// Chart design based on the recommendations of Stephen Few. Implementation

// based on the work of Clint Ivy, Jamie Love, and Jason Davies.

// http://projects.instantcognition.com/protovis/bulletchart/

d3.chart.bullet = function() {

  var orient = "left", // TODO top & bottom

      reverse = false,

      duration = 0,

      ranges = d3_chart_bulletRanges,

      markers = d3_chart_bulletMarkers,

      measures = d3_chart_bulletMeasures,

      width = 380,

      height = 30,

      tickFormat = null;

  // For each small multiple…

  function bullet(g) {

    g.each(function(d, i) {

      var rangez = ranges.call(this, d, i).slice().sort(d3.descending),

          markerz = markers.call(this, d, i).slice().sort(d3.descending),

          measurez = measures.call(this, d, i).slice().sort(d3.descending),

          g = d3.select(this);

      // Compute the new x-scale.

      var x1 = d3.scale.linear()

          .domain([0, Math.max(rangez[0], markerz[0], measurez[0])])

          .range(reverse ? [width, 0] : [0, width]);

      // Retrieve the old x-scale, if this is an update.

      var x0 = this.__chart__ || d3.scale.linear()

          .domain([0, Infinity])

          .range(x1.range());

      // Stash the new scale.

      this.__chart__ = x1;

      // Derive width-scales from the x-scales.

      var w0 = d3_chart_bulletWidth(x0),

          w1 = d3_chart_bulletWidth(x1);

      // Update the range rects.

      var range = g.selectAll("rect.range")

          .data(rangez);

      range.enter().append("svg:rect")

          .attr("class", function(d, i) { return "range s" + i; })

          .attr("width", w0)

          .attr("height", height)

          .attr("x", reverse ? x0 : 0)

        .transition()

          .duration(duration)

          .attr("width", w1)

          .attr("x", reverse ? x1 : 0);

      range.transition()

          .duration(duration)

          .attr("x", reverse ? x1 : 0)

          .attr("width", w1)

          .attr("height", height);

      // Update the measure rects.

      var measure = g.selectAll("rect.measure")

          .data(measurez);

      measure.enter().append("svg:rect")

          .attr("class", function(d, i) { return "measure s" + i; })

          .attr("width", w0)

          .attr("height", height / 3)

          .attr("x", reverse ? x0 : 0)

          .attr("y", height / 3)

        .transition()

          .duration(duration)

          .attr("width", w1)

          .attr("x", reverse ? x1 : 0);

      measure.transition()

          .duration(duration)

          .attr("width", w1)

          .attr("height", height / 3)

          .attr("x", reverse ? x1 : 0)

          .attr("y", height / 3);

      // Update the marker lines.

      var marker = g.selectAll("line.marker")

          .data(markerz);

      marker.enter().append("svg:line")

          .attr("class", "marker")

          .attr("x1", x0)

          .attr("x2", x0)

          .attr("y1", height / 6)

          .attr("y2", height * 5 / 6)

        .transition()

          .duration(duration)

          .attr("x1", x1)

          .attr("x2", x1);

      marker.transition()

          .duration(duration)

          .attr("x1", x1)

          .attr("x2", x1)

          .attr("y1", height / 6)

          .attr("y2", height * 5 / 6);

      // Compute the tick format.

      var format = tickFormat || x1.tickFormat(8);

      // Update the tick groups.

      var tick = g.selectAll("g.tick")

          .data(x1.ticks(8), function(d) {

            return this.textContent || format(d);

          });

      // Initialize the ticks with the old scale, x0.

      var tickEnter = tick.enter().append("svg:g")

          .attr("class", "tick")

          .attr("transform", d3_chart_bulletTranslate(x0))

          .style("opacity", 1e-6);

      tickEnter.append("svg:line")

          .attr("y1", height)

          .attr("y2", height * 7 / 6);

      tickEnter.append("svg:text")

          .attr("text-anchor", "middle")

          .attr("dy", "1em")

          .attr("y", height * 7 / 6)

          .text(format);

      // Transition the entering ticks to the new scale, x1.

      tickEnter.transition()

          .duration(duration)

          .attr("transform", d3_chart_bulletTranslate(x1))

          .style("opacity", 1);

      // Transition the updating ticks to the new scale, x1.

      var tickUpdate = tick.transition()

          .duration(duration)

          .attr("transform", d3_chart_bulletTranslate(x1))

          .style("opacity", 1);

      tickUpdate.select("line")

          .attr("y1", height)

          .attr("y2", height * 7 / 6);

      tickUpdate.select("text")

          .attr("y", height * 7 / 6);

      // Transition the exiting ticks to the new scale, x1.

      tick.exit().transition()

          .duration(duration)

          .attr("transform", d3_chart_bulletTranslate(x1))

          .style("opacity", 1e-6)

          .remove();

    });

    d3.timer.flush();

  }

  // left, right, top, bottom

  bullet.orient = function(x) {

    if (!arguments.length) return orient;

    orient = x;

    reverse = orient == "right" || orient == "bottom";

    return bullet;

  };

  // ranges (bad, satisfactory, good)

  bullet.ranges = function(x) {

    if (!arguments.length) return ranges;

    ranges = x;

    return bullet;

  };

  // markers (previous, goal)

  bullet.markers = function(x) {

    if (!arguments.length) return markers;

    markers = x;

    return bullet;

  };

  // measures (actual, forecast)

  bullet.measures = function(x) {

    if (!arguments.length) return measures;

    measures = x;

    return bullet;

  };

  bullet.width = function(x) {

    if (!arguments.length) return width;

    width = x;

    return bullet;

  };

  bullet.height = function(x) {

    if (!arguments.length) return height;

    height = x;

    return bullet;

  };

  bullet.tickFormat = function(x) {

    if (!arguments.length) return tickFormat;

    tickFormat = x;

    return bullet;

  };

  bullet.duration = function(x) {

    if (!arguments.length) return duration;

    duration = x;

    return bullet;

  };

  return bullet;

};

function d3_chart_bulletRanges(d) {

  return d.ranges;

}

function d3_chart_bulletMarkers(d) {

  return d.markers;

}

function d3_chart_bulletMeasures(d) {

  return d.measures;

}

function d3_chart_bulletTranslate(x) {

  return function(d) {

    return "translate(" + x(d) + ",0)";

  };

}

function d3_chart_bulletWidth(x) {

  var x0 = x(0);

  return function(d) {

    return Math.abs(x(d) - x0);

  };

}