Implement media path scheme

src/Umbraco.Core/IO/MediaPathSchemes/CombinedGuidsMediaPathScheme.cs

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+using System;
+using System.IO;
+
+namespace Umbraco.Core.IO.MediaPathSchemes
+{
+    /// <summary>
+    /// Implements a combined-guids media path scheme.
+    /// </summary>
+    /// <remarks>
+    /// <para>Path is "{combinedGuid}/{filename>}" where combinedGuid is a combination of itemGuid and propertyGuid.</para>
+    /// </remarks>
+    public class CombinedGuidsMediaPathScheme : IMediaPathScheme
+    {
+        /// <inheritdoc />
+        public void Initialize(IFileSystem filesystem)
+        { }
+
+        /// <inheritdoc />
+        public string GetFilePath(Guid itemGuid, Guid propertyGuid, string filename, string previous = null)
+        {
+            // assumes that cuid and puid keys can be trusted - and that a single property type
+            // for a single content cannot store two different files with the same name
+            var directory = Combine(itemGuid, propertyGuid).ToHexString(/*'/', 2, 4*/); // could use ext to fragment path eg 12/e4/f2/...
+            return Path.Combine(directory, filename).Replace('\\', '/');
+        }
+
+        /// <inheritdoc />
+        public string GetDeleteDirectory(string filepath)
+        {
+            return Path.GetDirectoryName(filepath);
+        }
+
+        private static byte[] Combine(Guid guid1, Guid guid2)
+        {
+            var bytes1 = guid1.ToByteArray();
+            var bytes2 = guid2.ToByteArray();
+            var bytes = new byte[bytes1.Length];
+            for (var i = 0; i < bytes1.Length; i++)
+                bytes[i] = (byte) (bytes1[i] ^ bytes2[i]);
+            return bytes;
+        }
+    }
+}

src/Umbraco.Core/IO/MediaPathSchemes/OriginalMediaPathScheme.cs

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+using System;
+using System.Globalization;
+using System.IO;
+using System.Threading;
+using Umbraco.Core.Configuration;
+
+namespace Umbraco.Core.IO.MediaPathSchemes
+{
+    /// <summary>
+    /// Implements the original media path scheme.
+    /// </summary>
+    /// <remarks>
+    /// <para>Path is "{number}/{filename}" or "{number}-{filename}" where number is an incremented counter.</para>
+    /// <para>Use '/' or '-' depending on UploadAllowDirectories setting.</para>
+    /// </remarks>
+    // scheme: path is "<number>/<filename>" where number is an incremented counter
+    public class OriginalMediaPathScheme : IMediaPathScheme
+    {
+        private readonly object _folderCounterLock = new object();
+        private IFileSystem _filesystem;
+        private long _folderCounter;
+        private bool _folderCounterInitialized;
+
+        /// <inheritdoc />
+        public void Initialize(IFileSystem filesystem)
+        {
+            _filesystem = filesystem;
+        }
+
+        /// <inheritdoc />
+        public string GetFilePath(Guid itemGuid, Guid propertyGuid, string filename, string previous = null)
+        {
+            string directory;
+            if (previous != null)
+            {
+                // old scheme, with a previous path
+                // prevpath should be "<int>/<filename>" OR "<int>-<filename>"
+                // and we want to reuse the "<int>" part, so try to find it
+
+                var sep = UmbracoConfig.For.UmbracoSettings().Content.UploadAllowDirectories ? "/" : "-";
+                var pos = previous.IndexOf(sep, StringComparison.Ordinal);
+                var s = pos > 0 ? previous.Substring(0, pos) : null;
+
+                directory = pos > 0 && int.TryParse(s, out _) ? s : GetNextDirectory();
+            }
+            else
+            {
+                directory = GetNextDirectory();
+            }
+
+            if (directory == null)
+                throw new InvalidOperationException("Cannot use a null directory.");
+
+            return UmbracoConfig.For.UmbracoSettings().Content.UploadAllowDirectories
+                ? Path.Combine(directory, filename).Replace('\\', '/')
+                : directory + "-" + filename;
+        }
+
+        /// <inheritdoc />
+        public string GetDeleteDirectory(string filepath)
+        {
+            return Path.GetDirectoryName(filepath);
+        }
+
+        private string GetNextDirectory()
+        {
+            EnsureFolderCounterIsInitialized();
+            return Interlocked.Increment(ref _folderCounter).ToString(CultureInfo.InvariantCulture);
+        }
+
+        private void EnsureFolderCounterIsInitialized()
+        {
+            lock (_folderCounterLock)
+            {
+                if (_folderCounterInitialized) return;
+
+                _folderCounter = 1000; // seed
+                var directories = _filesystem.GetDirectories("");
+                foreach (var directory in directories)
+                {
+                    if (long.TryParse(directory, out var folderNumber) && folderNumber > _folderCounter)
+                        _folderCounter = folderNumber;
+                }
+
+                // note: not multi-domains ie LB safe as another domain could create directories
+                // while we read and parse them - don't fix, move to new scheme eventually
+
+                _folderCounterInitialized = true;
+            }
+        }
+    }
+}

src/Umbraco.Core/IO/MediaPathSchemes/TwoGuidsMediaPathScheme.cs

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+using System;
+using System.IO;
+
+namespace Umbraco.Core.IO.MediaPathSchemes
+{
+    /// <summary>
+    /// Implements a two-guids media path scheme.
+    /// </summary>
+    /// <remarks>
+    /// <para>Path is "{itemGuid}-{propertyGuid}/{filename}".</para>
+    /// </remarks>
+    public class TwoGuidsMediaPathScheme : IMediaPathScheme
+    {
+        /// <inheritdoc />
+        public void Initialize(IFileSystem filesystem)
+        { }
+
+        /// <inheritdoc />
+        public string GetFilePath(Guid itemGuid, Guid propertyGuid, string filename, string previous = null)
+        {
+            var directory = itemGuid.ToString("N") + "-" + propertyGuid.ToString("N");
+            return Path.Combine(directory, filename).Replace('\\', '/');
+        }
+
+        /// <inheritdoc />
+        public string GetDeleteDirectory(string filepath)
+        {
+            return Path.GetDirectoryName(filepath);
+        }
+    }
+}