Add translation request abstraction

GoogleTranslationRequest.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Specialized;
+using System.Windows.Forms;
+
+namespace SpectacleTransformer {
+    
+    public class GoogleTranslationRequest : HttpTranslationRequest {
+        public static Uri GoogleTranslateUrl = new Uri("https://translate.google.com/m");
+        
+        public GoogleTranslationRequest(Uri InstanceUri, Language Source, Language Target, string Text) : base(InstanceUri, Source, Target, Text) { }
+
+        public static new bool MatchesInstance(Uri InstanceUri) {
+            return GoogleTranslateUrl.Host == InstanceUri.Host;
+        }
+
+        public override Uri Url {
+            get {
+                NameValueCollection nvc = new NameValueCollection(3);
+                nvc["sl"] = Source.SourceName;
+                nvc["tl"] = Target.TargetName;
+                nvc["q"] = Text;
+                return new Uri(GoogleTranslateUrl, Utils.ToQueryString(nvc));
+            }
+        }
+
+        public override string DecodeResponse(string response) {
+            WebBrowser wb = new WebBrowser();
+            wb.DocumentText = response;
+            foreach (HtmlElement element in wb.Document.GetElementsByTagName("div")) {
+                if (element.GetAttribute("class") == "result-container") {
+                    return element.InnerText.Trim();
+                }
+            }
+            return null;
+        }
+
+        public override string DecodeErrorResponse(string responseBody) {
+            // I have no idea what Google Translate errors look like.
+            return null;
+        }
+    }
+}

HttpTranslationRequest.cs

@@ -0,0 +1,102 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Text;
+using System.Windows.Forms;
+
+namespace SpectacleTransformer {
+
+    public abstract class HttpTranslationRequest : TranslationRequest {
+        /// <summary>
+        /// The URL to use when performing the request.
+        /// </summary>
+        public abstract Uri Url { get; }
+
+        public HttpTranslationRequest(Uri InstanceUri, Language Source, Language Target, string Text) : base(InstanceUri, Source, Target, Text) { }
+
+        public override string Run() {
+            HttpWebResponse response = null;
+            try {
+                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(Url);
+                request.UserAgent = String.Format("{0}/{1}", Application.ProductName, Application.ProductVersion);
+
+                response = (HttpWebResponse)request.GetResponse();
+
+                string responseBody;
+                using (Stream stream = response.GetResponseStream()) {
+                    StreamReader reader = new StreamReader(stream, Encoding.UTF8);
+                    responseBody = reader.ReadToEnd();
+                }
+
+                if (response.StatusCode == HttpStatusCode.OK || response.StatusCode == HttpStatusCode.Created) {
+                    string translation = DecodeResponse(responseBody);
+
+                    if (translation == null) {
+                        MessageBox.Show(
+                            "The API request was performed successfully, but the server did not return a valid translation payload. Response payload:\r\n" + responseBody,
+                            "API error",
+                            MessageBoxButtons.OK,
+                            MessageBoxIcon.Error
+                        );
+                    }
+
+                    return translation;
+                }
+
+                string errorMessage = DecodeErrorResponse(responseBody);
+
+                if (String.IsNullOrEmpty(errorMessage)) {
+                    errorMessage = String.Format(
+                        "An unknown error occured while translating (HTTP {0} {1})",
+                        response.StatusCode,
+                        response.StatusDescription
+                    );
+                } else {
+                    errorMessage = String.Format(
+                        "An error occured while translating (HTTP {0} {1}):\r\n{2}",
+                        response.StatusCode,
+                        response.StatusDescription,
+                        errorMessage
+                    );
+                }
+
+                MessageBox.Show(
+                    errorMessage,
+                    "API error",
+                    MessageBoxButtons.OK,
+                    MessageBoxIcon.Error
+                );
+                return null;
+            } catch (WebException ex) {
+                MessageBox.Show(
+                    "An error occured while running the API request:\r\n" + ex.ToString(),
+                    "API error",
+                    MessageBoxButtons.OK,
+                    MessageBoxIcon.Error
+                );
+                return null;
+            } finally {
+                if (response != null) response.Close();
+            }
+        }
+
+        /// <summary>
+        /// Decode a successful response body into a translated text.
+        /// </summary>
+        /// <param name="responseBody">The retrieved response body.</param>
+        /// <returns>The translated text, or null if the translation failed.</returns>
+        public virtual string DecodeResponse(string responseBody) {
+            return responseBody;
+        }
+
+        /// <summary>
+        /// Decode an error response body into an error message.
+        /// </summary>
+        /// <param name="responseBody">The retrieved response body.</param>
+        /// <returns>An error message, or null if there is no particular error message.</returns>
+        public virtual string DecodeErrorResponse(string responseBody) {
+            return responseBody;
+        }
+    }
+
+}

