"""Persistent state shared by the independent update services."""
from __future__ import annotations

import fcntl
import json
import os
from contextlib import contextmanager
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Iterator

CONFIG_FILE = Path('/etc/replypier-updater/config.json')
BUSY = {'queued', 'preparing', 'building', 'backing_up', 'deploying', 'migrating', 'verifying', 'rolling_back'}


def now() -> str:
    return datetime.now(timezone.utc).isoformat()


def config() -> dict[str, Any]:
    return json.loads(CONFIG_FILE.read_text())


def directory(cfg: dict[str, Any]) -> Path:
    return Path(cfg['state_dir'])


def read(cfg: dict[str, Any]) -> dict[str, Any]:
    p = directory(cfg) / 'status.json'
    return json.loads(p.read_text()) if p.exists() else {
        'current': {'revision': cfg['initial_revision'], 'subject': '已安装版本'},
        'latest': None, 'checked_at': None, 'checking': False,
        'check_error': None, 'update': {'status': 'idle', 'message': ''},
    }


def write(cfg: dict[str, Any], state: dict[str, Any]) -> None:
    target = directory(cfg) / 'status.json'
    temp = target.with_suffix('.tmp')
    with temp.open('w') as out:
        json.dump(state, out, ensure_ascii=False, indent=2)
        out.flush()
        os.fsync(out.fileno())
    temp.chmod(0o644)
    temp.replace(target)


@contextmanager
def transaction(cfg: dict[str, Any]) -> Iterator[dict[str, Any]]:
    directory(cfg).mkdir(parents=True, exist_ok=True)
    with (directory(cfg) / 'state.lock').open('a') as lock:
        fcntl.flock(lock, fcntl.LOCK_EX)
        state = read(cfg)
        yield state
        write(cfg, state)


def progress(cfg: dict[str, Any], status: str, message: str, **values: Any) -> None:
    with transaction(cfg) as state:
        state['update'].update(status=status, message=message, **values)


def public_status(cfg: dict[str, Any]) -> dict[str, Any]:
    state = read(cfg)
    current = state['current']['revision']
    latest = (state.get('latest') or {}).get('revision')
    return {**state, 'configured': True, 'can_manage': True,
            'repository_url': cfg['web_url'], 'branch': cfg['branch'],
            'check_interval_minutes': 30,
            'update_available': bool(latest and latest != current and not state.get('check_error'))}