Optional fixOffByOneWithPreferSouceMapSymbols arg to make names match align with JS stack (#88)

src/SourceMapToolkit.CallstackDeminifier/StackTraceDeminifier.cs

@@ -16,12 +16,16 @@ namespace SourcemapToolkit.CallstackDeminifier
 		{
 			_stackFrameDeminifier = stackFrameDeminifier;
 			_stackTraceParser = stackTraceParser;
-		}
-
-		/// <summary>
+		}
+
+		/// <summary>
 		/// Parses and deminifies a string containing a minified stack trace.
-		/// </summary>
-		public DeminifyStackTraceResult DeminifyStackTrace(string stackTraceString, bool preferSourceMapsSymbols = false)
+		/// </summary>
+		/// <param name="stackTraceString">stack trace as string, to deobfuscate</param>
+		/// <param name="preferSourceMapsSymbols">if true, we will use exact sourcemap names for deobfuscation, without guessing the wrapper function name from source code</param>
+		/// <param name="fixOffByOneWithPreferSouceMapSymbols">preferSourceMapsSymbols uses name at call site in deobfuscated frame. Passing this as true fixes that case, to use the caller function name from next frame</param>
+		/// <returns></returns>
+		public DeminifyStackTraceResult DeminifyStackTrace(string stackTraceString, bool preferSourceMapsSymbols = false, bool fixOffByOneWithPreferSouceMapSymbols = false)
 		{
 			var minifiedStackFrames = _stackTraceParser.ParseStackTrace(stackTraceString, out string message);
 			var deminifiedStackFrameResults = new List<StackFrameDeminificationResult>(minifiedStackFrames.Count);
@@ -37,7 +41,26 @@ namespace SourcemapToolkit.CallstackDeminifier
 			}
 
 			deminifiedStackFrameResults.Reverse();
-
+			if (preferSourceMapsSymbols && fixOffByOneWithPreferSouceMapSymbols)
+			{
+				// we want to move all method names by one frame, so each frame will contain caller name and not callee name. To make callstacks more familiar to C# and js debug versions.
+				// However, for first frame we want to keep calee name (if avaliable) as well since this is interesting info we don't want to lose.
+				// However it means that for last frame (N), if have more then 1 frame in callstack, N-1 frame will have the same name.
+				// It is confusing, so lets replace last one with null. This will cause toString to use the obfuscated name
+				for (int i = 0; i < deminifiedStackFrameResults.Count - 1; i++)
+				{
+					string updatedMethodName = deminifiedStackFrameResults[i + 1].DeminifiedStackFrame.MethodName;
+					if (i == 0 && deminifiedStackFrameResults[i].DeminifiedStackFrame.MethodName != null)
+					{
+						updatedMethodName = updatedMethodName + "=>" + deminifiedStackFrameResults[i].DeminifiedStackFrame.MethodName;
+					}
+					deminifiedStackFrameResults[i].DeminifiedStackFrame.MethodName = updatedMethodName;
+				}
+				if (deminifiedStackFrameResults.Count > 1)
+				{
+					deminifiedStackFrameResults[deminifiedStackFrameResults.Count - 1].DeminifiedStackFrame.MethodName = null;
+				}
+			}
 			var result = new DeminifyStackTraceResult(message, minifiedStackFrames, deminifiedStackFrameResults);
 
 			return result;