#!/usr/bin/env python3
# =============================================================================
# ci/render-keycloak-client-urls.py
#
# Render platform/keycloak/client-urls.yaml FROM platform/keycloak/keycloak-realm-import.yaml.
#
# WHY THIS EXISTS
# ---------------
# The Keycloak realm import is a ONE-SHOT that fails OPEN: once it rests at
# Done=True / Started=False it never re-runs, so a redirect URI changed in git is
# never applied to the realm. The client-secret half of that failure class is
# already healed by a level-triggered CronJob (platform/keycloak/client-secret-
# reconciler.yaml). This renderer supplies the DESIRED STATE that the same CronJob
# needs to heal the URL half.
#
# THE CONSTRAINT THAT SHAPES IT: the reconciler pod runs with
# automountServiceAccountToken: false. It has NO Kubernetes API access at all, by
# design (R-SEC-02) — so it cannot read the KeycloakRealmImport CR to learn what
# the realm is supposed to look like. Its inputs must be MOUNTED. Hence a
# ConfigMap.
#
# A hand-authored ConfigMap would be a SECOND SOURCE OF TRUTH for every public
# hostname in the realm, free to disagree with the realm import — and "two
# declarations that can disagree" is the same shape as the bug this whole effort
# is closing. So the ConfigMap is GENERATED from the realm import and the
# generation is GATED: conformance/tests/l0-static/keycloak-client-secret-
# reconciler/check.sh runs this script with --check on every merge, and the merge
# fails if the committed file is not what this renderer produces. That is the same
# render==golden idiom catalog/render.py + ci/render-golden.sh already use for
# apps/.
#
# STRINGS ARE COPIED VERBATIM, NEVER RE-DERIVED. If a URL in the realm import is
# written as a Flux substitution token (https://grafana.${BASE_DOMAIN}/...), the
# token is carried through into the ConfigMap CHARACTER FOR CHARACTER. Both files
# are rendered by the SAME Flux Kustomization (./platform-config, whose
# postBuild.substituteFrom reads cluster-vars), so both are substituted in the
# same pass with the same values and cannot disagree about what BASE_DOMAIN is.
# This renderer never parses, splits, or reconstructs a hostname, and never reads
# cluster-vars — so there is no second place for the domain to be decided.
#
# USAGE
#   python3 ci/render-keycloak-client-urls.py            # print the rendered file
#   python3 ci/render-keycloak-client-urls.py --write     # write it (regenerate)
#   python3 ci/render-keycloak-client-urls.py --check      # exit 1 if it has drifted
# =============================================================================
from __future__ import annotations

import argparse
import difflib
import json
import sys
from pathlib import Path

try:
    import yaml
except ImportError:  # pragma: no cover
    print("FATAL: PyYAML is required (same dependency as catalog/render.py)",
          file=sys.stderr)
    raise SystemExit(1)

ROOT = Path(__file__).resolve().parent.parent
IMPORT_FILE = "platform/keycloak/keycloak-realm-import.yaml"
OUT_FILE = "platform/keycloak/client-urls.yaml"
DATA_KEY = "client-urls.json"
CONFIGMAP_NAME = "keycloak-client-urls"
NAMESPACE = "keycloak"

# The client fields this renderer exports, and therefore the ONLY fields the
# reconciler may write. Every one of them is an environment-derived URL: it changes
# when BASE_DOMAIN changes, and a stale value breaks OIDC login (a wrong
# redirectUri) or silently widens trust (a stale wildcard left behind).
#
# DELIBERATELY ABSENT: `secret` (healed by the secret pass from the SOPS Secret,
# and it must never appear in a ConfigMap), and every non-URL field —
# protocolMappers, defaultClientScopes, attributes, flags. Those are not
# environment-derived, so nothing re-renders them on a domain flip; keeping them
# out keeps the reconciler's write surface as narrow as the problem.
LIST_FIELDS = ("redirectUris", "webOrigins")
STR_FIELDS = ("rootUrl", "baseUrl", "adminUrl")


def render(root: Path) -> str:
    """Return the full text of client-urls.yaml as it should be committed."""
    docs = list(yaml.safe_load_all((root / IMPORT_FILE).read_text()))
    imp = next((d for d in docs if d and d.get("kind") == "KeycloakRealmImport"), None)
    if imp is None:
        raise SystemExit("FATAL: no KeycloakRealmImport document in %s" % IMPORT_FILE)
    clients = (imp.get("spec") or {}).get("realm", {}).get("clients") or []
    if not clients:
        # Fail closed. Emitting an empty desired state would make the reconciler
        # believe every client is unmanaged and silently stop reconciling URLs.
        raise SystemExit("FATAL: %s declares zero clients — refusing to render an "
                         "empty desired state" % IMPORT_FILE)

