FactoryMethod.cs

namespace Lab2.Patterns.FactoryMethod;

public enum SubscriptionType
{
    Domestic,
    Educational,
    Premium
}

public abstract class Subscription
{
    protected Subscription(decimal monthlyFee, int minimumPeriodMonths, IReadOnlyList<string> channels, IReadOnlyList<string> features)
    {
        MonthlyFee = monthlyFee;
        MinimumPeriodMonths = minimumPeriodMonths;
        Channels = channels;
        Features = features;
    }

    public decimal MonthlyFee { get; }
    public int MinimumPeriodMonths { get; }
    public IReadOnlyList<string> Channels { get; }
    public IReadOnlyList<string> Features { get; }
    public abstract string Name { get; }

    public override string ToString() =>
        $"{Name}: {MonthlyFee:C}/міс, мін. {MinimumPeriodMonths} міс., " +
        $"канали [{string.Join(", ", Channels)}], можливості [{string.Join(", ", Features)}]";
}

public sealed class DomesticSubscription() : Subscription(
    199m,
    3,
    ["News UA", "Family TV", "Cinema Home"],
    ["HD-якість", "2 пристрої"])
{
    public override string Name => nameof(DomesticSubscription);
}

public sealed class EducationalSubscription() : Subscription(
    149m,
    6,
    ["Discovery Learn", "History Lab", "Science Kids"],
    ["Лекції", "Архів записів", "Батьківський контроль"])
{
    public override string Name => nameof(EducationalSubscription);
}

public sealed class PremiumSubscription() : Subscription(
    349m,
    1,
    ["All Sports", "Cinema Max", "World Series", "Music 4K"],
    ["4K-якість", "5 пристроїв", "Преміум підтримка", "Офлайн перегляд"])
{
    public override string Name => nameof(PremiumSubscription);
}

public abstract class SubscriptionCreator
{
    public abstract string ChannelName { get; }

    public Subscription CreateSubscription(SubscriptionType type)
    {
        Subscription subscription = type switch
        {
            SubscriptionType.Domestic => CreateDomesticSubscription(),
            SubscriptionType.Educational => CreateEducationalSubscription(),
            SubscriptionType.Premium => CreatePremiumSubscription(),
            _ => throw new ArgumentOutOfRangeException(nameof(type), type, null)
        };

        ApplyPurchaseBonus(subscription);
        return subscription;
    }

    protected abstract DomesticSubscription CreateDomesticSubscription();
    protected abstract EducationalSubscription CreateEducationalSubscription();
    protected abstract PremiumSubscription CreatePremiumSubscription();

    protected virtual void ApplyPurchaseBonus(Subscription subscription)
    {
    }
}

public sealed class WebSite : SubscriptionCreator
{
    public override string ChannelName => "WebSite";

    protected override DomesticSubscription CreateDomesticSubscription() => new();
    protected override EducationalSubscription CreateEducationalSubscription() => new();
    protected override PremiumSubscription CreatePremiumSubscription() => new();
}

public sealed class MobileApp : SubscriptionCreator
{
    public override string ChannelName => "MobileApp";

    protected override DomesticSubscription CreateDomesticSubscription() => new();
    protected override EducationalSubscription CreateEducationalSubscription() => new();
    protected override PremiumSubscription CreatePremiumSubscription() => new();
}

public sealed class ManagerCall : SubscriptionCreator
{
    public override string ChannelName => "ManagerCall";

    protected override DomesticSubscription CreateDomesticSubscription() => new();
    protected override EducationalSubscription CreateEducationalSubscription() => new();
    protected override PremiumSubscription CreatePremiumSubscription() => new();
}