import logging
from datetime import date

from .entities import Pitstop


class ConsumableStats:
    def __init__(self, vehicle, consumable):
        self.name = consumable.name
        self.id = consumable.id
        self.unit = consumable.unit
        self.overall_amount = 0
        self.average_distance = 0
        self.average_amount_fuelled = 0
        self.average_amount_used = 0
        self.average_amount = []
        self.amounts = []

        pitstops = [stop for stop in vehicle.pitstops if stop.consumable_id == consumable.id]
        pitstop_count = len(pitstops)

        if pitstop_count > 0:
            for pitstop in pitstops:
                self.overall_amount += pitstop.amount
                self.amounts.append(StatsEvent(pitstop.date, pitstop.amount))
            self.average_amount_fuelled = self.overall_amount / pitstop_count
        if pitstop_count > 1:
            overall_distance = vehicle.pitstops[-1].odometer - vehicle.pitstops[0].odometer
            self.average_distance = overall_distance / (pitstop_count - 1)
            self.average_amount_used = 100 * (self.overall_amount - pitstops[0].amount) / overall_distance
            for index in range(1, pitstop_count):
                last_ps = pitstops[index - 1]
                current_ps = pitstops[index]
                self.average_amount.append(
                    StatsEvent(
                        current_ps.date,
                        round(100 * current_ps.amount/(current_ps.odometer - last_ps.odometer), 2)))


class VehicleStats:
    def __init__(self, vehicle):
        self.name = vehicle.name
        self.id = vehicle.id
        self.overall_distance = 0
        self.overall_costs = 0
        self.consumables = []
        self.odometers = []

        for consumable in vehicle.consumables:
            self.consumables.append(ConsumableStats(vehicle, consumable))

        pitstop_count = len(vehicle.pitstops)

        if pitstop_count > 0:
             for pitstop in vehicle.pitstops:
                 self.odometers.append(StatsEvent(pitstop.date, pitstop.odometer))
                 if pitstop.costs is not None:
                    self.overall_costs += pitstop.costs

        if pitstop_count > 1:
            self.overall_distance = vehicle.pitstops[-1].odometer - vehicle.pitstops[0].odometer


class StatsEvent:
    def __init__(self, date, value):
        self.date = date
        self.value = value


def db_log_add(entity):
    logging.info('db_add: %s' % str(entity))


def db_log_delete(entity):
    logging.info('db_delete: %s' % str(entity))


def db_log_update(entity):
    logging.info('db_update: %s' % str(entity))


def check_vehicle_name_is_unique(current_user, name_field):
    """
    Checks if the vehicle name given in the name_field is unique for the vehicles of the current user. An error is added
    to the field it the name is not unique.

    :param current_user: the user currently logged in
    :param name_field: the form field to enter the name to
    :return: True if the name is unique, False otherwise.
    """
    vehicle_name = name_field.data
    for vehicle in current_user.vehicles:
        if vehicle.name == vehicle_name:
            name_field.default = vehicle_name
            name_field.errors.append('Vehicle "%s" already exists.' % vehicle_name)
            return False
    return True


def get_latest_pitstop_for_vehicle(vehicle_id):
    """
    return the latest pit stop for the vehicle with the given id.
    :param vehicle_id: the id of the vehicle
    :return: the latest pitstop or None if no pitstop exists
    """
    latest_pitstop = Pitstop.query\
        .filter(Pitstop.vehicle_id == vehicle_id)\
        .order_by(Pitstop.id.desc())\
        .first()
    return latest_pitstop


def get_latest_pitstop_for_vehicle_and_consumable(vehicle_id, consumable_id):
    """
    return the latest pit stop for the vehicle and consumable with the given ids.
    :param vehicle_id: the id of the vehicle
    :param consumable_id: the id of the consumable
    :return: the latest pitstop or None if no pitstop exists
    """
    latest_pitstop_consumable = Pitstop.query\
        .filter(Pitstop.vehicle_id == vehicle_id)\
        .filter(Pitstop.consumable_id == consumable_id)\
        .order_by(Pitstop.id.desc())\
        .first()
    return latest_pitstop_consumable


def compute_lower_limits_for_new_pitstop(latest_pitstop, last_pitstop_consumable, consumable_id):
    """
    This function figures out the lower limits for date and odometer of a new pitstop.
    :param latest_pitstop:
    :param last_pitstop_consumable:
    :param consumable_id:
    :return:
    """
    odometer = 0
    date_of_pitstop = date(1970, 1, 1)
    amount = 0
    costs = 0

    if latest_pitstop is not None:
        odometer = latest_pitstop.odometer
        date_of_pitstop = latest_pitstop.date

    if last_pitstop_consumable is not None:
        amount = last_pitstop_consumable.amount
        costs = last_pitstop_consumable.costs

    return Pitstop(odometer, amount, date_of_pitstop, costs, consumable_id)


    # if latest_pitstop is not None:
    #     if last_pitstop_consumable is not None and last_pitstop_consumable != latest_pitstop:
    #         if latest_pitstop.id > last_pitstop_consumable.id:
    #             return Pitstop(latest_pitstop.odometer,
    #                            last_pitstop_consumable.overall_amount,
    #                            latest_pitstop.date,
    #                            last_pitstop_consumable.costs,
    #                            consumable_id)
    #         else:
    #             return Pitstop(last_pitstop_consumable.odometer,
    #                            last_pitstop_consumable.overall_amount,
    #                            last_pitstop_consumable.date,
    #                            last_pitstop_consumable.costs,
    #                            consumable_id)
    #     else:
    #         # either only one pitstop exists or both are the same
    #         litres = 0
    #         costs = 0
    #         if latest_pitstop.consumable_id == last_pitstop_consumable.consumable_id:
    #             litres = latest_pitstop.overall_amount
    #             costs = latest_pitstop.costs
    #         return Pitstop(latest_pitstop.odometer, litres, latest_pitstop.date, costs, consumable_id)
    # else:
    #     # No existing pitstop at all: insert fake data
    #     return Pitstop(0, 0, date(1970, 1, 1), 0, None)


def pitstop_service_key(x):
    return x.odometer, x.date