"""Gateway-specific env config (NATS/gRPC/certs/write flags).

Separate from ingestor.py's inline os.getenv (Redis/Mongo/TTLs) — this module
covers only the new gateway wiring consumed by app.py in Task 18.
"""

from dataclasses import dataclass
from os import getenv


def _env_bool(name: str, default: bool) -> bool:
    value = getenv(name)
    if value is None:
        return default
    return value.strip().lower() in ('true', '1', 'yes')


@dataclass
class GatewayConfig:
    nats_url: str = 'nats://localhost:4222'
    nats_write_subject: str = 'opc.write'
    nats_queue: str = 'gateway-writers'
    grpc_enabled: bool = False
    grpc_port: int = 50051
    # The certificate bucket and objects come from the slot / the write lookup
    # (opc_certificates, SIENTIAPDE-1974); only the local cache dir is configured here.
    cert_cache_dir: str = '/tmp/opc-certs'  # noqa: S108 # nosec B108 - default is spec'd, overridable via env
    write_timestamp: bool = True
    write_quality: bool = True
    write_min_pause_s: float = 0.0
    idle_conn_max_s: float = 300.0

    @classmethod
    def certs_from_env(cls) -> 'GatewayConfig':
        """Only the certificate settings — what the read path needs. Plain strings,
        no number parsing, so a malformed write/gRPC env var (GRPC_PORT,
        WRITE_MIN_PAUSE_S, ...) can only disable the runtime, never the reads."""
        return cls(cert_cache_dir=getenv('CERT_CACHE_DIR', cls.cert_cache_dir))

    @classmethod
    def from_env(cls) -> 'GatewayConfig':
        return cls(
            nats_url=getenv('NATS_URL', cls.nats_url),
            nats_write_subject=getenv('NATS_WRITE_SUBJECT', cls.nats_write_subject),
            nats_queue=getenv('NATS_QUEUE', cls.nats_queue),
            grpc_enabled=_env_bool('GRPC_ENABLED', cls.grpc_enabled),
            grpc_port=int(getenv('GRPC_PORT', cls.grpc_port)),
            cert_cache_dir=getenv('CERT_CACHE_DIR', cls.cert_cache_dir),
            write_timestamp=_env_bool('WRITE_TIMESTAMP', cls.write_timestamp),
            write_quality=_env_bool('WRITE_QUALITY', cls.write_quality),
            write_min_pause_s=float(getenv('WRITE_MIN_PAUSE_S', cls.write_min_pause_s)),
            idle_conn_max_s=float(getenv('IDLE_CONN_MAX_S', cls.idle_conn_max_s)),
        )