Fix overlapping capture groups

processor/regex.go

@@ -208,6 +208,8 @@ func (p *RegexProcessor) ProcessContent(content string, pattern string, luaExpr
 			}
 		}
 
+		captureGroups = deduplicateGroups(captureGroups)
+
 		if err := p.ToLua(L, captureGroups); err != nil {
 			logger.Error("Failed to set Lua variables: %v", err)
 			continue
@@ -285,6 +287,14 @@ func (p *RegexProcessor) ProcessContent(content string, pattern string, luaExpr
 
 			for _, command := range commands {
 				logger.Trace("Replace pos %d-%d with %q", command.From, command.To, command.With)
+				if command.To < command.From {
+					logger.Error("Command to is less than from: %v", command)
+					continue
+				}
+				if command.From > len(replacement) || command.To > len(replacement) {
+					logger.Error("Command from or to is greater than replacement length: %v", command)
+					continue
+				}
 				replacement = replacement[:command.From] + command.With + replacement[command.To:]
 			}
 		}
@@ -305,6 +315,30 @@ func (p *RegexProcessor) ProcessContent(content string, pattern string, luaExpr
 	return result, modificationCount, len(indices), nil
 }
 
+func deduplicateGroups(captureGroups []*CaptureGroup) []*CaptureGroup {
+	deduplicatedGroups := make([]*CaptureGroup, 0)
+	for _, group := range captureGroups {
+		overlaps := false
+		logger.Debug("Checking capture group: %s with range %v", group.Name, group.Range)
+		for _, existingGroup := range deduplicatedGroups {
+			logger.Debug("Comparing with existing group: %s with range %v", existingGroup.Name, existingGroup.Range)
+			if group.Range[0] < existingGroup.Range[1] && group.Range[1] > existingGroup.Range[0] {
+				overlaps = true
+				logger.Warning("Detected overlap between capture group '%s' and existing group '%s' in range %v-%v and %v-%v", group.Name, existingGroup.Name, group.Range[0], group.Range[1], existingGroup.Range[0], existingGroup.Range[1])
+				break
+			}
+		}
+		if overlaps {
+			// We CAN just continue despite this fuckup
+			logger.Error("Overlapping capture group: %s", group.Name)
+			continue
+		}
+		logger.Debug("No overlap detected for capture group: %s. Adding to deduplicated groups.", group.Name)
+		deduplicatedGroups = append(deduplicatedGroups, group)
+	}
+	return deduplicatedGroups
+}
+
 // The order of these replaces is important
 // This one handles !num-s inside of named capture groups
 // If it were not here our !num in a named capture group would