#!/usr/bin/env python3
"""Remove obsolete Atlas annual-availability series after the request-v4 migration."""

from __future__ import annotations

import json
import os
import time
from datetime import datetime, timedelta, timezone
from urllib.parse import urlencode
from urllib.request import Request, urlopen


VM_URL = os.environ.get(
    "VM_URL", "http://victoria-metrics-single-server:8428"
).rstrip("/")
LEGACY_SELECTOR = (
    '{__name__="atlas:availability:ratio_365d",scope="atlas",'
    'definition!="request-v4"}'
)
PROTECTED_SELECTOR = (
    '{__name__="atlas:availability:ratio_365d",scope="atlas",'
    'definition="request-v4"}'
)


def list_series(selector: str) -> list[dict[str, str]]:
    """List recently visible series matching an exact safety selector."""
    end = datetime.now(timezone.utc)
    start = end - timedelta(hours=48)
    query = urlencode(
        {
            "match[]": selector,
            "start": start.isoformat().replace("+00:00", "Z"),
            "end": end.isoformat().replace("+00:00", "Z"),
        }
    )
    with urlopen(f"{VM_URL}/api/v1/series?{query}", timeout=60) as response:
        payload = json.load(response)
    if payload.get("status") != "success":
        raise RuntimeError(f"VictoriaMetrics series lookup failed: {payload}")
    return payload["data"]


def delete_legacy_series() -> None:
    """Delete only annual Atlas series outside the protected request-v4 label set."""
    query = urlencode({"match[]": LEGACY_SELECTOR})
    request = Request(
        f"{VM_URL}/api/v1/admin/tsdb/delete_series?{query}",
        data=b"",
        method="POST",
    )
    with urlopen(request, timeout=60) as response:
        if response.status not in {200, 204}:
            raise RuntimeError(f"VictoriaMetrics deletion returned HTTP {response.status}")


def main() -> None:
    """Guard the new series, delete retired definitions, and verify convergence."""
    protected_before = list_series(PROTECTED_SELECTOR)
    if len(protected_before) != 1:
        raise RuntimeError(
            f"expected exactly one protected request-v4 series, found {len(protected_before)}"
        )
    legacy_before = list_series(LEGACY_SELECTOR)
    if legacy_before:
        delete_legacy_series()

    legacy_after = legacy_before
    for _ in range(10):
        legacy_after = list_series(LEGACY_SELECTOR)
        if not legacy_after:
            break
        time.sleep(1)
    if legacy_after:
        raise RuntimeError(f"legacy availability series remain: {legacy_after}")
    if len(list_series(PROTECTED_SELECTOR)) != 1:
        raise RuntimeError("protected request-v4 series was not preserved")

    print(
        json.dumps(
            {
                "deleted_legacy_series": len(legacy_before),
                "protected_series": len(protected_before),
                "selector": LEGACY_SELECTOR,
            },
            sort_keys=True,
        )
    )


if __name__ == "__main__":
    main()