from datetime import timedelta

from django.utils import timezone


CARD_TTLS = {
    "farmOverviewKpis": timedelta(days=3),
    "farmWeatherCard": timedelta(days=1),
    "farmAlertsTracker": timedelta(days=1),
    "sensorValuesList": timedelta(days=1),
    "sensorRadarChart": timedelta(days=1),
    "sensorComparisonChart": timedelta(days=1),
    "anomalyDetectionCard": timedelta(days=1),
    "farmAlertsTimeline": timedelta(days=1),
    "waterNeedPrediction": timedelta(days=1),
    "harvestPredictionCard": timedelta(days=1),
    "yieldPredictionChart": timedelta(days=1),
    "soilMoistureHeatmap": timedelta(days=1),
    "ndviHealthCard": timedelta(days=1),
    "recommendationsList": timedelta(days=1),
    "economicOverview": timedelta(days=1),
}


WMO_CONDITIONS = {
    0: "صاف",
    1: "عمدتاً صاف",
    2: "نیمه‌ابری",
    3: "ابری",
    45: "مه",
    48: "مه یخ‌زده",
    51: "نم‌نم باران",
    61: "بارش خفیف",
    63: "بارش متوسط",
    65: "بارش شدید",
    71: "برف خفیف",
    80: "رگبار",
    95: "رعد و برق",
}

PERSIAN_WEEKDAYS = ["دوشنبه", "سه‌شنبه", "چهارشنبه", "پنج‌شنبه", "جمعه", "شنبه", "یکشنبه"]


def ttl_for_card(card_name: str):
    return CARD_TTLS[card_name]


def is_fresh(snapshot) -> bool:
    return snapshot and snapshot.expires_at > timezone.now()


def safe_number(value, default=0):
    return default if value is None else value


def average(values, default=0):
    clean_values = [value for value in values if value is not None]
    if not clean_values:
        return default
    return sum(clean_values) / len(clean_values)


def latest_history_value(history, field_name, default=None):
    if not history:
        return default
    return getattr(history[0], field_name, default)


def compute_trend(current, previous):
    current_value = safe_number(current, 0)
    previous_value = safe_number(previous, current_value)
    diff = round(current_value - previous_value, 1)
    return {
        "trendNumber": diff,
        "trend": "positive" if diff >= 0 else "negative",
    }


def weather_condition(weather_code):
    return WMO_CONDITIONS.get(weather_code, "نامشخص")