"""Backend lifecycle benchmark — kql (Longhorn disk snapshots) vs k7d (warm VM fork).

Measures, per backend, wall-clock time for:

- ``create``        — ``create_sandbox()`` call + pod Ready
- ``exec``          — ``echo`` round-trip in a Ready sandbox
- ``snapshot``      — named snapshot until ready (kql only; k7d rejects it)
- ``fork_call``     — the ``fork_sandbox()`` call itself
- ``fork_ready``    — fork call + forked pod Ready + exec answering
- ``pause``         — pause until effective (kql: pods gone; k7d: VM frozen)
- ``resume``        — resume until an exec answers again
- ``delete``        — ``delete_sandbox()`` call
- ``sidecar_*``     — docker-in-VM sidecar: create+docker-ready, docker pull, docker run

Same node, same images, interleaved runs. Invocation (on the k7 node):

    K7_BENCH_BACKENDS=kata-qemu-longhorn,k7d K7_BENCH_REPS=3 \
    uv run pytest -m bench tests/integration/bench_backend_lifecycle.py -v -s

Results land as a markdown table on stdout and JSON under ``$K7_BENCH_OUT``
(default ``/tmp``), one file per run: ``bench-backends-<ts>.json``.
"""

from __future__ import annotations

import asyncio
import json
import os
import statistics
import subprocess
import time
from datetime import datetime, timezone
from pathlib import Path

import pytest

from k7.core.core import K7Core, _is_k7d_family
from k7.core.models import SandboxConfig

pytestmark = pytest.mark.bench

REPS = int(os.environ.get("K7_BENCH_REPS", "3"))
EXEC_REPS = int(os.environ.get("K7_BENCH_EXEC_REPS", "10"))
OUT_DIR = Path(os.environ.get("K7_BENCH_OUT", "/tmp"))
BACKENDS = [b.strip() for b in os.environ.get("K7_BENCH_BACKENDS", "kata-qemu-longhorn,k7d").split(",") if b.strip()]

SANDBOX_IMAGE = "alpine:3.20"
SIDECAR_IMAGE = "docker:27.5-cli"
DOCKER_PULL_IMAGE = "alpine:3.21"


def _pod_ready(sandbox: str, namespace: str) -> bool:
    result = subprocess.run(
        [
            "k3s",
            "kubectl",
            "get",
            "pods",
            "-n",
            namespace,
            "-l",
            f"app={sandbox}",
            "-o",
            "json",
        ],
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode != 0:
        return False
    try:
        items = json.loads(result.stdout).get("items", [])
    except json.JSONDecodeError:
        return False
    for pod in items:
        statuses = pod.get("status", {}).get("containerStatuses", [])
        if statuses and all(s.get("ready") for s in statuses):
            return True
    return False


def _wait(predicate, timeout: float, what: str, interval: float = 0.5) -> None:
    deadline = time.monotonic() + timeout
    while time.monotonic() < deadline:
        if predicate():
            return
        time.sleep(interval)
    raise TimeoutError(f"timed out waiting for {what} after {timeout}s")


def _no_pods(sandbox: str, namespace: str) -> bool:
    result = subprocess.run(
        ["k3s", "kubectl", "get", "pods", "-n", namespace, "-l", f"app={sandbox}", "--no-headers"],
        capture_output=True,
        text=True,
        check=False,
    )
    return result.returncode == 0 and not result.stdout.strip()


async def _exec_ok(core: K7Core, sandbox: str, namespace: str, cmd: str = "echo bench-ok") -> bool:
    try:
        result = await core.exec_command(sandbox, cmd, namespace=namespace)
        return result.exit_code == 0
    except Exception:
        return False


async def _wait_exec(core: K7Core, sandbox: str, namespace: str, timeout: float = 180) -> None:
    deadline = time.monotonic() + timeout
    while time.monotonic() < deadline:
        if await _exec_ok(core, sandbox, namespace):
            return
        await asyncio.sleep(1)
    raise TimeoutError(f"exec in {sandbox} never answered within {timeout}s")


