feat: add image handling actions and improve IRC message formatting

src/EchoHub.Server.Irc/IrcMessageFormatter.cs

@@ -1,20 +1,20 @@
 using System.Text;
-using System.Text.RegularExpressions;
-using EchoHub.Core.Contracts;
 using EchoHub.Core.DTOs;
 using EchoHub.Core.Models;
-using EchoHub.Core.Security;
 
 namespace EchoHub.Server.Irc;
 
-public static partial class IrcMessageFormatter
+public static class IrcMessageFormatter
 {
     private const int MaxIrcLineContentBytes = 400;
 
     /// <summary>
     /// Format a MessageDto as one or more IRC PRIVMSG lines.
+    /// Attachments are rendered as single link lines \u2014 the widely-supported IRC convention
+    /// (clients auto-preview or open plain http(s) URLs) \u2014 never as terminal color art.
+    /// <paramref name="publicBaseUrl"/> makes the links absolute so any IRC client can open them.
     /// </summary>
-    public static List<string> FormatMessage(MessageDto message)
+    public static List<string> FormatMessage(MessageDto message, string? publicBaseUrl = null)
     {
         var lines = new List<string>();
         var ircChannel = $"#{message.ChannelName}";
@@ -27,34 +27,19 @@ public static partial class IrcMessageFormatter
                 lines.Add($"{prefix} PRIVMSG {ircChannel} :{chunk}");
         }
 
-        // One block per attachment
+        // One link line per attachment
         if (message.Attachments is { Count: > 0 })
         {
             foreach (var attachment in message.Attachments)
             {
-                switch (attachment.Kind)
+                var url = ToAbsoluteUrl(attachment.Url, publicBaseUrl);
+                var tag = attachment.Kind switch
                 {
-                    case AttachmentKind.Image:
-                        lines.Add($"{prefix} PRIVMSG {ircChannel} :[Image: {attachment.FileName}] {attachment.Url}");
-                        if (attachment.AsciiPreview is not null && !IsCiphertext(attachment.AsciiPreview))
-                        {
-                            foreach (var line in attachment.AsciiPreview.Split('\n'))
-                            {
-                                var trimmed = line.TrimEnd('\r');
-                                if (trimmed.Length > 0)
-                                    lines.Add($"{prefix} PRIVMSG {ircChannel} :{ColorTagsToAnsi(trimmed)}");
-                            }
-                        }
-                        break;
-
-                    case AttachmentKind.Audio:
-                        lines.Add($"{prefix} PRIVMSG {ircChannel} :\u266a [Audio: {attachment.FileName}] {attachment.Url}");
-                        break;
-
-                    default:
-                        lines.Add($"{prefix} PRIVMSG {ircChannel} :[File: {attachment.FileName}] {attachment.Url}");
-                        break;
-                }
+                    AttachmentKind.Image => $"[Image: {attachment.FileName}]",
+                    AttachmentKind.Audio => $"\u266a [Audio: {attachment.FileName}]",
+                    _ => $"[File: {attachment.FileName}]",
+                };
+                lines.Add($"{prefix} PRIVMSG {ircChannel} :{tag} {url}");
             }
         }
 
@@ -69,13 +54,15 @@ public static partial class IrcMessageFormatter
     }
 
     /// <summary>
-    /// True when a preview is still encrypted — transport ($ENC$v1$) if a broadcast path
-    /// forgot to decrypt it, or E2E room ciphertext ($RC1$) the server cannot decrypt.
-    /// Emitting it would flood IRC clients with a multi-KB base64 blob.
+    /// Joins a relative attachment path onto the configured public base URL.
+    /// Already-absolute URLs and unset base URLs pass through unchanged.
     /// </summary>
-    private static bool IsCiphertext(string text) =>
-        text.StartsWith(IMessageEncryptionService.CiphertextPrefix, StringComparison.Ordinal)
-        || text.StartsWith(RoomCrypto.CiphertextPrefix, StringComparison.Ordinal);
+    public static string ToAbsoluteUrl(string url, string? publicBaseUrl)
+    {
+        if (string.IsNullOrWhiteSpace(publicBaseUrl) || Uri.IsWellFormedUriString(url, UriKind.Absolute))
+            return url;
+        return $"{publicBaseUrl.TrimEnd('/')}/{url.TrimStart('/')}";
+    }
 
     /// <summary>
     /// Format a link embed as IRC PRIVMSG lines (text-only, no ASCII thumbnail).
@@ -104,35 +91,6 @@ public static partial class IrcMessageFormatter
         return lines;
     }
 
-    /// <summary>
-    /// Convert printable color tags ({F:RRGGBB}, {B:RRGGBB}, {X}) to ANSI escape codes for IRC clients.
-    /// Also passes through content that already uses ANSI codes unchanged.
-    /// </summary>
-    public static string ColorTagsToAnsi(string text)
-    {
-        if (!text.Contains('{'))
-            return text;
-
-        return ColorTagRegex().Replace(text, match =>
-        {
-            if (match.Groups[1].Success) // {X} reset
-                return "\x1b[0m";
-            if (match.Groups[2].Success) // {F:RRGGBB} or {B:RRGGBB}
-            {
-                var hex = match.Groups[3].Value;
-                var r = Convert.ToInt32(hex[..2], 16);
-                var g = Convert.ToInt32(hex[2..4], 16);
-                var b = Convert.ToInt32(hex[4..6], 16);
-                var code = match.Groups[2].Value == "F" ? "38" : "48";
-                return $"\x1b[{code};2;{r};{g};{b}m";
-            }
-            return match.Value;
-        });
-    }
-
-    [GeneratedRegex(@"\{(?:(X)|(?:(F|B):([0-9A-Fa-f]{6})))\}")]
-    private static partial Regex ColorTagRegex();
-
     /// <summary>
     /// Split a message into chunks of approximately maxBytes (UTF-8), at word boundaries.
     /// </summary>