angular.module('app').directive('slider', ['$window', function ($window) {

  return {
    restrict: 'A',
    scope:{
      max: '=',
      unit: '=',
      change: '&onChange'
    },
    link: function(scope, element) {
      var margin = {top: -10, right: 130, bottom: 0, left: 50},
          height = 40,    // Height is fixed
          h = height - margin.top - margin.bottom,
          fmt = d3.format('.2f'),
          pct = d3.format('.1%'),
          unit = scope.unit,
          val = scope.max,
          svg = d3.select(element[0]).append("svg"),
          vis = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")"),
          xAxis = vis.append("g").attr("class", "x slider-axis").attr("transform", "translate(0," + h / 2 + ")"),
          x = d3.scale.linear(),
          slider = vis.append("g").attr("class", "slider"),
          filled = slider.append('path').attr('class', 'filled').attr("transform", "translate(0," + h/2 + ")"),
          brush = d3.svg.brush().x(x).extent([scope.max, scope.max]).on("brush", brushed),
          handle = slider.append("circle").attr("class", "handle").attr("r", '0.75em'),
          lbl = slider.append("g").append("text").attr("y", h/2);

      slider.call(brush);
      slider.select(".background").attr("height", h);
      handle.attr("transform", "translate(0," + h / 2 + ")");

      /**
       * Watch for changes in the max, window size
       */
      scope.$watch('max', function(newMax, oldMax) {
        val = newMax * (val / oldMax); // Retain percentage filled
        render();
      });

      angular.element($window).bind('orientationchange resize', render);

      function render() {
        var width = element[0].offsetWidth, w = width - margin.left - margin.right;

        svg.attr("width", width).attr("height", height);
        x.domain([0, scope.max]).range([0, w]).clamp(true);
        handle.attr("cx", x(val));
        xAxis
          .call(d3.svg.axis()
            .scale(x)
            .orient("bottom")
            .tickFormat(function(d) { return d + unit; })
            .tickSize(0)
            .tickPadding(12))
        .select(".domain");
        lbl.attr('x', w + 20);
        slider.call(brush.extent([val, val])).call(brush.event);
        slider.selectAll(".extent,.resize").remove();
      }

      function brushed() {
        val = brush.extent()[0];
        if (d3.event.sourceEvent) { // not a programmatic event
          val = x.invert(d3.mouse(this)[0]);
          brush.extent([val, val]);
        }
        lbl.text(fmt(val) + ' ' +  unit + ' ' + pct(val / scope.max));
        scope.change({val: val});
        handle.attr("cx", x(val));
        filled.attr("d", "M0,0V0H" + x(val) + "V0");
      }
    }
  };
}]);