"""Structured JSON logging configuration.

In **production** (``AEGIS_ENV=production``), emits one JSON object per
line so that log aggregators (ELK, CloudWatch, Datadog) can ingest them
without custom parsing.

In **development** (default), uses a human-readable text format for
comfortable local work.
"""

from __future__ import annotations

import json
import logging
import os
import sys
from datetime import datetime, timezone


class _JSONFormatter(logging.Formatter):
    """Emit each log record as a single-line JSON object."""

    def format(self, record: logging.LogRecord) -> str:
        payload: dict = {
            "timestamp": datetime.fromtimestamp(record.created, tz=timezone.utc).isoformat(),
            "level": record.levelname,
            "logger": record.name,
            "message": record.getMessage(),
        }

        if record.exc_info and record.exc_info[1] is not None:
            payload["exception"] = self.formatException(record.exc_info)

        extra = getattr(record, "_extra", None)
        if extra:
            payload.update(extra)

        return json.dumps(payload, default=str)


_DEV_FORMAT = "%(asctime)s  %(levelname)-8s  %(name)s — %(message)s"


def setup_logging() -> None:
    """Configure the root logger based on the environment."""
    is_production = os.environ.get("AEGIS_ENV", "").lower() == "production"
    level_name = os.environ.get("LOG_LEVEL", "INFO").upper()
    level = getattr(logging, level_name, logging.INFO)

    root = logging.getLogger()
    root.setLevel(level)

    if root.handlers:
        root.handlers.clear()

    handler = logging.StreamHandler(sys.stdout)
    handler.setLevel(level)

    if is_production:
        handler.setFormatter(_JSONFormatter())
    else:
        handler.setFormatter(logging.Formatter(_DEV_FORMAT))

    root.addHandler(handler)

    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
    logging.getLogger("sqlalchemy.engine").setLevel(logging.WARNING)