<!-- Author: Bo Ericsson, bo@boe.net -->
<!-- Inspiration from numerous examples by Mike Bostock, http://bl.ocks.org/mbostock, -->
<!-- and example by Andy Aiken, http://blog.scottlogic.com/2014/09/19/interactive.html -->
'use strict';

function realTimeChartMulti() {

  var version = "0.1.0",
      datum, data,
      maxSeconds = 300, pixelsPerSecond = 10,
      svgWidth = 700, svgHeight = 300,
      margin = { top: 20, bottom: 20, left: 100, right: 30, topNav: 10, bottomNav: 20 },
      dimension = { chartTitle: 20, xAxis: 20, yAxis: 20, xTitle: 20, yTitle: 20, navChart: 70 },
      maxY = 100, minY = 0,
      chartTitle, yTitle, xTitle,
      drawXAxis = true, drawYAxis = true, drawNavChart = true,
      border,
      selection,
      barId = 0,
      yDomain = [],
      debug = false,
      barWidth = 5,
      halted = false,
      x, y,
      xNav, yNav,
      width, height,
      widthNav, heightNav,
      xAxisG, yAxisG,
      xAxis, yAxis,
      svg;

  // create the chart
  var chart = function(s) {
    selection = s;
    if (selection == undefined) {
      console.error("selection is undefined");
      return;
    };

    // process titles
    chartTitle = chartTitle || "";
    xTitle = xTitle || "";
    yTitle = yTitle || "";

    // compute component dimensions
    var chartTitleDim = chartTitle == "" ? 0 : dimension.chartTitle,
        xTitleDim = xTitle == "" ? 0 : dimension.xTitle,
        yTitleDim = yTitle == "" ? 0 : dimension.yTitle,
        xAxisDim = !drawXAxis ? 0 : dimension.xAxis,
        yAxisDim = !drawYAxis ? 0 : dimension.yAxis,
        navChartDim = !drawNavChart ? 0 : dimension.navChart;

    // compute dimension of main and nav charts, and offsets
    var marginTop = margin.top + chartTitleDim;
    height = svgHeight - marginTop - margin.bottom - chartTitleDim - xTitleDim - xAxisDim - navChartDim + 30;
    heightNav = navChartDim - margin.topNav - margin.bottomNav;
    var marginTopNav = svgHeight - margin.bottom - heightNav - margin.topNav;
    width = svgWidth - margin.left - margin.right;
    widthNav = width;

    // append the svg
    svg = selection.append("svg")
        .attr("width", svgWidth)
        .attr("height", svgHeight)
        .style("border", function(d) { 
          if (border) return "1px solid lightgray"; 
          else return null;
        });

    // create main group and translate
    var main = svg.append("g")
        .attr("transform", "translate (" + margin.left + "," + marginTop + ")");

    // define clip-path
    main.append("defs").append("clipPath")
        .attr("id", "myClip")
      .append("rect")
        .attr("x", 0)
        .attr("y", 0)
        .attr("width", width)
        .attr("height", height);

    // create chart background
    main.append("rect")
        .attr("x", 0)
        .attr("y", 0)
        .attr("width", width)
        .attr("height", height)
        .style("fill", "#f5f5f5");

    // note that two groups are created here, the latter assigned to barG;
    // the former will contain a clip path to constrain objects to the chart area; 
    // no equivalent clip path is created for the nav chart as the data itself
    // is clipped to the full time domain
    var barG = main.append("g")
        .attr("class", "barGroup")
        .attr("transform", "translate(0, 0)")
        .attr("clip-path", "url(#myClip")
      .append("g");

    // add group for x axis
    xAxisG = main.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + height + ")");

    // add group for y axis
    yAxisG = main.append("g")
        .attr("class", "y axis");

    // in x axis group, add x axis title
    xAxisG.append("text")
        .attr("class", "title")
        .attr("x", width / 2)
        .attr("y", 25)
        .attr("dy", ".71em")
        .text(function(d) { 
          var text = xTitle == undefined ? "" : xTitle;
          return text; 
        });

    // in y axis group, add y axis title
    yAxisG.append("text")
        .attr("class", "title")
        .attr("transform", "rotate(-90)")
        .attr("x", - height / 2)
        .attr("y", -margin.left + 15) //-35
        .attr("dy", ".71em")
        .text(function(d) { 
          var text = yTitle == undefined ? "" : yTitle;
          return text; 
        });

    // in main group, add chart title
    main.append("text")
        .attr("class", "chartTitle")
        .attr("x", width / 2)
        .attr("y", -20)
        .attr("dy", ".71em")
        .text(function(d) { 
          var text = chartTitle == undefined ? "" : chartTitle;
          return text; 
        });

    // define main chart scales
    x = d3.time.scale().range([0, width]);
    y = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([height, 0], 1)

