package alda.dheap;

public class DHeap<AnyType extends Comparable<? super AnyType>> {

    /**
     * Construct the binary heap.
     */
    int children; //Number of children allowed (d)
    private static final int DEFAULT_CAPACITY = 10;
    private int currentSize;      // Number of elements in heap
    private AnyType[] array; // The heap array

    public DHeap() {
        this(DEFAULT_CAPACITY);
        this.children = 2;
    }

    /**
     * Construct the binary heap.
     *
     * @param capacity the capacity of the binary heap.
     */
//    public DHeap( int capacity )
//    {
//        currentSize = 0;
//        array = (AnyType[]) new Comparable[ capacity + 1 ];
//    }
    public DHeap(int d) {
        if (d > 1) {
            this.children = d;
        } else {
            throw new IllegalArgumentException();
        }
        array = (AnyType[]) new Comparable[d];
    }

    /**
     * Construct the binary heap given an array of items.
     */
    public DHeap(AnyType[] items) {
        currentSize = items.length;
        array = (AnyType[]) new Comparable[(currentSize + 2) * 11 / 10];

        int i = 1;
        for (AnyType item : items) {
            array[ i++] = item;
        }
        buildHeap();
    }

    /**
     * Insert into the priority queue, maintaining heap order. Duplicates are
     * allowed.
     *
     * @param x the item to insert.
     */
    //om mindre än parent perculate annars lägg till som child
    //lägg till children tills children= max nr av children i ett subträd
    public void insert(AnyType x) {
        if (currentSize == array.length - 1) {
            enlargeArray(array.length * children + 1);
        }
        // Percolate up
        int hole = ++currentSize;
        for (array[ 0] = x; hole > 1 && x.compareTo(array[ parentIndex(hole)]) < 0; hole = parentIndex(hole)) {
            array[ hole] = array[ parentIndex(hole)];
        }
        array[ hole] = x;
    }

    private void enlargeArray(int newSize) {
        AnyType[] old = array;
        array = (AnyType[]) new Comparable[newSize];
        for (int i = 0; i < old.length; i++) {
            array[ i] = old[ i];
        }

    }

    /**
     * Find the smallest item in the priority queue.
     *
     * @return the smallest item, or throw an UnderflowException if empty.
     */
    public AnyType findMin() {
        if (isEmpty()) {
            throw new UnderflowException();
        }
        return array[ 1];
    }

    /**
     * Remove the smallest item from the priority queue.
     *
     * @return the smallest item, or throw an UnderflowException if empty.
     */
    public AnyType deleteMin() {
        if (isEmpty()) {
            throw new UnderflowException();
        }

        AnyType minItem = findMin();
        array[1] = array[ currentSize];
        array[currentSize] = null;
        currentSize--;
        percolateDown(1);

        return minItem;
    }

    /**
     * Establish heap order property from an arbitrary arrangement of items.
     * Runs in linear time.
     */
    private void buildHeap() {
        for (int i = currentSize / 2; i > 0; i--) {
            percolateDown(i);
        }
    }

    /**
     * Test if the priority queue is logically empty.
     *
     * @return true if empty, false otherwise.
     */
    public int size() {
        return currentSize;
    }

    public boolean isEmpty() {
        return currentSize == 0;
    }

    /**
     * Make the priority queue logically empty.
     */
    public void makeEmpty() {
        currentSize = 0;
    }

    /**
     * Internal method to percolate down in the heap.
     *
     * @param hole the index at which the percolate begins.
     */
    private void percolateDown(int hole) {
        int child;
        AnyType tmp = array[ hole];

        for (; firstChildIndex(hole) <= currentSize; hole = child) {
            child = firstChildIndex(hole) + 1;
            int smallestChild = firstChildIndex(hole);
            int test = firstChildIndex(hole);

            for (int i = 0; i < children; i++) {
                System.out.println("i "+i);
                System.out.println("child index" + child + " and child value "+array[child]);
                System.out.println("array length "+array.length);
                if (array[child] != null) {
                    if (array[child] != null && array[smallestChild].compareTo(array[ child]) < 0) {
                        child++;
                    } else {
                        smallestChild = child;
                        child++;
                    }
                } else if((child+1)>=array.length) {
                    break;

                } else {
                    child++;
                }
            }
            child = smallestChild;
            if (array[child] != null && array[ child].compareTo(tmp) < 0) {
                array[ hole] = array[ child];
            } else {
                break;
            }
        }

        array[ hole] = tmp;
    }

    //generiska get-metoder för att hitta first child och parent
    public int firstChildIndex(int parent) {
        if (parent == 0) {
            throw new IllegalArgumentException();
        }
        return parent * children - (children - 2);
        //return 2 + (children *(parent-1));
    }

    public int parentIndex(int child) {
        if (child < 2) {
            throw new IllegalArgumentException();
        }
        //return (child - 2) / children + 1;
        //return (int)Math.floor((child-1)/children);
        //return (child + children - 1) / children;
        //int tal = (int)Math.ceil((child - 1.0) / children);
        //System.out.println("tal wo ceil "+tal);
        //tal =Math.ceil(tal);
        //System.out.println("tal w ceil "+tal);
        return (int) Math.ceil((child - 1.0) / children);

    }

    public AnyType get(int i) {
        return array[i];
    }

//    public AnyType getIndex(int i){
//    	AnyType yeah = array[i];
//    	return yeah;
//    }
    // Test program
//    public static void main( String [ ] args )
//    {
//        int numItems = 10000;
//        BinaryHeap<Integer> h = new BinaryHeap<>( );
//        int i = 37;
//
//        for( i = 37; i != 0; i = ( i + 37 ) % numItems )
//            h.insert( i );
//        for( i = 1; i < numItems; i++ )
//            if( h.deleteMin( ) != i )
//                System.out.println( "Oops! " + i );
//    }
}