import os
from collections import defaultdict


def load_data(filepath: str) -> list[dict]:
    orders = []
    try:
        with open(filepath, 'r', encoding='utf-8') as file:
            for line_num, line in enumerate(file, 1):
                line = line.strip()
                if not line:
                    continue

                parts = line.split(',')
                if len(parts) != 4:
                    continue

                try:
                    user_id = int(parts[0].strip())
                    order_total = float(parts[1].strip())
                    city = parts[2].strip().lower()
                    payment_method = parts[3].strip().lower()

                    orders.append({
                        'user_id': user_id,
                        'order_total': order_total,
                        'city': city,
                        'payment_method': payment_method
                    })
                except ValueError:
                    continue

    except FileNotFoundError:
        return []

    return orders


def filter_by_city(orders: list[dict], city: str) -> list[dict]:
    city_lower = city.lower()
    return [order for order in orders if order['city'] == city_lower]


def filter_by_min_total(orders: list[dict], min_total: float) -> list[dict]:
    return [order for order in orders if order['order_total'] >= min_total]


def get_unique_users(orders: list[dict]) -> list[int]:
    return list(set(order['user_id'] for order in orders))


def total_revenue(orders: list[dict]) -> float:
    return sum(order['order_total'] for order in orders)


def average_order_value(orders: list[dict]) -> float:
    if not orders:
        return 0.0
    return total_revenue(orders) / len(orders)


def payment_method_stats(orders: list[dict]) -> dict[str, int]:
    stats = defaultdict(int)
    for order in orders:
        stats[order['payment_method']] += 1
    return dict(stats)


def city_revenue(orders: list[dict]) -> dict[str, float]:
    revenue = defaultdict(float)
    for order in orders:
        revenue[order['city']] += order['order_total']
    return dict(revenue)


def top_users_by_spent(orders: list[dict], top_n: int) -> list[tuple[int, float]]:
    user_spent = defaultdict(float)
    for order in orders:
        user_spent[order['user_id']] += order['order_total']

    sorted_users = sorted(user_spent.items(), key=lambda x: x[1], reverse=True)
    return sorted_users[:top_n]


def filter_top_cities_by_orders(orders: list[dict], min_orders: int) -> list[str]:
    city_orders = defaultdict(int)
    for order in orders:
        city_orders[order['city']] += 1

    filtered_cities = [(city, count) for city, count in city_orders.items() if count >= min_orders]
    filtered_cities.sort(key=lambda x: x[1], reverse=True)

    return [city for city, _ in filtered_cities]


def main():
    filepath = "data/orders.txt"

    orders = load_data(filepath)
    if not orders:
        return

    revenue = total_revenue(orders)
    print(f"Общая выручка: {revenue:.2f} руб.")

    avg_order = average_order_value(orders)
    print(f"Средняя сумма заказа: {avg_order:.2f} руб.")

    payment_stats = payment_method_stats(orders)
    print("Статистика по методам оплаты:")
    for method, count in payment_stats.items():
        print(f"  {method}: {count}")

    top_users = top_users_by_spent(orders, 2)
    print("Топ-2 пользователей по сумме трат:")
    for user_id, spent in top_users:
        print(f"  Пользователь {user_id}: {spent:.2f} руб.")

    filtered_orders = filter_by_min_total(orders, 1000)
    if filtered_orders:
        city_rev = city_revenue(filtered_orders)
        print("Выручка по городам (заказы >= 1000 руб.):")
        for city, rev in sorted(city_rev.items(), key=lambda x: x[1], reverse=True):
            print(f"  {city.capitalize()}: {rev:.2f} руб.")

    top_cities = filter_top_cities_by_orders(orders, 2)
    if top_cities:
        print("Города с количеством заказов >= 2:")
        for city in top_cities:
            print(f"  {city.capitalize()}")


if __name__ == "__main__":
    main()