import json
import logging
from datetime import datetime, timedelta, timezone
from pathlib import Path

log = logging.getLogger(__name__)


def auto_out_path(logs_dir: Path, vin: str) -> Path:
    stamp = datetime.now(timezone.utc).strftime("%Y_%m_%d_%H_%M_%S")
    return logs_dir / f"{stamp}_{vin}.json"


def load_store(path: Path, vin: str, interval: int) -> dict:
    if path.exists():
        try:
            data = json.loads(path.read_text())
            if isinstance(data, dict) and "records" in data:
                return data
        except json.JSONDecodeError:
            log.warning("Output file is corrupt — starting fresh")
    return {
        "meta": {
            "vin": vin,
            "created_at": datetime.now(timezone.utc).isoformat(),
            "interval_seconds": interval,
        },
        "records": [],
    }


def save_store(path: Path, store: dict, max_records: int | None) -> None:
    if max_records and len(store["records"]) > max_records:
        store["records"] = store["records"][-max_records:]
    path.write_text(json.dumps(store, indent=2, default=str))


def load_last_24h_records(logs_dir: Path, vin: str) -> list:
    """Load records from the last 24 hours across log files (may span midnight)."""
    now = datetime.now(timezone.utc)
    cutoff = now - timedelta(hours=24)
    cutoff_str = cutoff.isoformat()

    # Log files are named YYYY_MM_DD_…_VIN.json; the 24 h window can span two calendar days.
    prefixes = {
        cutoff.strftime("%Y_%m_%d_"),
        now.strftime("%Y_%m_%d_"),
    }

    records = []
    for prefix in sorted(prefixes):
        for path in sorted(logs_dir.glob(f"{prefix}*_{vin}.json")):
            try:
                data = json.loads(path.read_text())
                if isinstance(data, dict) and "records" in data:
                    kept = [r for r in data["records"] if r is not None and r.get("ts", "") >= cutoff_str]
                    records.extend(kept)
                    log.debug("Loaded %d/%d records from %s", len(kept), len(data["records"]), path.name)
            except (json.JSONDecodeError, OSError):
                log.warning("Could not load %s", path)

    records.sort(key=lambda r: r.get("ts", "") if r is not None else "")
    return records