetValue(path, out var fid)) return fid;

            var parts = path.Split(Path.DirectorySeparatorChar);

            fid = 0;
            foreach (var s in parts)
            {
                var d = allFolders.First(p => p.FolderId == fid && p.Name == s);
                fid = d.Id;
            }

            folderPathToIdCache[path] = fid;
            return fid;
        }

        var fullPath = Path.GetFullPath(folderPath);

        var fse = new FileSystemEnumerable<FSE>(
            fullPath,
            (ref FileSystemEntry p) => new(
                p.IsDirectory,
                p.ToFullPath(),
                p.Length,
                p.LastWriteTimeUtc
            ),
            new()
            {
                RecurseSubdirectories = true,
            });

        var trimPathPrefixLength = fullPath.Length + 1;

        foreach (var e in fse)
        {
            var rPath = e.path.Substring(trimPathPrefixLength);

            var directoryName = Path.GetDirectoryName(rPath);
            var fileName = Path.GetFileName(rPath);
            var folderId = string.IsNullOrEmpty(directoryName) ? 0 : GetFolderId(directoryName!);

            if (e.isDir)
            {
                var folderEntry = new FolderEntry
                {
                    Id = DateTime.Now.Ticks,
                    FolderId = folderId,
                    Name = fileName,
                    LastChangedTime = e.lastWrited,
                };

                //allEntries.Add(folderEntry);
                allFolders.Add(folderEntry);
            }
            else
            {
                var fileEntry = new FileEntry
                {
                    Id = DateTime.Now.Ticks,
                    FolderId = folderId,
                    Name = fileName,
                    LastChangedTime = e.lastWrited,
                    Size = e.size,
                };

                //allEntries.Add(fileEntry);
                allFiles.Add(fileEntry);
            }
        }

        //var allById = allEntries.ToDictionary(e => e.Id);
        //var allInFolder = allEntries
        //    .GroupBy(e => e.FolderId)
        //    .ToDictionary(g => g.Key, g => (IReadOnlyList<IFsEntry>)g.ToArray());

        //var folderById = allFolders.ToDictionary(f => f.Id);
        //var foldersInFolder = allFolders
        //    .GroupBy(f => f.FolderId)
        //    .ToDictionary(g => g.Key, g => (IReadOnlyList<FolderEntry>)g.ToArray());

        //var fileById = allFiles.ToDictionary(f => f.Id);
        //var filesInFolder = allFiles
        //    .GroupBy(f => f.FolderId)
        //    .ToDictionary(g => g.Key, g => (IReadOnlyList<FileEntry>)g.ToArray());

        return new FolderScanResult
        {
            //All = allEntries,
            //AllById = allById,
            //AllInFolder = allInFolder,
            Folders = allFolders.ToArray(),
            //FolderById = folderById,
            //FoldersInFolder = foldersInFolder,
            Files = allFiles.ToArray(),
            //FileById = fileById,
            //FilesInFolder = filesInFolder,
            //add folderPathToIdCache on demands
        };
    }
}