package blatt7;

public class HeadList {

    Entry head;

    /**
     * constructor empty HeadList
     */
    public HeadList() {
        head = null;
    }

    /**
     * Appends a new element with value info to the end of this list
     *
     * @param info value of the new element
     */
    public void add(int info) {
        if (head != null) {
            add(head, info);
        } else {
            head = new Entry(null, null, info);
            head.first = head;
        }
    }

    private void add(Entry node, int info) {
        if (node.next == null) {
            node.next = new Entry(node.first, null, info);
        } else {
            add(node.next, info);
        }
    }

    /**
     * Removes and returns the element at position index from this list.
     *
     * @param index position of the element that is removed
     * @return value of the removed element
     */
    public int remove(int index) {
        int counter=0;
        Entry current = head;
        Entry current3 = head;
        while (current3.next != null) {
            current3=current3.next;
            counter++;
        }
        if (index>counter) {
            return Integer.MIN_VALUE;
        }
        if (index < 0 ) {
            return Integer.MIN_VALUE;
        }
        Entry current1 = head;

        if (index == 0) {
            head = head.next;
            current1.next = null;
            head.first = head;
            setHead(head);
            //czy zmieniam wszystkie first czy tylko dla nastepnego?
            return current.elem;
        }
        if (index == 1){
        for (int i = 0; i < index; i++) {
            current = current.next;
        }
        current1.next = current1.next.next;
        current.next = null;
        //setHead(head.next);
        return current.elem;}

      for (int i = 0; i < index; i++) {
            current1 = current1.next;
        }
        for (int i = 0; i < index-1; i++) {
            current = current.next;
        }
        current.next=current.next.next;
        current1.next=null;
        return current1.elem;

    }

    /**
     * sets the head of each list element to newHead
     *
     * @param newHead reference to the new head
     */
    private void setHead(Entry newHead) {
        int counter = 0;
        Entry current = head;
        Entry current1 = head;
        current.first = newHead;
         System.out.println(current.first);
        while (current1.next != null) {
            current1=current1.next;
            counter++;
        }
        for (int i = 0; i < counter; i++) {
            current = current.next;
            current.first = newHead;
            System.out.println(current.first);
        }
    }
private Entry getTail() {
        Entry entry = head;

        while (entry.next != null) {
            entry = entry.next;
        }

        return entry;
    }
    /**
     * reverse the list example: [1,2,3,4,5] --> [5,4,3,2,1], [] --> [], [1] -->
     * [1]
     */
    public void reverse() {
       if (head!=null){
        Entry prev = null;
        Entry current = head;
        Entry next = current.next;

        while (current != null) {
            current.next=prev;
            prev=current;
            current=next;
            next = next == null ? null : next.next;
        }

        head=prev;
       setHead(getTail());}
    }

    @Override
    public String toString() {
        String out = "[";
        if (head != null) {
            out += head.elem;
            Entry tmp = head.next;
            while (tmp != null) {
                out = out + "," + tmp.elem;
                tmp = tmp.next;
            }
        }
        out += "]";
        return out;
    }



    public static void main(String[] args) {
        HeadList l = new HeadList();
        l.add(3);
        l.add(4);
        l.add(5);
        l.add(6);
        l.add(7);
        //System.out.println(l.remove(555));
        l.reverse();
        //l.getTail();
        System.out.println("empty list: " + l);

        // Test implementation

    }

    class Entry {

        Entry first;
        Entry next;
        int elem;

        public Entry(Entry first, Entry next, int elem) {
            this.first = first;
            this.next = next;
            this.elem = elem;
        }

    }

}