/**
 *
 */
var Visualizer = function() {
    this.itemW = 20;
    this.itemH = 50;

    this.svg = null;
    this.instructions = null;
};
Visualizer.prototype.svg = null;
Visualizer.prototype.instructions = null;

/**
 *
 */
Visualizer.prototype.init = function(data) {
    // 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 data) {
        data[i].index = n++;
    }

    this.svg = d3.select('body').append('svg')
        .attr('class', 'quicksort-random');

    this.svg.selectAll('rect').data(data).enter()
        .append('rect')
            .attr('height', function h(d) { return d.h; })
            .attr('width', function w(d) { return d.w; })
            .attr('fill', function fill(d) { return d.fill; })
            .attr('y', function y(d) { return d.y; })
            .attr('x', function x(d) { return d.x; })
        .append('text')
            .text(function t(d) { return d.val; })
            .attr('fill', '#000')
            .attr('x', function x(d) { return d.x; })
        .transition(500)
            .attr('x', function expand(d, i) {
                data[i].x = i * (d.w + 2);
                return data[i].x;
            });

    // 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
};

/**
 *
 */
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
    this.svg.selectAll('rect')
        // .transition()
        //     .duration(100)
        //     .attr('y', function ya(d) {
        //         if (d.index === indexA || d.index === indexB) {
        //             d.y = 5;
        //         }

        //         return d.y;    // NOTE d[i].y has been modified too. But, the bound value in the dataset
        //                                 // will not be updated until after the chain is completed, so it has to be explicitly defined here.
        //     })

        // Switch places
        // NOTE discuss chained transitions: http://bl.ocks.org/mbostock/1125997
        // TODO now that elements aren't cached, is there a need for .index?
        .transition()
            .duration(400)
            .attr('x', function xa(d) {
                if (d.index === indexA) {
                    d.index = indexB;
                    d.x = d.index * (d.w + 2);
                }
                else if (d.index === indexB) {
                    d.index = indexA;
                    d.x = d.index * (d.w + 2);
                }

                return d.x;
            })

        // Move down
        // .transition()
        //     .duration(100)
        //     .attr('y', function ya(d) {
        //         if (d.index === indexA || d.index === indexB) {
        //             d.y = 20;
        //         }

        //         return d.y;
        //     });
};

/**
 *
 */
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', 0)
        .attr('y', 10)
        .attr('width', 20)
        .attr('height', 20)
        .attr('fill', '#333')
        .attr('font-size', 20)
        .attr('alignment-baseline', 'middle')
        .attr('text-anchor', 'middle')
        .attr('transform', 'rotate(90 10,10)')
        .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 || index > 25) {
        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);
    }
};