    // define main chart axis
    xAxis = d3.svg.axis().orient("bottom");
    yAxis = d3.svg.axis().orient("left").innerTickSize(-width);

    // add nav chart
    var nav = svg.append("g")
        .attr("transform", "translate (" + margin.left + "," + marginTopNav + ")");

    // add nav background
    nav.append("rect")
        .attr("x", 0)
        .attr("y", 0)
        .attr("width", width)
        .attr("height", heightNav)
        .style("fill", "#F5F5F5")
        .style("shape-rendering", "crispEdges")
        .attr("transform", "translate(0, 0)");

    // add group to data items
    var navG = nav.append("g")
        .attr("class", "nav");

    // add group to hold nav x axis
    // please note that a clip path has yet to be added here (tbd)
    var xAxisGNav = nav.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + heightNav + ")");

    // define nav chart scales
    xNav = d3.time.scale().range([0, widthNav]);
    yNav = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([heightNav, 0], 1)

    // define nav axis
    var xAxisNav = d3.svg.axis().orient("bottom");

    // compute initial time domains...
    var ts = new Date().getTime();

    // first, the full time domain
    var endTime = new Date(ts);
    var startTime = new Date(endTime.getTime() - maxSeconds * 1000);
    var interval = endTime.getTime() - startTime.getTime();

    // then the viewport time domain (what's visible in the main chart and the viewport in the nav chart)
    var endTimeViewport = new Date(ts);
    var startTimeViewport = new Date(endTime.getTime() - width / pixelsPerSecond * 1000);
    var intervalViewport = endTimeViewport.getTime() - startTimeViewport.getTime();
    var offsetViewport = startTimeViewport.getTime() - startTime.getTime();

    // set the scale domains for main and nav charts
    x.domain([startTimeViewport, endTimeViewport]);
    xNav.domain([startTime, endTime]); 

    // update axis with modified scale
    xAxis.scale(x)(xAxisG);
    yAxis.scale(y)(yAxisG);
    xAxisNav.scale(xNav)(xAxisGNav);

    // create brush (moveable, changable rectangle that determines the time domain of main chart)
    var viewport = d3.svg.brush()
        .x(xNav)
        .extent([startTimeViewport, endTimeViewport])
        .on("brush", function () {
          // get the current time extent of viewport
          var extent = viewport.extent();
          startTimeViewport = extent[0];
          endTimeViewport = extent[1];

          // compute viewport extent in milliseconds
          intervalViewport = endTimeViewport.getTime() - startTimeViewport.getTime();
          offsetViewport = startTimeViewport.getTime() - startTime.getTime();

          // handle invisible viewport
          if (intervalViewport == 0) {
            intervalViewport = maxSeconds * 1000;
            offsetViewport = 0;
          }

          // update the x domain of the main chart
          x.domain(viewport.empty() ? xNav.domain() : extent);

          // update the x axis of the main chart
          xAxis.scale(x)(xAxisG);

          // update display
          refresh();
        });

    // create group and assign to brush
    var viewportG = nav.append("g")
        .attr("class", "viewport")
        .call(viewport)
        .selectAll("rect")
        .attr("height", heightNav);

    // initial invocation; update display
    data = [];
    refresh();

    // function to refresh the viz upon changes of the time domain 
    // (which happens constantly), or after arrival of new data, or at init
    function refresh() {

      // process data to remove too late data items 
      data = data.filter(function(d) {
        if (d.time.getTime() > startTime.getTime()) return true;
      })

      // determine number of categories
      var categoryCount = yDomain.length;
      if (debug) console.log("yDomain", yDomain)

      // here we bind the new data to the main chart
      // note: no key function is used here; therefore the data binding is
      // by index, which effectivly means that available DOM elements
      // are associated with each item in the available data array, from 
      // first to last index; if the new data array contains fewer elements
      // than the existing DOM elements, the LAST DOM elements are removed;
      // basically, for each step, the data items "walks" leftward (each data 
      // item occupying the next DOM element to the left);
      // This data binding is very different from one that is done with a key 
      // function; in such a case, a data item stays "resident" in the DOM
      // element, and such DOM element (with data) would be moved left, until
      // the x position is to the left of the chart, where the item would be 
      // exited
      var updateSel = barG.selectAll(".bar")
          .data(data);

      // remove items
      updateSel.exit().remove();

      // add items
      updateSel.enter()
          .append(function(d) { 
            if (debug) { console.log("d", JSON.stringify(d)); }
            if (d.type == undefined) console.error(JSON.stringify(d))
            var type = d.type || "circle";
            var node = document.createElementNS("http://www.w3.org/2000/svg", type);
            return node; 
          })
          .attr("class", "bar")
          .attr("id", function() { 
            return "bar-" + barId++; 
          });

