from __future__ import annotations

import re

import pytest
from prometheus_client import REGISTRY, CollectorRegistry, generate_latest

from vllm_omni.metrics import OmniPrometheusMetrics

pytestmark = [pytest.mark.core_model, pytest.mark.cpu]

_MODEL = "test-model"

_PIPELINE_METRICS = [
    "vllm_omni:num_requests_running",
    "vllm_omni:num_requests_waiting",
    "vllm_omni:requests_success",
    "vllm_omni:e2e_request_latency_s",
]


@pytest.fixture(scope="module")
def registry() -> CollectorRegistry:
    return REGISTRY


@pytest.fixture(scope="module")
def prom() -> OmniPrometheusMetrics:
    return OmniPrometheusMetrics(model_name=_MODEL)


@pytest.fixture(scope="module")
def scrape_output(prom: OmniPrometheusMetrics, registry: CollectorRegistry) -> str:
    # Two natural completions (stop) + one length-cap + one failure (abort)
    # exercise three distinct finished_reason buckets in the merged Counter.
    prom.request_succeeded(e2e_seconds=1.5, finished_reason="stop")
    prom.request_succeeded(e2e_seconds=2.0, finished_reason="stop")
    prom.request_succeeded(e2e_seconds=3.0, finished_reason="length")
    prom.request_failed()  # → finished_reason="abort"
    prom.set_running(5)
    prom.set_waiting(2)
    return generate_latest(registry).decode()


def _sample_value(output: str, metric_line: str) -> float | None:
    for line in output.splitlines():
        if line.startswith(metric_line):
            return float(line.split()[-1])
    return None


class TestMetricObservation:
    def test_all_metric_families_present(self, scrape_output: str) -> None:
        for name in _PIPELINE_METRICS:
            assert f"# HELP {name}" in scrape_output, f"missing metric family: {name}"

    def test_counter_values(self, scrape_output: str) -> None:
        # Per-reason buckets sourced from the merged completion Counter.
        stop = _sample_value(
            scrape_output,
            f'vllm_omni:requests_success_total{{finished_reason="stop",model_name="{_MODEL}"}}',
        )
        assert stop == 2.0

        length = _sample_value(
            scrape_output,
            f'vllm_omni:requests_success_total{{finished_reason="length",model_name="{_MODEL}"}}',
        )
        assert length == 1.0

        abort = _sample_value(
            scrape_output,
            f'vllm_omni:requests_success_total{{finished_reason="abort",model_name="{_MODEL}"}}',
        )
        assert abort == 1.0

    def test_gauge_values(self, scrape_output: str) -> None:
        running = _sample_value(
            scrape_output,
            f'vllm_omni:num_requests_running{{model_name="{_MODEL}"}}',
        )
        assert running == 5.0

        waiting = _sample_value(
            scrape_output,
            f'vllm_omni:num_requests_waiting{{model_name="{_MODEL}"}}',
        )
        assert waiting == 2.0

    def test_histogram_counts(self, scrape_output: str) -> None:
        # 3 successful completions (stop x2 + length x1) all observe e2e;
        # the 1 failed completion only increments the Counter without
        # observing the latency histogram, so the count stays at 3.
        e2e_count = _sample_value(
            scrape_output,
            f'vllm_omni:e2e_request_latency_s_count{{model_name="{_MODEL}"}}',
        )
        assert e2e_count == 3.0


class TestLabelCorrectness:
    def test_pipeline_metrics_carry_model_name(self, scrape_output: str) -> None:
        for name in _PIPELINE_METRICS:
            pattern = rf'^{re.escape(name)}.*model_name="{re.escape(_MODEL)}"'
            assert re.search(pattern, scrape_output, re.MULTILINE), f"{name} missing model_name label"

    def test_no_legacy_engine_label(self, scrape_output: str) -> None:
        assert 'engine="' not in scrape_output

    def test_no_legacy_seconds_or_ms_families(self, scrape_output: str) -> None:
        # Renamed: *_time_ms → *_s; *_time_seconds dropped.
        for legacy in (
            "vllm_omni:request_queue_time_seconds",
            "vllm_omni:e2e_request_latency_seconds",
        ):
            assert legacy not in scrape_output, f"legacy family {legacy} still registered"


