feat: support long text and safe attachment batches

2026-09-30 09:16:36 +08:00
parent a977902b25
commit edba7d0d38
26 changed files with 720 additions and 82 deletions
@@ -1,14 +1,54 @@
+using System.Globalization;
+
 namespace WxAgent.Core;

 public static class WechatTextInput
 {
+    public const int MaxSegmentLength = 4000;
+    public const int MaxTextLength = 20_000;
+
    public static string Prepare(string text)
+    {
+        var normalized = PrepareLongText(text);
+        if (normalized.Length > MaxSegmentLength)
+            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, $"Message text must not exceed {MaxSegmentLength} characters.");
+        return normalized;
+    }
+
+    public static string PrepareLongText(string text)
    {
        if (string.IsNullOrWhiteSpace(text))
            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, "Message text must not be empty.");
        var normalized = text.ReplaceLineEndings("\n");
-        if (normalized.Length > 4000 || normalized.Any(character => char.IsControl(character) && character is not ('\n' or '\t')))
-            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, "Message text must not exceed 4000 characters or contain unsupported control characters.");
+        if (normalized.Length > MaxTextLength || normalized.Any(character => char.IsControl(character) && character is not ('\n' or '\t')))
+            throw new WxAgentException(WxAgentErrorCode.InvalidArgument, $"Message text must not exceed {MaxTextLength} characters or contain unsupported control characters.");
        return normalized;
    }
+
+    public static IReadOnlyList<string> SplitForSend(string text)
+    {
+        var normalized = PrepareLongText(text);
+        if (normalized.Length <= MaxSegmentLength)
+            return [normalized];
+
+        var textElementStarts = StringInfo.ParseCombiningCharacters(normalized);
+        var segments = new List<string>();
+        var start = 0;
+        while (start < normalized.Length)
+        {
+            var end = Math.Min(start + MaxSegmentLength, normalized.Length);
+            if (end < normalized.Length)
+            {
+                var boundaryIndex = Array.BinarySearch(textElementStarts, end);
+                if (boundaryIndex < 0) boundaryIndex = ~boundaryIndex - 1;
+                if (boundaryIndex < 0 || textElementStarts[boundaryIndex] <= start)
+                    throw new WxAgentException(WxAgentErrorCode.InvalidArgument, "A text element exceeds the per-message length limit.");
+                end = textElementStarts[boundaryIndex];
+            }
+
+            segments.Add(normalized[start..end]);
+            start = end;
+        }
+        return segments;
+    }
 }