import hashlib
import os
from datetime import datetime, timezone
from typing import Dict

from .utils import load_json, save_json

BACKUPS_PATH = os.path.join(os.path.dirname(__file__), "..", "..", "infra", "backups.json")


def _timestamp() -> str:
    return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")


def _new_hash(device: str, timestamp: str) -> str:
    return hashlib.sha256(f"{device}-{timestamp}".encode()).hexdigest()[:8]


def oob_get_last_backup(device: str) -> Dict:
    backups = load_json(BACKUPS_PATH)
    info = backups.get(device)
    if not info:
        return {
            "device": device,
            "last_backup_at": None,
            "config_hash": None,
            "snapshots": [],
            "risk": "high",  # no backup means risky
            "message": "No backup found.",
        }

    age_msg = "Backup present"
    if info.get("last_backup_at"):
        age_msg = f"Last backup at {info['last_backup_at']}"

    risk = "low"
    # Optionally adjust risk based on recency; for now simple heuristic.
    return {
        "device": device,
        "last_backup_at": info.get("last_backup_at"),
        "config_hash": info.get("config_hash"),
        "snapshots": info.get("snapshots", []),
        "risk": risk,
        "message": age_msg,
    }


def oob_perform_backup(device: str) -> Dict:
    backups = load_json(BACKUPS_PATH)
    now = _timestamp()
    cfg_hash = _new_hash(device, now)

    entry = backups.get(device, {
        "last_backup_at": None,
        "config_hash": None,
        "snapshots": [],
    })

    entry.update({
        "last_backup_at": now,
        "config_hash": cfg_hash,
    })
    entry.setdefault("snapshots", []).append(cfg_hash)

    backups[device] = entry
    save_json(BACKUPS_PATH, backups)

    return {
        "device": device,
        "last_backup_at": now,
        "config_hash": cfg_hash,
        "snapshots": entry["snapshots"],
        "message": "Backup completed (simulated).",
    }