LingvaTranslationRequest.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace SpectacleTransformer {
+
+    public class LingvaTranslationRequest : HttpTranslationRequest {
+        public LingvaTranslationRequest(Uri InstanceUri, Language Source, Language Target, string Text) : base(InstanceUri, Source, Target, Text) { }
+
+        public override Uri Url {
+            get {
+                return new Uri(InstanceUri, String.Format(
+                    "api/v1/{0}/{1}/{2}",
+                    Uri.EscapeUriString(Source.SourceName),
+                    Uri.EscapeUriString(Target.TargetName),
+                    Uri.EscapeUriString(Text)
+                ));
+            }
+        }
+
+        public static new bool MatchesInstance(Uri InstanceUri) {
+            return GoogleTranslationRequest.GoogleTranslateUrl.Host != InstanceUri.Host;
+        }
+
+        public override string DecodeResponse(string responseBody) {
+            string translation = null;
+            try {
+                JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody).TryGetValue("translation", out translation);
+            } catch (Exception) { }
+            return translation;
+        }
+
+        public override string DecodeErrorResponse(string responseBody) {
+            string errorMessage;
+            try {
+                if (!JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody).TryGetValue("errorMsg", out errorMessage)) {
+                    return responseBody;
+                }
+                return errorMessage;
+            } catch (Exception) {
+                return responseBody;
+            }
+        }
+    }
+}

MainForm.cs

@@ -1,11 +1,5 @@
 using System;
-using System.IO;
-using System.Net;
-using System.Text;
 using System.Windows.Forms;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-using System.Collections.Generic;
 
 namespace SpectacleTransformer {
     public partial class MainForm : Form {
@@ -211,80 +205,36 @@ namespace SpectacleTransformer {
 
         private void translateButton_Click(object sender, EventArgs e) {
             mainTableLayoutPanel.Enabled = false;
-            Uri targetUri = new Uri(
-                new Uri(instanceUrlPicker.Text),
-                String.Format(
-                    "api/v1/{0}/{1}/{2}",
-                    Uri.EscapeUriString(((Language)sourceLanguagePicker.SelectedItem).SourceName),
-                    Uri.EscapeUriString(((Language)destinationLanguagePicker.SelectedItem).TargetName),
-                    Uri.EscapeUriString(sourceTextBox.Text)
-                )
+
+            // TODO: Use a list to allow registering various translation services
+            TranslationRequest tr;
+            Uri instanceUri = new Uri(instanceUrlPicker.Text);
+            if (GoogleTranslationRequest.MatchesInstance(instanceUri)) tr = new GoogleTranslationRequest(
+                instanceUri,
+                (Language)sourceLanguagePicker.SelectedItem,
+                (Language)destinationLanguagePicker.SelectedItem,
+                sourceTextBox.Text
             );
-            translator.RunWorkerAsync(targetUri);
+            else tr = new LingvaTranslationRequest(
+                instanceUri,
+                (Language)sourceLanguagePicker.SelectedItem,
+                (Language)destinationLanguagePicker.SelectedItem,
+                sourceTextBox.Text
+            );
+
+            translator.RunWorkerAsync(tr);
         }
 
         private void translator_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e) {
-            HttpWebResponse response = null;
             try {
-                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create((Uri)e.Argument);
-                request.UserAgent = String.Format("{0}/{1}", Application.ProductName, Application.ProductVersion);
-
-                response = (HttpWebResponse)request.GetResponse();
-
-                string responseBody;
-                using (Stream stream = response.GetResponseStream()) {
-                    StreamReader reader = new StreamReader(stream, Encoding.UTF8);
-                    responseBody = reader.ReadToEnd();
-                }
-
-                if (response.StatusCode == HttpStatusCode.OK || response.StatusCode == HttpStatusCode.Created) {
-                    string translation = null;
-                    try {
-                        JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody).TryGetValue("translation", out translation);
-                    } catch (Exception) { }
-
-                    if (String.IsNullOrEmpty(translation)) {
-                        MessageBox.Show(
-                            "The API request was performed successfully, but the server did not return a valid translation payload. Response payload:\r\n" + responseBody,
-                            "Unexpected API response",
-                            MessageBoxButtons.OK,
-                            MessageBoxIcon.Error
-                        );
-                        return;
-                    }
-
-                    e.Result = translation;
-                } else {
-                    string errorMessage;
-                    try {
-                        if (!JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody).TryGetValue("errorMsg", out errorMessage)) {
-                            errorMessage = responseBody;
-                        }
-                    } catch (Exception) {
-                        errorMessage = responseBody;
-                    }
-
-                    MessageBox.Show(
-                        String.Format(
-                            "An error occured while translating (HTTP {0} {1}):\r\n{2}",
-                            response.StatusCode,
-                            response.StatusDescription,
-                            errorMessage
-                        ),
-                        "API error",
-                        MessageBoxButtons.OK,
-                        MessageBoxIcon.Error
-                    );
-                }
-            } catch (WebException ex) {
+                e.Result = ((TranslationRequest)e.Argument).Run();
+            } catch (Exception ex) {
                 MessageBox.Show(
-                    "An error occured while running the API request:\r\n" + ex.ToString(),
-                    "API request error",
+                    "An unexpected error occurred when running the translation request: " + ex.ToString(),
+                    "Error",
                     MessageBoxButtons.OK,
                     MessageBoxIcon.Error
                 );
-            } finally {
-                if (response != null) response.Close();
             }
         }
 

