Add static helper for YAML serialisation / deserialisation.

#67

src/KubeClient/Models/Yaml.cs

@@ -0,0 +1,251 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using System;
+using System.IO;
+using System.Text;
+using YamlDotNet.Serialization;
+
+using KubeResourceClient = KubeClient.ResourceClients.KubeResourceClient;
+
+namespace KubeClient.Models
+{
+    /// <summary>
+    ///     Helper methods for YAML serialisation / deserialisation of models.
+    /// </summary>
+    public static class Yaml
+    {
+        /// <summary>
+        ///     The buffer size used when reading from / writing to streams.
+        /// </summary>
+        const int StreamBufferSize = 1024;
+
+        /// <summary>
+        ///     The singleton YAML <see cref="Deserializer"/> used by static methods on <see cref="Yaml"/>.
+        /// </summary>
+        static readonly Deserializer YamlDeserialiser = new DeserializerBuilder().IgnoreUnmatchedProperties().Build();
+
+        /// <summary>
+        ///     The singleton (JSON-compatible) YAML <see cref="Serializer"/> used by static methods on <see cref="Yaml"/>.
+        /// </summary>
+        static readonly Serializer YamlJsonSerialiser = new SerializerBuilder().JsonCompatible().Build();
+
+        /// <summary>
+        ///     The singleton <see cref="JsonSerializer"/> used by static methods on <see cref="Yaml"/>.
+        /// </summary>
+        static readonly JsonSerializer JsonSerializer = Newtonsoft.Json.JsonSerializer.Create(KubeResourceClient.SerializerSettings);
+
+        /// <summary>
+        ///     Convert YAML to JSON.
+        /// </summary>
+        /// <param name="yaml">
+        ///     A <see cref="TextReader"/> containing the YAML to convert.
+        /// </param>
+        /// <returns>
+        ///     A <see cref="JToken"/> representing the converted JSON.
+        /// </returns>
+        public static JToken ToJson(TextReader yaml)
+        {
+            if (yaml == null)
+                throw new ArgumentNullException(nameof(yaml));
+
+            object deserialisedYaml = YamlDeserialiser.Deserialize(yaml);
+
+            using (MemoryStream buffer = new MemoryStream())
+            {
+                using (TextWriter jsonWriter = CreateTextWriter(buffer))
+                {
+                    YamlJsonSerialiser.Serialize(jsonWriter, deserialisedYaml);
+                    jsonWriter.Flush();
+                }
+
+                buffer.Seek(0, SeekOrigin.Begin);
+
+                using (JsonReader jsonReader = CreateJsonReader(buffer))
+                {
+                    return JToken.Load(jsonReader);
+                }
+            }
+        }
+
+        /// <summary>
+        ///     Convert YAML to JSON.
+        /// </summary>
+        /// <param name="yaml">
+        ///     A string containing the YAML to convert.
+        /// </param>
+        /// <param name="formatting">
+        ///     A <see cref="Formatting"/> value indicating whether the converted JSON should be formatted (i.e. indented).
+        /// </param>
+        /// <returns>
+        ///     A string containing the converted JSON.
+        /// </returns>
+        public static string ToJson(string yaml, Formatting formatting = Formatting.None)
+        {
+            if (yaml == null)
+                throw new ArgumentNullException(nameof(yaml));
+
+            object deserialisedYaml = YamlDeserialiser.Deserialize(
+                new StringReader(yaml)
+            );
+
+            using (MemoryStream buffer = new MemoryStream())
+            {
+                using (TextWriter jsonWriter = CreateTextWriter(buffer))
+                {
+                    YamlJsonSerialiser.Serialize(jsonWriter, deserialisedYaml);
+                    jsonWriter.Flush();
+                }
+
+                buffer.Seek(0, SeekOrigin.Begin);
+
+                using (JsonReader jsonReader = CreateJsonReader(buffer))
+                {
+                    return JToken.Load(jsonReader).ToString(formatting);
+                }
+            }
+        }
+
+        /// <summary>
+        ///     Deserialise a <typeparamref name="TModel"/> from YAML.
+        /// </summary>
+        /// <typeparam name="TModel">
+        ///     The type of model to deserialise.
+        /// </typeparam>
+        /// <param name="yaml">
