"""Structured logging setup with request and trace correlation."""

import logging
from typing import Any

import structlog
from opentelemetry import trace
from opentelemetry.trace import SpanContext


def configure_structured_logging(log_level: str) -> None:
    resolved_level = _resolve_log_level(log_level)
    logging.basicConfig(level=resolved_level, format="%(message)s")

    structlog.configure(
        processors=[
            structlog.contextvars.merge_contextvars,
            structlog.stdlib.add_log_level,
            add_trace_context,
            structlog.processors.TimeStamper(fmt="iso", utc=True),
            structlog.processors.JSONRenderer(),
        ],
        logger_factory=structlog.stdlib.LoggerFactory(),
        wrapper_class=structlog.make_filtering_bound_logger(resolved_level),
        cache_logger_on_first_use=True,
    )


def add_trace_context(
    _: Any,
    __: str,
    event_dict: dict[str, Any],
) -> dict[str, Any]:
    span = trace.get_current_span()
    span_context = span.get_span_context()
    if _is_valid_span_context(span_context):
        event_dict["trace_id"] = format(span_context.trace_id, "032x")
        event_dict["span_id"] = format(span_context.span_id, "016x")
    return event_dict


def _resolve_log_level(log_level: str) -> int:
    candidate = log_level.strip().upper()
    return logging.getLevelNamesMapping().get(candidate, logging.INFO)


def _is_valid_span_context(span_context: SpanContext) -> bool:
    return bool(span_context.is_valid and span_context.trace_id and span_context.span_id)