# SPDX-License-Identifier: GPL-3.0-or-later
"""Command-line entry point.

  enodia-sentinel run        # daemon loop (default; used by systemd)
  enodia-sentinel check      # run every detector once, print alerts, exit
  enodia-sentinel baseline   # (re)build listener/SUID baselines and exit
"""
from __future__ import annotations

import argparse
import signal
import sys

from . import __version__, detectors
from .config import Config
from .daemon import Sentinel
from .system import SystemState, scan_suid_binaries


def _cmd_run(cfg: Config) -> int:
    sentinel = Sentinel(cfg)
    signal.signal(signal.SIGTERM, sentinel.stop)
    signal.signal(signal.SIGINT, sentinel.stop)
    sentinel.run()
    return 0


def _cmd_baseline(cfg: Config) -> int:
    sentinel = Sentinel(cfg)
    sentinel.build_baselines()
    print(f"Baselines written under {cfg.log_dir}")
    return 0


def _cmd_check(cfg: Config) -> int:
    # One-shot: arm everything immediately, force the SUID scan.
    sentinel = Sentinel(cfg)
    sentinel.start_time = 0.0  # past the grace window
    sentinel.load_baselines()
    if not sentinel.listener_baseline:
        sentinel.build_baselines()
    alerts = sentinel.sweep(force_suid=True)
    if not alerts:
        print("No alerts.")
        return 0
    for a in sorted(alerts, key=lambda x: -x.severity):
        print(f"[{a.severity}] {a.signature:<14} {a.detail}")
    return 0


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(
        prog="enodia-sentinel",
        description="Host intrusion-detection daemon.",
    )
    parser.add_argument("--version", action="version",
                        version=f"enodia-sentinel {__version__}")
    parser.add_argument("-c", "--config", help="path to TOML config")
    sub = parser.add_subparsers(dest="cmd")
    sub.add_parser("run", help="run the daemon loop (default)")
    sub.add_parser("check", help="run detectors once and print alerts")
    sub.add_parser("baseline", help="rebuild listener/SUID baselines")
    sub.add_parser("list-detectors", help="list available detectors")
    sub.add_parser("web", help="serve the read-only dashboard")
    sub.add_parser("triage", help="classify captured alerts as likely-FP vs review")
    sub.add_parser("fim-baseline", help="build the file-integrity baseline")
    sub.add_parser("fim-update", help="refresh the FIM baseline (run by the pacman hook)")
    fc = sub.add_parser("fim-check", help="scan monitored files and report changes")
    fc.add_argument("--packages", action="store_true",
                    help="also verify package-owned files via pacman -Qkk")

    args = parser.parse_args(argv)
    cfg = Config.load(args.config)

    if args.cmd == "list-detectors":
        for det in detectors.REGISTRY:
            mark = "on " if cfg.enabled(det.name) else "off"
            print(f"  [{mark}] {det.name}")
        return 0
    if args.cmd == "baseline":
        return _cmd_baseline(cfg)
    if args.cmd == "check":
        return _cmd_check(cfg)
    if args.cmd == "web":
        from .web import serve
        serve(cfg)
        return 0
    if args.cmd == "triage":
        return _cmd_triage(cfg)
    if args.cmd in ("fim-baseline", "fim-update"):
        n = Sentinel(cfg).build_fim_baseline()
        print(f"FIM baseline written: {n} files under {cfg.log_dir}")
        return 0
    if args.cmd == "fim-check":
        return _cmd_fim_check(cfg, args.packages)
    return _cmd_run(cfg)


def _cmd_fim_check(cfg: Config, packages: bool) -> int:
    from . import fim
    sentinel = Sentinel(cfg)
    sentinel.load_fim_baseline()
    current = fim.scan_paths(cfg.fim_path_list())
    d = fim.diff(sentinel.fim_baseline, current)
    changed = len(d["added"]) + len(d["removed"]) + len(d["modified"])
    for path, changes in d["modified"]:
        print(f"[MODIFIED] {path}  ({', '.join(changes)})")
    for path in d["added"]:
        print(f"[ADDED]    {path}")
    for path in d["removed"]:
        print(f"[REMOVED]  {path}")
    if not changed:
        print("FIM: no changes against baseline.")
    if packages:
        print("\nVerifying package-owned files (pacman -Qkk, may take a while)…")
        hits = fim.pacman_verify()
        for pkg, path, reason in hits:
            print(f"[PKG]      {path}  ({pkg}: {reason})")
        if not hits:
            print("Packages: all verified files match the distro checksums.")
    return 1 if changed else 0


def _cmd_triage(cfg: Config) -> int:
    import json
    from collections import OrderedDict

    from .triage import LIKELY_FP, triage_alert

    seen: OrderedDict[tuple, dict] = OrderedDict()
    for p in sorted(cfg.log_dir.glob("alert-*.json")):
        try:
            d = json.loads(p.read_text())
        except (OSError, ValueError):
            continue
        procs = d.get("processes", [])
        for a in d.get("alerts", []):
            key = (a.get("signature"), a.get("detail", "").split(" cmd=")[0])
            if key in seen:
                seen[key]["count"] += 1
                continue
            v = triage_alert(a, procs, cfg)
            seen[key] = {"alert": a, "verdict": v, "count": 1}

    if not seen:
        print("No alerts to triage.")
        return 0

    fp = sum(1 for e in seen.values() if e["verdict"].label == LIKELY_FP)
    print(f"{len(seen)} distinct detections — {fp} likely false-positive, "
          f"{len(seen) - fp} to review.\n")
    suggestions = set()
    for e in sorted(seen.values(), key=lambda e: e["verdict"].label):
        a, v = e["alert"], e["verdict"]
        tag = "FP  " if v.label == LIKELY_FP else "REVIEW"
        print(f"[{tag}] {a.get('signature'):14} x{e['count']:<3} {v.reason}")
        print(f"         {a.get('detail', '')[:100]}")
        if v.suggest:
            suggestions.add(v.suggest)
    if suggestions:
        print("\nTo suppress the false positives, add to your config:")
        for s in sorted(suggestions):
            print(f"  # {s}")
    return 0


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