import json
import datetime
import traceback
from pathlib import Path
from typing import Optional

class JsonSink:
    def __init__(
        self,
        log_file_path: str,
        rotation_size_bytes: int = 10 * 1024 * 1024,
        max_backup_files: int = 5,
    ):
        self.log_file_path = Path(log_file_path)
        self.rotation_size = rotation_size_bytes
        self.max_backup_files = max_backup_files
        self._open_log_file()

    def _open_log_file(self):
        # ensure the parent directory exists
        parent_dir = self.log_file_path.parent
        if not parent_dir.exists():
            parent_dir.mkdir(parents=True, exist_ok=True)
        self.log_file = self.log_file_path.open("a", encoding="utf-8")

    def _should_rotate(self) -> bool:
        return self.log_file_path.exists() and self.log_file_path.stat().st_size >= self.rotation_size

    def _rotate(self):
        self.log_file.close()
        timestamp = datetime.datetime.now().strftime("%Y%m%d%H%M%S")
        rotated_path = self.log_file_path.with_name(f"{self.log_file_path.stem}_{timestamp}{self.log_file_path.suffix}")
        self.log_file_path.rename(rotated_path)
        self._cleanup_old_backups()
        self._open_log_file()

    def _cleanup_old_backups(self):
        parent = self.log_file_path.parent
        stem = self.log_file_path.stem
        suffix = self.log_file_path.suffix

        backup_files = sorted(
            parent.glob(f"{stem}_*{suffix}"),
            key=lambda p: p.stat().st_mtime,
            reverse=True,
        )

        for old_file in backup_files[self.max_backup_files:]:
            try:
                old_file.unlink()
            except Exception as e:
                print(f"Failed to delete old backup {old_file}: {e}")

    def __call__(self, message):
        record = message.record
        if self._should_rotate():
            self._rotate()

        log_entry = {
            "level": record["level"].name.lower(),
            "timestamp": int(record["time"].timestamp() * 1000),
            "text": record["message"],
            "fields": record["extra"].get("properties", {}),
            "context": {
                "app": record["extra"].get("app"),
                "env": record["extra"].get("env"),
                "log_file": record["extra"].get("log_file"),
                "log_line": record["extra"].get("log_line"),
                "topic": record["extra"].get("topic"),
                "sender_id": record["extra"].get("sender_id"),
                "receiver_id": record["extra"].get("receiver_id"),
                "subject": record["extra"].get("subject"),
                "event": record["extra"].get("event"),
                "host_ip": record["extra"].get("host_ip"),
                "host_name": record["extra"].get("host_name"),
            },
            "stacktrace": None
        }

        if record["exception"]:
            exc_type, exc_value, exc_tb = record["exception"]
            log_entry["stacktrace"] = traceback.format_exception(exc_type, exc_value, exc_tb)

        self.log_file.write(json.dumps(log_entry, ensure_ascii=False, default=str) + "\n")
        self.log_file.flush()