from sqlalchemy import or_
import requests
import logging
from datetime import date, datetime, timedelta

from .entities import Pitstop
from . import db, app


class RegularCostInstance:
    def __init__(self, regular_id, date, odometer, costs, name):
        self.id = regular_id
        self.date = date
        self.odometer = odometer
        self.costs = costs
        self.name = name


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 = []
        self.price = []

        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))
                # some pitstops seem to have lost their costs...
                if pitstop.costs:                
                    self.price.append(StatsEvent(pitstop.date, pitstop.costs/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 = []
        self.costs = []
        self.costs_per_distance = "N/A"

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

        events = get_event_line_for_vehicle(vehicle)
        pitstop_count = len(events)

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

        # add the instances to the overall costs
        for regular_cost_instance in calculate_regular_cost_instances(vehicle):
            self.overall_costs += regular_cost_instance.costs
            self.costs.append(
                StatsEvent(regular_cost_instance.date, regular_cost_instance.costs)
            )

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

        self.costs.sort(key=lambda x: x.date)
        accumulated_costs = 0
        for c in self.costs:
            accumulated_costs += c.value
            c.value = accumulated_costs

        if self.overall_distance > 0:
            self.costs_per_distance = float(self.overall_costs) / (
                float(self.overall_distance) / 100
            )


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

    def __repr__(self):
        return str(self.date)


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)


def pitstop_service_key(x):
    # if the entry got no odometer (regular costs!) then we assume it's okay
    # to have regular cost at a virtual odometer of 0 on that day.
    return x.date, x.odometer or 0


def get_event_line_for_vehicle(vehicle):
    data = []
    for pitstop in vehicle.pitstops:
        data.append(pitstop)
    for service in vehicle.services:
        data.append(service)
    data.sort(key=pitstop_service_key)
    return data


def chunks(l, n):
    """Yield successive n-sized chunks from l."""
    for i in range(0, len(l), n):
        yield l[i : i + n]


def calculate_regular_cost_instances(vehicle):
    data = []
    for regular in vehicle.regulars:
        if date.today() < regular.start_at:
            # skip regular costs that are not yet active
            continue
        if regular.ends_at:
            end_date = regular.ends_at
        else:
            end_date = date.today()

        start_year = regular.start_at.year
        end_year = end_date.year

        for year in range(start_year, end_year + 1):
            for day in regular.days.split(","):
                m, d = day.split("-")
                d = date(year, int(m), int(d))
                if regular.start_at <= d and d <= end_date:
                    r = RegularCostInstance(
                        regular.id,
                        date=d,
                        odometer=None,
                        costs=regular.costs,
                        name=regular.description,
                    )
                    data.append(r)
    return data


def get_users_active_vehicle(user):
    def selector(vehicle):
        if not vehicle.pitstops:
            return date.today()
        return vehicle.pitstops[-1].date

    active_vehicles = [g for g in user.vehicles if g.is_active]
    active_vehicles.sort(key=selector, reverse=True)
    return active_vehicles