"""Regression tests for observability-audit metric fixes (Phase 2)."""

from __future__ import annotations

import re

from mcp_hangar import metrics as m


def _hist_count(server: str, tool: str) -> float:
    """Parse the tool_call_duration_seconds histogram _count for one labelset."""
    out = m.get_metrics()
    pat = re.compile(
        r'mcp_hangar_tool_call_duration_seconds_count\{[^}]*mcp_server="'
        + re.escape(server)
        + r'"[^}]*tool="'
        + re.escape(tool)
        + r'"[^}]*\}\s+([0-9.]+)'
    )
    mobj = pat.search(out)
    return float(mobj.group(1)) if mobj else 0.0


def test_failed_call_does_not_observe_latency_histogram() -> None:
    # Unique labels avoid cross-test contamination.
    server, tool = "srv-fail-iso", "tool-fail-iso"
    before = _hist_count(server, tool)
    m.observe_tool_call(server, tool, duration=0.0, success=False, error_type="timeout")
    assert _hist_count(server, tool) == before  # histogram untouched by the failure


def test_successful_call_observes_latency_histogram() -> None:
    server, tool = "srv-ok-iso", "tool-ok-iso"
    before = _hist_count(server, tool)
    m.observe_tool_call(server, tool, duration=1.25, success=True)
    assert _hist_count(server, tool) == before + 1


def test_events_compacted_has_no_stream_id_label() -> None:
    m.record_events_compacted("stream-" + "x" * 40, 3)
    out = m.get_metrics()
    assert any(line.startswith("mcp_hangar_events_compacted_total") for line in out.splitlines())
    assert "stream_id" not in out


def test_connection_active_gauge_toggles() -> None:
    m.set_connection_active("srv-conn-a", True)
    assert 'mcp_hangar_connections_active{mcp_server="srv-conn-a"} 1' in m.get_metrics()
    m.set_connection_active("srv-conn-a", False)
    assert 'mcp_hangar_connections_active{mcp_server="srv-conn-a"} 0' in m.get_metrics()


def test_redundant_connection_metrics_removed() -> None:
    # connections_total and connection_duration_seconds were deleted (audit).
    out = m.get_metrics()
    assert "mcp_hangar_connections_total" not in out
    assert "mcp_hangar_connection_duration_seconds" not in out
    assert not hasattr(m, "CONNECTIONS_TOTAL")
    assert not hasattr(m, "CONNECTION_DURATION_SECONDS")