    want: dict[str, dict] = {}
    for c in clients:
        cid = c.get("clientId")
        if not isinstance(cid, str) or not cid:
            raise SystemExit("FATAL: %s has a client with no clientId" % IMPORT_FILE)
        entry: dict[str, object] = {}
        for f in LIST_FIELDS:
            if f not in c:
                continue                 # not declared => NOT MANAGED (never forced empty)
            v = c[f]
            if not isinstance(v, list) or not all(isinstance(x, str) for x in v):
                raise SystemExit("FATAL: %s client %r field %s is not a list of strings"
                                 % (IMPORT_FILE, cid, f))
            entry[f] = list(v)           # verbatim, order as authored
        for f in STR_FIELDS:
            if f not in c:
                continue
            v = c[f]
            if not isinstance(v, str):
                raise SystemExit("FATAL: %s client %r field %s is not a string"
                                 % (IMPORT_FILE, cid, f))
            entry[f] = v
        if entry:
            want[cid] = entry
    if not want:
        raise SystemExit("FATAL: no client in %s declares any of %s — refusing to render "
                         "an empty desired state"
                         % (IMPORT_FILE, ", ".join(LIST_FIELDS + STR_FIELDS)))

    body = json.dumps(want, indent=2, sort_keys=True, ensure_ascii=False)
    indented = "\n".join(("    " + ln) if ln else "" for ln in body.splitlines())
    return HEADER + indented + "\n"


HEADER = """---
# =============================================================================
# GENERATED FILE — DO NOT EDIT BY HAND.
#
#   source:      platform/keycloak/keycloak-realm-import.yaml (spec.realm.clients)
#   regenerate:  python3 ci/render-keycloak-client-urls.py --write
#   gated by:    conformance/tests/l0-static/keycloak-client-secret-reconciler
#                (runs this renderer with --check on every merge)
#
# WHAT THIS IS: the DESIRED STATE for every environment-derived client URL in the
# `homelab` realm — redirectUris, webOrigins, rootUrl, baseUrl, adminUrl. The
# client-secret reconciler CronJob mounts it and makes the live realm match it.
#
# WHY IT IS A SEPARATE OBJECT: the realm import is a ONE-SHOT that never re-runs
# once Done=True, so a redirect URI edited in git never reaches the realm. Prod's
# stored redirect URIs were measured still pointing at the pre-migration hostname
# while git declared the new one, and every OIDC login would have failed with a
# redirect_uri mismatch. The reconciler is the level-triggered loop that closes
# that; this file is what it reconciles TOWARDS.
#
# WHY IT IS GENERATED AND NOT AUTHORED: a hand-written copy of every public
# hostname would be a second source of truth, free to disagree with the realm
# import. It is rendered from the import and the render is gated, so the two
# cannot drift. URL strings are copied VERBATIM — if the source uses a
# ${BASE_DOMAIN} token it appears here unchanged, and both files are substituted
# by the SAME Flux Kustomization (./platform-config), so the domain is decided in
# exactly one place.
#
# A field that is NOT declared on a client in the realm import is simply ABSENT
# here, and the reconciler leaves it alone. Absence means UNMANAGED, never
# "force to empty".
# =============================================================================
apiVersion: v1
kind: ConfigMap
metadata:
  name: %s
  namespace: %s
  labels:
    app.kubernetes.io/name: %s
    app.kubernetes.io/part-of: keycloak
data:
  %s: |
""" % (CONFIGMAP_NAME, NAMESPACE, CONFIGMAP_NAME, DATA_KEY)


def main() -> int:
    ap = argparse.ArgumentParser(description=__doc__)
    g = ap.add_mutually_exclusive_group()
    g.add_argument("--write", action="store_true", help="write %s" % OUT_FILE)
    g.add_argument("--check", action="store_true",
                   help="exit 1 if the committed file has drifted from the source")
    args = ap.parse_args()

    want = render(ROOT)
    target = ROOT / OUT_FILE

    if args.write:
        target.write_text(want, encoding="utf-8")
        print("wrote %s" % OUT_FILE)
        return 0

    if args.check:
        if not target.is_file():
            print("CHECK FAIL: %s does not exist. Run: python3 "
                  "ci/render-keycloak-client-urls.py --write" % OUT_FILE, file=sys.stderr)
            return 1
        have = target.read_text(encoding="utf-8")
        if have == want:
            print("client-urls.yaml is in sync with %s" % IMPORT_FILE)
            return 0
        print("CHECK FAIL: %s has DRIFTED from %s — the reconciler would converge the "
              "realm on a desired state the realm import does not declare.\n"
              "Regenerate with: python3 ci/render-keycloak-client-urls.py --write\n"
              % (OUT_FILE, IMPORT_FILE), file=sys.stderr)
        for line in difflib.unified_diff(have.splitlines(True), want.splitlines(True),
                                         fromfile="committed " + OUT_FILE,
                                         tofile="rendered from " + IMPORT_FILE):
            sys.stderr.write(line)
        return 1

    sys.stdout.write(want)
    return 0


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