// Plot US GDP Scatterplot over time
var margin = {top: 20, right: 20, bottom: 30, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

/* 
 * value accessor - returns the value to encode for a given data object.
 * scale - maps value to a visual display encoding, such as a pixel position.
 * map function - maps from data value to display value
 * axis - sets up axis
 */ 

// setup x 
var xValue3 = function(d) { return d.Year;}, // data -> value
    xScale3 = d3.scale.linear().range([0, width]), // value -> display
    xMap3 = function(d) { return xScale3(xValue3(d));}, // data -> display
    xAxis3 = d3.svg.axis().scale(xScale3).orient("bottom").tickFormat(d3.format(""));

// setup y
var yValue3 = function(d) { return d.GDP;}, // data -> value
    yScale3 = d3.scale.linear().range([height, 0]), // value -> display
    yMap3 = function(d) { return yScale3(yValue3(d));}, // data -> display
    yAxis3 = d3.svg.axis().scale(yScale3).orient("left");

// setup fill color
var cValue3 = function(d) { if ( d.Country == "UnitedStates") { return "#35586C";}
                          else { return "#8E2323";}
                        };


// add the graph canvas to the body of the webpage
var svg3 = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

// add the tooltip area to the webpage
var tooltip = d3.select("body").append("div")
    .attr("class", "tooltip")
    .style("opacity", 0);

// load data
d3.csv("RawCountryData.csv", function(error, data) {
   // change string (from CSV) into number format

  data.forEach(function(d) {
    d.Year = +d.Year;
    d.GDP = +d.GDP;
//    console.log(d);
  });

  // don't want dots overlapping axis, so add in buffer to data domain
  xScale3.domain([d3.min(data, xValue3)-1, d3.max(data, xValue3)+1]);
  yScale3.domain([d3.min(data, yValue3)-1, d3.max(data, yValue3)+1]);

  // x-axis
  svg3.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis3)
    .append("text")
      .attr("class", "label")
      .attr("x", width)
      .attr("y", -6)
      .style("text-anchor", "end")
      .text("Year");

  // y-axis
  svg3.append("g")
      .attr("class", "y axis")
      .call(yAxis3)
    .append("text")
      .attr("class", "label")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("GDP");

//Add Title
svg3.append("text")
        .attr("x", (width / 2))             
        .attr("y", 0 - (margin.top / 6))
        .attr("text-anchor", "middle")  
        .style("font-size", "16px") 
        .style("text-decoration", "underline")  
        .text("USA and UK GDP");

  // draw dots
  svg3.selectAll(".dot")
      .data(data)
    .enter().append("circle")
      .filter(function(d) {return (d.Country == "UnitedStates" || d.Country == "UK")})
      .attr("class", "dot")
      .attr("r", 5)
      .attr("cx", xMap3)
      .attr("cy", yMap3)
      .style("fill", cValue3) 
      .on("mouseover", function(d) {
          tooltip.transition()
               .duration(200)
               .style("opacity", .9);
          tooltip.html(d["Country"] + "<br/> (" + xValue3(d) 
          + ", " + yValue3(d) + ")")
               .style("left", (d3.event.pageX + 5) + "px")
               .style("top", (d3.event.pageY - 12) + "px");
      })
      .on("mouseout", function(d) {
          tooltip.transition()
               .duration(500)
               .style("opacity", 0);
      });


  var countries = ["UnitedStates","UK"]

  // draw legend
  var legend = svg3.selectAll(".legend")
      .data(countries)
    .enter().append("g")
      .attr("class", "legend")
      .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });

  // draw legend colored rectangles
  legend.append("rect")
      .attr("x", width - 18)
      .attr("y",  40)
      .attr("width", 18)
      .attr("height", 18)
      .style("fill", function(d) { if ( d == "UnitedStates") { return "#35586C";}
                          else { return "#8E2323";}
                        });

  // draw legend text
  legend.append("text")
      .attr("x", width - 24)
      .attr("y",  49)
      .attr("dy", ".35em")
      .style("text-anchor", "end")
      .text(function(d) { return d;})
});