[Client encryption]: Refactor EncryptionProcessor

Microsoft.Azure.Cosmos.Encryption.Custom/src/AeadAes/AeAesEncryptionProcessor.cs

@@ -0,0 +1,116 @@
+// ------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+// ------------------------------------------------------------
+
+namespace Microsoft.Azure.Cosmos.Encryption.Custom
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.IO;
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Newtonsoft.Json;
+    using Newtonsoft.Json.Linq;
+
+    internal static class AeAesEncryptionProcessor
+    {
+        public static async Task<Stream> EncryptAsync(
+            Stream input,
+            Encryptor encryptor,
+            EncryptionOptions encryptionOptions,
+            CancellationToken cancellationToken)
+        {
+            JObject itemJObj = EncryptionProcessor.BaseSerializer.FromStream<JObject>(input);
+            List<string> pathsEncrypted = new ();
+            EncryptionProperties encryptionProperties = null;
+            byte[] plainText = null;
+            byte[] cipherText = null;
+
+            JObject toEncryptJObj = new ();
+
+            foreach (string pathToEncrypt in encryptionOptions.PathsToEncrypt)
+            {
+                string propertyName = pathToEncrypt.Substring(1);
+                if (!itemJObj.TryGetValue(propertyName, out JToken propertyValue))
+                {
+                    continue;
+                }
+
+                toEncryptJObj.Add(propertyName, propertyValue.Value<JToken>());
+                itemJObj.Remove(propertyName);
+            }
+
+            MemoryStream memoryStream = EncryptionProcessor.BaseSerializer.ToStream<JObject>(toEncryptJObj);
+            Debug.Assert(memoryStream != null);
+            Debug.Assert(memoryStream.TryGetBuffer(out _));
+            plainText = memoryStream.ToArray();
+
+            cipherText = await encryptor.EncryptAsync(
+                plainText,
+                encryptionOptions.DataEncryptionKeyId,
+                encryptionOptions.EncryptionAlgorithm,
+                cancellationToken);
+
+            if (cipherText == null)
+            {
+                throw new InvalidOperationException($"{nameof(Encryptor)} returned null cipherText from {nameof(EncryptAsync)}.");
+            }
+
+            encryptionProperties = new EncryptionProperties(
+                    encryptionFormatVersion: 2,
+                    encryptionOptions.EncryptionAlgorithm,
+                    encryptionOptions.DataEncryptionKeyId,
+                    encryptedData: cipherText,
+                    encryptionOptions.PathsToEncrypt);
+
+            itemJObj.Add(Constants.EncryptedInfo, JObject.FromObject(encryptionProperties));
+            input.Dispose();
+            return EncryptionProcessor.BaseSerializer.ToStream(itemJObj);
+        }
+
+        internal static async Task<DecryptionContext> DecryptContentAsync(
+            JObject document,
+            EncryptionProperties encryptionProperties,
+            Encryptor encryptor,
+            CosmosDiagnosticsContext diagnosticsContext,
+            CancellationToken cancellationToken)
+        {
+            _ = diagnosticsContext;
+
+            if (encryptionProperties.EncryptionFormatVersion != 2)
+            {
+                throw new NotSupportedException($"Unknown encryption format version: {encryptionProperties.EncryptionFormatVersion}. Please upgrade your SDK to the latest version.");
+            }
+
+            byte[] plainText = await encryptor.DecryptAsync(
+                encryptionProperties.EncryptedData,
+                encryptionProperties.DataEncryptionKeyId,
+                encryptionProperties.EncryptionAlgorithm,
+                cancellationToken) ?? throw new InvalidOperationException($"{nameof(Encryptor)} returned null plainText from {nameof(EncryptionProcessor.DecryptAsync)}.");
+            JObject plainTextJObj;
+            using (MemoryStream memoryStream = new (plainText))
+            using (StreamReader streamReader = new (memoryStream))
+            using (JsonTextReader jsonTextReader = new (streamReader))
+            {
+                jsonTextReader.ArrayPool = JsonArrayPool.Instance;
+                plainTextJObj = JObject.Load(jsonTextReader);
+            }
+
+            List<string> pathsDecrypted = new ();
+            foreach (JProperty property in plainTextJObj.Properties())
+            {
+                document.Add(property.Name, property.Value);
+                pathsDecrypted.Add("/" + property.Name);
+            }
+
+            DecryptionContext decryptionContext = EncryptionProcessor.CreateDecryptionContext(
+                pathsDecrypted,
+                encryptionProperties.DataEncryptionKeyId);
+
+            document.Remove(Constants.EncryptedInfo);
+
+            return decryptionContext;
+        }
+    }
+}