Predator.java

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Random;
import java.util.LinkedList;
import javafx.scene.paint.Color; 

/**
 * A simple model of a predator.
 * Predators age, move, eat preys, and die.
 * 
 * @author Yingtao Zheng(Kevin)
 * @time 2025.02.21
 * @version 1.0
 */

public class Predator extends Animal {
    private static final int MAX_FOOD_LEVEL = 40;
    private static final int FLAMINGO_FOOD_VALUE = 5;
    private static final int SHEEP_FOOD_VALUE = 7;
    private static final Random rand = Randomizer.getRandom();
    
    private int age;
    private double foodLevel;
    
    // record animals have already bred in this round
    private static List<Animal> alreadyBred = new ArrayList<>();
    
    /**
     * Create a predator. A predator can be created as a new born (age zero
     * and not hungry) or with a random age and food level.
     * 
     * @param isFirstGeneration If true, the predator will have random age and hunger level.
     * @param field The field currently occupied.
     * @param location The location within the field.
     * @param col The color of the predator.
     * @param type The type of the predator.
     * @param isFirstGeneration If true, the predator is the first generation.
     */
    public Predator(Field field, Location location, Color col, Type type, boolean isFirstGeneration) {
        super(field, location, col, type, isFirstGeneration);
        
        if(isFirstGeneration) {
            setAge(rand.nextInt(getMaxAge()));
            foodLevel = rand.nextInt(MAX_FOOD_LEVEL);
        }
        else {
            setAge(0);
            foodLevel = MAX_FOOD_LEVEL;
        }
    }
    
    /**
     * This is what the predator does most of the time: it hunts for
     * preys. In the process, it might breed, die of hunger,
     * or die of old age.
     * @param newPredators A list to return newly born predators.
     */
    public void act(List<Animal> newPredators) {
        super.incrementAge();
        metabolism();
        checkSick();
        if(isAlive()) {
            Breeding.giveBirth(this, newPredators);           
            // Move towards a source of food if found.
            Location newLocation = findFood();
            if(newLocation == null) { 
                // No food found - try to move to a free location.
                newLocation = getField().getFreeAdjacentLocation(getLocation());
            }
            // See if it was possible to move.
            if(newLocation != null) {
                setLocation(newLocation);
            }
            else {
                // Overcrowding.
                setDead(DeathReason.OUT_OF_BOUNDS);
            }
        }
    }
    
    /**
     * Natural metabolism. This could result in the predator's death.
     */
    private void metabolism() {
        foodLevel -= getMetabolism();
        if(foodLevel <= 0) {
            setDead(DeathReason.HUNGER);
        }
    }
    
    /**
     * Look for preys adjacent to the current location.
     * Only the first live prey is eaten.
     * @return Where food was found, or null if it wasn't.
     */
    private Location findFood() {
        Field field = getField();
        List<Location> adjacent = field.adjacentLocations(getLocation());
        Iterator<Location> it = adjacent.iterator();
        while(it.hasNext()) {
            Location where = it.next();
            Object animal = field.getObjectAt(where);
            if(animal instanceof Prey) {
                Prey prey = (Prey) animal;
                if(prey.isAlive()) { 
                    prey.setDead(DeathReason.EATEN);
                    if (prey.getType() == Animal.Type.SHEEP){
                        foodLevel += SHEEP_FOOD_VALUE;
                    }
                    else if (prey.getType() == Animal.Type.FLAMINGO){
                        foodLevel += FLAMINGO_FOOD_VALUE;
                    }
                    if (foodLevel > MAX_FOOD_LEVEL) foodLevel = MAX_FOOD_LEVEL;
                    return where;
                }
            }
        }
        return null;
    }
    
    public double getFoodLevel() {
        return this.foodLevel;
    }
}