class Recorder:
    def __init__(self) -> None:
        self.samples: dict[tuple[str, str], list[float]] = {}

    def add(self, backend: str, metric: str, seconds: float) -> None:
        self.samples.setdefault((backend, metric), []).append(seconds)
        print(f"    [{backend}] {metric}: {seconds:.2f}s", flush=True)

    def table(self) -> str:
        metrics: list[str] = []
        for _, metric in self.samples:
            if metric not in metrics:
                metrics.append(metric)
        lines = [
            "| Metric | " + " | ".join(BACKENDS) + " |",
            "|--------|" + "|".join(["------"] * len(BACKENDS)) + "|",
        ]
        for metric in metrics:
            row = [metric]
            for backend in BACKENDS:
                vals = self.samples.get((backend, metric))
                if vals:
                    med = statistics.median(vals)
                    row.append(f"{med:.2f}s (n={len(vals)})")
                else:
                    row.append("n/a")
            lines.append("| " + " | ".join(row) + " |")
        return "\n".join(lines)

    def dump(self) -> Path:
        ts = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
        out = OUT_DIR / f"bench-backends-{ts}.json"
        payload = {
            "backends": BACKENDS,
            "reps": REPS,
            "sandbox_image": SANDBOX_IMAGE,
            "samples": {f"{b}/{m}": v for (b, m), v in self.samples.items()},
        }
        out.write_text(json.dumps(payload, indent=2))
        return out


async def _bench_lifecycle(core: K7Core, recorder: Recorder, backend: str, namespace: str, rep: int) -> None:
    name = f"bench-{backend.split('-')[-1][:4]}-{rep}"
    fork_name = f"{name}-fork"

    # --- create → Ready ---
    start = time.monotonic()
    result = await core.create_sandbox(
        SandboxConfig(
            name=name,
            image=SANDBOX_IMAGE,
            namespace=namespace,
            backend=backend,
            node_name=os.uname().nodename,
        )
    )
    assert result.success, f"create failed: {result.error}"
    _wait(lambda: _pod_ready(name, namespace), 300, f"{name} Ready")
    recorder.add(backend, "create_to_ready", time.monotonic() - start)

    try:
        # --- exec round-trips ---
        exec_times = []
        for _ in range(EXEC_REPS):
            t0 = time.monotonic()
            assert await _exec_ok(core, name, namespace)
            exec_times.append(time.monotonic() - t0)
        recorder.add(backend, "exec_median", statistics.median(exec_times))

        # seed state the fork should inherit
        await core.exec_command(name, "echo inherited > /tmp/bench-marker", namespace=namespace)

        # --- named snapshot (kql only — k7d rejects loudly by design) ---
        if backend == "kata-qemu-longhorn":
            snap_name = f"{name}-snap"
            t0 = time.monotonic()
            snap = await core.create_snapshot(name, snap_name, namespace=namespace)
            assert snap.success, f"snapshot failed: {snap.error}"
            ready = await core._wait_for_snapshot_ready(snap_name, namespace=namespace)
            assert ready.success, f"snapshot never ready: {ready.error}"
            recorder.add(backend, "snapshot_ready", time.monotonic() - t0)
            await core.delete_snapshot(snap_name, namespace=namespace)

        # --- fork ---
        t0 = time.monotonic()
        fork = await core.fork_sandbox(name, fork_name, namespace=namespace)
        assert fork.success, f"fork failed: {fork.error}"
        fork_call = time.monotonic() - t0
        recorder.add(backend, "fork_call", fork_call)
        _wait(lambda: _pod_ready(fork_name, namespace), 300, f"{fork_name} Ready")
        await _wait_exec(core, fork_name, namespace)
        recorder.add(backend, "fork_to_ready", time.monotonic() - t0)

        if _is_k7d_family(backend):
            inherited = await core.exec_command(fork_name, "cat /tmp/bench-marker", namespace=namespace)
            assert inherited.exit_code == 0 and "inherited" in inherited.stdout, (
                f"{backend} fork lost the source's in-memory state"
            )

        await core.delete_sandbox(fork_name, namespace=namespace)

