src/models/cumulativeLineChart.js

nv.models.cumulativeLineChart = function() {
  "use strict";
  //============================================================
  // Public Variables with Default Settings
  //------------------------------------------------------------

  var lines = nv.models.line()
    , xAxis = nv.models.axis()
    , yAxis = nv.models.axis()
    , legend = nv.models.legend()
    , controls = nv.models.legend()
    , interactiveLayer = nv.interactiveGuideline()
    ;

  var margin = {top: 30, right: 30, bottom: 50, left: 60}
    , color = nv.utils.defaultColor()
    , width = null
    , height = null
    , showLegend = true
    , showXAxis = true
    , showYAxis = true
    , rightAlignYAxis = false
    , tooltips = true
    , showControls = true
    , useInteractiveGuideline = false
    , rescaleY = true
    , tooltip = function(key, x, y, e, graph) {
        return '<h3>' + key + '</h3>' +
               '<p>' +  y + ' at ' + x + '</p>'
      }
    , x //can be accessed via chart.xScale()
    , y //can be accessed via chart.yScale()
    , id = lines.id()
    , state = { index: 0, rescaleY: rescaleY }
    , defaultState = null
    , noData = 'No Data Available.'
    , average = function(d) { return d.average }
    , dispatch = d3.dispatch('tooltipShow', 'tooltipHide', 'stateChange', 'changeState')
    , transitionDuration = 250
    ;

  xAxis
    .orient('bottom')
    .tickPadding(7)
    ;
  yAxis
    .orient((rightAlignYAxis) ? 'right' : 'left')
    ;

  //============================================================
  controls.updateState(false);

  //============================================================
  // Private Variables
  //------------------------------------------------------------

   var dx = d3.scale.linear()
     , index = {i: 0, x: 0}
     ;

  var showTooltip = function(e, offsetElement) {
    var left = e.pos[0] + ( offsetElement.offsetLeft || 0 ),
        top = e.pos[1] + ( offsetElement.offsetTop || 0),
        x = xAxis.tickFormat()(lines.x()(e.point, e.pointIndex)),
        y = yAxis.tickFormat()(lines.y()(e.point, e.pointIndex)),
        content = tooltip(e.series.key, x, y, e, chart);

    nv.tooltip.show([left, top], content, null, null, offsetElement);
  };

  //============================================================

  function chart(selection) {
    selection.each(function(data) {
      var container = d3.select(this).classed('nv-chart-' + id, true),
          that = this;

      var availableWidth = (width  || parseInt(container.style('width')) || 960)
                             - margin.left - margin.right,
          availableHeight = (height || parseInt(container.style('height')) || 400)
                             - margin.top - margin.bottom;


      chart.update = function() { container.transition().duration(transitionDuration).call(chart) };
      chart.container = this;

      //set state.disabled
      state.disabled = data.map(function(d) { return !!d.disabled });

      if (!defaultState) {
        var key;
        defaultState = {};
        for (key in state) {
          if (state[key] instanceof Array)
            defaultState[key] = state[key].slice(0);
          else
            defaultState[key] = state[key];
        }
      }

      var indexDrag = d3.behavior.drag()
                        .on('dragstart', dragStart)
                        .on('drag', dragMove)
                        .on('dragend', dragEnd);


      function dragStart(d,i) {
        d3.select(chart.container)
            .style('cursor', 'ew-resize');
      }

      function dragMove(d,i) {
        index.x = d3.event.x;
        index.i = Math.round(dx.invert(index.x));
        updateZero();
      }

      function dragEnd(d,i) {
        d3.select(chart.container)
            .style('cursor', 'auto');

        // update state and send stateChange with new index
        state.index = index.i;
        dispatch.stateChange(state);
      }

      //------------------------------------------------------------
      // Display No Data message if there's nothing to show.

      if (!data || !data.length || !data.filter(function(d) { return d.values.length }).length) {
        var noDataText = container.selectAll('.nv-noData').data([noData]);

        noDataText.enter().append('text')
          .attr('class', 'nvd3 nv-noData')
          .attr('dy', '-.7em')
          .style('text-anchor', 'middle');

        noDataText
          .attr('x', margin.left + availableWidth / 2)
          .attr('y', margin.top + availableHeight / 2)
          .text(function(d) { return d });

        return chart;
      } else {
        container.selectAll('.nv-noData').remove();
      }

      //------------------------------------------------------------


      //------------------------------------------------------------
      // Setup Scales

      x = lines.xScale();
      y = lines.yScale();


      if (!rescaleY) {
        var seriesDomains = data
          .filter(function(series) { return !series.disabled })
          .map(function(series,i) {
            var initialDomain = d3.extent(series.values, lines.y());

