#!/usr/bin/env python3
"""Measure the classification coverage published in `pep-stance.yaml`.

Read-only. No network, no OpenBao, no secret material.

Why this exists. security-layer-model v0.8 §6.4 obligation 3 requires a dated
classification-coverage figure beside each stance, and §13.1 carries a Coverage
column whose first entries are ops-warden's — because ops-warden asked for the
column after measuring that 0 of 3 signing targets resolve to a zone.

Having asked for it, we own the figure's accuracy. A hand-counted number in a
published register decays silently: the register explicitly does not compute
anyone's coverage, and a stale figure beside a marked cell is worse than a blank,
which at least reads as "not reported". So the figure is measured from the same
two artifacts the runtime uses, and `tests/test_layer_conformance.py` asserts the
published block equals what this reports — the same property that makes the stance
map worth publishing (`pep-stance.yaml` equals `PolicyConfig.failure_modes` by
test), applied one level up.

Two populations, deliberately not summed. They answer different questions and
share no denominator:

  signing targets — actor resources in the flex-auth registry snapshot. This is
    the population the stance map actually governs: `warden sign` resolves a zone
    per actor resource, and an unresolved one takes the `unknown` cell.
  routing lanes — catalog entries with an explicit workload reference. Wider than
    the stance map's reach, and the figure that shows *why* coverage is low: an
    unknown lane is almost always another repository's undeclared workload
    identity, which `ADR-0009` rule 3 forbids closing by inference here.

Usage:
  python scripts/report_coverage.py [--json]

Exit: 0 always. This reports; it does not gate. Coverage is disclosure, never a
transitional licence, and a script that failed on low coverage would be arguing
the case v0.8 declined.
"""
from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path
from typing import Any

REPO = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(REPO / "src"))

SNAPSHOT = REPO / "registry" / "flex-auth" / "production_registry_snapshot.json"
NOT_APPLICABLE = "not-applicable"


def signing_target_coverage(snapshot_path: Path = SNAPSHOT) -> dict[str, int]:
    """Zone resolution across the actor resources `warden sign` can name."""
    registry = json.loads(snapshot_path.read_text())
    resolved = unknown = not_applicable = 0
    for manifest in registry.get("resource_manifests") or []:
        for resource in manifest.get("resources") or []:
            if str(resource.get("type")) != "ssh-certificate":
                continue
            attributes = resource.get("attributes") or {}
            admission = str(attributes.get("security_zone_admission") or "unknown")
            zone = str(attributes.get("security_zone") or "unknown")
            if admission == NOT_APPLICABLE:
                not_applicable += 1
            elif zone == "unknown":
                unknown += 1
            else:
                resolved += 1
    return {"resolved": resolved, "unknown": unknown, "not_applicable": not_applicable}


def routing_lane_coverage(estate_root: Path | None = None) -> dict[str, int]:
    """Workload resolution across catalog lanes.

    Delegates to `report_workload_join.build` rather than re-deriving the join: two
    implementations of "is this lane resolved" would drift, and the published figure
    should be the one the join report shows.
    """
    import importlib.util

    spec = importlib.util.spec_from_file_location(
        "report_workload_join", Path(__file__).resolve().parent / "report_workload_join.py"
    )
    join = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(join)

    report = join.build(
        REPO / "registry" / "routing" / "catalog.yaml",
        estate_root if estate_root is not None else Path.home(),
    )
    return {
        "resolved": len(report["resolved"]),
        "unknown": len(report["unknown"]),
        "not_applicable": len(report["not_applicable"]),
    }


def measure(estate_root: Path | None = None) -> dict[str, Any]:
    return {
        "signing_targets": signing_target_coverage(),
        "routing_lanes": routing_lane_coverage(estate_root),
    }


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--json", action="store_true", dest="as_json")
    args = parser.parse_args(argv)

    report = measure()
    if args.as_json:
        print(json.dumps(report, indent=2))
        return 0

    for name, counts in report.items():
        total = sum(counts.values())
        scoped = counts["resolved"] + counts["unknown"]
        print(f"{name.replace('_', ' ')}: {counts['resolved']}/{scoped} resolved "
              f"({counts['unknown']} unknown, {counts['not_applicable']} not-applicable, "
              f"{total} total)")
    print()
    print("Coverage is disclosure, not a transitional licence (v0.8 §6.4 obligation 3).")
    print("Publish in pep-stance.yaml; §13.1 does not compute it for you.")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())