"""Desired agent config per host (poll delivery)."""

from __future__ import annotations

from sqlalchemy.orm import Session
from sqlalchemy.orm.attributes import flag_modified

from app.models import Host
from app.services.agent_update_settings import PRODUCT_RDP, PRODUCT_SSH

RDP_CONFIG_KEYS = frozenset(
    {
        "ServerDisplayName",
        "EnableRcmShadowControlMonitoring",
        "EnableWinRmInboundMonitoring",
        "EnableAdminShareMonitoring",
        "GetInventory",
        "SacCommandPollIntervalSec",
    }
)
SSH_CONFIG_KEYS = frozenset(
    {
        "SERVER_DISPLAY_NAME",
        "HEARTBEAT_INTERVAL",
        "DAILY_REPORT_ENABLED",
        "UseSAC",
    }
)


def _allowed_keys(host: Host) -> frozenset[str]:
    product = (host.product or "").strip()
    if product == PRODUCT_RDP or (host.os_family or "").strip().lower() == "windows":
        return RDP_CONFIG_KEYS
    if product == PRODUCT_SSH or (host.os_family or "").strip().lower() == "linux":
        return SSH_CONFIG_KEYS
    return frozenset()


def get_host_agent_settings(host: Host) -> dict:
    raw = host.agent_config if isinstance(host.agent_config, dict) else {}
    allowed = _allowed_keys(host)
    if not allowed:
        return {}
    return {k: v for k, v in raw.items() if k in allowed}


def build_agent_config_payload(host: Host) -> dict:
    settings = get_host_agent_settings(host)
    if not settings:
        return {}
    return {"settings": settings}


def update_host_agent_config(db: Session, host: Host, settings: dict) -> Host:
    allowed = _allowed_keys(host)
    if not allowed:
        raise ValueError("Host product does not support desired agent config")

    current = host.agent_config if isinstance(host.agent_config, dict) else {}
    merged = dict(current)
    for key, value in settings.items():
        if key not in allowed:
            raise ValueError(f"Unsupported config key: {key}")
        if value is None:
            merged.pop(key, None)
        else:
            merged[key] = value

    host.agent_config = merged
    host.agent_config_revision = int(host.agent_config_revision or 0) + 1
    flag_modified(host, "agent_config")
    db.flush()
    return host