Container

package container;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

import util.searchable.ISearchFilter;
import util.searchable.ISearchableByFilter;

public class Container<E> implements Collection<E>, ISearchableByFilter<E> { //Eldira 11815163
    public IContainerElement<E> head;
    public IContainerElement<E> tail;

    //constructor
    public Container() {
        this.head = null;
        this.tail = null;
    }

    public boolean add(E e) {
        if (e == null) {
            throw new NullPointerException("You cant enter null");
        }

        ContainerElement<E> node = new ContainerElement<>(e);
        if (head == null) {
            head = node;
            tail = node;
        }
        else {
            tail.setNextElement(node);
            tail = node;
        }

        return true;
    }



    public boolean addAll(Collection<? extends E> c) {
        if (this.containsAll(c)) return false;
        for(E e : c) {
            this.add(e);
        }

        return true;
    }

    public void clear() {
        this.head = null;
        this.tail = null;
    }

    public boolean contains(Object o) {
        IContainerElement<E> n = head;
        while(n.hasNextElement()) {
            if(n.getData().equals(o)) return true;
            n=n.getNextElement();
        }
        if(n.getData().equals(o)) return true;

        return false;
    }

    public int size() {
        int counter=0;
        IContainerElement<E> n = head;
        while(n != null) {
            counter += 1;
            n=n.getNextElement();
        }

        return counter;
    }

    public E get(int index) throws IndexOutOfBoundsException{
        if(index<0 || index>=this.size()) throw new IndexOutOfBoundsException ("Index is out of bounds!");

        IContainerElement<E> n = head;
        int counter = 0;
        while(n != null) {
            if(index==counter) {
                return n.getData();
            }

            n = n.getNextElement();
        }

        return null;
    }

    public boolean isEmpty() {
        return (head==null);
    }

    public boolean containsAll(Collection<?> c) {
        for(Object e : c) {
            if (!this.contains(e)) {
                return false;
            }
        }

        return true;
    }

    public boolean remove(Object o) {
        ContainerElement<E> current = (ContainerElement<E>) head;
        ContainerElement<E> previous = null;
        while (current != null){
            if(current.getData().equals(o) && previous != null){
                if (current == tail) {
                    tail = previous;
                }

                previous.setNextElement(current.getNextElement());
                return true;
            }else if(current.getData().equals(o) && previous == null){
                head = head.getNextElement();
                return true;
            }
            previous = current;
            current = (ContainerElement<E>) current.getNextElement();
        }

        return false;
    }






    public boolean removeAll(Collection<?> c) {
        //ContainerElement<E> n = (ContainerElement<E>) head;
        int brojac = 0;
        for(Object e : c) {
            if(this.remove(e)) brojac++;
            this.remove(e);
        }
        if(brojac > 0) {
            return true;
        }
        else return false;
    }


    public boolean retainAll(Collection <?> c) throws  UnsupportedOperationException{
        throw new  UnsupportedOperationException("This is not supported by the container! ");
    }

    public Object[] toArray() throws UnsupportedOperationException {
        throw new UnsupportedOperationException("This is not supported by the container!");

        }

    public <T> T[] toArray(T[] a) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("This is not supported by the container!");

    }


    public Iterator<E> iterator(){
        return new Itr<E>(this.head);
    }



    public Collection<E> searchByFilter(ISearchFilter filter, Object filterObject){

        ArrayList<E> listOfMatches = new ArrayList<>();
        if(head != null){
            ContainerElement<E> current = (ContainerElement<E>) head;
            while (current.hasNextElement()){ //proci kroz cijelu listu
                if(filter.searchFilterFunction(current, filterObject)){ //kad god se nadje element za koji searchFilter vrati true u poredjenju s ovim
                    //sto je poslan u paramtru, on se doda u listu i ta lista se vrati
                    listOfMatches.add(current.getData());
                }
                current = (ContainerElement<E>) current.getNextElement(); //predji na sljedeci element
            }
        }

        return listOfMatches;
    }


    @Override
    public String toString() {
        return "Container [head=" + head + "]";
    }


}