class Animal {
    name = "Unknown";
    age = 0;
    _species = "Animal";

    Animal(this, name, age) {
        this.name = name;
        this.age = age;
        print("Animal created:", this.name);
    }

    ~Animal(this) {
        print("Animal destroyed:", this.name);
    }

    speak(this) {
        print(this.name, "makes a sound");
    }

    getInfo(this) {
        return this.name + " is " + str(this.age) + " years old";
    }

    birthday(this) {
        this.age++;
        print(this.name, "is now", this.age, "years old");
    }
}

class Dog {
    name = "";
    age = 0;
    breed = "Unknown";
    _tricks = null;

    Dog(this, name, age, breed = "Mixed") {
        this.name = name;
        this.age = age;
        this.breed = breed;
        this._tricks = {};
        print("Dog created:", this.name, "the", this.breed);
    }

    speak(this) {
        print(this.name, "says: Woof!");
    }

    fetch(this, item) {
        print(this.name, "fetches the", item);
    }

    learnTrick(this, trick) {
        this._tricks.push(trick);
        print(this.name, "learned:", trick);
    }

    performTricks(this) {
        if (len(this._tricks) == 0) {
            print(this.name, "doesn't know any tricks yet");
            return;
        }
        print(this.name + "'s tricks:");
        for (i = 0; i < len(this._tricks); i++) {
            print("  -", this._tricks[i]);
        }
    }
}

class Cat {
    name = "";
    lives = 9;
    __secretThoughts = "I am plotting world domination";

    Cat(this, name) {
        this.name = name;
        print("Cat created:", this.name);
    }

    speak(this) {
        print(this.name, "says: Meow!");
    }

    loseLife(this) {
        if (this.lives > 0) {
            this.lives--;
            print(this.name, "lost a life. Lives remaining:", this.lives);
        } else {
            print(this.name, "has no more lives!");
        }
    }
}

print("=== Class System Demo ===");
print("");

print("--- Creating Animals ---");
animal = new Animal("Generic", 5);
animal.speak();
print(animal.getInfo());
animal.birthday();

print("");
print("--- Dog Class ---");
dog = new Dog("Buddy", 3, "Golden Retriever");
dog.speak();
dog.fetch("ball");
dog.learnTrick("sit");
dog.learnTrick("roll over");
dog.learnTrick("play dead");
dog.performTricks();

print("");
print("--- Cat Class ---");
cat = new Cat("Whiskers");
cat.speak();
print("Cat has", cat.lives, "lives");
cat.loseLife();
cat.loseLife();
print("Cat now has", cat.lives, "lives");

print("");
print("--- Default Parameters ---");
mutt = new Dog("Max", 2);
print("Breed:", mutt.breed);

print("");
print("--- Property Access ---");
print("Dog name:", dog.name);
print("Dog age:", dog.age);
print("Dog breed:", dog.breed);

dog.age = 4;
print("Updated dog age:", dog.age);

print("");
print("--- Convention-based Privacy ---");
print("_species (single underscore):", animal._species);
cat.__secretThoughts = "Actually, I just want treats";
print("__secretThoughts (double underscore):", cat.__secretThoughts);