"""Check every alert rule against the alerting contract (see the header of
k8s/prometheus/rules/ledgerline.rules.yml).

    python observability/alerts/check_contract.py

Needs PyYAML. Skips scratch.* and host.* rule files.
"""
import sys
from pathlib import Path

import yaml

ROOT = Path(__file__).resolve().parents[2]
RULES = ROOT / "k8s" / "prometheus" / "rules"

SEVERITIES = {"critical", "warning", "info"}
TEAMS = {"platform", "payments", "risk", "data"}  # placeholders: edit to taste
ANNOTATIONS = ("summary", "description", "runbook_url", "dashboard")
RUNBOOK_MARKER = "/docs/runbooks/"


def check(path: Path) -> list[str]:
    problems = []
    for group in yaml.safe_load(path.read_text())["groups"]:
        for rule in group["rules"]:
            name = rule.get("alert")
            if name is None:  # recording rule
                continue
            where = f"{path.name}:{name}"
            labels, ann = rule.get("labels", {}), rule.get("annotations", {})
            if labels.get("severity") not in SEVERITIES:
                problems.append(f"{where}: severity must be one of {sorted(SEVERITIES)}")
            if labels.get("team") not in TEAMS:
                problems.append(f"{where}: team must be one of {sorted(TEAMS)}")
            for key in ANNOTATIONS:
                if not ann.get(key):
                    problems.append(f"{where}: missing annotation {key}")
            url = ann.get("runbook_url", "")
            if RUNBOOK_MARKER in url:
                local = ROOT / "docs" / "runbooks" / url.rsplit("/", 1)[-1]
                if not local.exists():
                    problems.append(f"{where}: runbook {local.relative_to(ROOT)} does not exist")
            elif url:
                problems.append(f"{where}: runbook_url should point under {RUNBOOK_MARKER}")
    return problems


def main() -> int:
    files = [p for p in sorted(RULES.glob("*.yml")) if p.name.split(".")[0] not in ("scratch", "host")]
    problems = [msg for p in files for msg in check(p)]
    for msg in problems:
        print(msg)
    print(f"{len(files)} file(s) checked, {len(problems)} problem(s)")
    return 1 if problems else 0


if __name__ == "__main__":
    sys.exit(main())