            //account for series being disabled when losing 95% or more
            if (initialDomain[0] < -.95) initialDomain[0] = -.95;

            return [
              (initialDomain[0] - initialDomain[1]) / (1 + initialDomain[1]),
              (initialDomain[1] - initialDomain[0]) / (1 + initialDomain[0])
            ];
          });

        var completeDomain = [
          d3.min(seriesDomains, function(d) { return d[0] }),
          d3.max(seriesDomains, function(d) { return d[1] })
        ]

        lines.yDomain(completeDomain);
      } else {
        lines.yDomain(null);
      }


      dx  .domain([0, data[0].values.length - 1]) //Assumes all series have same length
          .range([0, availableWidth])
          .clamp(true);

      //------------------------------------------------------------


      var data = indexify(index.i, data);


      //------------------------------------------------------------
      // Setup containers and skeleton of chart
      var interactivePointerEvents = (useInteractiveGuideline) ? "none" : "all";
      var wrap = container.selectAll('g.nv-wrap.nv-cumulativeLine').data([data]);
      var gEnter = wrap.enter().append('g').attr('class', 'nvd3 nv-wrap nv-cumulativeLine').append('g');
      var g = wrap.select('g');

      gEnter.append('g').attr('class', 'nv-interactive');
      gEnter.append('g').attr('class', 'nv-x nv-axis').style("pointer-events","none");
      gEnter.append('g').attr('class', 'nv-y nv-axis');
      gEnter.append('g').attr('class', 'nv-background');
      gEnter.append('g').attr('class', 'nv-linesWrap').style("pointer-events",interactivePointerEvents);
      gEnter.append('g').attr('class', 'nv-avgLinesWrap').style("pointer-events","none");
      gEnter.append('g').attr('class', 'nv-legendWrap');
      gEnter.append('g').attr('class', 'nv-controlsWrap');
      

      //------------------------------------------------------------
      // Legend

      if (showLegend) {
        legend.width(availableWidth);

        g.select('.nv-legendWrap')
            .datum(data)
            .call(legend);

        if ( margin.top != legend.height()) {
          margin.top = legend.height();
          availableHeight = (height || parseInt(container.style('height')) || 400)
                             - margin.top - margin.bottom;
        }

        g.select('.nv-legendWrap')
            .attr('transform', 'translate(0,' + (-margin.top) +')')
      }

      //------------------------------------------------------------


      //------------------------------------------------------------
      // Controls

      if (showControls) {
        var controlsData = [
          { key: 'Re-scale y-axis', disabled: !rescaleY }
        ];

        controls.width(140).color(['#444', '#444', '#444']);
        g.select('.nv-controlsWrap')
            .datum(controlsData)
            .attr('transform', 'translate(0,' + (-margin.top) +')')
            .call(controls);
      }

      //------------------------------------------------------------


      wrap.attr('transform', 'translate(' + margin.left + ',' + margin.top + ')');

      if (rightAlignYAxis) {
          g.select(".nv-y.nv-axis")
              .attr("transform", "translate(" + availableWidth + ",0)");
      }

      // Show error if series goes below 100%
      var tempDisabled = data.filter(function(d) { return d.tempDisabled });

      wrap.select('.tempDisabled').remove(); //clean-up and prevent duplicates
      if (tempDisabled.length) {
        wrap.append('text').attr('class', 'tempDisabled')
            .attr('x', availableWidth / 2)
            .attr('y', '-.71em')
            .style('text-anchor', 'end')
            .text(tempDisabled.map(function(d) { return d.key }).join(', ') + ' values cannot be calculated for this time period.');
      }

      //------------------------------------------------------------
      // Main Chart Component(s)
      
      //------------------------------------------------------------
      //Set up interactive layer
      if (useInteractiveGuideline) {
        interactiveLayer
          .width(availableWidth)
          .height(availableHeight)
          .margin({left:margin.left,top:margin.top})
          .svgContainer(container)
          .xScale(x);
        wrap.select(".nv-interactive").call(interactiveLayer);
      }

      gEnter.select('.nv-background')
        .append('rect');

      g.select('.nv-background rect')
          .attr('width', availableWidth)
          .attr('height', availableHeight);

      lines
        //.x(function(d) { return d.x })
        .y(function(d) { return d.display.y })
        .width(availableWidth)
        .height(availableHeight)
        .color(data.map(function(d,i) {
          return d.color || color(d, i);
        }).filter(function(d,i) { return !data[i].disabled && !data[i].tempDisabled; }));



      var linesWrap = g.select('.nv-linesWrap')
          .datum(data.filter(function(d) { return  !d.disabled && !d.tempDisabled }));

      //d3.transition(linesWrap).call(lines);
      linesWrap.call(lines);

