defineSuite([
        'Core/Heap'
    ], function(
        Heap) {
    'use strict';

    var length = 100;

    function checkHeap(heap, comparator) {
        var array = heap.internalArray;
        var pass = true;
        var length = heap.length;
        for (var i = 0; i < length; ++i) {
            var left = 2 * (i + 1) - 1;
            var right = 2 * (i + 1);
            if (left < heap.length) {
                pass = pass && (comparator(array[i], array[left]) <= 0);
            }
            if (right < heap.length) {
                pass = pass && (comparator(array[i], array[right]) <= 0);
            }
        }
        return pass;
    }

    // min heap
    function comparator(a, b) {
        return a - b;
    }

    it('maintains heap property on insert', function() {
        var heap = new Heap({
            comparator : comparator
        });
        var pass = true;
        for (var i = 0; i < length; ++i) {
            heap.insert(Math.random());
            pass = pass && checkHeap(heap, comparator);
        }

        expect(pass).toBe(true);
    });

    it('maintains heap property on pop', function() {
        var heap = new Heap({
            comparator : comparator
        });
        var i;
        for (i = 0; i < length; ++i) {
            heap.insert(Math.random());
        }
        var pass = true;
        for (i = 0; i < length; ++i) {
            heap.pop();
            pass = pass && checkHeap(heap, comparator);
        }
        expect(pass).toBe(true);
    });

    it('limited by maximum length', function() {
        var heap = new Heap({
            comparator : comparator
        });
        heap.maximumLength = length / 2;
        var pass = true;
        for (var i = 0; i < length; ++i) {
            heap.insert(Math.random());
            pass = pass && checkHeap(heap, comparator);
        }
        expect(pass).toBe(true);
        expect(heap.length <= heap.maximumLength).toBe(true);
        // allowed one extra slot for swapping
        expect(heap.internalArray.length).toBeLessThanOrEqualTo(heap.maximumLength + 1);
    });

    it('pops in sorted order', function() {
        var heap = new Heap({
            comparator : comparator
        });
        var i;
        for (i = 0; i < length; ++i) {
            heap.insert(Math.random());
        }
        var curr = heap.pop();
        var pass = true;
        for (i = 0; i < length - 1; ++i) {
            var next = heap.pop();
            pass = pass && (comparator(curr, next) <= 0);
            curr = next;
        }
        expect(pass).toBe(true);
    });

    it('insert returns the removed element when maximumLength is set', function() {
        var heap = new Heap({
            comparator : comparator
        });
        heap.maximumLength = length;

        var i;
        var max = 0.0;
        var min = 1.0;
        var values = new Array(length);
        for (i = 0; i < length; ++i) {
            var value = Math.random();
            max = Math.max(max, value);
            min = Math.min(min, value);
            values[i] = value;
        }

        // Push 99 values
        for (i = 0; i < length - 1; ++i) {
            heap.insert(values[i]);
        }

        // Push 100th, nothing is removed so it returns undefined
        var removed = heap.insert(values[length - 1]);
        expect(removed).toBeUndefined();

        // Insert value, an element is removed
        removed = heap.insert(max - 0.1);
        expect(removed).toBeDefined();

        // If this value is the least priority it will be returned
        removed = heap.insert(max + 0.1);
        expect(removed).toBe(max + 0.1);
    });

    it('resort', function() {
        function comparator(a, b) {
            return a.distance - b.distance;
        }

        var i;
        var heap = new Heap({
            comparator : comparator
        });
        for (i = 0; i < length; ++i) {
            heap.insert({
                distance : i / (length - 1),
                id : i
            });
        }

        // Check that elements are initially sorted
        var element;
        var elements = [];
        var currentId = 0;
        while (heap.length > 0) {
            element = heap.pop();
            elements.push(element);
            expect(element.id).toBeGreaterThanOrEqualTo(currentId);
            currentId = element.id;
        }

        // Add back into heap
        for (i = 0; i < length; ++i) {
            heap.insert(elements[i]);
        }

        // Invert priority
        for (i = 0; i < length; ++i) {
            elements[i].distance = 1.0 - elements[i].distance;
        }

        // Resort and check the the elements are popped in the opposite order now
        heap.resort();
        while (heap.length > 0) {
            element = heap.pop();
            expect(element.id).toBeLessThanOrEqualTo(currentId);
            currentId = element.id;
        }
    });
});