"""Loguru-based structured logging configuration.

All logs are written to server.log as JSON lines for full traceability.

Stdlib logging is intercepted and funneled to loguru.

Context vars (request_id, node_id, chat_id) from contextualize() are

included at top level for easy grep/filter.

"""

import json

import logging

from loguru import logger

_configured = False

# Context keys we promote to top-level JSON for traceability

_CONTEXT_KEYS = ("request_id", "node_id", "chat_id")

def _serialize_with_context(record) -> str:

"""Format record as JSON with context vars at top level.

Returns a format template; we inject _json into record for output.

"""

extra = record.get("extra", {})

out = {

"time": str(record["time"]),

"level": record["level"].name,

"message": record["message"],

"module": record["name"],

"function": record["function"],

"line": record["line"],

}

for key in _CONTEXT_KEYS:

if key in extra and extra[key] is not None:

out[key] = extra[key]

record["_json"] = json.dumps(out, default=str)

return "{_json}\n"

class InterceptHandler(logging.Handler):

"""Redirect stdlib logging to loguru."""

def emit(self, record: logging.LogRecord) -> None:

try:

level = logger.level(record.levelname).name

except ValueError:

level = record.levelno

frame, depth = logging.currentframe(), 2

while frame is not None and frame.f_code.co_filename == logging.__file__:

frame = frame.f_back

depth += 1

logger.opt(depth=depth, exception=record.exc_info).log(

level, record.getMessage()

)

def configure_logging(log_file: str, *, force: bool = False) -> None:

"""Configure loguru with JSON output to log_file and intercept stdlib logging.

Idempotent: skips if already configured (e.g. hot reload).

Use force=True to reconfigure (e.g. in tests with a different log path).

"""

global _configured

if _configured and not force:

return

_configured = True

# Remove default loguru handler (writes to stderr)

logger.remove()

# Truncate log file on fresh start for clean debugging

open(log_file, "w", encoding="utf-8").close()

# Add file sink: JSON lines, DEBUG level, context vars at top level

logger.add(

log_file,

level="DEBUG",

format=_serialize_with_context,

encoding="utf-8",

mode="a",

)

# Intercept stdlib logging: route all root logger output to loguru

intercept = InterceptHandler()

logging.root.handlers = [intercept]

logging.root.setLevel(logging.DEBUG)