"""Prometheus Metrics Publisher - Infrastructure implementation.

This adapter implements the IMetricsPublisher contract using Prometheus metrics.
"""

import types

from ..domain.contracts.metrics_publisher import IMetricsPublisher


class PrometheusMetricsPublisher(IMetricsPublisher):
    """Prometheus implementation of metrics publisher."""

    def __init__(self):
        """Initialize with lazy import to avoid circular dependencies."""
        self._metrics: types.ModuleType | None = None

    def _ensure_metrics(self) -> types.ModuleType:
        """Lazy load metrics module."""
        if self._metrics is None:
            from mcp_hangar import metrics

            self._metrics = metrics
        return self._metrics

    def record_cold_start(self, mcp_server_id: str, duration_s: float, mode: str) -> None:
        """Record a cold start event."""
        self._ensure_metrics().record_cold_start(mcp_server_id, duration_s, mode)

    def begin_cold_start(self, mcp_server_id: str) -> None:
        """Mark the beginning of a cold start."""
        self._ensure_metrics().cold_start_begin(mcp_server_id)

    def end_cold_start(self, mcp_server_id: str) -> None:
        """Mark the end of a cold start."""
        self._ensure_metrics().cold_start_end(mcp_server_id)

    def set_connection_active(self, mcp_server_id: str, active: bool) -> None:
        """Record whether a backend connection is currently established."""
        self._ensure_metrics().set_connection_active(mcp_server_id, active)