fix: remove unused parameter prefixes and update tail filter implementation

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/filter_plugin/tail.rs

@@ -25,6 +25,7 @@ impl FilterPlugin for TailBytesFilter {
     }
 
     fn finish(&mut self) -> Result<Vec<u8>> {
+        // Collect all bytes from the ring buffer
         let mut result = Vec::with_capacity(self.ring_buffer.len());
         for byte in self.ring_buffer.iter() {
             result.push(*byte);
@@ -61,35 +62,34 @@ impl FilterPlugin for TailLinesFilter {
     }
 
     fn finish(&mut self) -> Result<Vec<u8>> {
-        // Count lines in the buffer to find where to start
-        let mut lines_to_keep = std::cmp::min(self.count, self.lines_found);
-        let mut bytes_to_keep = 0;
-        let mut lines_seen = 0;
+        // For ring buffer, we can use the iter() method to get all elements
+        // Since it's a circular buffer, we need to handle the wrap-around
+        let mut result = Vec::with_capacity(self.ring_buffer.len());
         
-        // Iterate backwards to find the starting point
-        for i in (0..self.ring_buffer.len()).rev() {
-            let index = (self.ring_buffer.write_pos() as isize - 1 - i as isize)
-                .rem_euclid(self.ring_buffer.capacity() as isize) as usize;
-            let byte = self.ring_buffer[index];
-            
-            if byte == b'\n' {
-                lines_seen += 1;
-                if lines_seen > lines_to_keep {
-                    break;
-                }
-            }
-            bytes_to_keep += 1;
+        // The ring buffer maintains elements in insertion order
+        for byte in self.ring_buffer.iter() {
+            result.push(*byte);
         }
         
-        // Extract the relevant bytes
-        let start_index = self.ring_buffer.len() - bytes_to_keep;
-        let mut result = Vec::with_capacity(bytes_to_keep);
-        for i in start_index..self.ring_buffer.len() {
-            let index = (self.ring_buffer.write_pos() as isize - (self.ring_buffer.len() - i) as isize)
-                .rem_euclid(self.ring_buffer.capacity() as isize) as usize;
-            result.push(self.ring_buffer[index]);
+        // Now, we need to find the last 'count' lines
+        if self.count == 0 {
+            return Ok(Vec::new());
         }
         
-        Ok(result)
+        // Split into lines and take the last 'count' lines
+        let text = String::from_utf8_lossy(&result);
+        let lines: Vec<&str> = text.split('\n').collect();
+        
+        // Take the last 'count' lines
+        let start_index = if lines.len() > self.count {
+            lines.len() - self.count
+        } else {
+            0
+        };
+        
+        let selected_lines = &lines[start_index..];
+        let result_text = selected_lines.join("\n");
+        
+        Ok(result_text.into_bytes())
     }
 }