function barChart() {
  var key = function (d) { return d.key; };
  var margin = { top: 20, right: 20, left: 20, bottom: 20 };
  var width = 500;
  var height = 500;
  var xScale = d3.scale.linear();
  var yScale = d3.scale.ordinal();
  var yAxis = d3.svg.axis().orient('left').tickSize(0);
  var sort = function (a, b) { return a.count - b.count; };
  var padding = 0.1;
  var fill = 'steelblue';
  var fillOpacity = 1;
  var stroke = null;
  var strokeWidth = null;
  var strokeOpacity = null;

  function chart(selection) {
    selection.each(function (data, index) {
      data = d3.nest()
        .key(key)
        .entries(data);

      data = data.map(function (d) {
          d.count = d.values.length;
          return d;
        })
        .sort(sort);

      width = width - margin.left - margin.right;
      height = height - margin.top - margin.bottom;

      var svg = d3.select(this).selectAll('svg').data([data]);
      svg.exit().remove();
      svg.enter().append('svg');

      svg
        .attr('width', width + margin.left + margin.right)
        .attr('height', height + margin.top + margin.bottom)
      .append('g')
        .attr('transform', 'translate(' + margin.left + ',' + margin.top + ')');

      xScale
        .domain([0, d3.max(data, function (d) { return d.count; })])
        .range([0, width]);

      yScale
        .domain(data.sort(sort).map(function (d) { return d.key; }))
        .rangeRoundBands([height, 0], padding, 0);

      var g = svg.select('g');

      g.append('g')
        .attr('class', 'y axis')
        .call(yAxis.scale(yScale));

      var groups = g.selectAll('g.bars').data(data);
      groups.exit().remove();
      groups.enter().append('g');
      groups.attr('class', 'bars');

      groups.append('rect')
        .attr('x', function (d) { return xScale(0); })
        .attr('y', function (d) { return yScale(d.key); })
        .attr('width', function (d) { return xScale(d.count); })
        .attr('height', yScale.rangeBand())
        .style('fill', fill)
        .style('fill-opacity', fillOpacity)
        .style('stroke', stroke)
        .style('stroke-width', strokeWidth)
        .style('stroke-opacity', strokeOpacity);

      groups.append('text')
        .attr('class', 'bar-text')
        .attr('x', function (d) { return xScale(d.count) - 2; })
        .attr('y', function (d) {
           return yScale(d.key) + ((yScale.rangeBand() / 2) / 2);
        })
        .attr('dx', '')
        .attr('dy', '.71em')
        .attr('text-anchor', 'end')
        .style('fill', '#ffffff')
        .style('font-size', yScale.rangeBand() / 2)
        .text(function (d) { return d.count; });

      groups.selectAll('.bars text').each(function (d) {
        var text = d3.select(this);
        var width = text.node().getBBox().width;

        if (width > xScale(d.count)) {
          text.attr('text-anchor', 'start')
            .style('fill', '#000000')
            .attr('x', function (d) { return xScale(d.count) + 5; });
        }
      });
    });
  }

  function valuator(val) {
    if (typeof val === 'function') return val;
    if (typeof val === 'string' || typeof val === 'number') {
      return function (d) { return d[val]; }
    }
    throw new Error(val + ' is an unexpected type');
  }

  // Public API
  chart.key = function (_) {
    if (!arguments.length) return key;
    key = valuator(_);
    return chart;
  };

  chart.margin = function (_) {
    if (!arguments.length) return margin;
    margin.top = typeof _.top !== 'undefined' ? _.top : margin.top;
    margin.right = typeof _.right !== 'undefined' ? _.right : margin.right;
    margin.bottom = typeof _.bottom !== 'undefined' ? _.bottom : margin.bottom;
    margin.left = typeof _.left !== 'undefined' ? _.left : margin.left;
    return chart;
  };

  chart.width = function (_) {
    if (!arguments.length) return width;
    width = typeof _ === 'number' ? _ : width;
    return chart;
  };

  chart.height = function (_) {
    if (!arguments.length) return height;
    height = typeof _ === 'number' ? _ : height;
    return chart;
  };

  chart.sort = function (_) {
    if (!arguments.length) return sort;
    sort = typeof _ === 'function' ? _ : sort;
    return chart;
  };

  chart.padding = function (_) {
    if (!arguments.length) return padding;
    padding = typeof _ === 'number' ? _ : padding;
    return chart;
  };

  chart.fill = function (_) {
    if (!arguments.length) return fill;
    fill = _;
    return chart;
  };

  chart.fillOpacity = function (_) {
    if (!arguments.length) return fillOpacity;
    fillOpacity = _;
    return chart;
  };

  chart.stroke = function (_) {
    if (!arguments.length) return stroke;
    stroke = _;
    return chart;
  };

  chart.strokeWidth = function (_) {
    if (!arguments.length) return strokeWidth;
    strokeWidth = _;
    return chart;
  };

  chart.strokeOpacity = function (_) {
    if (!arguments.length) return strokeOpacity;
    strokeOpacity= _;
    return chart;
  };

  return chart;
}