from datetime import datetime
from functools import reduce

from dateutil import parser

from app.utils.csv import get_user_preferred_timezone_obj


def sum_of_statistics(delivery_statistics):
    statistics_keys = (
        "emails_delivered",
        "emails_requested",
        "emails_failed",
        "sms_requested",
        "sms_delivered",
        "sms_failed",
    )

    if not delivery_statistics or not delivery_statistics[0]:
        return {key: 0 for key in statistics_keys}

    return reduce(
        lambda x, y: {key: x.get(key, 0) + y.get(key, 0) for key in statistics_keys},
        delivery_statistics,
    )


def add_rates_to(delivery_statistics):
    preferred_tz = get_user_preferred_timezone_obj()
    return dict(
        emails_failure_rate=get_formatted_percentage(
            delivery_statistics["emails_failed"],
            delivery_statistics["emails_requested"],
        ),
        sms_failure_rate=get_formatted_percentage(
            delivery_statistics["sms_failed"], delivery_statistics["sms_requested"]
        ),
        week_end_datetime=parser.parse(
            delivery_statistics.get("week_end", str(datetime.now(preferred_tz)))
        ),
        **delivery_statistics
    )


def get_formatted_percentage(x, tot):
    """
    Return a percentage to one decimal place (respecting )
    """
    return "{0:.1f}".format((float(x) / tot * 100)) if tot else "0"


def get_formatted_percentage_two_dp(x, tot):
    """
    Return a percentage to two decimal places
    """
    return "{0:.2f}".format((float(x) / tot * 100)) if tot else "0"


def statistics_by_state(statistics):
    return {
        "sms": {
            "processed": statistics["sms_requested"],
            "sending": (
                statistics["sms_requested"]
                - statistics["sms_failed"]
                - statistics["sms_delivered"]
            ),
            "delivered": statistics["sms_delivered"],
            "failed": statistics["sms_failed"],
        },
        "email": {
            "processed": statistics["emails_requested"],
            "sending": (
                statistics["emails_requested"]
                - statistics["emails_failed"]
                - statistics["emails_delivered"]
            ),
            "delivered": statistics["emails_delivered"],
            "failed": statistics["emails_failed"],
        },
    }