#!/usr/bin/env python3
"""Persistent state for incremental log scanning.

Tracks the last processed byte offset per absolute log file path so a scan
only reads new entries instead of re-reading the whole file. The state file
is written atomically (temp file + rename) to avoid corruption.
"""

from __future__ import annotations

import json
import os

from .constants import SCAN_STATE_PATH


def load_state() -> dict[str, int]:
    """Return ``{absolute log path: byte offset}`` from the scan-state file."""
    try:
        with open(SCAN_STATE_PATH, "r", encoding="utf-8") as f:
            data = json.load(f)
        return {k: int(v) for k, v in data.items()}
    except (OSError, ValueError, TypeError):
        return {}


def save_state(state: dict[str, int]) -> None:
    """Write the scan-state file atomically (temp file + rename)."""
    os.makedirs(os.path.dirname(SCAN_STATE_PATH), exist_ok=True)
    tmp = SCAN_STATE_PATH + ".tmp"
    with open(tmp, "w", encoding="utf-8") as f:
        json.dump(state, f, indent=2, sort_keys=True)
    os.replace(tmp, SCAN_STATE_PATH)