/**
 *
 */
function Visualizer(parent) {
    var top = document.createElement('div');
    top.className = 'top';
    parent.appendChild(top);

    var bottom = document.createElement('div');
    bottom.className = 'bottom';
    parent.appendChild(bottom);

    var range = this.initRange();
    parent.querySelector('.bottom').appendChild(range);

    var controls = this.initControls();
    parent.querySelector('.bottom').appendChild(controls);

    this.groups = null;
    this.parent = parent;
    this.init(10);

    // this.instructions = null;
    // this.currentInstruction = 0;
};

// Public static properties (mutable)
Visualizer.spacerW  = 5;
Visualizer.itemW    = 14;
Visualizer.itemH    = 50;
Visualizer.itemY    = 20;

/**
 *
 */
Visualizer.prototype.init = function(n) {
    // Sorter setup.
    var QS = new Quicksort();
    var data = QS.generate(n);
    var shuffled = QS.shuffle(data);
    var ordered = Object.create(shuffled);
    QS.sort(ordered, 0, ordered.length - 1);


    var x = []
    ordered.forEach(function(obj0) {
        x.push(obj0.value);
    })

    console.log(x.join(','));

    // A swap on the dataset will not take effect until after transition is complete, so custom index is required.
    var n = 0;
    for (i in shuffled) {
        shuffled[i].index = n++;
    }

    var svg = d3.select(this.parent.querySelector('.top')).append('svg');

    this.groups = svg.selectAll('g').data(shuffled).enter().append('g')
        .attr('transform', `translate(0, ${Visualizer.itemY})`);

    this.groups.append('rect')
        .attr('height', Visualizer.itemH)
        .attr('width', Visualizer.itemW)
        .attr('fill', function doFill(d) { return `rgb(0, 0, ${d.value})`; });

    this.groups.transition(500)
        .attr('transform', function doTransform(d, i) {
            return `translate(${i * (Visualizer.itemW + Visualizer.spacerW)}, ${Visualizer.itemY})`;
        });

    this.groups.append('text')
        .text(function t(d) { return d.value; })
        .attr('fill', '#aaa')
        .attr('font-size', 10)
        .attr('font-family', 'sans-serif')
        .attr('transform', function doTransform(d) {
            return `rotate(90 0,0), translate(5, -3)`;
        });

    // V.addMarker('quicksort-left-marker');
    // V.moveMarker('quicksort-left-marker', 2);

    // this.svg.append('sometext').id('left-marker'); L
    // this.svg.append('sometext').id('right-marker'); R
    // this.svg.append('sometext').id('pivot-marker'); triangle or arrow



    setTimeout(this.followInstruction.bind(this, QS.instructions, 0), 500);
};

/**
 *
 */
Visualizer.prototype.swap = function(indexA, indexB) {
    // Move up
    // NOTE Two way binding here between dataset and function parameter?
    // NOTE swapping will not reorder index and i parameter will be off
    // NOTE discuss chained transitions: http://bl.ocks.org/mbostock/1125997
    this.groups
        .transition().duration(400)
            .attr('transform', function doTransform(d) {
                if (d.index === indexA) {
                    d.index = indexB;
                }
                else if (d.index === indexB) {
                    d.index = indexA;
                }

                return `translate(${d.index * (Visualizer.itemW + Visualizer.spacerW)}, ${Visualizer.itemY})`;
            })
};

/**
 *
 * /
Visualizer.prototype.moveMarker = function(id, toIndex) {
    this.svg.select('#' + id).attr('x', toIndex * 22);
};

/**
 *
 * /
Visualizer.prototype.addMarker = function(id) {
    // this.svg.append('text')
    //     .attr('id', id)
    //     .attr('x', 53)
    //     .attr('y', 50)
    //     .attr('width', 20)
    //     .attr('height', 20)
    //     .attr('fill', '#aaa')
    //     .attr('font-size', 20)
    //     .attr('alignment-baseline', 'middle')
    //     .attr('text-anchor', 'middle')
    //     .attr('transform', 'rotate(0 53,50)')
    //     .text('P');
};

/**
 *
 */
Visualizer.prototype.fade = function(startIndex, endIndex) {
    console.log(`fading from ${startIndex} to ${endIndex}`)

    this.svg.selectAll('rect')
        // NOTE this replaces the fill function reference for each rectangle - key point!
        .attr('fill', function fill(d) {
            if (d.index >= startIndex && d.index <= endIndex) {
                console.log(`${d.index} to ${d.fade}`)
                return d.fade;
            }
            return d.fill;
        });
};

/**
 *
 */
Visualizer.prototype.unfade = function() {
    this.svg.selectAll('rect')
        .attr('fill', function fill(d) {
            console.log(`unfade ${d.index}`)
            return d.fill;
        })
};

/**
 *
 */
Visualizer.prototype.followInstruction = function(instructions, index) {
    if (index >= instructions.length) {
        return;
    }

    var i = instructions[index];
    console.log(i);

    if (i.operation === 'swap' && i.left < i.right) {
        this.swap(i.left, i.right);
        setTimeout(this.followInstruction.bind(this, instructions, index + 1), 400);
    }
    else if (i.operation === 'init') {
        // this.unfade();
        // this.fade(0, i.left - 1);
        // this.fade(i.right + 1, 1000)
        this.followInstruction(instructions, index + 1);
    }
    else if (i.operation === 'swap') {
        this.followInstruction(instructions, index + 1);
    }
    else {
        this.followInstruction(instructions, index + 1);
    }
};


/**
 *
 */
Visualizer.prototype.initRange = function(Visualizer) {
    var container = document.createElement('div');
    container.className = 'range-container';

    var label = document.createElement('div');
    label.innerHTML = "n: 40";

    var range = document.createElement('input');
    range.setAttribute('type', 'range');
    range.setAttribute('value', 40);
    range.setAttribute('min', 5);
    range.setAttribute('max', 80);
    range.addEventListener('change', this.rangeChange.bind(this));
    range.addEventListener('input', this.rangeInput.bind(null, label));

    container.appendChild(range);
    container.appendChild(label);

    return container;
};

/**
 *
 */
Visualizer.prototype.rangeInput = function(label, event) {
    label.innerHTML = 'Items: ' + event.target.value;
};

/**
 *
 */
Visualizer.prototype.rangeChange = function(event) {
    this.init(event.target.value);
};

/**
 *
 */
Visualizer.prototype.initControls = function() {
    var play = document.createElement('button');
    play.className = 'fa fa-play';
    play.title = 'Play'
    play.addEventListener('click', onclick);

    var back = document.createElement('button');
    back.className = 'fa fa-step-backward';
    back.title = 'Step Backward';
    back.addEventListener('click', onclick);

    var forward = document.createElement('button');
    forward.className = 'fa fa-step-forward'
    forward.title = 'Step Forward';
    forward.addEventListener('click', onclick);

    var reset = document.createElement('button');
    reset.className = 'fa fa-fast-backward';
    reset.title = 'Restart'
    reset.addEventListener('click', onclick);

    var container = document.createElement('div');
    container.className = 'controls';

    container.appendChild(reset);
    container.appendChild(back);
    container.appendChild(play);
    container.appendChild(forward);

    return container;
};