"""Debug logger — writes detailed LLM interaction logs to JSONL files."""

from __future__ import annotations

import json
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from app.models.message import Message


class DebugLogger:
    """Writes detailed LLM interaction logs to JSONL files for debugging."""

    def __init__(self, log_dir: Path, max_files: int = 10) -> None:
        self._log_dir = log_dir
        self._log_dir.mkdir(parents=True, exist_ok=True)
        self._max_files = max_files
        self._file = self._log_dir / f"debug_{datetime.now(UTC).strftime('%Y%m%d_%H%M%S')}.jsonl"
        self._rotate()

    def log_request(self, messages: list[Message], model: str) -> None:
        """Log outbound LLM request (message roles/lengths, model)."""
        self._write({
            "event": "llm_request",
            "model": model,
            "message_count": len(messages),
            "messages": [
                {"role": m.role, "content_len": len(m.content or "")}
                for m in messages
            ],
        })

    def log_response(
        self,
        message: Message,
        usage: Any | None,
        elapsed_ms: float,
    ) -> None:
        """Log LLM response with timing and token counts."""
        self._write({
            "event": "llm_response",
            "elapsed_ms": round(elapsed_ms, 1),
            "content_len": len(message.content or ""),
            "tool_call_count": len(message.tool_calls or []),
            "tool_calls": [tc.function.name for tc in (message.tool_calls or [])],
            "usage": usage.__dict__ if usage else None,
        })

    def log_tool_execution(
        self,
        tool_name: str,
        result_status: str,
        elapsed_ms: float,
    ) -> None:
        """Log tool execution with timing."""
        self._write({
            "event": "tool_execution",
            "tool": tool_name,
            "status": result_status,
            "elapsed_ms": round(elapsed_ms, 1),
        })

    def _write(self, record: dict[str, Any]) -> None:
        record["timestamp"] = datetime.now(UTC).isoformat()
        with open(self._file, "a") as f:
            f.write(json.dumps(record) + "\n")

    def _rotate(self) -> None:
        """Remove old debug log files beyond max_files."""
        files = sorted(
            self._log_dir.glob("debug_*.jsonl"),
            key=lambda p: p.stat().st_mtime,
        )
        while len(files) > self._max_files:
            files.pop(0).unlink()