"""Runtime configuration for the backend service."""

from __future__ import annotations

import os
from dataclasses import dataclass


def _env_str(name: str, default: str) -> str:
    value = os.getenv(name)
    return value if value not in (None, "") else default


def _env_int(name: str, default: int) -> int:
    value = os.getenv(name)
    if value in (None, ""):
        return default
    return int(value)


def _env_float(name: str, default: float) -> float:
    value = os.getenv(name)
    if value in (None, ""):
        return default
    return float(value)


def _env_bool(name: str, default: bool) -> bool:
    value = os.getenv(name)
    if value in (None, ""):
        return default
    return value.strip().lower() in {"1", "true", "yes", "on"}


@dataclass(frozen=True)
class BackendSettings:
    db_dsn: str
    log_level: str
    db_pool_min_size: int
    db_pool_max_size: int
    broadcaster_queue_maxsize: int
    packet_tracker_finalize_delay_seconds: float
    packet_tracker_retention_seconds: float
    packet_tracker_min_flush_interval_seconds: float
    packet_tracker_persist_timeout_seconds: float
    packet_tracker_stop_join_timeout_seconds: float
    packet_tracker_reject_correlation_window_seconds: float
    sniffer_buffer_capacity: int
    sniffer_socket_rcvbuf_bytes: int
    sniffer_selector_timeout_seconds: float
    sniffer_recv_bytes: int
    sniffer_buffer_drain_interval_seconds: float
    sniffer_thread_join_timeout_seconds: float
    bridge_bpf_build_dir: str
    bridge_link_state_thread_join_timeout_seconds: float
    bridge_link_state_failure_holdoff_seconds: float
    bridge_link_state_recovery_holdoff_seconds: float
    bridge_link_state_degraded_recheck_seconds: float
    telemetry_process_stop_timeout_seconds: float
    telemetry_reader_join_timeout_seconds: float
    tshark_enabled: bool
    tshark_display_filter: str
    tshark_try_heuristic_first: bool
    tshark_cache_ttl_seconds: float
    tshark_match_window_ms: int
    tshark_reader_join_timeout_seconds: float
    tshark_process_stop_timeout_seconds: float


def load_settings() -> BackendSettings:
    return BackendSettings(
        db_dsn=_env_str("BACKEND_DB_DSN", "postgresql://mitm_user:mitm_password@localhost:5432/mitm_db"),
        log_level=_env_str("BACKEND_LOG_LEVEL", "DEBUG"),
        db_pool_min_size=_env_int("BACKEND_DB_POOL_MIN_SIZE", 1),
        db_pool_max_size=_env_int("BACKEND_DB_POOL_MAX_SIZE", 5),
        broadcaster_queue_maxsize=_env_int("BACKEND_BROADCAST_QUEUE_MAXSIZE", 1024),
        packet_tracker_finalize_delay_seconds=_env_float("BACKEND_PACKET_TRACKER_FINALIZE_DELAY_SECONDS", 0.25),
        packet_tracker_retention_seconds=_env_float("BACKEND_PACKET_TRACKER_RETENTION_SECONDS", 10.0),
        packet_tracker_min_flush_interval_seconds=_env_float("BACKEND_PACKET_TRACKER_MIN_FLUSH_INTERVAL_SECONDS", 0.05),
        packet_tracker_persist_timeout_seconds=_env_float("BACKEND_PACKET_TRACKER_PERSIST_TIMEOUT_SECONDS", 2.0),
        packet_tracker_stop_join_timeout_seconds=_env_float("BACKEND_PACKET_TRACKER_STOP_JOIN_TIMEOUT_SECONDS", 2.0),
        packet_tracker_reject_correlation_window_seconds=_env_float(
            "BACKEND_PACKET_TRACKER_REJECT_CORRELATION_WINDOW_SECONDS",
            1.0,
        ),
        sniffer_buffer_capacity=_env_int("BACKEND_SNIFFER_BUFFER_CAPACITY", 20_000),
        sniffer_socket_rcvbuf_bytes=_env_int("BACKEND_SNIFFER_SOCKET_RCVBUF_BYTES", 4 * 1024 * 1024),
        sniffer_selector_timeout_seconds=_env_float("BACKEND_SNIFFER_SELECTOR_TIMEOUT_SECONDS", 1.0),
        sniffer_recv_bytes=_env_int("BACKEND_SNIFFER_RECV_BYTES", 65_536),
        sniffer_buffer_drain_interval_seconds=_env_float("BACKEND_SNIFFER_BUFFER_DRAIN_INTERVAL_SECONDS", 5.0),
        sniffer_thread_join_timeout_seconds=_env_float("BACKEND_SNIFFER_THREAD_JOIN_TIMEOUT_SECONDS", 2.0),
        bridge_bpf_build_dir=_env_str("BACKEND_BRIDGE_BPF_BUILD_DIR", "/tmp/mitm-bpf"),
        bridge_link_state_thread_join_timeout_seconds=_env_float(
            "BACKEND_BRIDGE_LINK_STATE_THREAD_JOIN_TIMEOUT_SECONDS",
            2.0,
        ),
        bridge_link_state_failure_holdoff_seconds=_env_float(
            "BACKEND_BRIDGE_LINK_STATE_FAILURE_HOLDOFF_SECONDS",
            0.75,
        ),
        bridge_link_state_recovery_holdoff_seconds=_env_float(
            "BACKEND_BRIDGE_LINK_STATE_RECOVERY_HOLDOFF_SECONDS",
            1.0,
        ),
        bridge_link_state_degraded_recheck_seconds=_env_float(
            "BACKEND_BRIDGE_LINK_STATE_DEGRADED_RECHECK_SECONDS",
            0.5,
        ),
        telemetry_process_stop_timeout_seconds=_env_float("BACKEND_TELEMETRY_PROCESS_STOP_TIMEOUT_SECONDS", 3.0),
        telemetry_reader_join_timeout_seconds=_env_float("BACKEND_TELEMETRY_READER_JOIN_TIMEOUT_SECONDS", 2.0),
        tshark_enabled=_env_bool("BACKEND_TSHARK_ENABLED", True),
        tshark_display_filter=_env_str("BACKEND_TSHARK_DISPLAY_FILTER", ""),
        tshark_try_heuristic_first=_env_bool("BACKEND_TSHARK_TRY_HEURISTIC_FIRST", True),
        tshark_cache_ttl_seconds=_env_float("BACKEND_TSHARK_CACHE_TTL_SECONDS", 5.0),
        tshark_match_window_ms=_env_int("BACKEND_TSHARK_MATCH_WINDOW_MS", 5_000),
        tshark_reader_join_timeout_seconds=_env_float("BACKEND_TSHARK_READER_JOIN_TIMEOUT_SECONDS", 2.0),
        tshark_process_stop_timeout_seconds=_env_float("BACKEND_TSHARK_PROCESS_STOP_TIMEOUT_SECONDS", 3.0),
    )


settings = load_settings()