feat: add native POP3 receiver adapters (MailKit + Rebex)

SW.Bitween.NativeAdapters/Pop3Receiver/NativePop3Receiver.cs

@@ -0,0 +1,78 @@
+using System.Text;
+using MailKit.Net.Pop3;
+using MailKit.Security;
+using MimeKit;
+using SW.PrimitiveTypes;
+
+namespace SW.Bitween.NativeAdapters.Pop3Receiver;
+
+public class NativePop3Receiver : INativeInfolinkReceiver
+{
+    private Pop3ReceiverInput _options = new();
+    private Pop3Client? _client;
+
+    // Connection defaults matching the standard implicit-SSL POP3 endpoint.
+    // Not user-configurable; exposed internally only so tests can point at a local fake server.
+    internal int Port { get; set; } = 995;
+    internal bool UseSsl { get; set; } = true;
+
+    public async Task Initialize()
+    {
+        _client = new Pop3Client();
+        var sslOptions = UseSsl ? SecureSocketOptions.SslOnConnect : SecureSocketOptions.None;
+        await _client.ConnectAsync(_options.Host, Port, sslOptions);
+        await _client.AuthenticateAsync(_options.Username, _options.Password);
+    }
+
+    public async Task Finalize()
+    {
+        await _client!.DisconnectAsync(true);
+        _client.Dispose();
+    }
+
+    public Task<IEnumerable<string>> ListFiles()
+    {
+        var count = Math.Min(_client!.Count, _options.BatchSize);
+        return Task.FromResult(Enumerable.Range(0, count).Select(i => i.ToString()));
+    }
+
+    public async Task<XchangeFile> GetFile(string fileId)
+    {
+        var index = int.Parse(fileId);
+        var message = await _client!.GetMessageAsync(index);
+
+        var attachment = message.Attachments.FirstOrDefault();
+        if (attachment == null)
+            return new XchangeFile(message.TextBody ?? message.HtmlBody ?? string.Empty, message.Subject);
+
+        using var memoryStream = new MemoryStream();
+        if (attachment is MessagePart rfc822)
+            await rfc822.Message.WriteToAsync(memoryStream);
+        else
+            await ((MimePart)attachment).Content.DecodeToAsync(memoryStream);
+
+        var buffer = memoryStream.ToArray();
+
+        return _options.ResponseEncoding.ToLower() switch
+        {
+            "base64" => new XchangeFile(Convert.ToBase64String(buffer), message.Subject),
+            "utf8" => new XchangeFile(Encoding.UTF8.GetString(buffer), message.Subject),
+            _ => throw new ArgumentException(
+                $"Unknown {nameof(Pop3ReceiverInput.ResponseEncoding)} '{_options.ResponseEncoding}'")
+        };
+    }
+
+    public async Task DeleteFile(string fileId)
+    {
+        await _client!.DeleteMessageAsync(int.Parse(fileId));
+    }
+
+    public string Name => "NativePop3Receiver";
+
+    public void InitializeStartupValues(IDictionary<string, string> settings)
+    {
+        _options = settings.ConvertTo<Pop3ReceiverInput>();
+    }
+
+    public Type StartupValuesType => typeof(Pop3ReceiverInput);
+}

SW.Bitween.NativeAdapters/Pop3Receiver/Pop3ReceiverInput.cs

@@ -0,0 +1,23 @@
+using System.ComponentModel;
+using System.ComponentModel.DataAnnotations;
+
+namespace SW.Bitween.NativeAdapters.Pop3Receiver;
+
+public class Pop3ReceiverInput
+{
+    [Required]
+    public string Host { get; set; } = string.Empty;
+
+    [Required]
+    public string Username { get; set; } = string.Empty;
+
+    [Required]
+    [Secure]
+    public string Password { get; set; } = string.Empty;
+
+    [DefaultValue(50)]
+    public int BatchSize { get; set; } = 50;
+
+    [DefaultValue("utf8")]
+    public string ResponseEncoding { get; set; } = "utf8";
+}

