"""slow_sanctions and sanctions_errors -- phase-0-base-project-spec.md §7.

Both flags belong to `sanctions`, the fake third-party watchlist vendor.
"""
import math
import random

from common.chaos_flags import is_enabled

_MEDIAN_SECONDS = 0.04
_P99_SECONDS = 1.8
_MU = math.log(_MEDIAN_SECONDS)
_Z99 = 2.326347874
_SIGMA = (math.log(_P99_SECONDS) - _MU) / _Z99
_TIMEOUT_TRIGGER_PROBABILITY = 0.015
_TIMEOUT_TRIGGER_SECONDS = 5.0
_ERROR_PROBABILITY = 0.03


async def slow_sanctions_enabled() -> bool:
    return await is_enabled("slow_sanctions")


async def sanctions_errors_enabled() -> bool:
    return await is_enabled("sanctions_errors")


def sample_delay_seconds() -> float:
    """Log-normal delay: median ~40ms, p99 ~1.8s. 1.5% of calls sleep 5s,
    which exceeds the caller's 3s downstream timeout and surfaces as one."""
    if random.random() < _TIMEOUT_TRIGGER_PROBABILITY:
        return _TIMEOUT_TRIGGER_SECONDS
    return random.lognormvariate(_MU, _SIGMA)


def should_error() -> bool:
    return random.random() < _ERROR_PROBABILITY