Reimplement OAuth2 library - Step 1

Src/GoogleApis.DotNet4/Apis/Util/Store/FileDataStore.cs

+/*
+Copyright 2011 Google Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+using System;
+using System.IO;
+using System.Threading.Tasks;
+
+using Google.Apis.Util.Store;
+using Google.Apis.Json;
+
+namespace Google.Apis.Apis.Util.Store
+{
+/// <summary>
+/// File data store that implements <seealso cref="IDataStore"/>. This store
creates a different file for each·
+/// combination of type and key.
+/// </summary>
+public class FileDataStore : IDataStore
+{
+readonly string folderPath;
+/// <summary>Gets the full folder path.</summary>
+public string FolderPath { get { return folderPath; } }
+
+/// <summary>
+/// Constructs a new file data store with the specified folder. This fol
der is created (if it doesn't exist·
+/// yet) under <seealso cref="Environment.SpecialFolder.ApplicationData"
/>.
+/// </summary>
+/// <param name="folder">Folder name</param>
+public FileDataStore(string folder)
+{
+folderPath = Path.Combine(Environment.GetFolderPath(Environment.Spec
ialFolder.ApplicationData), folder);
+if (!Directory.Exists(folderPath))
+{
+Directory.CreateDirectory(folderPath);
+}
+}
+
+/// <summary>
+/// Stores the given value for the given key. It creates a new file (nam
ed <see cref="GetStoredKey"/>) in·
+/// <see cref="FolderPath"/>.
+/// </summary>
+/// <typeparam name="T">The type to store in the data store</typeparam>
+/// <param name="key">The key</param>
+/// <param name="value">The value to store in the data store</param>
+public Task Store<T>(string key, T value)
+{
+if (string.IsNullOrEmpty(key))
+{
+throw new ArgumentException("Key MUST have a value");
+}
+
+var serialized = NewtonsoftJsonSerializer.Instance.Serialize(value);
+var filePath = Path.Combine(folderPath, GetStoredKey(key, typeof(T))
);
+File.WriteAllText(filePath, serialized);
+return TaskEx.Delay(0);
+}
+
+/// <summary>
+/// Deletes the given key. It deletes the <see cref="GetStoredKey"/> nam
ed file in <see cref="FolderPath"/>.
+/// </summary>
+/// <param name="key">The key to delete from the data store</param>
+/// <param name="t">The type of the stored value</param>
+public Task Delete(string key, Type t)
+{
+if (string.IsNullOrEmpty(key))
+{
+throw new ArgumentException("Key MUST have a value");
+}
+if (t == null)
+{
+throw new ArgumentException("Type can't be null");
+}
+
+var filePath = Path.Combine(folderPath, GetStoredKey(key, t));
+if (File.Exists(filePath))
+{
+File.Delete(filePath);
+}
+return TaskEx.Delay(0);
+}
+
+/// <summary>
+/// Returns the stored value for the given key or <c>null</c> if the mat
ching file (<see cref="GetStoredKey"/>
+/// in <see cref="FolderPath"/> doesn't exist.
+/// </summary>
+/// <typeparam name="T">The type to retrieve</typeparam>
+/// <param name="key">The key to retrieve from the data store</param>
+/// <returns>The stored object</returns>
+public Task<T> Get<T>(string key)
+{
+if (string.IsNullOrEmpty(key))
+{
+throw new ArgumentException("Key MUST have a value");
+}
+
+TaskCompletionSource<T> tcs = new TaskCompletionSource<T>();
+var filePath = Path.Combine(folderPath, GetStoredKey(key, typeof(T))
);
+if (File.Exists(filePath))
+{
+try
+{
+var obj = File.ReadAllText(filePath);
+tcs.SetResult(NewtonsoftJsonSerializer.Instance.Deserialize<
T>(obj));
+}
+catch (Exception ex)
+{
+tcs.SetException(ex);
+}
+}
+else
+{
+tcs.SetResult(default(T));
+}
+return tcs.Task;
+}
+
+/// <summary>
+/// Clears all values in the data store. This method deletes all files i
n <see cref="FolderPath"/>.
+/// </summary>
+public Task Clear()
+{
+if (Directory.Exists(folderPath))
+{
+Directory.Delete(folderPath, true);
+Directory.CreateDirectory(folderPath);
+}
+
+return TaskEx.Delay(0);
+}
+
+/// <summary>Creates a unique stored key based on the key and the class
type.</summary>
+/// <param name="key">The object key</param>
+/// <param name="t">The type to store or retrieve</param>
+public static string GetStoredKey(string key, Type t)
+{
+return string.Format("{0}-{1}", t.FullName, key);
+}
+}
+}