import java.util.NoSuchElementException;

/**
 * A LinkedList implementation. Tied to the Rabbit class rather than being
 * generic
 */
public class LinkedListOfRabbits implements LinkedListInterface {

    /**
     * The node class. Each element in the linked list is an instance of Node
     */
    private class Node {
        /** The data item in the node. An instance of rabbit */
        public Rabbit data;
        /** The next item in the linked list */
        public Node next;

        /**
         * Node constructor. Takes a rannit and another node
         */
        public Node(Rabbit data, Node next) {
            this.data = data;
            this.next = next;
        }
    }

    /** The start, first element, of the linked list */
    private Node head = null;

    /** THe last element in the linked list */
    private Node tail = null;

    /** The number of items in the linked list */
    private int size = 0;

    /**
     * The number of items in the linked list
     * 
     * @return the number of items in the linked list
     */
    @Override
    public int size() {
        return size;
    }

    /**
     * Returns true iff the linked list has no elements
     * 
     * @return true iff the linked list has no elements
     */
    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    /**
     * Get the first element in the linked list
     * 
     * @return the first element in the linked list
     * @throws NoSuchElementException is the list is empty
     */
    @Override
    public Rabbit first() throws NoSuchElementException {
        if (head == null)
            throw new NoSuchElementException("There are no rabbits");
        return head.data;
    }

    /**
     * The last element in the linked list
     * 
     * @return the last elment
     * @throws NoSuchElementException if the linked list is empty
     */
    @Override
    public Rabbit last() throws NoSuchElementException {
        if (head == null)
            throw new NoSuchElementException("There are no rabbits");
        return tail.data;
    }

    /**
     * Add a rabbit to the end of the list
     * 
     * @param c the rabbit to be added
     */
    @Override
    public void addLast(Rabbit c) {
        Node newest = new Node(c, null);
        if (isEmpty()) {
            head = newest;
        } else {
            tail.next = newest;
        }
        tail = newest;
        size++;
    }

    /**
     * Add a rabbit at the front of the list
     * 
     * @param c the rabbit to be added
     */
    @Override
    public void addFirst(Rabbit c) {
        Node newest = new Node(c, null);
        if (isEmpty()) {
            head = newest;
            tail = newest;
        } else {
            newest.next = head;
        }
        head = newest;
        size++;
    }

    /**
     * Remove the last rabbit from the list
     * 
     * @return the last rabbit, or null if the list is empty
     */
    @Override
    public Rabbit removeFirst() {
        if (head == null)
            return null;
        Rabbit rtn = head.data;
        head = head.next;
        if (head == null)
            tail = null;
        return rtn;
    }

    /**
     * Remove the last rabbit from the list
     * 
     * @return the last rabbit, or null if the list is empty
     */
    @Override
    public Rabbit removeLast() {
        if (head == null)
            return null;
        if (head == tail) {
            head = null;
            Rabbit rtn = tail.data;
            size = 0;
            tail = null;
            return rtn;
        }
        // start at front and get to the node prior to the last
        Node curr = head;
        while (curr.next != tail) {
            curr = curr.next;
        }
        Rabbit rtn = tail.data;
        tail = curr;
        tail.next = null;
        size--;
        return rtn;
    }

    /**
     * Remove the specified rabbit from the list
     * 
     * @param r the rabbit to be removed
     * @return the removed rabbit, or null is the rabbit was not in the list
     */
    @Override
    public Rabbit remove(Rabbit r) {
        // Do something much like find, but need to trak the previous node
        Node prev = null;
        Node curr = head;
        while (curr != null) {
            if (curr.data.equals(r)) {
                break;
            }
            prev = curr;
            curr = curr.next;
        }
        // three cases:
        if (curr == null) {
            // 1. the rabbit was not found
            return null;
        }
        if (prev == null) {
            // 2. the rabbit was the first item in the list
            size--;
            head = head.next;
            return r;
        }
        // 3. Rabbit is somewhere it list
        // special -- rabbit is at end of list
        size--;
        prev.next = curr.next;
        if (curr == tail)
            tail = prev;
        return null;
    }

    /**
     * Find a rabbit in the list by its iD
     * 
     * @param iD
     * @return the found rabbit, or null if a match could not be found
     */
    @Override
    public Rabbit find(String iD) {
        Node curr = head;
        while (curr != null) {
            if (curr.data.getId().equals(iD)) {
                return curr.data;
            }
            curr = curr.next;
        }
        return null;
    }

    public String toString() {
        StringBuffer s = new StringBuffer();
        for (Node n = head; n != null; n = n.next) {
            s.append(n.data.toString());
            if (n != tail) {
                s.append("\n");
            }
        }
        return s.toString();
    }

    public static void main(String[] args) {
        LinkedListOfRabbits llr = new LinkedListOfRabbits();
        Rabbit ar = new Rabbit(BreedEnum.Angora, "A1");
        llr.addFirst(ar);
        llr.addFirst(new Rabbit(BreedEnum.DwarfDutch, "DD1"));
        llr.addLast(new Rabbit(BreedEnum.FrenchLop, "FL1"));
        System.out.println(llr);
        // llr.removeFirst();
        // llr.removeLast();
        llr.remove(ar);
        System.out.println();
        System.out.println(llr);
    }
}