"""Read queue hints without contacting the platform; unknown is conservative."""
import json
import os
from pathlib import Path


def queue_depth():
    value = os.environ.get('ASYNC_QUEUE_DEPTH')
    if value is None and os.environ.get('QUEUE_SNAPSHOT_JSON'):
        try:
            data = json.loads(Path(os.environ['QUEUE_SNAPSHOT_JSON']).read_text())
            if isinstance(data, dict):
                value = next((data[k] for k in ('depth', 'queue_depth', 'async_queue_depth', 'ASYNC_QUEUE_DEPTH') if k in data), None)
        except (OSError, ValueError):
            return None
    try:
        if isinstance(value, bool):
            return None
        depth = int(str(value))
        return depth if depth >= 0 else None
    except (TypeError, ValueError):
        return None