      /*Handle average lines [AN-612] ----------------------------*/

      //Store a series index number in the data array.
      data.forEach(function(d,i) {
            d.seriesIndex = i;
      });

      var avgLineData = data.filter(function(d) {
          return !d.disabled && !!average(d);
      });

      var avgLines = g.select(".nv-avgLinesWrap").selectAll("line")
              .data(avgLineData, function(d) { return d.key; });

      var getAvgLineY = function(d) {
          //If average lines go off the svg element, clamp them to the svg bounds.
          var yVal = y(average(d));
          if (yVal < 0) return 0;
          if (yVal > availableHeight) return availableHeight;
          return yVal;
      };

      avgLines.enter()
              .append('line')
              .style('stroke-width',2)
              .style('stroke-dasharray','10,10')
              .style('stroke',function (d,i) {
                  return lines.color()(d,d.seriesIndex);
              })
              .attr('x1',0)
              .attr('x2',availableWidth)
              .attr('y1', getAvgLineY)
              .attr('y2', getAvgLineY);

      avgLines
              .style('stroke-opacity',function(d){
                  //If average lines go offscreen, make them transparent
                  var yVal = y(average(d));
                  if (yVal < 0 || yVal > availableHeight) return 0;
                  return 1;
              })
              .attr('x1',0)
              .attr('x2',availableWidth)
              .attr('y1', getAvgLineY)
              .attr('y2', getAvgLineY);

      avgLines.exit().remove();

      //Create index line -----------------------------------------

      var indexLine = linesWrap.selectAll('.nv-indexLine')
          .data([index]);
      indexLine.enter().append('rect').attr('class', 'nv-indexLine')
          .attr('width', 3)
          .attr('x', -2)
          .attr('fill', 'red')
          .attr('fill-opacity', .5)
          .style("pointer-events","all")
          .call(indexDrag)

      indexLine
          .attr('transform', function(d) { return 'translate(' + dx(d.i) + ',0)' })
          .attr('height', availableHeight)

      //------------------------------------------------------------


      //------------------------------------------------------------
      // Setup Axes

      if (showXAxis) {
        xAxis
          .scale(x)
          //Suggest how many ticks based on the chart width and D3 should listen (70 is the optimal number for MM/DD/YY dates)
          .ticks( Math.min(data[0].values.length,availableWidth/70) )
          .tickSize(-availableHeight, 0);

        g.select('.nv-x.nv-axis')
            .attr('transform', 'translate(0,' + y.range()[0] + ')');
        d3.transition(g.select('.nv-x.nv-axis'))
            .call(xAxis);
      }


      if (showYAxis) {
        yAxis
          .scale(y)
          .ticks( availableHeight / 36 )
          .tickSize( -availableWidth, 0);

        d3.transition(g.select('.nv-y.nv-axis'))
            .call(yAxis);
      }
      //------------------------------------------------------------


      //============================================================
      // Event Handling/Dispatching (in chart's scope)
      //------------------------------------------------------------


      function updateZero() {
        indexLine
          .data([index]);
        
        //When dragging the index line, turn off line transitions.
        // Then turn them back on when done dragging.
        var oldDuration = chart.transitionDuration();
        chart.transitionDuration(0);
        chart.update();
        chart.transitionDuration(oldDuration);
      }

      g.select('.nv-background rect')
          .on('click', function() {
            index.x = d3.mouse(this)[0];
            index.i = Math.round(dx.invert(index.x));

            // update state and send stateChange with new index
            state.index = index.i;
            dispatch.stateChange(state);

            updateZero();
          });

      lines.dispatch.on('elementClick', function(e) {
        index.i = e.pointIndex;
        index.x = dx(index.i);

        // update state and send stateChange with new index
        state.index = index.i;
        dispatch.stateChange(state);

        updateZero();
      });

      controls.dispatch.on('legendClick', function(d,i) { 
        d.disabled = !d.disabled;
        rescaleY = !d.disabled;

        state.rescaleY = rescaleY;
        dispatch.stateChange(state);
        chart.update();
      });


      legend.dispatch.on('stateChange', function(newState) {
        state.disabled = newState.disabled; 
        dispatch.stateChange(state);
        chart.update();
      });

      interactiveLayer.dispatch.on('elementMousemove', function(e) {
          lines.clearHighlights();
          var singlePoint, pointIndex, pointXLocation, allData = [];
          
          
          data
          .filter(function(series, i) { 
            series.seriesIndex = i;
            return !series.disabled; 
          })
          .forEach(function(series,i) {
              pointIndex = nv.interactiveBisect(series.values, e.pointXValue, chart.x());
              lines.highlightPoint(i, pointIndex, true);
              var point = series.values[pointIndex];
              if (typeof point === 'undefined') return;
              if (typeof singlePoint === 'undefined') singlePoint = point;
              if (typeof pointXLocation === 'undefined') pointXLocation = chart.xScale()(chart.x()(point,pointIndex));
              allData.push({
                  key: series.key,
                  value: chart.y()(point, pointIndex),
                  color: color(series,series.seriesIndex)
              });
          });

