"""Connection settings of the OPC server a write command targets (SIENTIAPDE-1975 GW1).

The Laborious only knows the `server_id` of a write tag (pipeline `write_tags`); the
connection (url, server URI, security) belongs to the gateway, which owns every OPC
session. It is resolved with the same rule the orchestrator uses to build the read slots
(SIENTIAPDE-1974): the tag database `connectors` first, the legacy `opc-servers` otherwise.
"""

from typing import Any

from sientia_do.observability.logger import Logger

from ingestor.connection.clock import MonotonicClock
from ingestor.connection.pool import OpcConnectionPool

CONNECTORS = 'connectors'
OPC_SERVERS = 'opc-servers'


def _id_forms(server_id: str) -> list[Any]:
    """`server_id` as stored: the tag database keeps ints, opc-servers strings or ints."""
    forms: list[Any] = [server_id]
    if server_id.isdigit():
        forms.append(int(server_id))
    return forms


def _connector_cfg(connector: dict[str, Any]) -> dict[str, Any] | None:
    if not connector.get('url'):
        return None
    return {
        'url': connector['url'],
        'server_uri': connector.get('server_uri'),
        'use_security': bool(connector.get('use_security', False)),
    }


def _opc_server_cfg(server: dict[str, Any]) -> dict[str, Any] | None:
    if not server.get('url'):
        return None
    return {
        'url': server['url'],
        'server_uri': server.get('uri'),
        # The certificate comes from MinIO now: a cert_path only says the server uses
        # security, as in the orchestrator's slot (SIENTIAPDE-1974 RF4).
        'use_security': bool(server.get('cert_path')),
    }


class ServerConfigResolver:
    """Resolve and cache the connection settings of an OPC server by `server_id`.

    Order: settings carried by the command itself (an explicit override; the C2
    command of the Laborious carries none), the live pooled connection (what the read
    path opened, so writes never fight the reads over settings), then MongoDB. Lookups
    are cached for `ttl_s`; a server that is not found, for `missing_ttl_s`, so a
    pipeline pointing at a removed server does not query MongoDB on every command."""

    def __init__(
        self,
        pool: OpcConnectionPool,
        mongo,
        logger: Logger,
        ttl_s: float = 60.0,
        missing_ttl_s: float = 10.0,
        metadata: dict | None = None,
    ):
        self.pool = pool
        self.mongo = mongo
        self.logger = logger
        self.ttl_s = ttl_s
        self.missing_ttl_s = missing_ttl_s
        self.metadata = metadata or {}
        self.clock = MonotonicClock()
        self._cache: dict[str, tuple[dict[str, Any] | None, float]] = {}

    async def resolve(self, server_id: str, cmd: dict) -> dict[str, Any] | None:
        """Connection settings for `server_id`, or None when no source knows it.

        Raises:
            Exception: When MongoDB cannot be read (the caller reports the write as
                failed).
        """
        if cmd.get('url'):
            return {
                'url': cmd['url'],
                'server_uri': cmd.get('server_uri'),
                'use_security': cmd.get('use_security', False),
            }
        server_id = str(server_id)
        pooled = self.pool.config_for(server_id)
        if pooled is not None:
            return pooled
        now = self.clock.elapsed()
        cached = self._cache.get(server_id)
        if cached is not None:
            cfg, cached_at = cached
            if now - cached_at < (self.ttl_s if cfg is not None else self.missing_ttl_s):
                return dict(cfg) if cfg is not None else None
        cfg = await self._lookup(server_id)
        self._cache[server_id] = (cfg, now)
        return dict(cfg) if cfg is not None else None

    async def _lookup(self, server_id: str) -> dict[str, Any] | None:
        ids = {'$in': _id_forms(server_id)}
        connector = await self.mongo.find_one(
            CONNECTORS,
            {'connector_id': ids, 'type': 'opc_ua', 'status': 'Active'},
            self.metadata,
        )
        cfg = _connector_cfg(connector) if connector else None
        if cfg is not None:
            return cfg
        server = await self.mongo.find_one(OPC_SERVERS, {'id': ids}, self.metadata)
        cfg = _opc_server_cfg(server) if server else None
        if cfg is None:
            self.logger.warning(
                f'OPC server {server_id} not found in {CONNECTORS} nor {OPC_SERVERS}'
            )
        return cfg