class TestScrapeOutput:
    def test_omni_metrics_in_default_registry(self, scrape_output: str) -> None:
        for name in _PIPELINE_METRICS:
            assert name in scrape_output

    def test_process_metrics_in_default_registry(self, scrape_output: str) -> None:
        # vllm:* metrics require a full PrometheusStatLogger with VllmConfig
        # and are registered by the Orchestrator at server startup. Verifying
        # their presence is covered by integration tests. Here we confirm the
        # default registry is being scraped by checking for process_* metrics
        # from the Python prometheus_client runtime.
        assert "process_" in scrape_output


class TestRequestLifecycleGauges:
    """Regression tests for the running/waiting gauge race at request finalize.

    Before the fix, the per-stage publish in OmniBase._process_single_result
    ran while the completed request was still in self.request_states even
    though the orchestrator had already decremented _running_counter — so a
    single completed request briefly exposed running=0, total=1 → waiting=1,
    which stuck on /metrics until another request triggered a refresh.

    Two-layer fix: _process_single_result excludes the finalizing request
    from `total`, and _log_summary_and_cleanup republishes gauges after the
    pop as a fallback. These tests pin the post-cleanup state.
    """

    def test_running_and_waiting_zero_after_request_completes(self, registry: CollectorRegistry) -> None:
        from types import SimpleNamespace

        from vllm_omni.entrypoints.omni_base import OmniBase
        from vllm_omni.metrics.prometheus import OmniPrometheusMetrics, OmniRequestCounter

        obj = object.__new__(OmniBase)
        obj.engine = SimpleNamespace(_running_counter=OmniRequestCounter())
        obj.prom_metrics = OmniPrometheusMetrics(model_name="lifecycle-test")
        obj.request_states = {}
        obj._consumed_metric_messages = {}
        obj.log_stats = False

        # Simulate request lifecycle: start (counter 0→1, dict {} → {req}),
        # then finalize (counter 1→0, dict still holds the request because
        # _log_summary_and_cleanup hasn't run yet — this is the exact race
        # window the fix addresses).
        obj.engine._running_counter.increment()
        obj.request_states["req-1"] = SimpleNamespace(metrics=SimpleNamespace(e2e_done={"req-1"}))
        obj.engine._running_counter.decrement()

        obj._log_summary_and_cleanup("req-1")

        assert obj.engine._running_counter.value == 0
        assert len(obj.request_states) == 0
        out = generate_latest(registry).decode()
        assert _sample_value(out, 'vllm_omni:num_requests_running{model_name="lifecycle-test"}') == 0.0
        assert _sample_value(out, 'vllm_omni:num_requests_waiting{model_name="lifecycle-test"}') == 0.0

    def test_gauges_reflect_remaining_requests_after_one_completes(self, registry: CollectorRegistry) -> None:
        from types import SimpleNamespace

        from vllm_omni.entrypoints.omni_base import OmniBase
        from vllm_omni.metrics.prometheus import OmniPrometheusMetrics, OmniRequestCounter

        obj = object.__new__(OmniBase)
        obj.engine = SimpleNamespace(_running_counter=OmniRequestCounter())
        obj.prom_metrics = OmniPrometheusMetrics(model_name="lifecycle-test-2")
        obj.request_states = {}
        obj._consumed_metric_messages = {}
        obj.log_stats = False

        # Two in flight, one finalizes — running should report 1, waiting 0.
        obj.engine._running_counter.increment()
        obj.engine._running_counter.increment()
        obj.request_states["req-1"] = SimpleNamespace(metrics=SimpleNamespace(e2e_done={"req-1"}))
        obj.request_states["req-2"] = SimpleNamespace(metrics=SimpleNamespace(e2e_done=set()))
        obj.engine._running_counter.decrement()

        obj._log_summary_and_cleanup("req-1")

        out = generate_latest(registry).decode()
        assert _sample_value(out, 'vllm_omni:num_requests_running{model_name="lifecycle-test-2"}') == 1.0
        assert _sample_value(out, 'vllm_omni:num_requests_waiting{model_name="lifecycle-test-2"}') == 0.0