"""Shared low-level access to the `chaos:flags` Redis hash.

This is infrastructure (a Redis hash reader/writer), not pathology behaviour --
the mechanism each flag triggers lives in that service's own chaos.py, per
phase-0-base-project-spec.md §7 ("each pathology lives in a clearly named
chaos.py module inside its owning service"). Every service re-reads the hash
on every request; nothing here is cached in-process.
"""
import random
import time

from .redis_client import redis_client

FLAGS_KEY = "chaos:flags"

ALL_FLAGS = [
    "slow_sanctions",
    "sanctions_errors",
    "n_plus_one",
    "pool_starvation",
    "row_lock_contention",
    "blocking_event_loop",
    "retry_storm",
    "no_batching",
    "unbounded_cache",
    "slow_consumer",
    "cold_cache",
    "poison_data",
    "chatty_health",
]

NAMED_PROFILES = {
    "clean": set(),
    "light": {"slow_sanctions", "cold_cache"},
    "nightmare": set(ALL_FLAGS),
}


async def get_flags() -> dict:
    raw = await redis_client.hgetall(FLAGS_KEY)
    return {flag: raw.get(flag) == "1" for flag in ALL_FLAGS}


async def is_enabled(flag: str) -> bool:
    return await redis_client.hget(FLAGS_KEY, flag) == "1"


async def set_flag(flag: str, enabled: bool) -> None:
    if flag not in ALL_FLAGS:
        raise ValueError(f"unknown flag {flag!r}")
    await redis_client.hset(FLAGS_KEY, flag, "1" if enabled else "0")


async def set_profile(profile: str) -> dict:
    if profile == "random":
        # Seed derived from time.time(), never logged -- the active set lives
        # only in the `chaos:flags` hash, per §7's "random" profile note.
        rng = random.Random(time.time())
        chosen = set(rng.sample(ALL_FLAGS, k=rng.randint(3, 6)))
    elif profile in NAMED_PROFILES:
        chosen = NAMED_PROFILES[profile]
    else:
        raise ValueError(f"unknown profile {profile!r}")

    mapping = {flag: ("1" if flag in chosen else "0") for flag in ALL_FLAGS}
    await redis_client.hset(FLAGS_KEY, mapping=mapping)
    return await get_flags()


async def flags_fingerprint() -> str:
    """A short, stable string identifying the current flag combination. Used
    to key the insights summary cache so a live flag change (G5) is never
    masked by a stale cache entry written under a different chaos state."""
    flags = await get_flags()
    return "".join("1" if flags[f] else "0" for f in ALL_FLAGS)