"""blocking_event_loop -- phase-0-base-project-spec.md §7. Owned by `fraud`."""
import hashlib
import time

from common.chaos_flags import is_enabled

_CPU_WORK_SECONDS = 0.15


async def blocking_event_loop_enabled() -> bool:
    return await is_enabled("blocking_event_loop")


def synchronous_cpu_work() -> None:
    """~120ms of real, synchronous, CPU-bound work run directly inside an
    `async def` handler -- no run_in_executor/to_thread. This is the point:
    it blocks the whole event loop, serialising every other in-flight
    request on this worker for the duration."""
    deadline = time.perf_counter() + _CPU_WORK_SECONDS
    data = b"ledgerline-fraud-scoring"
    while time.perf_counter() < deadline:
        data = hashlib.sha256(data).digest()