"""Utility functions."""

from __future__ import annotations

import json
import random
from datetime import timedelta
from typing import Any

from lambdacommon.common_config import logger

from src.constants import RETRY_BASE_SECONDS, RETRY_EXPONENT, RETRY_JITTER_PCT


def calc_retry_delta(retry_count: int) -> timedelta:
    """Calculate a time delta for the next retry.

    Uses exponential backoff with jitter to prevent thundering herd.

    Args:
        retry_count: The number of previous retry attempts.

    Returns:
        timedelta: Time to wait before next retry.
    """
    # Calculate exponential backoff
    base_secs = RETRY_BASE_SECONDS * (RETRY_EXPONENT**retry_count)
    # Add jitter (plus/minus a percentage of base)
    jitter_secs = (2 * random.random() - 1) * (base_secs * RETRY_JITTER_PCT)
    # Return result
    delta_secs = base_secs + jitter_secs
    return timedelta(seconds=delta_secs)


def try_json(value: Any) -> Any:
    """Attempt to parse a value as JSON.

    Args:
        value: The value to parse. If not a string, returns unchanged.

    Returns:
        Any: Parsed JSON if value is valid JSON string, otherwise original value.
    """
    if not isinstance(value, str):
        return value

    try:
        return json.loads(value)
    except json.JSONDecodeError:
        logger.warning('Could not parse data as JSON')

    return value