+        ///     A <see cref="TextReader"/> containing the YAML.
+        /// </param>
+        /// <returns>
+        ///     The deserialised <typeparamref name="TModel"/>.
+        /// </returns>
+        /// <remarks>
+        ///     Delegates the actual deserialisation to JSON.NET, after converting the YAML to JSON.
+        /// 
+        ///     Not particularly efficient, but safe and reliable.
+        /// </remarks>
+        public static TModel Deserialize<TModel>(TextReader yaml)
+        {
+            if (yaml == null)
+                throw new ArgumentNullException(nameof(yaml));
+
+            object deserialisedYaml = YamlDeserialiser.Deserialize(yaml);
+
+            using (MemoryStream buffer = new MemoryStream())
+            {
+                using (JsonWriter jsonWriter = CreateJsonWriter(buffer))
+                {
+                    JsonSerializer.Serialize(jsonWriter, deserialisedYaml);
+                    jsonWriter.Flush();
+                }
+
+                buffer.Seek(0, SeekOrigin.Begin);
+
+                using (JsonReader jsonReader = CreateJsonReader(buffer))
+                {
+                    return JsonSerializer.Deserialize<TModel>(jsonReader);
+                }
+            }
+        }
+
+        /// <summary>
+        ///     Create a <see cref="JsonReader"/> that reads from the specified stream.
+        /// </summary>
+        /// <param name="stream">
+        ///     The target stream.
+        /// </param>
+        /// <returns>
+        ///     The new <see cref="JsonReader"/>.
+        /// </returns>
+        static JsonReader CreateJsonReader(Stream stream)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            TextReader textReader = null;
+            JsonReader jsonReader = null;
+
+            try
+            {
+                textReader = CreateTextReader(stream);
+                jsonReader = new JsonTextReader(textReader);
+            }
+            catch (Exception)
+            {
+                using (jsonReader)
+                using (textReader)
+                {
+                    throw;
+                }
+            }
+
+            return jsonReader;
+        }
+
+        /// <summary>
+        ///     Create a <see cref="JsonWriter"/> that writes to the specified stream.
+        /// </summary>
+        /// <param name="stream">
+        ///     The target stream.
+        /// </param>
+        /// <returns>
+        ///     The new <see cref="JsonWriter"/>.
+        /// </returns>
+        static JsonWriter CreateJsonWriter(Stream stream)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            TextWriter textWriter = null;
+            JsonWriter jsonWriter = null;
+
+            try
+            {
+                textWriter = CreateTextWriter(stream);
+                jsonWriter = new JsonTextWriter(textWriter);
+            }
+            catch (Exception)
+            {
+                using (jsonWriter)
+                using (textWriter)
+                {
+                    throw;
+                }
+            }
+
+            return jsonWriter;
+        }
+
+        /// <summary>
+        ///     Create a <see cref="TextReader"/> that reads from the specified stream.
+        /// </summary>
+        /// <param name="stream">
+        ///     The target stream.
+        /// </param>
+        /// <returns>
+        ///     The new <see cref="TextReader"/>.
+        /// </returns>
+        static TextReader CreateTextReader(Stream stream)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            return new StreamReader(stream, Encoding.UTF8, detectEncodingFromByteOrderMarks: false, bufferSize: StreamBufferSize, leaveOpen: true);
+        }
+
+        /// <summary>
+        ///     Create a <see cref="TextWriter"/> that writes to the specified stream.
+        /// </summary>
+        /// <param name="stream">
+        ///     The target stream.
+        /// </param>
+        /// <returns>
+        ///     The new <see cref="TextWriter"/>.
+        /// </returns>
+        static TextWriter CreateTextWriter(Stream stream)
+        {
+            if (stream == null)
+                throw new ArgumentNullException(nameof(stream));
+
+            return new StreamWriter(stream, Encoding.UTF8, bufferSize: StreamBufferSize, leaveOpen: true);
+        }
+    }
+}