      // update items; added items are now part of the update selection
      updateSel
          .attr("x", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "rect":
                var size = d.size || 6;
                retVal = Math.round(x(d.time) - size / 2);
                break;
              default:
            }
            return retVal; 
          })
          .attr("y", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "rect":
                var size = d.size || 6;
                retVal = y(d.category) - size / 2;
                break;
              default:
            }
            return retVal; 
          })
          .attr("cx", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "circle":
                retVal = Math.round(x(d.time));
                break;
              default:
            }
            return retVal; 
          })
          .attr("cy", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "circle":
                retVal = y(d.category);
                break;
              default:
            }
            return retVal; 
          })
          .attr("r", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "circle":
                retVal = d.size / 2;
                break;
              default:
            }
            return retVal; 
          })
          .attr("width", function(d) {
            var retVal = null;
            switch (getTagName(this)) {
              case "rect":
                retVal = d.size;
                break;
              default:
            }
            return retVal; 
          })
          .attr("height", function(d) { 
            var retVal = null;
            switch (getTagName(this)) {
              case "rect":
                retVal = d.size; 
                break;
              default:
            }
            return retVal; 
          })
          .style("fill", function(d) { return d.color || "black"; })
          //.style("stroke", "orange")
          //.style("stroke-width", "1px")
          //.style("stroke-opacity", 0.8)
          .style("fill-opacity", function(d) { return d.opacity || 1; });

      // create update selection for the nav chart, by applying data
      var updateSelNav = navG.selectAll("circle")
          .data(data);

      // remove items
      updateSelNav.exit().remove();

      // add items
      updateSelNav.enter().append("circle")
          .attr("r", 1)
          .attr("fill", "black")

      // added items now part of update selection; set coordinates of points
      updateSelNav
          .attr("cx", function(d) {
            return Math.round(xNav(d.time));
          })
          .attr("cy", function(d) {
            return yNav(d.category);
          })
    
    } // end refreshChart function


    function getTagName(that) {
      var tagName = d3.select(that).node().tagName;
      return (tagName);
    }


    // function to keep the chart "moving" through time (right to left) 
    setInterval(function() {

      if (halted) return;

      // get current viewport extent
      var extent = viewport.empty() ? xNav.domain() : viewport.extent();
      var interval = extent[1].getTime() - extent[0].getTime();
      var offset = extent[0].getTime() - xNav.domain()[0].getTime();

      // compute new nav extents
      endTime = new Date();
      startTime = new Date(endTime.getTime() - maxSeconds * 1000);

      // compute new viewport extents 
      startTimeViewport = new Date(startTime.getTime() + offset);
      endTimeViewport = new Date(startTimeViewport.getTime() + interval);
      viewport.extent([startTimeViewport, endTimeViewport])

      // update scales
      x.domain([startTimeViewport, endTimeViewport]);
      xNav.domain([startTime, endTime]);

      // update axis
      xAxis.scale(x)(xAxisG);
      xAxisNav.scale(xNav)(xAxisGNav);

      // refresh svg
      refresh();

    }, 200)

    // end setInterval function

    return chart;

  } // end chart function


  // chart getters/setters

  // new data item (this most recent item will appear 
  // on the right side of the chart, and begin moving left)
  chart.datum = function(_) {
    if (arguments.length == 0) return datum;
    datum = _;
    data.push(datum);
    return chart;
  }

  // svg width
  chart.width = function(_) {
    if (arguments.length == 0) return svgWidth;
    svgWidth = _;
    return chart;
  }

  // svg height
  chart.height = function(_) {
    if (arguments.length == 0) return svgHeight;
    svgHeight = _;
    return chart;
  }

  // svg border
  chart.border = function(_) {
    if (arguments.length == 0) return border;
    border = _;
    return chart;       
  }

  // chart title
  chart.title = function(_) {
    if (arguments.length == 0) return chartTitle;
    chartTitle = _;
    return chart;   
  }

  // x axis title
  chart.xTitle = function(_) {
    if (arguments.length == 0) return xTitle;
    xTitle = _;
    return chart;       
  }

  // y axis title
  chart.yTitle = function(_) {
    if (arguments.length == 0) return yTitle;
    yTitle = _;
    return chart;       
  }

  // yItems (can be dynamically added after chart construction)
  chart.yDomain = function(_) {
    if (arguments.length == 0) return yDomain;
    yDomain = _;
    if (svg) {
      // update the y ordinal scale
      y = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([height, 0], 1);
      // update the y axis
      yAxis.scale(y)(yAxisG);
      // update the y ordinal scale for the nav chart
      yNav = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([heightNav, 0], 1);
    }
    return chart;       
  }

  // debug
  chart.debug = function(_) {
    if (arguments.length == 0) return debug;
    debug = _;
    return chart;       
  }  

  // halt
  chart.halt = function(_) {
    if (arguments.length == 0) return halted;
    halted = _;
    return chart;       
  }

  // version
  chart.version = version;
  
  return chart;

} // end realTimeChart function