"""
Stability-specific conftest: when pytest is executed under this directory,
resource monitoring is started before each test and finalized after each test,
so each stability test case gets its own HTML report (one report per case).
No need to wrap pytest with `bash resource_monitor.sh run -- pytest ...`.
"""

import os
import subprocess
import sys
import threading
import time
from pathlib import Path

import pytest

STABILITY_DIR = Path(__file__).resolve().parent
RESOURCE_MONITOR_SCRIPT = STABILITY_DIR / "scripts" / "resource_monitor.sh"
REPO_ROOT = STABILITY_DIR.parent.parent.parent


def _start_resource_monitor():
    """Start `resource_monitor.sh start` in the background and return `Popen` or `None`."""
    if not RESOURCE_MONITOR_SCRIPT.is_file():
        return None
    try:
        proc = subprocess.Popen(
            ["bash", str(RESOURCE_MONITOR_SCRIPT), "start", "--backend", "gpu"],
            cwd=str(REPO_ROOT),
            stdout=subprocess.DEVNULL,
            stderr=subprocess.PIPE,
            start_new_session=True,
        )
        try:
            proc.wait(timeout=2)
            if proc.returncode != 0:
                stderr = proc.stderr.read().decode("utf-8", errors="ignore") if proc.stderr else ""
                if stderr.strip():
                    sys.stderr.write(f"[Stability] Resource monitor failed to start: {stderr.strip()}\n")
                return None
        except subprocess.TimeoutExpired:
            pass
        return proc
    except (FileNotFoundError, OSError):
        return None


def _get_monitor_data_root() -> Path:
    data_root = os.environ.get("RESOURCE_MONITOR_DATA_ROOT") or os.environ.get("GPU_MONITOR_DATA_ROOT")
    if data_root:
        return Path(data_root)
    return STABILITY_DIR / "gpu_monitor_data"


def _wait_for_run_dir(timeout_sec: int = 10) -> Path | None:
    data_root = _get_monitor_data_root()
    run_id_file = data_root / "current_run_id"
    deadline = time.time() + timeout_sec
    while time.time() < deadline:
        if run_id_file.is_file():
            run_id = run_id_file.read_text(encoding="utf-8").strip()
            if run_id:
                run_dir = data_root / run_id
                if run_dir.is_dir():
                    return run_dir
        time.sleep(0.5)
    return None


def _report_latest_gpu_samples(stop_event: threading.Event) -> None:
    """Periodically print the latest sampled GPU line."""
    log_interval = int(
        os.environ.get("RESOURCE_MONITOR_LOG_INTERVAL") or os.environ.get("GPU_MONITOR_LOG_INTERVAL") or "15"
    )
    log_interval = max(log_interval, 1)
    last_line = ""

    time.sleep(min(log_interval, 5))
    while not stop_event.wait(log_interval):
        run_dir = _wait_for_run_dir(timeout_sec=1)
        if run_dir is None:
            continue
        csv_file = run_dir / "gpu_metrics.csv"
        if not csv_file.is_file():
            continue
        try:
            lines = csv_file.read_text(encoding="utf-8").splitlines()
        except OSError:
            continue
        if len(lines) <= 1:
            continue
        latest = lines[-1].strip()
        if latest and latest != last_line:
            last_line = latest
            sys.stderr.write(f"[GPU] {latest}\n")


def _finalize_resource_monitor() -> str | None:
    """
    Run `resource_monitor.sh finalize` for the current run and generate the report.
    Returns the bundle dir path (for this test case's report) if successful, else None.
    """
    if not RESOURCE_MONITOR_SCRIPT.is_file():
        return None
    try:
        result = subprocess.run(
            ["bash", str(RESOURCE_MONITOR_SCRIPT), "finalize", "--backend", "gpu"],
            cwd=str(REPO_ROOT),
            capture_output=True,
            text=True,
            timeout=60,
            check=False,
        )
        if result.returncode != 0:
            return None
        for line in (result.stdout or "").splitlines():
            if line.startswith("GPU_MONITOR_BUNDLE_DIR=") or line.startswith("RESOURCE_MONITOR_BUNDLE_DIR="):
                _, _, value = line.partition("=")
                return value.strip() if value else None
        return None
    except (FileNotFoundError, OSError, subprocess.TimeoutExpired):
        return None


@pytest.fixture(autouse=True)
def stability_resource_monitor_per_test(request: pytest.FixtureRequest):
    """
    For each test under this directory: start GPU monitor before the test,
    then finalize after the test so this case gets its own report.html.
    """
    proc = _start_resource_monitor()
    stop_event = threading.Event()
    reporter: threading.Thread | None = None

    if proc is not None:
        reporter = threading.Thread(
            target=_report_latest_gpu_samples,
            args=(stop_event,),
            name="stability-resource-monitor-reporter",
            daemon=True,
        )
        reporter.start()
        run_dir = _wait_for_run_dir(timeout_sec=5)
        node_name = request.node.name
        if run_dir is not None:
            sys.stderr.write(f"[Stability] Resource monitor started for test: {node_name} | run dir: {run_dir}\n")
        else:
            sys.stderr.write(f"[Stability] Resource monitor started for test: {node_name} (run dir not ready yet)\n")

    yield

    # Teardown: stop reporter, stop monitor, finalize → one HTML per test
    if proc is not None:
        stop_event.set()
        if reporter is not None and reporter.is_alive():
            reporter.join(timeout=2)
        if proc.poll() is None:
            proc.terminate()
            try:
                proc.wait(timeout=10)
            except subprocess.TimeoutExpired:
                proc.kill()
                proc.wait()
        bundle_dir = _finalize_resource_monitor()
        node_name = request.node.name
        if bundle_dir:
            sys.stderr.write(f"[Stability] Report for test «{node_name}»: {bundle_dir}/report.html\n")
        else:
            sys.stderr.write(f"[Stability] Finalize skipped or failed for test «{node_name}»\n")