        # --- pause / resume ---
        t0 = time.monotonic()
        pause = await core.pause_sandbox(name, namespace=namespace)
        assert pause.success, f"pause failed: {pause.error}"
        if not _is_k7d_family(backend):
            _wait(lambda: _no_pods(name, namespace), 180, f"{name} pods gone")
        recorder.add(backend, "pause_effective", time.monotonic() - t0)

        t0 = time.monotonic()
        resume = await core.resume_sandbox(name, namespace=namespace)
        assert resume.success, f"resume failed: {resume.error}"
        await _wait_exec(core, name, namespace, timeout=300)
        recorder.add(backend, "resume_to_exec", time.monotonic() - t0)
    finally:
        t0 = time.monotonic()
        await core.delete_sandbox(name, namespace=namespace)
        recorder.add(backend, "delete", time.monotonic() - t0)


async def _bench_sidecar(core: K7Core, recorder: Recorder, backend: str, namespace: str, rep: int) -> None:
    name = f"bench-dind-{backend.split('-')[-1][:4]}-{rep}"

    start = time.monotonic()
    result = await core.create_sandbox(
        SandboxConfig(name=name, image=SIDECAR_IMAGE, namespace=namespace, backend=backend, sidecar="docker")
    )
    assert result.success, f"sidecar create failed: {result.error}"
    _wait(lambda: _pod_ready(name, namespace), 300, f"{name} Ready")

    async def docker_ready() -> bool:
        probe = await core.exec_command(name, "docker info >/dev/null 2>&1 && echo ok", namespace=namespace)
        return probe.exit_code == 0 and "ok" in probe.stdout

    deadline = time.monotonic() + 180
    while time.monotonic() < deadline:
        if await docker_ready():
            break
        await asyncio.sleep(2)
    else:
        raise TimeoutError(f"docker daemon in {name} never became ready")
    recorder.add(backend, "sidecar_create_to_docker_ready", time.monotonic() - start)

    try:
        t0 = time.monotonic()
        pull = await core.exec_command(name, f"docker pull {DOCKER_PULL_IMAGE}", namespace=namespace)
        assert pull.exit_code == 0, f"docker pull failed: {pull.stderr}"
        recorder.add(backend, "sidecar_docker_pull", time.monotonic() - t0)

        t0 = time.monotonic()
        run = await core.exec_command(name, f"docker run --rm {DOCKER_PULL_IMAGE} echo dind-ok", namespace=namespace)
        assert run.exit_code == 0 and "dind-ok" in run.stdout, f"docker run failed: {run.stderr}"
        recorder.add(backend, "sidecar_docker_run", time.monotonic() - t0)
    finally:
        await core.delete_sandbox(name, namespace=namespace)


async def test_bench_backend_lifecycle(k7_core: K7Core, test_namespace: str):
    recorder = Recorder()
    print(f"\nBenchmarking backends {BACKENDS} — {REPS} rep(s), image {SANDBOX_IMAGE}", flush=True)
    for rep in range(REPS):
        for backend in BACKENDS:
            print(f"  rep {rep + 1}/{REPS} backend={backend}", flush=True)
            await _bench_lifecycle(k7_core, recorder, backend, test_namespace, rep)
    for backend in BACKENDS:
        if _is_k7d_family(backend):
            print(f"  skip sidecar backend={backend} (use bench_docker_perf --docker)", flush=True)
            continue
        print(f"  sidecar backend={backend}", flush=True)
        await _bench_sidecar(k7_core, recorder, backend, test_namespace, 0)

    out = recorder.dump()
    print("\n== Backend lifecycle benchmark (median) ==\n", flush=True)
    print(recorder.table(), flush=True)
    print(f"\nraw samples: {out}", flush=True)