#!/usr/bin/env python3
"""Upload and optionally apply a Nexus release bundle over SSH.

The script deliberately avoids local shell pipelines so it behaves consistently
on Windows, Git Bash, WSL, and Linux/macOS. By default it only uploads the
tarball and runs the remote preflight; applying the release requires --apply.
"""

from __future__ import annotations

import argparse
import hashlib
import posixpath
import shlex
import subprocess
import sys
from pathlib import Path


DEFAULT_DEPLOY_PATH = "/opt/nexus"
DEFAULT_REMOTE_TARBALL = "/tmp/nexus-release-20260708.tar.gz"
DEFAULT_REMOTE_EXTRACT_DIR = "/tmp"


def sha256_file(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def run(cmd: list[str], *, dry_run: bool = False) -> None:
    printable = " ".join(shlex.quote(part) for part in cmd)
    print(f"\n$ {printable}", flush=True)
    if dry_run:
        return
    subprocess.run(cmd, check=True)


def build_ssh_base(args: argparse.Namespace) -> list[str]:
    cmd = ["ssh"]
    if args.identity_file:
        cmd.extend(["-i", str(args.identity_file)])
    for option in args.ssh_option:
        cmd.extend(["-o", option])
    return cmd


def build_scp_base(args: argparse.Namespace) -> list[str]:
    cmd = ["scp"]
    if args.identity_file:
        cmd.extend(["-i", str(args.identity_file)])
    for option in args.ssh_option:
        cmd.extend(["-o", option])
    return cmd


def remote_bash(ssh_base: list[str], remote: str, script: str, *, dry_run: bool = False) -> None:
    run([*ssh_base, remote, "bash", "-lc", script], dry_run=dry_run)


def q(value: str | Path) -> str:
    return shlex.quote(str(value))


def remote_join(*parts: str) -> str:
    return posixpath.join(*parts)


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--remote", required=True, help="SSH target, for example 'nexus' or 'root@1.2.3.4'.")
    parser.add_argument("--tarball", required=True, type=Path, help="Local release tarball path.")
    parser.add_argument("--sha256", required=True, help="Expected tarball SHA256.")
    parser.add_argument("--deploy-path", default=DEFAULT_DEPLOY_PATH, help=f"Remote deploy path. Default: {DEFAULT_DEPLOY_PATH}")
    parser.add_argument("--remote-tarball", default=DEFAULT_REMOTE_TARBALL, help=f"Remote tarball path. Default: {DEFAULT_REMOTE_TARBALL}")
    parser.add_argument("--remote-extract-dir", default=DEFAULT_REMOTE_EXTRACT_DIR, help=f"Remote extract dir. Default: {DEFAULT_REMOTE_EXTRACT_DIR}")
    parser.add_argument("--identity-file", type=Path, help="Optional SSH private key.")
    parser.add_argument("--ssh-option", action="append", default=[], help="Extra ssh/scp -o option. Can be repeated.")
    parser.add_argument("--no-upload", action="store_true", help="Skip scp upload and use --remote-tarball already on the host.")
    parser.add_argument("--apply", action="store_true", help="Apply the release after preflight. Without this flag, only preflight runs.")
    parser.add_argument("--no-sudo", action="store_true", help="Do not prefix the apply command with sudo.")
    parser.add_argument("--dry-run", action="store_true", help="Print commands without executing them.")
    args = parser.parse_args()

    tarball = args.tarball.resolve()
    if not tarball.exists():
        print(f"ERROR: local tarball not found: {tarball}", file=sys.stderr)
        return 2

    actual_sha = sha256_file(tarball)
    if actual_sha.lower() != args.sha256.lower():
        print("ERROR: local tarball SHA256 mismatch", file=sys.stderr)
        print(f"expected: {args.sha256}", file=sys.stderr)
        print(f"actual:   {actual_sha}", file=sys.stderr)
        return 2

    ssh_base = build_ssh_base(args)
    scp_base = build_scp_base(args)

    print(f"Local tarball SHA256 OK: {actual_sha}")
    print(f"Remote target: {args.remote}")
    print(f"Remote tarball: {args.remote_tarball}")
    print(f"Remote deploy path: {args.deploy_path}")
    print(f"Mode: {'apply release' if args.apply else 'preflight only'}")

    if not args.no_upload:
        remote_target = f"{args.remote}:{args.remote_tarball}"
        run([*scp_base, str(tarball), remote_target], dry_run=args.dry_run)

    extract_script = " && ".join(
        [
            f"test -f {q(args.remote_tarball)}",
            f"mkdir -p {q(args.remote_extract_dir)}",
            (
                f"tar xzf {q(args.remote_tarball)} -C {q(args.remote_extract_dir)} "
                "nexus-release/deploy/preflight-release-host.sh "
                "nexus-release/deploy/apply-release-bundle.sh"
            ),
        ]
    )
    remote_bash(ssh_base, args.remote, extract_script, dry_run=args.dry_run)

    preflight = (
        f"bash {q(remote_join(args.remote_extract_dir, 'nexus-release/deploy/preflight-release-host.sh'))} "
        f"--tarball {q(args.remote_tarball)} "
        f"--sha256 {q(args.sha256)} "
        f"--deploy-path {q(args.deploy_path)}"
    )
    remote_bash(ssh_base, args.remote, preflight, dry_run=args.dry_run)

    if args.apply:
        apply_prefix = "" if args.no_sudo else "sudo "
        apply_cmd = (
            f"{apply_prefix}bash {q(remote_join(args.remote_extract_dir, 'nexus-release/deploy/apply-release-bundle.sh'))} "
            f"--tarball {q(args.remote_tarball)} "
            f"--sha256 {q(args.sha256)} "
            f"--deploy-path {q(args.deploy_path)}"
        )
        remote_bash(ssh_base, args.remote, apply_cmd, dry_run=args.dry_run)
    else:
        print("\nPreflight finished. Re-run with --apply to apply the release after reviewing the output.")

    return 0


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