Move credentials and options to json config file so that driver/example program can be

published to public repositories i.e., github
In doing so,
- provide a list of patterns in config so that internal / confidential strings
  can be put there
- add namespace 'WPExportApp' to share it with JsonConfig class
- add unicode examples: weird char replacements

And,
- comment 'CustomMetadata' out, for actual applications

// Initial PR Date: 11-21-2021

Author: atiq-cs

Goodbye.WordPress.Example/JsonConfig.cs

@@ -0,0 +1,74 @@
+namespace WPExportApp {
+  using System;
+  using System.Threading.Tasks;
+
+  /// <summary>
+  /// Credentials Related
+  /// Provides
+  /// - Credentials
+  /// - Additional options i.e., for SSL
+  /// - Patterns for substitution/pre-processing content
+  /// </summary>
+  class JsonConfig {
+    public WPExpJsonConfig? Options { get; set; }
+
+    /// <summary>
+    /// Config file path
+    /// </summary>
+    private string JsonConfigFilePath { get; set; }
+
+    /// <remarks>
+    /// <see href="https://docs.microsoft.com/en-us/dotnet/api/system.environment.specialfolder">
+    /// Accessing Local App Data via Environment
+    /// </see>
+    /// </remarks>
+    public JsonConfig() {
+      JsonConfigFilePath = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)
+        + @"\WPExportConfig.json";
+
+      if (!System.IO.File.Exists(JsonConfigFilePath)) {
+        throw new InvalidOperationException($"Required config: {JsonConfigFilePath} not found!" + 
+          "Please create the config file and run this application again.");
+      }
+    }
+
+    public class ReplacePattern {
+      public string Needle { get; set; }
+      public string Substitute { get; set; }
+    }
+
+    /// <summary>
+    /// Structure to read records from config file (json format)
+    /// Self explanatory props
+    /// </summary>
+    public class WPExpJsonConfig {
+      public string Host { get; set; }
+      public string Database { get; set; }
+      public string Username { get; set; }
+      public string Password { get; set; }
+      public string TlsVersion { get; set; }
+      public string ContentOutputDirectory { get; set; }
+      public string ArchiveOutputFilePath { get; set; }
+      /// <summary>
+      /// Some of the patterns might be internal only and should not be published online
+      /// Therefore, it might be good idea to keep them in the json config file.
+      /// </summary>
+      public ReplacePattern[] Patterns { get; set; }
+    }
+
+
+    /// <summary>
+    /// Read and Parse Config file
+    /// </summary>
+    public async Task Load() {
+      using System.IO.FileStream openStream = System.IO.File.OpenRead(JsonConfigFilePath);
+      Options = await System.Text.Json.JsonSerializer.DeserializeAsync<WPExpJsonConfig>(openStream);
+
+      if (Options == null || string.IsNullOrEmpty(Options.Host) || string.IsNullOrEmpty(
+        Options.Database) || string.IsNullOrEmpty(Options.Username) || string.IsNullOrEmpty(
+          Options.Password)) {
+            throw new NullReferenceException("Database Credentials are empty in Json config file!");
+      }
+    }
+  }
+}

Goodbye.WordPress.Example/Program.cs

@@ -1,41 +1,82 @@
-using Goodbye.WordPress;
+namespace WPExportApp {
+  using System.Threading.Tasks;
+  using Goodbye.WordPress;
 
