OpenTween/Api/MicrosoftTranslatorApi.cs

   1 // OpenTween - Client of Twitter
   2 // Copyright (c) 2016 kim_upsilon (@kim_upsilon) <https://upsilo.net/~upsilon/>
   3 // All rights reserved.
   4 //
   5 // This file is part of OpenTween.
   6 //
   7 // This program is free software; you can redistribute it and/or modify it
   8 // under the terms of the GNU General Public License as published by the Free
   9 // Software Foundation; either version 3 of the License, or (at your option)
  10 // any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  15 // for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License along
  18 // with this program. If not, see <http://www.gnu.org/licenses/>, or write to
  19 // the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  20 // Boston, MA 02110-1301, USA.
  21
  22 using System;
  23 using System.Collections.Generic;
  24 using System.Linq;
  25 using System.Net.Http;
  26 using System.Net.Http.Headers;
  27 using System.Runtime.Serialization.Json;
  28 using System.Text;
  29 using System.Threading.Tasks;
  30 using System.Xml;
  31 using System.Xml.Linq;
  32 using System.Xml.XPath;
  33 using OpenTween.Connection;
  34
  35 namespace OpenTween.Api
  36 {
  37     public class MicrosoftTranslatorApi
  38     {
  39         public static readonly Uri IssueTokenEndpoint = new Uri("https://api.cognitive.microsoft.com/sts/v1.0/issueToken");
  40         public static readonly Uri TranslateEndpoint = new Uri("https://api.cognitive.microsofttranslator.com/translate");
  41
  42         public string AccessToken { get; internal set; }
  43         public DateTimeUtc RefreshAccessTokenAt { get; internal set; }
  44
  45         private HttpClient Http => this.localHttpClient ?? Networking.Http;
  46         private readonly HttpClient localHttpClient;
  47
  48         public MicrosoftTranslatorApi()
  49             : this(null)
  50         {
  51         }
  52
  53         public MicrosoftTranslatorApi(HttpClient http)
  54             => this.localHttpClient = http;
  55
  56         public async Task<string> TranslateAsync(string text, string langTo, string langFrom = null)
  57         {
  58             await this.UpdateAccessTokenIfExpired()
  59                 .ConfigureAwait(false);
  60
  61             var param = new Dictionary<string, string>
  62             {
  63                 ["api-version"] = "3.0",
  64                 ["to"] = langTo,
  65             };
  66
  67             if (langFrom != null)
  68                 param["from"] = langFrom;
  69
  70             var requestUri = new Uri(TranslateEndpoint, "?" + MyCommon.BuildQueryString(param));
  71
  72             using (var request = new HttpRequestMessage(HttpMethod.Post, requestUri))
  73             {
  74                 request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", this.AccessToken);
  75
  76                 var escapedText = JsonUtils.EscapeJsonString(text);
  77                 var json = $@"[{{""Text"": ""{escapedText}""}}]";
  78
  79                 using (var body = new StringContent(json, Encoding.UTF8, "application/json"))
  80                 {
  81                     request.Content = body;
  82
  83                     using (var response = await this.Http.SendAsync(request).ConfigureAwait(false))
  84                     {
  85                         response.EnsureSuccessStatusCode();
  86
  87                         var responseJson = await response.Content.ReadAsByteArrayAsync()
  88                             .ConfigureAwait(false);
  89
  90                         using (var jsonReader = JsonReaderWriterFactory.CreateJsonReader(responseJson, XmlDictionaryReaderQuotas.Max))
  91                         {
  92                             var xElm = XElement.Load(jsonReader);
  93                             var transtlationTextElm = xElm.XPathSelectElement("/item/translations/item/text[1]");
  94
  95                             return transtlationTextElm?.Value ?? "";
  96                         }
  97                     }
  98                 }
  99             }
 100         }
 101
 102         public async Task UpdateAccessTokenIfExpired()
 103         {
 104             if (this.AccessToken != null && this.RefreshAccessTokenAt > DateTimeUtc.Now)
 105                 return;
 106
 107             var (accessToken, expiresIn) = await this.GetAccessTokenAsync()
 108                 .ConfigureAwait(false);
 109
 110             this.AccessToken = accessToken;
 111
 112             // アクセストークンの実際の有効期限より 30 秒早めに失効として扱う
 113             this.RefreshAccessTokenAt = DateTimeUtc.Now + expiresIn - TimeSpan.FromSeconds(30);
 114         }
 115
 116         internal virtual async Task<(string AccessToken, TimeSpan ExpiresIn)> GetAccessTokenAsync()
 117         {
 118             using (var request = new HttpRequestMessage(HttpMethod.Post, IssueTokenEndpoint))
 119             {
 120                 request.Headers.Add("Ocp-Apim-Subscription-Key", ApplicationSettings.TranslatorSubscriptionKey);
 121
 122                 using (var response = await this.Http.SendAsync(request).ConfigureAwait(false))
 123                 {
 124                     var accessToken = await response.Content.ReadAsStringAsync()
 125                         .ConfigureAwait(false);
 126
 127                     return (accessToken, TimeSpan.FromMinutes(10));
 128                 }
 129             }
 130         }
 131     }
 132 }