#!/opt/ci/venv/bin/python
"""Mint a Gitea act_runner registration token using the stored GiteaPAT.

The PAT never leaves this process and the registration token is written to a
0600 file instead of stdout, so neither secret lands in a shell history, a
process argument list, or a terminal log.

Usage:
    sudo -u ci-runner /opt/ci/venv/bin/python tools/gitea-runner-token.py \
        --out /var/lib/ci/.rust-runner-regtoken

    # non-instance scopes
    ... --scope user
    ... --scope org  --org  myorg
    ... --scope repo --repo Simone/local-ci-cd-system

Instance scope (the default) requires the PAT to belong to an admin user and
produces a runner visible to every repository — which is what a shared build
host wants. Registration tokens are short-lived and single-use.
"""
from __future__ import annotations

import argparse
import json
import os
import sys
import urllib.error
import urllib.request

DEFAULT_INSTANCE = "https://gitea.emulab.it"
CRED_TARGET = "GiteaPAT"
USER_AGENT = "ci-orchestrator-gitea-runner-token/1.0"


def _read_pat(target: str) -> str:
    """Read the PAT via the same two-tier scheme as KeyringCredentialStore."""
    try:
        import keyring
    except ImportError:  # pragma: no cover - environment problem, not logic
        sys.exit("keyring not installed")

    cred = keyring.get_credential(target, None)
    if cred and cred.password:
        return str(cred.password)

    username = keyring.get_password(f"{target}:meta", "username")
    if username:
        password = keyring.get_password(target, username)
        if password:
            return str(password)
    sys.exit(f"credential {target!r} not found in keyring")


def _endpoint(scope: str, org: str, repo: str) -> str:
    if scope == "admin":
        return "/api/v1/admin/actions/runners/registration-token"
    if scope == "user":
        return "/api/v1/user/actions/runners/registration-token"
    if scope == "org":
        if not org:
            sys.exit("--scope org requires --org")
        return f"/api/v1/orgs/{org}/actions/runners/registration-token"
    if not repo or "/" not in repo:
        sys.exit("--scope repo requires --repo owner/name")
    owner, name = repo.split("/", 1)
    return f"/api/v1/repos/{owner}/{name}/actions/runners/registration-token"


def main() -> int:
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("--instance", default=DEFAULT_INSTANCE)
    ap.add_argument("--scope", default="admin", choices=("admin", "user", "org", "repo"))
    ap.add_argument("--org", default="")
    ap.add_argument("--repo", default="")
    ap.add_argument("--target", default=CRED_TARGET, help="keyring target holding the PAT")
    ap.add_argument("--out", required=True, help="file to write the token to (mode 0600)")
    args = ap.parse_args()

    pat = _read_pat(args.target)
    url = args.instance.rstrip("/") + _endpoint(args.scope, args.org, args.repo)

    req = urllib.request.Request(
        url,
        method="POST",
        data=b"",
        headers={
            "Authorization": f"token {pat}",
            "Accept": "application/json",
            "Content-Length": "0",
            # Cloudflare in front of the instance rejects the default
            # "Python-urllib/x.y" agent with error 1010; any explicit agent
            # passes. Identify the caller rather than impersonate a browser.
            "User-Agent": USER_AGENT,
        },
    )
    try:
        with urllib.request.urlopen(req, timeout=30) as resp:
            payload = json.loads(resp.read().decode("utf-8"))
    except urllib.error.HTTPError as exc:
        body = exc.read().decode("utf-8", "replace")[:300]
        # 403 on the admin scope usually means the PAT owner is not an admin.
        print(f"HTTP {exc.code} from {url}\n{body}", file=sys.stderr)
        return 1
    except urllib.error.URLError as exc:
        print(f"cannot reach {url}: {exc.reason}", file=sys.stderr)
        return 1

    token = payload.get("token") or payload.get("data", {}).get("token")
    if not token:
        print(f"no token in response: {sorted(payload)}", file=sys.stderr)
        return 1

    fd = os.open(args.out, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600)
    with os.fdopen(fd, "w", encoding="ascii") as fh:
        fh.write(token)
    print(f"OK — registration token ({len(token)} chars) written to {args.out}")
    print("Single-use and short-lived: delete the file once the runner is registered.")
    return 0


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