import json
import logging
from datetime import datetime, 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_today_records(logs_dir: Path, vin: str) -> list:
    """Load and merge all records from today's log files for this VIN."""
    today_prefix = datetime.now(timezone.utc).strftime("%Y_%m_%d_")
    records = []
    for path in sorted(logs_dir.glob(f"{today_prefix}*_{vin}.json")):
        try:
            data = json.loads(path.read_text())
            if isinstance(data, dict) and "records" in data:
                records.extend(data["records"])
                log.debug("Loaded %d records from %s", len(data["records"]), path.name)
        except (json.JSONDecodeError, OSError):
            log.warning("Could not load %s", path)
    records.sort(key=lambda r: r.get("ts", ""))
    return records