          //Highlight the tooltip entry based on which point the mouse is closest to.
          if (allData.length > 2) {
            var yValue = chart.yScale().invert(e.mouseY);
            var domainExtent = Math.abs(chart.yScale().domain()[0] - chart.yScale().domain()[1]);
            var threshold = 0.03 * domainExtent;
            var indexToHighlight = nv.nearestValueIndex(allData.map(function(d){return d.value}),yValue,threshold);
            if (indexToHighlight !== null)
              allData[indexToHighlight].highlight = true;
          }

          var xValue = xAxis.tickFormat()(chart.x()(singlePoint,pointIndex), pointIndex);
          interactiveLayer.tooltip
                  .position({left: pointXLocation + margin.left, top: e.mouseY + margin.top})
                  .chartContainer(that.parentNode)
                  .enabled(tooltips)
                  .valueFormatter(function(d,i) {
                     return yAxis.tickFormat()(d);
                  })
                  .data(
                      {
                        value: xValue,
                        series: allData
                      }
                  )();

          interactiveLayer.renderGuideLine(pointXLocation);

      });

      interactiveLayer.dispatch.on("elementMouseout",function(e) {
          dispatch.tooltipHide();
          lines.clearHighlights();
      });

      dispatch.on('tooltipShow', function(e) {
        if (tooltips) showTooltip(e, that.parentNode);
      });


      // Update chart from a state object passed to event handler
      dispatch.on('changeState', function(e) {

        if (typeof e.disabled !== 'undefined') {
          data.forEach(function(series,i) {
            series.disabled = e.disabled[i];
          });

          state.disabled = e.disabled;
        }


        if (typeof e.index !== 'undefined') {
          index.i = e.index;
          index.x = dx(index.i);

          state.index = e.index;

          indexLine
            .data([index]);
        }


        if (typeof e.rescaleY !== 'undefined') {
          rescaleY = e.rescaleY;
        }

        chart.update();
      });

      //============================================================

    });

    return chart;
  }


  //============================================================
  // Event Handling/Dispatching (out of chart's scope)
  //------------------------------------------------------------

  lines.dispatch.on('elementMouseover.tooltip', function(e) {
    e.pos = [e.pos[0] +  margin.left, e.pos[1] + margin.top];
    dispatch.tooltipShow(e);
  });

  lines.dispatch.on('elementMouseout.tooltip', function(e) {
    dispatch.tooltipHide(e);
  });

  dispatch.on('tooltipHide', function() {
    if (tooltips) nv.tooltip.cleanup();
  });

  //============================================================


  //============================================================
  // Expose Public Variables
  //------------------------------------------------------------

  // expose chart's sub-components
  chart.dispatch = dispatch;
  chart.lines = lines;
  chart.legend = legend;
  chart.xAxis = xAxis;
  chart.yAxis = yAxis;
  chart.interactiveLayer = interactiveLayer;

  d3.rebind(chart, lines, 'defined', 'isArea', 'x', 'y', 'xScale','yScale', 'size', 'xDomain', 'yDomain', 'xRange', 'yRange', 'forceX', 'forceY', 'interactive', 'clipEdge', 'clipVoronoi','useVoronoi',  'id');

  chart.options = nv.utils.optionsFunc.bind(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 = _;
    return chart;
  };

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

  chart.color = function(_) {
    if (!arguments.length) return color;
    color = nv.utils.getColor(_);
    legend.color(color);
    return chart;
  };

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

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

  chart.useInteractiveGuideline = function(_) {
    if(!arguments.length) return useInteractiveGuideline;
    useInteractiveGuideline = _;
    if (_ === true) {
       chart.interactive(false);
       chart.useVoronoi(false);
    }
    return chart;
  };

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

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

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

  chart.rightAlignYAxis = function(_) {
    if(!arguments.length) return rightAlignYAxis;
    rightAlignYAxis = _;
    yAxis.orient( (_) ? 'right' : 'left');
    return chart;
  };

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

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

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

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

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

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

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

  //============================================================


  //============================================================
  // Functions
  //------------------------------------------------------------

  /* Normalize the data according to an index point. */
  function indexify(idx, data) {
    return data.map(function(line, i) {
      if (!line.values) {
         return line;
      }
      var v = lines.y()(line.values[idx], idx);

      //TODO: implement check below, and disable series if series loses 100% or more cause divide by 0 issue
      if (v < -.95) {
        //if a series loses more than 100%, calculations fail.. anything close can cause major distortion (but is mathematically correct till it hits 100)
        line.tempDisabled = true;
        return line;
      }

      line.tempDisabled = false;

      line.values = line.values.map(function(point, pointIndex) {
        point.display = {'y': (lines.y()(point, pointIndex) - v) / (1 + v) };
        return point;
      })

      return line;
    })
  }

  //============================================================


  return chart;
}