Added Hangfire and Hangfire SQLite extension for future task framework. Added a basic directory scanning implementation.

API/Services/DirectoryService.cs

@@ -1,16 +1,28 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Security;
+using System.Threading;
 using System.Threading.Tasks;
+using API.DTOs;
 using API.Interfaces;
+using Microsoft.Extensions.Logging;
 
 namespace API.Services
 {
     public class DirectoryService : IDirectoryService
     {
-        /// <summary>
+       private readonly ILogger<DirectoryService> _logger;
+
+       public DirectoryService(ILogger<DirectoryService> logger)
+       {
+          _logger = logger;
+       }
+
+       /// <summary>
         /// Lists out top-level folders for a given directory. Filters out System and Hidden folders.
         /// </summary>
         /// <param name="rootPath">Absolute path </param>
@@ -27,5 +39,132 @@ namespace API.Services
             
             return dirs;
         }
+
+        public void ScanLibrary(LibraryDto library)
+        {
+           foreach (var folderPath in library.Folders)
+           {
+              try {
+                 TraverseTreeParallelForEach(folderPath, (f) =>
+                 {
+                    // Exceptions are no-ops.
+                    try {
+                       // Do nothing with the data except read it.
+                       //byte[] data = File.ReadAllBytes(f);
+                       ProcessManga(f);
+                    }
+                    catch (FileNotFoundException) {}
+                    catch (IOException) {}
+                    catch (UnauthorizedAccessException) {}
+                    catch (SecurityException) {}
+                    // Display the filename.
+                    Console.WriteLine(f);
+                 });
+              }
+              catch (ArgumentException) {
+                 Console.WriteLine(@"The directory 'C:\Program Files' does not exist.");
+              }
+           }
+        }
+
+        private static void ProcessManga(string filename)
+        {
+            Console.WriteLine($"Found {filename}");
+        }
+        
+        public static void TraverseTreeParallelForEach(string root, Action<string> action)
+         {
+            //Count of files traversed and timer for diagnostic output
+            int fileCount = 0;
+            var sw = Stopwatch.StartNew();
+
+            // Determine whether to parallelize file processing on each folder based on processor count.
+            int procCount = System.Environment.ProcessorCount;
+
+            // Data structure to hold names of subfolders to be examined for files.
+            Stack<string> dirs = new Stack<string>();
+
+            if (!Directory.Exists(root)) {
+                   throw new ArgumentException();
+            }
+            dirs.Push(root);
+
+            while (dirs.Count > 0) {
+               string currentDir = dirs.Pop();
+               string[] subDirs = {};
+               string[] files = {};
+
+               try {
+                  subDirs = Directory.GetDirectories(currentDir);
+               }
+               // Thrown if we do not have discovery permission on the directory.
+               catch (UnauthorizedAccessException e) {
+                  Console.WriteLine(e.Message);
+                  continue;
+               }
+               // Thrown if another process has deleted the directory after we retrieved its name.
+               catch (DirectoryNotFoundException e) {
+                  Console.WriteLine(e.Message);
+                  continue;
+               }
+
+               try {
+                  files = Directory.GetFiles(currentDir);
+               }
+               catch (UnauthorizedAccessException e) {
+                  Console.WriteLine(e.Message);
+                  continue;
+               }
+               catch (DirectoryNotFoundException e) {
+                  Console.WriteLine(e.Message);
+                  continue;
+               }
+               catch (IOException e) {
+                  Console.WriteLine(e.Message);
+                  continue;
+               }
+
+               // Execute in parallel if there are enough files in the directory.
+               // Otherwise, execute sequentially.Files are opened and processed
+               // synchronously but this could be modified to perform async I/O.
+               try {
+                  if (files.Length < procCount) {
+                     foreach (var file in files) {
+                        action(file);
+                        fileCount++;
+                     }
+                  }
+                  else {
+                     Parallel.ForEach(files, () => 0, (file, loopState, localCount) =>
+                                                  { action(file);
+                                                    return (int) ++localCount;
+                                                  },
+                                      (c) => {
+                                                Interlocked.Add(ref fileCount, c);
+                                      });
+                  }
+               }
+               catch (AggregateException ae) {
+                  ae.Handle((ex) => {
+                               if (ex is UnauthorizedAccessException) {
+                                  // Here we just output a message and go on.
+                                  Console.WriteLine(ex.Message);
+                                  return true;
+                               }
+                               // Handle other exceptions here if necessary...
+
+                               return false;
+                  });
+               }
+
+               // Push the subdirectories onto the stack for traversal.
+               // This could also be done before handing the files.
+               foreach (string str in subDirs)
+                  dirs.Push(str);
+            }
+
+            // For diagnostic purposes.
+            Console.WriteLine("Processed {0} files in {1} milliseconds", fileCount, sw.ElapsedMilliseconds);
+         }
     }
 }