"""Structured logging configuration for FusionAGI.

Supports JSON and text output formats, configurable via environment variables:
- ``FUSIONAGI_LOG_LEVEL``: DEBUG, INFO, WARNING, ERROR (default: INFO)
- ``FUSIONAGI_LOG_FORMAT``: json, text (default: text)
"""

from __future__ import annotations

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


class JsonFormatter(logging.Formatter):
    """JSON structured log formatter for log aggregation (ELK, Loki, Datadog)."""

    def format(self, record: logging.LogRecord) -> str:
        log_entry: dict[str, Any] = {
            "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]:
            log_entry["exception"] = self.formatException(record.exc_info)

        # Include extra fields
        extra_keys = set(record.__dict__) - {
            "name", "msg", "args", "created", "relativeCreated", "exc_info",
            "exc_text", "stack_info", "lineno", "funcName", "filename",
            "module", "pathname", "thread", "threadName", "process",
            "processName", "levelname", "levelno", "msecs", "message",
            "taskName",
        }
        for key in extra_keys:
            val = getattr(record, key, None)
            if val is not None:
                log_entry[key] = val

        return json.dumps(log_entry, default=str)


def configure_logging() -> None:
    """Configure logging based on environment variables."""
    level_name = os.environ.get("FUSIONAGI_LOG_LEVEL", "INFO").upper()
    log_format = os.environ.get("FUSIONAGI_LOG_FORMAT", "text").lower()

    level = getattr(logging, level_name, logging.INFO)

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

    # Remove existing handlers
    for handler in root.handlers[:]:
        root.removeHandler(handler)

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

    if log_format == "json":
        handler.setFormatter(JsonFormatter())
    else:
        handler.setFormatter(logging.Formatter(
            "%(asctime)s %(levelname)-8s %(name)s — %(message)s",
            datefmt="%Y-%m-%d %H:%M:%S",
        ))

    root.addHandler(handler)

    # Quiet noisy libraries
    for lib in ("uvicorn.access", "httpx", "httpcore"):
        logging.getLogger(lib).setLevel(logging.WARNING)