/**
 * Zoo.java
 * Maintains a collections of Animal objects.
 * Uses an array to keep the animal instances
 *
 * @author cs230 (SK)
 * @version Sept 2020
 */
public class Zoo
{
    // instance variables 
    private final int initialCapacity;

    private Animal[] members;
    private int size; //number of actual animals in this zoo, at any point

    /**
     * Creates an empty Zoo
     * 
     * @param initCap The initial capacity of this zoo
     */
    public Zoo(int initCap)
    {
        // initialise instance variables
        initialCapacity = initCap;
        members = new Animal[initialCapacity];
        size = 0;
    }

    /**
     *  Gets the size of this zoo
     *
     * @return  the number of animals in this zoo
     */
    public int getSize()
    {
        return size;
    }

    /**
     *  Adds the input animal to this zoo. If this zoo
     *  is too small to accept it, (miracilously!:) it becomes bigger.
     *
     * @param  a the Animal instance to be added to this zoo
     */
    public void addAnimal(Animal a) {
        //enlarge the zoo, if need be
        if (size >= members.length) {
            extendCapacity();
        }
        //now, safely add the new animal
        members[size] = a;
        size++;
    }

     /**
     * Helper, private, to be used in the addAnimal() method
     * 
     */
    private void extendCapacity() {
        //double the number of the containers
        Animal[] largerArray = new Animal[2*members.length];
        //copy the animals from the old container, 
        //to the new and larger
        for (int i=0; i<members.length; i++) {
            largerArray[i] = members[i];
        }
        //establish the new array
        members = largerArray;
    }

    /**
     * Returns a strin g representation of this zoo.
     * 
     * @return The String representation of this zoo,
     * including its size, as well as all animals in there.
     * 
     */
    public String toString() {
        String res = "This zoo has " + size + " animals:\n";
        for (int i=0; i<size; i++) {
            res = res + members[i] + "\n";
        }
        return res;
    }

    /**
     * Returns the index in the array the input animal was found, 
     * or -1 if it was not found 
     * 
     * @input a the animal to look for in the zoo
     * @return the index of the input animal in the array, 
     *         or -1 if not found
     */
    public int findAnimal(Animal a) {
        int index = -1;
        for (int i=0; i<size; i++) {
            if (a.equals(members[i])) { //notice the use of .equals() on Animals
                return i;
            }
        }
        return index;
    }

    /**
     * Removes the given animal from the array.
     * Returns true if the animal was found and removed, 
     * or false if the animal was not found in the zoo.
     * 
     * @param a the animal to be removed
     * @return true if the animal was found and removed from the zoo, 
     *         false if it was not found
     */
    public boolean removeAnimal(Animal a) {
        //find the position of the animal in the array
        int index = findAnimal(a);
        
        //if animal not in the array, return
        if (index == -1) {
            return false;
        }
        //otherwise, noverride the animal to be removed with 
        //the last one in the array.Notice, order is NOT maintained
        members[index] = members[size-1];
        size--; //make sure to update the number of animals in the array!
        
        return true;
    }

    /**
     * Finds and returns an array with all the healthy animals in the zoo
     * 
     * @return array with all the whealthy animals in this zoo
     */
    public Animal[] getHealthyAnimals() {
        //create array to hold the healthy animals
        Animal[] healthy = new Animal[size];
        
        int j = 0; //index into the healthy array

        for (int i=0; i<size; i++) { //for each animal in the members array
            if (members[i].isHealthGood()) { //if health status is good
                //add it to the results array
                healthy[j] = members[i];
                j++;
            }
        }
        return healthy;
    }

    /**
     * Returns the number of healthy animals in this Zoo
     * 
     * @return the number of healthy animals in this Zoo
     */
    public int getNumOfHealthyAnimals() {
        int numHealthyAnimals = 0; 
        //call the getHealthyAnimals to filder all animals for the healthy ones
        Animal[] healthy = getHealthyAnimals();

        //healthy array may have empty spots at its right end!
        //count how many animals (non-null objects) the array contains
        //this can be done using a while-loop, alternatively
        for (int i=0; i<size; i++) {
            if (healthy[i] != null) {
                numHealthyAnimals++;
            }
        }
        return numHealthyAnimals;
    }

    /**
     * Returns the number of sick animals in the zoo
     * 
     * @return the number of sick animals in the zoo
     */
    public int getNumOfSickAnimals() {
        return size - getNumOfHealthyAnimals();
    }

    /**
     * for testing purposes
     * 
     */
    public static void main(String[] args) {
        Zoo myZoo = new Zoo(10);
        Animal a1 = new Animal("snake", "Zig zag");
        a1.setHealth(false);
        myZoo.addAnimal(a1);

        Animal a2 = new Animal("chicken", "Red Crest");
        myZoo.addAnimal(a2);

        Animal a3 = new Animal("rooster", "Mean");
        myZoo.addAnimal(a3);


        //Animal a4 = Animal.readAndCreateAnimal();
        //myZoo.addAnimal(a4);

        System.out.println(myZoo);
        
        System.out.println("===========");
        Animal[] healthy = myZoo.getHealthyAnimals();
        System.out.println("There are " + myZoo.getNumOfHealthyAnimals() 
            + " healthy animals in this zoo.");
        System.out.println("There are " + myZoo.getNumOfSickAnimals()
            + " sick animals in this zoo.");
        
        //myZoo.removeAnimal(a2);
        //myZoo.removeAnimal(a1);
        //myZoo.removeAnimal(a3);
        //myZoo.removeAnimal(a2);
        
        //System.out.println(myZoo);

    }
}