var Legend = function(group)
{
    group.attr('class', 'legend');
    this.group = group;
    this.markWidth = 25;
    this.markHeight = 25;
    this.markPadding = 5;
}

Legend.prototype.draw = function(dataset)
{
    var marks = this.group.selectAll('.legend-label')
        .data(dataset)
        .enter()
        .append('g')
        .attr('class', 'legend-mark');
    
    var thisLegend = this;

    marks.append('rect')
        .attr('x', 0)
        .attr('y', function(d, i) {
            return (thisLegend.markHeight + thisLegend.markPadding) * i;
        })
        .attr('width', thisLegend.markWidth)
        .attr('height', thisLegend.markHeight)
        .attr('fill', function(d) {
            return d.color;
        });

    marks.append('text')
        .attr('transform', function(d, i) {
            var x = thisLegend.markWidth + thisLegend.markPadding;
            var y = (thisLegend.markHeight + thisLegend.markPadding) * i;
            y += 20;
            return 'translate(' + x + ',' + y + ')';
        })
        .attr('class', 'legend-text-0')
        .text(function(d) {
            return d.category;
        });
}