-var exporter = WordPressExporter.Create(
-  postReader: new MysqlPostReader(new ConnectionStringBuilder
+  class WPExportMain {
+    /// <summary>
+    /// Entry Point
+    /// </summary>
+    /// <param name="args">CLA</param>
+    static async Task Main(string[] args)
+    {
+      var config = new JsonConfig();
+      await config.Load();
+      if (config.Options == null)
+        throw new System.NullReferenceException();
+
+      var exporter = WordPressExporter.Create(
+      postReader: new MysqlPostReader(
+        new ConnectionStringBuilder {
+          Host = config.Options.Host,
+          Database = config.Options.Database,
+          Username = config.Options.Username,
+          Password = config.Options.Password
+          // , TlsVersion = config.Options.TlsVersion
+        }),
+        contentOutputDirectory: config.Options.ContentOutputDirectory,
+        archiveOutputFilePath: config.Options.ArchiveOutputFilePath,
+        // And now the delegate...
+        @delegate: new CustomExporterDelegate(config.Options.Patterns)
+      );
+
+      await exporter.ExportAsync();
+    }
+  }
+
+
+  sealed class CustomExporterDelegate : WordPressExporterDelegate
   {
-    Host = "localhost",
-    Username = "user",
-    Password = "***",
-    Database = "wordpressdb"
-  }),
-  contentOutputDirectory: "exported-posts",
-  archiveOutputFilePath: "exported-posts/archive.json",
-
-  // And now the delegate...
-  @delegate: new CustomExporterDelegate());
-
-await exporter.ExportAsync();
-
-sealed class CustomExporterDelegate : WordPressExporterDelegate
-{
-  /// <summary>Process post contents</summary>
-  public override Post ProcessPost(
-    WordPressExporter exporter,
-    Post post)
+    JsonConfig.ReplacePattern[] StrPatterns;
+
+    public CustomExporterDelegate(JsonConfig.ReplacePattern[] patterns)
+    {
+        StrPatterns = patterns;
+    }
+
+    // Replace weird unicode chars
+    private string SubstituteCommon(string str) =>
+      str.Replace("‘", "'").Replace("’", "'")
+        .Replace("“", "\"").Replace("”", "\"");
+
+    private string ProcessContent(string content) {
+      content = SubstituteCommon(content)
+        .Replace("http://", "https://");
+
+      if (StrPatterns != null && StrPatterns.Length > 0)
+        foreach( var pattern in StrPatterns)
+          content = content.Replace(pattern.Needle, pattern.Substitute);
+      
+      return content;
+    }
+
+    /// <summary>Process post contents</summary>
+    public override Post ProcessPost(
+      WordPressExporter exporter,
+      Post post)
     // Perform the default post processing first by calling base
     => base.ProcessPost(exporter, post) with
     {
-      // Then replace '--' with Unicode em dash '—'
-      Content = post.Content.Replace("--", "—")
+      Content = ProcessContent(post.Content)
     };
 
-  /// <summary>Add 'CustomMetadata' to each post's YAML front matter</summary>
-  public override void PopulatePostYamlFrontMatter(
-    WordPressExporter exporter,
-    Post post,
-    SharpYaml.Serialization.YamlMappingNode rootNode)
-  {
-    base.PopulatePostYamlFrontMatter(exporter, post, rootNode);
-    rootNode.Add("CustomMetadata", "Some Value");
+    /// <summary>Add 'CustomMetadata' to each post's YAML front matter</summary>
+    public override void PopulatePostYamlFrontMatter(
+      WordPressExporter exporter,
+      Post post,
+      SharpYaml.Serialization.YamlMappingNode rootNode)
+    {
+      base.PopulatePostYamlFrontMatter(exporter, post, rootNode);
+      // rootNode.Add("CustomMetadata", "Some Value");
+    }
   }
-}
+}

Goodbye.WordPress.Example/README.md

@@ -0,0 +1,24 @@
+## Example Json Config
+Default config path: "$Env:LocalAppData\WPExportConfig.json"
+
+For example, `C:\Users\UserName\AppData\Local\WPExportConfig.json`
+
+An example config looks like following,
+
+    {
+      "Host": "localhost",
+      "Username": "user",
+      "Password": "your_password",
+      "Database": "wordpress_db_name",
+      "ContentOutputDirectory": "posts",
+      "ArchiveOutputFilePath": "posts/archive.json",
+      "Patterns": [
+        {
+          "Needle": "old-domain.com",
+          "Substitute": "new-domain.com"
+        }
+      ]
+    }
+
+
+For example without json config, please have a look at [primary ReadMe](https://github.com/abock/goodbye-wordpress#example-programcs).