#!/usr/bin/env python3
"""Check the article's snapshot publication example in a disposable directory."""
import argparse
import hashlib
import platform
from datetime import datetime, timezone
def validate_snapshot(data):
    if not isinstance(data, dict):
        raise ValueError("snapshot must be an object")
    if type(data.get("version")) is not int:
        raise ValueError("version must be an integer")
    if not isinstance(data.get("items"), list):
        raise ValueError("items must be a list")
    for item in data["items"]:
        if not isinstance(item, dict) or type(item.get("id")) is not int:
            raise ValueError("invalid item")

import json
import os
import tempfile
from pathlib import Path

def publish_snapshot(target, data):
    target = Path(target)
    validate_snapshot(data)
    candidate = None
    try:
        with tempfile.NamedTemporaryFile(
            mode="w", encoding="utf-8", dir=target.parent,
            prefix=".snapshot-", delete=False
        ) as stream:
            candidate = Path(stream.name)
            json.dump(data, stream, ensure_ascii=False)
        validate_snapshot(json.loads(candidate.read_text(encoding="utf-8")))
        os.replace(candidate, target)
    finally:
        if candidate is not None and candidate.exists():
            candidate.unlink()

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('--output', required=True)
    output = Path(parser.parse_args().output)
    if output.exists():
        raise SystemExit('Existing evidence will not be overwritten.')
    with tempfile.TemporaryDirectory(prefix='punchblog-publish-') as directory:
        target = Path(directory) / 'snapshot.json'
        target.write_text(json.dumps({'version': 1, 'items': [{'id': 1}]}))
        publish_snapshot(target, {'version': 2, 'items': [{'id': n} for n in range(1, 6)]})
        expected = target.read_bytes()
        rows = [['정상 후보 교체', '성공', 2, 5, 0]]
        errors = []
        for label, invalid in [
            ('구조 검사 실패', {'version': 3, 'items': 'wrong'}),
            ('직렬화 실패', {'version': 3, 'items': [], 'extra': object()})
        ]:
            try:
                publish_snapshot(target, invalid)
            except (ValueError, TypeError) as error:
                errors.append(type(error).__name__)
            else:
                raise AssertionError('Invalid candidate was accepted')
            assert target.read_bytes() == expected
            leftovers = len(list(Path(directory).glob('.snapshot-*')))
            assert leftovers == 0
            rows.append([label, errors[-1], 2, 5, leftovers])
        assert json.loads(expected)['version'] == 2
        mode = oct(target.stat().st_mode & 0o777)
        digest = hashlib.sha256(expected).hexdigest()
    record = {
        'schema_version': 1, 'observed_at': datetime.now(timezone.utc).isoformat(),
        'environment': {'os': platform.system(), 'python': platform.python_version()},
        'method': '본문의 validate_snapshot·publish_snapshot 함수로 임시 경로에서 정상 교체, 구조 오류, 직렬화 오류를 순서대로 확인했다. 오류 뒤 정상 파일 바이트와 남은 후보 수를 대조했다.',
        'limits': '단일 사용자·단일 writer. fsync·전원 장애·권한 전환·NFS·동시 writer·디스크 부족은 검증하지 않았다.',
        'observations': {'last_good_sha256': digest, 'published_mode': mode, 'errors': errors},
        'tables': {'publish': {'headers': ['입력', '결과', '유지된 버전', '항목 수', '남은 후보 파일'], 'rows': rows}}
    }
    output.parent.mkdir(parents=True, exist_ok=True)
    with output.open('x') as stream:
        json.dump(record, stream, ensure_ascii=False, indent=2)
        stream.write('\n')
    print(json.dumps(record['tables'], ensure_ascii=False))

if __name__ == '__main__':
    main()