"""Headless CLI for IoT PreTester 4.6 Demo.

Examples:
    python -m analyzer.cli capture.pcapng
    python -m analyzer.cli capture.pcapng --format json -o report.json
    python -m analyzer.cli capture.pcapng --format txt --packet-limit 50000

Exit codes:
    0  Analysis completed without high or critical findings
    2  Analysis completed with at least one high or critical finding
    1  Capture or runtime dependency error
"""

from __future__ import annotations

import argparse
import sys

from . import __version__
from .engine import AnalysisEngine
from .findings import Severity
from .reporting import render, FORMATS


def build_parser() -> argparse.ArgumentParser:
    p = argparse.ArgumentParser(
        prog="analyzer",
        description="Analyze the security of a PCAP or PCAPNG network capture.",
    )
    p.add_argument("capture", help="Path to a .pcap or .pcapng file")
    p.add_argument("-f", "--format", choices=FORMATS, default="md",
                   help="Output format (default: md)")
    p.add_argument("-o", "--output", default=None,
                   help="Output file (default: standard output)")
    p.add_argument("--packet-limit", type=int, default=None,
                   help="Maximum packets to read from a large capture")
    p.add_argument(
        "--version",
        action="version",
        version=f"IoT PreTester 4.6 Demo analyzer {__version__}",
    )
    return p


def main(argv=None) -> int:
    args = build_parser().parse_args(argv)

    try:
        result = AnalysisEngine().analyze_pcap(args.capture, packet_limit=args.packet_limit)
    except FileNotFoundError as exc:
        print(f"Error: {exc}", file=sys.stderr)
        return 1
    except RuntimeError as exc:
        print(f"Error: {exc}", file=sys.stderr)
        return 1

    report = render(result, args.format)

    if args.output:
        with open(args.output, "w", encoding="utf-8") as fh:
            fh.write(report)
        print(f"Report written: {args.output} "
              f"({result.meta.get('finding_count', 0)} Findings)", file=sys.stderr)
    else:
        print(report)

    worst = max((f.severity.rank for f in result.findings), default=0)
    return 2 if worst >= Severity.HIGH.rank else 0


if __name__ == "__main__":  # pragma: no cover
    raise SystemExit(main())