SW.Bitween.NativeAdapters/RebexPop3Receiver/NativeRebexPop3Receiver.cs

@@ -0,0 +1,81 @@
+using System.Text;
+using Rebex.Net;
+using SW.PrimitiveTypes;
+
+namespace SW.Bitween.NativeAdapters.RebexPop3Receiver;
+
+public class NativeRebexPop3Receiver : INativeInfolinkReceiver
+{
+    public const string LicenseKeyEnvironmentVariable = "REBEX_LICENSE_KEY";
+
+    private RebexPop3ReceiverInput _options = new();
+    private Pop3 _pop3 = new();
+
+    // Connection defaults matching the standard implicit-SSL POP3 endpoint.
+    // Not user-configurable; exposed internally only so tests can point at a local fake server.
+    internal int Port { get; set; } = 995;
+    internal bool UseSsl { get; set; } = true;
+
+    public async Task Initialize()
+    {
+        Rebex.Licensing.Key = Environment.GetEnvironmentVariable(LicenseKeyEnvironmentVariable);
+        _pop3 = new Pop3();
+        var sslMode = UseSsl ? SslMode.Implicit : SslMode.None;
+        await _pop3.ConnectAsync(_options.Host, Port, sslMode);
+        await _pop3.LoginAsync(_options.Username, _options.Password);
+    }
+
+    public async Task Finalize()
+    {
+        await _pop3.DisconnectAsync(false);
+        _pop3.Dispose();
+    }
+
+    public async Task<IEnumerable<string>> ListFiles()
+    {
+        var messages = await _pop3.GetMessageListAsync(Pop3ListFields.Fast);
+
+        return messages.Select(m => m.SequenceNumber.ToString())
+            .Take(_options.BatchSize)
+            .ToList();
+    }
+
+    public async Task<XchangeFile> GetFile(string fileId)
+    {
+        var sequenceNumber = int.Parse(fileId);
+        var message = await _pop3.GetMailMessageAsync(sequenceNumber);
+
+        if (message.Attachments.Count < 1)
+            return new XchangeFile(message.BodyText, message.Subject);
+
+        var attachment = message.Attachments[0];
+        await _pop3.GetMessageAsync(sequenceNumber, attachment.FileName);
+
+        await using var stream = attachment.GetContentStream();
+        using var memoryStream = new MemoryStream();
+        await stream.CopyToAsync(memoryStream);
+        var buffer = memoryStream.ToArray();
+
+        return _options.ResponseEncoding.ToLower() switch
+        {
+            "base64" => new XchangeFile(Convert.ToBase64String(buffer), message.Subject),
+            "utf8" => new XchangeFile(Encoding.UTF8.GetString(buffer), message.Subject),
+            _ => throw new ArgumentException(
+                $"Unknown {nameof(RebexPop3ReceiverInput.ResponseEncoding)} '{_options.ResponseEncoding}'")
+        };
+    }
+
+    public async Task DeleteFile(string fileId)
+    {
+        await _pop3.DeleteAsync(int.Parse(fileId));
+    }
+
+    public string Name => "NativeRebexPop3Receiver";
+
+    public void InitializeStartupValues(IDictionary<string, string> settings)
+    {
+        _options = settings.ConvertTo<RebexPop3ReceiverInput>();
+    }
+
+    public Type StartupValuesType => typeof(RebexPop3ReceiverInput);
+}

SW.Bitween.NativeAdapters/RebexPop3Receiver/RebexPop3ReceiverInput.cs

@@ -0,0 +1,23 @@
+using System.ComponentModel;
+using System.ComponentModel.DataAnnotations;
+
+namespace SW.Bitween.NativeAdapters.RebexPop3Receiver;
+
+public class RebexPop3ReceiverInput
+{
+    [Required]
+    public string Host { get; set; } = string.Empty;
+
+    [Required]
+    public string Username { get; set; } = string.Empty;
+
+    [Required]
+    [Secure]
+    public string Password { get; set; } = string.Empty;
+
+    [DefaultValue(50)]
+    public int BatchSize { get; set; } = 50;
+
+    [DefaultValue("utf8")]
+    public string ResponseEncoding { get; set; } = "utf8";
+}

SW.Bitween.NativeAdapters/SW.Bitween.NativeAdapters.csproj

@@ -9,9 +9,16 @@
         <FrameworkReference Include="Microsoft.AspNetCore.App" />
     </ItemGroup>
 
+    <ItemGroup>
+        <InternalsVisibleTo Include="SW.Bitween.UnitTests" />
+    </ItemGroup>
+
     <ItemGroup>
       <PackageReference Include="DotLiquid" Version="2.2.692" />
+      <PackageReference Include="MailKit" Version="4.17.0" />
       <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+      <PackageReference Include="Rebex.Mail" Version="6.0.8060" />
+      <PackageReference Include="Rebex.Pop3" Version="6.0.8060" />
       <PackageReference Include="Scriban" Version="7.0.6" />
       <PackageReference Include="SimplyWorks.PrimitiveTypes" Version="8.1.2" />
     </ItemGroup>

SW.Bitween.NativeAdapters/ServiceCollectionExtensions.cs

@@ -1,5 +1,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using SW.Bitween.NativeAdapters.HttpReceiver;
+using SW.Bitween.NativeAdapters.Pop3Receiver;
+using SW.Bitween.NativeAdapters.RebexPop3Receiver;
 
 namespace SW.Bitween.NativeAdapters;
 
@@ -30,5 +32,14 @@ public static void AddNativeAdapters(this IServiceCollection serviceCollection)
 
         serviceCollection.AddScoped<INativeInfolinkReceiver, NativeHttpReceiver>();
         serviceCollection.AddScoped<INativeAdapter, NativeHttpReceiver>();
+
+        serviceCollection.AddScoped<INativeInfolinkReceiver, NativePop3Receiver>();
+        serviceCollection.AddScoped<INativeAdapter, NativePop3Receiver>();
+
+        if (!string.IsNullOrEmpty(Environment.GetEnvironmentVariable(NativeRebexPop3Receiver.LicenseKeyEnvironmentVariable)))
+        {
+            serviceCollection.AddScoped<INativeInfolinkReceiver, NativeRebexPop3Receiver>();
+            serviceCollection.AddScoped<INativeAdapter, NativeRebexPop3Receiver>();
+        }
     }
 }