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 #nullable enable
  23
  24 using System;
  25 using System.Collections.Generic;
  26 using System.Linq;
  27 using System.Net.Http;
  28 using System.Net.Http.Headers;
  29 using System.Runtime.Serialization.Json;
  30 using System.Text;
  31 using System.Threading.Tasks;
  32 using System.Xml;
  33 using System.Xml.Linq;
  34 using System.Xml.XPath;
  35 using OpenTween.Connection;
  36
  37 namespace OpenTween.Api
  38 {
  39     public class MicrosoftTranslatorApi
  40     {
  41         public static readonly Uri IssueTokenEndpoint = new Uri("https://api.cognitive.microsoft.com/sts/v1.0/issueToken");
  42         public static readonly Uri TranslateEndpoint = new Uri("https://api.cognitive.microsofttranslator.com/translate");
  43
  44         public string AccessToken { get; internal set; } = "";
  45         public DateTimeUtc RefreshAccessTokenAt { get; internal set; } = DateTimeUtc.MinValue;
  46
  47         private HttpClient Http => this.localHttpClient ?? Networking.Http;
  48         private readonly HttpClient? localHttpClient;
  49
  50         public MicrosoftTranslatorApi()
  51             : this(null)
  52         {
  53         }
  54
  55         public MicrosoftTranslatorApi(HttpClient? http)
  56             => this.localHttpClient = http;
  57
  58         public async Task<string> TranslateAsync(string text, string langTo, string? langFrom = null)
  59         {
  60             await this.UpdateAccessTokenIfExpired()
  61                 .ConfigureAwait(false);
  62
  63             var param = new Dictionary<string, string>
  64             {
  65                 ["api-version"] = "3.0",
  66                 ["to"] = langTo,
  67             };
  68
  69             if (langFrom != null)
  70                 param["from"] = langFrom;
  71
  72             var requestUri = new Uri(TranslateEndpoint, "?" + MyCommon.BuildQueryString(param));
  73
  74             using var request = new HttpRequestMessage(HttpMethod.Post, requestUri);
  75             request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", this.AccessToken);
  76
  77             var escapedText = JsonUtils.EscapeJsonString(text);
  78             var json = $@"[{{""Text"": ""{escapedText}""}}]";
  79
  80             using var body = new StringContent(json, Encoding.UTF8, "application/json");
  81             request.Content = body;
  82
  83             using var response = await this.Http.SendAsync(request)
  84                 .ConfigureAwait(false);
  85
  86             response.EnsureSuccessStatusCode();
  87
  88             var responseJson = await response.Content.ReadAsByteArrayAsync()
  89                 .ConfigureAwait(false);
  90
  91             using var jsonReader = JsonReaderWriterFactory.CreateJsonReader(responseJson, XmlDictionaryReaderQuotas.Max);
  92             var xElm = XElement.Load(jsonReader);
  93             var transtlationTextElm = xElm.XPathSelectElement("/item/translations/item/text[1]");
  94
  95             return transtlationTextElm?.Value ?? "";
  96         }
  97
  98         public async Task UpdateAccessTokenIfExpired()
  99         {
 100             if (!string.IsNullOrEmpty(this.AccessToken) && this.RefreshAccessTokenAt > DateTimeUtc.Now)
 101                 return;
 102
 103             var (accessToken, expiresIn) = await this.GetAccessTokenAsync()
 104                 .ConfigureAwait(false);
 105
 106             this.AccessToken = accessToken;
 107
 108             // 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
 109             this.RefreshAccessTokenAt = DateTimeUtc.Now + expiresIn - TimeSpan.FromSeconds(30);
 110         }
 111
 112         internal virtual async Task<(string AccessToken, TimeSpan ExpiresIn)> GetAccessTokenAsync()
 113         {
 114             using var request = new HttpRequestMessage(HttpMethod.Post, IssueTokenEndpoint);
 115             request.Headers.Add("Ocp-Apim-Subscription-Key", ApplicationSettings.TranslatorSubscriptionKey);
 116
 117             using var response = await this.Http.SendAsync(request)
 118                 .ConfigureAwait(false);
 119
 120             var accessToken = await response.Content.ReadAsStringAsync()
 121                 .ConfigureAwait(false);
 122
 123             return (accessToken, TimeSpan.FromMinutes(10));
 124         }
 125     }
 126 }