SpectacleTransformer.csproj

@@ -58,7 +58,8 @@
     <ApplicationIcon>icon.ico</ApplicationIcon>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="Newtonsoft.Json">
+    <Reference Include="Newtonsoft.Json, Version=13.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
       <HintPath>lib\Newtonsoft.Json\Newtonsoft.Json.dll</HintPath>
     </Reference>
     <Reference Include="System" />
@@ -66,7 +67,10 @@
     <Reference Include="System.Windows.Forms" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="GoogleTranslationRequest.cs" />
+    <Compile Include="HttpTranslationRequest.cs" />
     <Compile Include="Language.cs" />
+    <Compile Include="LingvaTranslationRequest.cs" />
     <Compile Include="MainForm.cs">
       <SubType>Form</SubType>
     </Compile>
@@ -74,6 +78,9 @@
       <DependentUpon>MainForm.cs</DependentUpon>
     </Compile>
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="TranslationResult.cs" />
+    <Compile Include="Utils.cs" />
+    <Compile Include="TranslationRequest.cs" />
     <EmbeddedResource Include="MainForm.resx">
       <DependentUpon>MainForm.cs</DependentUpon>
     </EmbeddedResource>

TranslationRequest.cs

@@ -0,0 +1,49 @@
+using System;
+
+namespace SpectacleTransformer {
+    public abstract class TranslationRequest {
+        public readonly Uri InstanceUri;
+        public readonly Language Source;
+        public readonly Language Target;
+        public readonly string Text;
+
+        /// <summary>
+        /// Create a new translation request.
+        /// </summary>
+        /// <param name="InstanceUri">URI pointing to the server instance to use.</param>
+        /// <param name="Source">The source language.</param>
+        /// <param name="Target">The target language.</param>
+        /// <param name="Text">The text to translate.</param>
+        public TranslationRequest(Uri InstanceUri, Language Source, Language Target, string Text) {
+            if (Source.Equals(Target)) throw new ArgumentException("The source and target languages cannot be the same.");
+            this.InstanceUri = InstanceUri;
+            this.Source = Source;
+            this.Target = Target;
+            this.Text = Text;
+        }
+
+        /// <summary>
+        /// Determines if this TranslationRequest can be instanciated with an instance URI.
+        /// </summary>
+        /// <param name="InstanceUri">The instance URI to check.</param>
+        /// <returns>Whether this translation request can be performed on this instance URI.</returns>
+        public static bool MatchesInstance(Uri InstanceUri) {
+            return true;
+        }
+
+        /// <summary>
+        /// Perform a translation request.
+        /// </summary>
+        /// <returns>The translated text, or null if the translation failed.</returns>
+        public abstract string Run();
+
+        /// <summary>
+        /// Called in the main thread with UI controls to allow further post-processing that could require them.
+        /// </summary>
+        /// <param name="response">The response returned by Run().</param>
+        /// <returns>A processed response.</returns>
+        public virtual string PostProcess(string response) {
+            return response;
+        }
+    }
+}

Utils.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Specialized;
+using System.Text;
+
+namespace SpectacleTransformer {
+    internal static class Utils {
+        internal static string ToQueryString(NameValueCollection nvc) {
+            if (nvc.Count <= 0) return "";
+            StringBuilder sb = new StringBuilder("?");
+            foreach (string key in nvc.AllKeys) {
+                foreach (string value in nvc.GetValues(key)) {
+                    sb.Append(Uri.EscapeUriString(key));
+                    sb.Append("=");
+                    sb.Append(Uri.EscapeUriString(value));
+                    sb.Append("&");
+                }
+            }
+            return sb.ToString().TrimEnd('&');
+        }
+    }
+}