"""§4.4 collector emit tests — each collector MUST produce >=1 row when
run for a few seconds against a synthesized busy workload. A collector
that fails this is removed from the active set (PIPELINE.md §4.4) — no
silent zero-row inclusion.

These tests intentionally invoke the real collector binaries (perf,
tcpdump) against real subprocesses. They will skip on environments
where the binary or capability is unavailable, but they will fail —
not skip — when the binary IS present and the collector still emits
zero rows. The whole point is to catch the "collector silently
disabled" failure mode.
"""

from __future__ import annotations

import json
import os
import shutil
import socket
import subprocess
import threading
import time
from pathlib import Path

import pytest

from collectors import perf_qemu


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _spawn_busy_loop() -> subprocess.Popen:
    """Spawn a CPU-burning child whose PID we can hand to a collector.
    `exec yes` so the captured PID IS the busy process — without exec,
    the captured PID is the wrapping shell that sits parked waiting on
    its child, and perf samples an idle process."""
    return subprocess.Popen(
        ["sh", "-c", "exec yes >/dev/null"],
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
    )


def _run_collector_briefly(target, *, seconds: float, **kw) -> int:
    """Spin a collector run_loop in a thread for `seconds`, then stop it.
    Returns the row count the collector reports."""
    stop = threading.Event()
    result: dict[str, int] = {}

    def _go() -> None:
        result["rows"] = target(stop_event=stop, **kw)

    th = threading.Thread(target=_go, daemon=True)
    th.start()
    time.sleep(seconds)
    stop.set()
    th.join(timeout=seconds + 5.0)
    return result.get("rows", 0)


# ---------------------------------------------------------------------------
# perf
# ---------------------------------------------------------------------------


@pytest.mark.skipif(
    shutil.which("perf") is None,
    reason="perf binary not on PATH; this host can't host the perf collector",
)
def test_perf_emits_rows_against_busy_pid(tmp_path: Path) -> None:
    """The perf collector must emit at least one row when pointed at a
    busy PID for a few seconds. Software events (page-faults,
    context-switches, cpu-clock) are used so the test is portable
    across CPUs that lack hardware performance counters; the production
    DEFAULT_EVENTS adds hardware events on top, which is fine where
    they're available and degrades gracefully where they're not.

    Regression for: perf stat -j writes to stderr by default with -p,
    so reading proc.stdout silently gives 0 lines and 0 rows. Fixed
    by passing --log-fd 1 in the perf invocation.
    """
    busy = _spawn_busy_loop()
    try:
        out = tmp_path / "telemetry-perf.jsonl"
        rows = _run_collector_briefly(
            perf_qemu.run_loop,
            seconds=2.0,
            pid=busy.pid,
            output_path=out,
            t_mono_origin_ns=0,
            interval_ms=200,
            events=("page-faults", "context-switches", "cpu-clock"),
        )
    finally:
        busy.terminate()
        try:
            busy.wait(timeout=2.0)
        except subprocess.TimeoutExpired:
            busy.kill()
            busy.wait(timeout=1.0)

    assert rows >= 1, (
        f"perf collector wrote 0 rows against a busy PID — see "
        f"PIPELINE.md §4.4. File: {out}, exists={out.exists()}, "
        f"size={out.stat().st_size if out.exists() else 'n/a'}"
    )
    # Sanity-check the on-disk file matches what run_loop reported.
    on_disk = out.read_text().splitlines() if out.exists() else []
    assert len(on_disk) == rows, (
        f"row count mismatch: run_loop returned {rows} but "
        f"{len(on_disk)} lines on disk"
    )
    # Spot-check the row shape — one parsed row should have the
    # expected schema.
    sample = json.loads(on_disk[0])
    assert sample["source"] == "host_perf"
    assert sample["available_in_deployment"] is False
    assert "t_mono_ns" in sample and "interval_s" in sample
    # At least one row must have a populated metric — if every metric
    # is None on every row, the parser is dropping values. Regression
    # for: event names come back as "cycles:u" / "instructions:u"
    # under perf_event_paranoid=2 (userspace-only), but `_build_row`
    # looks up plain "cycles" / "instructions" — so every metric was
    # silently null even when perf reported real numbers. The mapped
    # fields in the row schema are cycles, instructions, page_faults,
    # context_switches, branches, branch_misses, cache_references,
    # cache_misses; we only need ANY of them populated to confirm the
    # parser is wiring values into the row.
    parsed = [json.loads(l) for l in on_disk]
    metric_keys = ("cycles", "instructions", "page_faults",
                   "context_switches", "branches")
    assert any(r.get(k) is not None for r in parsed for k in metric_keys), (
        f"every metric is None on every row — perf parser is dropping "
        f"values. Sample row: {parsed[0]}"
    )


# ---------------------------------------------------------------------------
# Tier-3 demo wiring regression
# ---------------------------------------------------------------------------


def test_run_tier3_demo_wires_collector_sockets_into_episode_config() -> None:
    """`run_tier3_demo.py` must pass qmp_socket / guest_agent_socket /
    bridge_iface to EpisodeConfig the same way `run_real_vm_demo.py`
    does. Without these, those collectors silently emit zero rows on
    every Tier-3 episode even though launch_target.sh creates the
    underlying chardevs. Regression for: bug found 2026-05-03 against
    elliott-thinkpad + k-gamingcom (rows_qmp=0 / rows_guest=0 / pcap=0
    on 100% of Tier-3 episodes).

    This is a source-grep test rather than an exec test because
    run_tier3_demo.py boots qemu + msfrpcd, neither of which is
    available in CI. The grep keeps the wiring honest with no
    runtime cost."""
    src = (Path(__file__).resolve().parent.parent
           / "tools" / "run_tier3_demo.py").read_text()
    # The exact fragments that, if absent, mean the collectors will
    # silently never start. Each must appear as a keyword arg of the
    # EpisodeConfig(...) constructor call site.
    for needle in (
        "qmp_socket=qmp_sock",
        "guest_agent_socket=agent_sock",
        "bridge_iface=os.environ.get(\"BRIDGE\")",
    ):
        assert needle in src, (
            f"run_tier3_demo.py is missing `{needle}` on its "
            f"EpisodeConfig — see PIPELINE.md §4.4. Tier-3 episodes "
            f"will silently produce 0 rows for the corresponding "
            f"collector."
        )